JP4791168B2 - Positioning robot - Google Patents

Description

  The present invention relates to a positioning robot that grips a workpiece in cooperation with each other by a plurality of articulated arms and positions the cooperatively gripped workpiece at a target position.

  As a prior art, there is a jig robot that positions a gripped work at a predetermined position. The jig robot disclosed in Patent Document 1 is realized by a 4-axis horizontal articulated robot. The jig robot disclosed in Patent Document 2 is realized including three telescopic actuators and a three-axis rotation unit. In the technologies disclosed in Patent Documents 1 and 2, it is disclosed that when a workpiece is gripped and aligned, the workpiece is shared and gripped by a plurality of jig robots and the workpiece is positioned at a target position. Yes.

JP-A-8-147014 (48th paragraph, FIG. 5) JP 11-77446 A (15th paragraph, FIG. 1)

  In order to move a workpiece and position it at a predetermined position while a plurality of robots are holding the workpieces together, it is necessary to coordinately control each robot. For example, when a single work is gripped and positioned by three six-axis multi-joint robots, six degrees of freedom are controlled with a total of 18 axes. In this case, if an error occurs in the workpiece gripping position, a servo delay occurs in the motor of one of the robots, or a mechanical shift occurs for each robot, each hand unit As a result, a relative shift occurs, and an excessive force is generated on the workpiece and the robot, which may damage the workpiece and the robot.

  Accordingly, an object of the present invention is to provide a positioning robot capable of aligning a work in cooperation while preventing damage to the work and the robot.

The present invention is a positioning robot capable of positioning a workpiece to be cooperatively held by a plurality of articulated arms at a target position,
(A) a plurality of articulated arms,
(A1) a plurality of arm bodies arranged in series,
(A2) a plurality of joint portions that connect two adjacent arm bodies so as to be capable of relative displacement, and a plurality of joint portions including a drive joint portion that can drive relative displacement between the two arm bodies ;
(A3) a hand unit that is connected to an arm body at one end in the series direction and grips a workpiece;
(A4) a plurality of articulated arms each having a base portion connected to the arm body at the other end in the series direction and fixed at a fixed position;
(B) the respectively provided on each drive dynamic joints, and a plurality of driving means for relative displacement drive two arms body driving joint portion is connected,
(C) A relative displacement position of each arm body to be moved to a target position for a work that is cooperatively gripped by a plurality of multi-joint arms is calculated, and each drive unit is set so that each arm body is relatively displaced according to the calculation result. and a control means for controlling each viewing including,
At least one of each multi-joint arm has the drive joint part and the non-drive joint part that the two arm bodies to be connected are passively relatively displaced but cannot be actively displaced relatively Driving articulated arm,
Among each joint part, each driving joint part fixes each relative displacement of the two arm bodies to be connected to each other so that each multi-joint arm is supported by each other through a work to be held in cooperation. It is a positioning robot characterized by being selected as a joint portion in which deformation of the arm is prevented .

In addition, the present invention further includes (d) a displacement preventing means that can be switched between a fastening state that prevents the relative displacement of the two arm bodies to which each joint portion is connected and an open state that allows the relative displacement,
The control means controls the displacement prevention means.

The present invention, the single driving articulated arm,
Displacement preventing means switchable between a fastening state that prevents relative displacement of the two arm bodies connected to the non-drive joint portion and an open state that allows relative displacement;
Detecting means for detecting a relative displacement position of the two arm bodies to which the non-driving joint portion is connected;
The control means switches the state of the corresponding displacement prevention means based on the detection result of the detection means.

  Further, according to the present invention, each joint portion is inclined with respect to the coaxial joint portion that connects the two arm bodies to be connected to each other so as to be rotatable about the rotation axis that is coaxial with the axis of one arm body and the axis of each arm body. It is realized by any one of the inclined joint portions that are rotatably connected around the rotation axis.

  Further, the present invention is characterized in that each multi-joint arm has six degrees of freedom and six or more drive joints are provided.

  According to the first aspect of the present invention, among all the joint parts, the drive means are provided in the drive joint parts excluding the non-drive joint parts. The drive joint portion is provided with a drive means and can be driven to relatively displace two arm bodies connected to each other. Further, the non-driving joint allows the relative displacement of the two arm bodies to be connected. Each drive means drives the corresponding arm body relative to each other in response to a movement control command given from the control means. In this case, each of the driving means is moved to the relative displacement position of the arm body that would be located when the work is located at the target position.

  In the present invention, the two arm bodies connected by the non-driving joint portion follow the arm body driven to be displaced by the driving means by connecting the non-driving joint portion in a state in which the displacement of the two arm bodies is allowed. Relative displacement. In this way, the relative displacement of the arm bodies connected by the drive joint and non-drive joints ensures that there are no errors such as misalignment of the gripping position of the hand part, arm mechanical error, and servo delay. In a typical state, the work to be gripped cooperatively can be positioned at the target position.

  Also, in a realistic state where various errors exist in moving the workpiece, when each driving means displaces the arm body in response to the movement control command given from the control means, the arm body that is relatively displaced is the ideal Compared to a typical state, the position is shifted due to various errors. Even if the two arm bodies are deviated compared to the ideal state, the two arm bodies connected to the non-drive joint part are allowed to be relatively displaced, so the two arm bodies are connected in a deviated state. can do.

  As described above, according to the present invention, by providing the non-drive joint portion, even if the two arm bodies are displaced from the ideal state, the two arm bodies are relatively moved so as to follow the displaced state. It can be displaced and connected. As a result, even if various errors occur during the movement of the workpiece, it is possible to prevent the arm bodies from being forcibly connected in a shifted state, and to reduce the deformation force generated in each arm body.

Therefore, when the workpiece is moved, the deformation force generated in the workpiece and the arm body due to the error can be released at the non-drive joint portion, and the workpiece and the positioning robot can be prevented from being damaged. Further, the non-driving joint portion can be made unnecessary for the driving means, and the structure of the positioning robot can be simplified and the manufacturing cost can be reduced as compared with the case where the driving means is provided for all the joint portions. Can be reduced. In addition, the non-drive joint portion may be included in each multi-joint arm, or any one multi-joint arm.
Further, by cooperatively gripping the workpiece with a plurality of multi-joint arms, the multi-joint arms are supported by each other via the cooperatively-holding workpiece and deformation of each multi-joint arm is prevented. In other words, each multi-joint arm that cooperatively grips the workpiece can be brought into an independent state. As a result, according to the present invention, even when one or more non-drive joint portions exist in each multi-joint arm, the deformation of each multi-joint arm is prevented, and the workpiece can be maintained by maintaining an independent state. It can be gripped stably.

  According to the second aspect of the present invention, the control means gives the movement control command to the driving means in a state where the opening command is given to the displacement preventing means and the displacement preventing means is switched to the opened state. Thus, as described above, the deformation force generated in the workpiece and the arm body during the movement of the workpiece can be released by the non-drive joint portion, and damage to the workpiece or the like can be prevented. Further, after the movement of the workpiece, the control means gives a fastening command to the displacement prevention means, and switches the displacement prevention means to the fastening state. As a result, the relative displacement of the two arm bodies connected to the non-drive joint can be prevented, and the lack of rigidity of the positioning robot due to the use of the non-drive joint can be compensated.

  As described above, according to the present invention, it is possible to increase the rigidity of the positioning robot in the cooperative gripping state after moving the workpiece while preventing the workpiece from being damaged, and to support the workpiece more reliably and stably. it can. For example, when a workpiece such as welding is applied to a supported workpiece after the workpiece is moved by another robot, the workpiece can be prevented from being displaced during the machining, and a suitable machining can be performed.

  According to the third aspect of the present invention, at least one of the multi-joint arms has a drive joint portion and a non-drive joint portion, and each non-drive joint portion includes a displacement prevention means and a detection means, respectively. Is a single drive articulated arm. In the single drive multi-joint arm, the hand unit can be positioned at an arbitrary position by displacing the arm body connected to the non-drive joint part by the drive means provided in the drive joint part.

  Specifically, the control means controls the displacement prevention means to bring the focused non-driving joint part into an open state and the remaining non-driving joint parts into a fastening state. Next, the arm body connected to the driving joint by the driving means is displaced to change the direction in which an external force such as gravity or inertia is applied, and is connected to the non-driving joint to be noticed by the external force. Relatively displace the arm body. When the detecting means detects that the displacement position of the arm body connected to the target non-drive joint portion is a predetermined displacement position, the control means controls the displacement prevention means to determine the target non-drive joint portion. It shall be in a fastening state. In this way, the operation of fixing the arm body connected to the focused non-drive joint portion at a predetermined displacement position is performed for each non-drive joint portion, thereby positioning the hand portion of the multi-joint arm at an arbitrary position. Can do.

  As described above, according to the present invention, even with a multi-joint arm having a non-drive joint portion, the hand portion can be positioned at an arbitrary position, and handling can be facilitated. For example, it is possible to eliminate the trouble of aligning the hand portion of the multi-joint arm to the gripping position by human power or another robot, and preparation for cooperative gripping of the workpiece can be facilitated. Further, even a multi-joint arm having a non-drive joint part can position the hand part independently, so there is no need to provide a drive means for each joint part, the structure can be simplified, and a positioning robot can be manufactured at low cost. Can be realized. Further, in the state where the workpiece is cooperatively gripped by a plurality of multi-joint arms, as described above, the control means gives a movement control command to each driving means, thereby opening the non-driving joint portion. Also, the workpiece can be moved to the target position.

According to this invention of Claim 4 , each joint part is comprised by either an inclination joint part or a coaxial joint part. In this case, in a state where the relative displacements of the arm bodies respectively provided in the respective drive joint portions are fixed, the movable areas of the work allowed in the respective multi-joint arms almost always intersect at one point, and almost all In some cases, each articulated arm that cooperatively grips the workpiece is in a self-supporting state. As a result, it is possible to prevent the workpiece gripped in cooperation from being undesirably displaced and to keep the workpiece position and posture constant.

  As described above, according to the present invention, in most cases in which the workpiece is cooperatively held, the workpiece can be gripped while preventing the displacement, so that the relative displacement of the two arm bodies to which the drive joint portion is connected is fixed. Thus, the deformation of each multi-joint arm can be prevented through the work to be gripped cooperatively.

According to the present invention of claim 5 , each multi-joint arm has 6 degrees of freedom and six or more drive joints are provided, so that the position and posture of the work can be aligned, Positioning to a predetermined target position and target posture can be performed. As described above, according to the present invention, the work gripped by the positioning robot can be positioned at the target position and the target posture, and convenience can be improved.

  FIG. 1 is a block diagram showing a positioning robot 20 according to the first embodiment of the present invention. FIG. 2 is a perspective view showing a state in which the work 40 is gripped cooperatively by the multi-joint arms 30A to 30C. As shown in FIG. 2, the positioning robot 20 grips the workpiece 40 in cooperation with the plurality of multi-joint arms 30 </ b> A to 30 </ b> C, and moves and positions the cooperatively gripped workpiece 40 from the gripping position to the target position. Can do. For example, in a state where the workpiece 40 is positioned at the target position by the positioning robot 20, another processing robot 50 performs processing. As described above, in the present embodiment, the positioning robot 40 is a robot for jig use that cooperatively holds the workpiece 40 at an arbitrary position. The positioning robot 20 includes a plurality of articulated arms 30A to 30C, sub-controllers 31A to 31C provided for each of the plurality of articulated arms 30A to 30C, and a host controller 32.

  In the present embodiment, the positioning robot 20 has three articulated arms 30A to 30C, and each is configured identically. Therefore, one multi-joint arm 30A will be described, and the description of the remaining multi-joint arms 30B and 30C will be omitted. Each articulated arm 30A-30C has six degrees of freedom. The multi-joint arm 30A includes six arm bodies 21 to 26 arranged in series, six joint portions Jt1 to Jt6 that rotatably connect two adjacent arm bodies, a hand portion 27, and a base 28. .

  Each arm body 21-26 comprises the arm structure 29 which is connected, respectively, and extends in series. The hand part 27 is connected to the arm body 26 at one end in the series direction in the arm structure 29 and is formed so as to be able to grip a workpiece 40 that is a gripping object. The hand unit 27 may be configured so as to be integrated with the workpiece 40 in a state where the workpiece 40 is gripped, in other words, to rigidly couple the workpiece 40. For example, the hand unit 27 may be configured to hold the work 40 with the work 40 sandwiched between two holding bodies, or may be configured to suck the work 40 with an adsorbing body.

  Further, the base 28 is connected to the arm body 21 at the other end in the series direction among the arm constituent bodies 29 and is fixed to a predetermined fixing position such as a wall or a floor. The arm body connected by the joint portions Jt1 to Jt6 is relatively displaced, so that the position and posture of the hand portion 27 can be aligned with respect to the base 28.

  Each joint part Jt1-Jt6 is either a coaxial joint part or an inclined joint part. The coaxial joint unit coaxially connects two adjacent objects to be connected, and can rotate one of the objects to be connected with respect to the other object to be connected around the axis of rotation of each of the objects to be connected. Connect to The inclined joint unit connects two adjacent objects to be connected, and connects one object to be conically rotated about a rotation axis inclined with respect to the axis of the other object to be connected. In the present embodiment, the connection object is realized by any of the arm bodies 21 to 26 and the base 28. Moreover, each arm body 21-26 is formed in a substantially cylindrical shape, and the axis line which passes the center of each arm body is set.

  The joint portions Jt1 to Jt6 are arranged in order from the base 28 to the first to sixth joint portions Jt1 to Jt6. The first joint portion Jt1 and the sixth joint portion Jt6 are coaxial joint portions, and the second joint portion Jt2 to the fifth joint portion Jt5 are inclined joint portions. In the present invention, the term “rotation” includes not only the rotation of 360 or more around the rotation axis, but also the case of angular displacement at an angle of 360 degrees or less around the axis.

  The first joint portion Jt1 connects one end portion in the series direction of the base 28 and the other end portion in the series direction of the first arm body 21. The first arm body 21 is rotatable about the first rotation axis A1 coaxial with the axis of the first arm body 21 with respect to the base 28 by the first joint portion Jt1. The second joint portion Jt2 connects the one end portion in the series direction of the first arm body 21 and the other end portion in the series direction of the second arm body 22. The second arm body 22 is rotatable by the second joint portion Jt2 around a second rotation axis A2 that is inclined at a predetermined angle with respect to the axis of the first arm body 21, 45 degrees in the present embodiment.

  The third joint portion Jt3 connects the one end portion in the series direction of the second arm body 22 and the other end portion in the series direction of the third arm body 23. The third arm body 23 is rotatable about the third rotation axis A3 inclined at a predetermined angle with respect to the axis of the second arm body 22, that is, 45 degrees in the present embodiment, by the third joint portion Jt3. The fourth joint portion Jt4 connects one end portion in the series direction of the third arm body 23 and the other end portion in the series direction of the fourth arm body 24. The fourth arm body 24 is rotatable by the fourth joint portion Jt4 about a fourth rotation axis A4 that is inclined at a predetermined angle with respect to the axis of the third arm body 23, in this embodiment, 45 degrees.

  The fifth joint portion Jt5 connects the one end portion in the series direction of the fourth arm body 24 and the other end portion in the series direction of the fifth arm body 25. The fifth arm body 25 is rotatable by the fifth joint portion Jt5 around a fifth rotation axis A5 that is inclined at a predetermined angle with respect to the axis of the fourth arm body 24, in this embodiment, 45 degrees. The sixth joint portion Jt6 connects the one end portion in the series direction of the fifth arm body 25 and the other end portion in the series direction of the sixth arm body 26. The sixth arm body 26 is rotatable around a sixth rotation axis A6 coaxial with the axis of the fifth arm body 25 by the sixth joint portion Jt6.

  Thus, each joint part Jt1-Jt6 connects adjacent arm bodies so that rotation is mutually possible. Further, as the arm bodies 21 to 26 rotate, the arm structure 29 can be transformed into a state in which the axes of the arm bodies 21 to 26 are coaxially arranged and extend in a straight line as shown in FIG. Composed. In a state where the axes of the arm bodies 21 to 26 extend in a straight line, the second rotation axis A2 and the third rotation axis A3 are parallel, and the fourth rotation axis A4 and the fifth rotation axis A5 are parallel. The third rotation axis A3 and the fourth rotation axis A4 are perpendicular to each other.

  Each articulated arm 30A to 30C can deform the arm structure 29 like a snake by relatively rotating each of the arm bodies 21 to 26, and can position the position and posture of the hand portion 27. Each of the multi-joint arms 30A to 30C is provided with a servo motor serving as a driving unit that rotationally drives two arm bodies connected by the joint portion around a rotation axis set in the joint portion.

  The joint portions Jt1 to Jt6 included in the multi-joint arm 30A are either driving joint portions or non-driving joint portions. The drive joint portion is a joint portion provided with a servo motor, and is a joint portion capable of relatively rotating and driving two arm bodies connected by the servo motor. The drive joints are provided more than the number that restricts the degree of freedom of the workpiece when moving the workpiece. The non-driving joint is a joint that is not provided with a servo motor and a speed reducer associated with the servo motor, and maintains a state in which relative displacement between two adjacent arm bodies is allowed. In other words, in the non-drive joint portion, the two arm bodies to be connected are passively displaced relatively, but cannot be actively displaced relatively.

  In the present embodiment, the first joint portion Jt1, the second joint portion Jt2, and the fourth joint portion Jt4 are drive joint portions, the third joint portion Jt3, the fifth joint portion Jt5, and the sixth joint portion. Jt6 is the non-drive joint. In FIG. 1, the drive joint portion is indicated by a black circle symbol, and the non-drive joint is indicated by a white circle symbol.

  FIG. 3 is a cross-sectional view showing the first to fourth joint portions Jt1 to Jt4 in the multi-joint arm 30A. In addition to the servo motor 41, the first joint portion Jt1, the second joint portion Jt2, and the fourth joint portion Jt4, which are drive joint portions, are each provided with a brake 42, an encoder 43, and a speed reducer 55. The brake 42 serves as a displacement prevention means that can be switched between a fastening state that prevents the relative displacement of the two arm bodies connected by the drive joint portion and an open state that allows the relative displacement. The encoder 43 serves as detection means for detecting the relative displacement position of the adjacent arm body. The speed reducer 55 decelerates the power provided from the servo motor 41 at a predetermined reduction ratio and transmits the power to the arm body to relatively displace the arm body.

  The third joint Jt3, which is a non-drive joint, is provided with a brake 42 and an encoder 43, respectively, and the servo motor 41 and the speed reducer 55 are removed. Although not shown in FIG. 3, the fifth joint portion Jt5 and the sixth joint portion Jt6, which are the remaining non-drive joint portions, are also provided with a brake 42 and an encoder 43, respectively, in the same manner as the third joint portion Jt3. The servo motor 41 and the speed reducer 55 are removed.

  As for the total number of the drive joint parts which each multi-joint arm 30A-30C has, six or more are preferable. In the present embodiment, a total of nine drive joints are provided for each of the multi-joint arms 30A to 30C. In other words, a total of nine non-drive joints are also provided in each of the multi-joint arms 30A to 30C.

  Each driving joint unit fixes the relative displacements of the two arm bodies to be coupled among the joint units, so that the multi-joint arms 30A to 30C are supported by each other through the work 40 to be cooperatively gripped. Thus, it is selected as a plurality of joint portions in which the deformation of each of the multi-joint arms 30A to 30C is prevented. In other words, each driving joint unit fixes each relative displacement of the two arm bodies to be connected when each of the joint units grips the workpiece 40 in cooperation with each other, thereby fixing each multi-joint arm 30A. ˜30C is selected as the joint portion that restrains the displacement of the workpiece 40.

  When the fifth joint portion Jt5 and the sixth joint portion Jt6 are non-drive joint portions, the workpiece 40 can rotate around the sixth rotation axis A6 in a state where the workpiece 40 is gripped only by the first multi-joint arm 30A. At the same time, the gripped work 40 is rotatable around the fifth rotation axis A5. On the other hand, as shown in FIG. 2, in a state where the work 40 is gripped cooperatively by a plurality of multi-joint arms 30 </ b> A to 30 </ b> C, the rotatable direction is different for each hand portion 27 of each multi-joint arm 30 </ b> A to 30 </ b> C. Thus, the articulated arms 30A to 30C are supported by each other, and the workpiece 40 rotates around the fifth rotational axis A5 and the sixth rotational axis A6 set in the first to third articulated arms 30A to 30C, respectively. Be blocked. As described above, even when one or the plurality of joints Jt5 and Jt6 on the one end side in the series direction is a non-drive joint, the plurality of multi-joint arms 30A to 30C cooperate to grip the workpiece 40. Thus, the displacement of the workpiece 40 can be prevented.

  In the present embodiment, the bases 28 of the three articulated arms 30 </ b> A to 30 </ b> C are respectively arranged on a horizontal floor surface, and are arranged so that a triangle is formed by a line segment connecting the bases 28. As a result, it is possible to prevent all the sixth rotational axes A6 of the first to third multi-joint arms 30A to 30C from being coaxial, and the displacement of the workpiece 40 can be more reliably prevented.

  The same applies to the case where the third joint portion Jt3 is a non-drive joint portion. In the state in which the positions of the third arm bodies 23 of the multi-joint arms 30A to 30C are determined by cooperatively gripping the workpiece 40, respectively. Since the rotatable direction of the second arm body 22 is different, the multi-joint arms 30A to 30C are supported by each other, and the third rotation axis A3 is set to the first to third multi-joint arms 30A to 30C, respectively. The third arm bodies 23 are prevented from rotating respectively.

  In this way, the drive joint unit prevents the deformation of the multi-joint arms 30 </ b> A to 30 </ b> C by fixing the relative displacements of the arm bodies provided in the respective drive joint units after holding the workpiece 40 in cooperation. Selected to be joints. In other words, in a state where the relative displacements of the arm bodies respectively provided in the respective driving joint portions are fixed, the movable region of the work 40 permitted by each non-driving joint portion provided in each multi-joint arm 30 is one point. It is set to cross at.

  FIG. 4 is a diagram showing a non-independent condition of the articulated arm that cooperatively grips the workpiece 40. In the positioning robot 20 according to the present embodiment, the non-driving joint portion, the movement path, and the like are appropriately set so as to satisfy the following conditions for avoiding the independence state, in other words, the independence conditions. FIG. 4 illustrates a case where two multi-joint arms 30D and 30E are used. The non-self-standing state means a state in which the movement of the workpiece 40 is allowed and the workpiece 40 can be angularly displaced even if each drive joint is rotated by the angular displacement amount at which the workpiece 40 is to be positioned.

  Specifically, as shown in FIG. 4 (1), when the coaxial joint portions 61 provided in one multi-joint arm 30D and the other multi-joint arm 30E are respectively employed as non-drive joint portions, When the rotation axis 61 of the non-drive coaxial joint 60 of each articulated arm 30D, 30E extends coaxially, the two articulated arms 30D, 30E can be angularly displaced around the rotation axis 61.

  In the present embodiment, as shown in FIG. 2, among the multi-joint arms 30 </ b> A to 30 </ b> C, the sixth rotation axis A <b> 6 of each sixth joint portion Jt <b> 6 serving as a non-drive coaxial joint portion extends in the vertical direction. Thus, the workpiece 40 is gripped in cooperation. Accordingly, the sixth rotation axis A6 can be prevented from being coaxial, and deformation of the multi-joint arms 30A to 30C can be prevented. In addition, since the workpieces 40 are cooperatively gripped in a state where the hand portions 27 are not aligned in a straight line, even if the sixth rotation axes A6 extend horizontally, the sixth rotation axes A6 are coaxial. This prevents the deformation of each of the multi-joint arms 30A to 30C.

  Further, as shown in FIG. 4 (2), when the vertical joint portions 62 provided on the two multi-joint arms 30D and 30E are respectively employed as non-drive joint portions, the multi-joint arms 30D and 30E are also used. When the rotation axis 63 of the non-driving vertical joint 62 extends coaxially, the articulated arms 30D and 30E can be angularly displaced around the rotation axis 61. Here, the vertical joint portion 62 is a joint portion that connects two arm bodies and connects the other arm body so as to be relatively rotatable around a rotation axis perpendicular to the axis of one arm body.

  As another example, when the rotation axis 63 of the vertical joint part 62 of one articulated arm and the rotation axis 61 of the coaxial joint part 60 of the other articulated arm are coaxial, each articulated arm rotates. Angular displacement is possible around the axes 61 and 63. In the present embodiment, each of the multi-joint arms 30A to 30C is configured not to have the non-drive vertical joint portion 62, so that the multi-joint arms 30A to 30C can be prevented from being deformed.

  As shown in FIG. 4 (3), when any one of the inclined joint portions 64 provided in the two multi-joint arms 30D and 30E is employed as the non-drive joint portion, the following (1) to (4) When all of the conditions are satisfied, each of the multi-joint arms 30D and 30E can be deformed. (1) Each of the multi-joint arms 30D and 30E is provided with two non-drive inclined joint portions 64a to 64d, and the rotation axes of the non-drive inclined joint portions 64a to 64d extend in parallel. (2) The distance L1 between the two non-drive inclined joint portions 64a and 64b provided in one multi-joint arm 30D, and the distance L2 between the two non-drive inclined joint portions 64c and 64d provided in the other multi-joint arm 30E Are equal. (3) A straight line connecting two non-drive inclined joint portions 64a and 64b provided in one multi-joint arm 30D, and a straight line connecting two non-drive inclined joint portions 64c and 64d provided in the other multi-joint arm 30E Become parallel. (4) A straight line connecting each of the non-driving inclined joint portions 64a and 64c provided in the two multi-joint arms 30D and 30E and the other in the series direction provided in the two multi-joint arms 30D and 30E. A straight line connecting the non-driving inclined joint portions 64b and 64d is parallel.

  In the present embodiment, each of the multi-joint arms 30A to 30C is provided with two non-drive inclined joint portions Jt3 and Jt5, respectively, but their rotation axes A3 to A5 are not positioned in parallel. Further, a straight line connecting the third joint portion Jt3 of the first multi-joint arm 30A and the third joint portion Jt3 of the second multi-joint arm 30B, the third joint portion Jt3 of the first multi-joint arm 30A, and the third multi-joint arm 30A. Since the straight line connecting the third joint portion Jt3 of the joint arm 30C does not match, the deformation of each of the multi-joint arms 30A to 30C can be prevented. As described above, the positioning robot satisfies a self-supporting condition in which each multi-joint arm satisfies a self-supporting state by preventing the movement of each work when a plurality of multi-joint arms are used to cooperatively grip the work. The independence condition will be described later in detail with reference to FIG.

The host controller 32 includes a storage unit, a calculation unit, a communication unit, and an input unit. The calculation unit executes a calculation program stored in the storage unit, calculates a workpiece movement path along which the workpiece 40 moves based on a workpiece movement plan input or stored in advance, and each multi-joint arm 30A to 30C. The hand movement path along which the hand unit 27 moves is calculated. The communication unit provides a signal indicating the hand movement path calculated for each multi-joint arm 30A to 30C to the sub-controllers 31A to 31C provided for each multi-joint arm 30A to 30C. The input unit receives a work movement plan from an operator or the like. The storage unit is a ROM (Read
This is realized by a memory circuit such as “Only Memory”. The calculation unit is a CPU (Central
This is realized by an arithmetic processing circuit such as a processing unit. The input unit may be a keyboard, a switch, or the like, and the movement plan of the workpiece 40 may be input via a teaching pendant that teaches the position of each robot.

  The sub-controllers 31A to 31C are configured to include a storage unit, a calculation unit, a communication unit, an input unit, and an output unit. The calculation unit executes a calculation program stored in the storage unit and responds to a signal indicating the hand movement path provided from the host controller 32 via the communication unit. The calculation unit is configured to provide servo motors for moving the hand unit 27 along the movement path based on the relative angle of the arm body provided from the encoder 43 via the input unit and the hand movement path provided from the communication unit. The operation amount 41 and the switching timing of the brake 42 are calculated. Specifically, the calculation unit calculates each motor 41 based on the inverse conversion calculation process for calculating the operation amount of each servo motor 41 based on the movement path of the hand unit, and the operation amount of each servo motor 41 as a result of the inverse conversion calculation. Servo processing to control. The storage unit is realized by a storage circuit such as a ROM (Read Only Memory). The arithmetic unit is realized by an arithmetic processing circuit such as a CPU (Central Processing Unit).

  The output unit is provided with a calculation result calculated by the calculation unit, and in response to the calculation result, provides power for operating the servo motor 41 and a signal for switching the state of the brake 42. For example, the output unit is realized by a servo amplifier that is an amplifier circuit. The servo amplifier supplies current corresponding to the operation amount of the servo motor 41 calculated by the calculation unit to each corresponding servo motor 41. As a result, the servo motor 41 relatively rotates the arm body by the operation amount calculated by the calculating means 46. The servo amplifier gives a command to the brake 42 according to the state of the brake 42 calculated by the calculation unit. The brake 42 prevents the relative displacement of the arm body when a fastening command for preventing the displacement of the arm body is given, and allows the relative displacement of the arm body when the release command for allowing the displacement of the arm body is given.

  Each of the sub-controllers 31A to 31C controls the multi-joint arms 30A to 30C in accordance with commands from the host controller 32, respectively. As a result, each hand unit 27 can be moved along a predetermined hand movement path, and one workpiece 40 that is cooperatively gripped by each hand unit 27 is aligned with a predetermined target position and target posture. be able to.

  FIG. 5 is a flowchart showing a work movement control procedure of the articulated arm 30A by the sub-controller 31A. Since each of the sub-controllers 31A to 31C performs the same operation, only one sub-controller 31A will be described, and description of the remaining sub-controllers 31B and 31C will be omitted. The calculation unit of the sub-controller 31A controls the servo motor 41 and the brake 42 by reading the workpiece movement control program stored in the storage unit and executing the control program.

  First, in step a0, when a workpiece movement command is given from the host controller 32 in a state where the workpiece 40 is cooperatively gripped by the hand portions 27 of the multi-joint arms 30A to 30C, the calculation unit causes the work of the multi-joint arm 30A to The movement control operation is started and the process proceeds to step a1.

  In step a1, the calculation unit gives a release command to the brakes 42 provided in the non-drive joints via the output unit. The brake 42 to which the release command is given allows the relative displacement of the corresponding arm body. When the arithmetic unit allows the relative displacement of the arm body connected to each non-drive joint unit, the calculation unit proceeds to step a2.

  In step a2, the arithmetic unit responds to a signal indicating the hand movement position and posture given from the host controller 32 via the communication unit, and moves the hand unit 27 to the hand movement position. Calculate the displacement position. Next, the servo motor 41 connected to each drive joint is servo-controlled according to the calculation result to relatively rotate each arm body, and the process proceeds to step a3.

  In step a3, the calculation unit determines whether or not the hand unit 27 has reached an end position to be finally moved. For example, when a movement end signal is given from the host controller 32, the arithmetic unit determines that the hand unit 27 has reached the end position. When the hand unit 27 reaches the end position, the workpiece 40 is positioned at a predetermined target position in an ideal state.

  If the calculation unit determines that the hand unit 27 has not reached the end position, the calculation unit waits until a signal indicating the next hand movement position is given from the host controller 32. When a signal indicating the next hand movement position is given, the process returns to step a2, and steps a2 and a3 are repeated. In step a3, when the calculation unit determines that the hand unit 27 has reached the end position, the calculation unit proceeds to step a4.

  In step a4, the calculation unit gives a fastening command to each brake 42 provided in each non-drive joint and each drive joint. The brake 42 to which the engagement command is given prevents the relative displacement of the corresponding arm body. As described above, when the arithmetic unit blocks the relative displacement of the arm body connected to each joint, the operation proceeds to step a5. In step a5, the calculation unit ends the work movement control operation of the articulated arm 30.

  Each of the sub-controllers 31A to 31C performs the operations of step a0 to step a5 described above. When the host controller 32 moves the work 40 to be gripped in cooperation, the host controller 32 sequentially sends a signal indicating the hand moving position where each hand unit 27 will be sequentially placed to each corresponding sub-controller 31A to 31C. give.

  As described above, in the state where the relative displacements of the arm bodies provided at the respective drive joints are fixed, the multi-joint arms 30 are supported by each other through the work to be gripped in cooperation, and the deformation of the respective multi-joint arms 30 is performed. Is blocked. Therefore, when the arm body connected to the drive joint part is displaced to the relative angular position that is located when the hand part 27 moves to the hand movement position, the arm body connected to the non-drive joint part becomes the drive joint part. Following the movement of the connected arm bodies, the relative displacement is passively performed.

  In this way, the arm bodies connected by the drive joint part and the non-drive joint part are relatively displaced, so that various errors such as a shift in the gripping position of the hand part 27, a mechanical error of the arm body, and a servo delay occur. In an ideal state that does not exist, the work to be gripped cooperatively can be positioned at the target position.

  Further, in a realistic state where various errors exist in moving the workpiece, the arm body that is relatively displaced by the servo motor 41 is positioned at a position shifted due to various errors as compared to the ideal state. It will be. Even if the two arm bodies are deviated from the ideal state, the two arm bodies connected to the non-drive joint portion can be relatively displaced, so the two arm bodies are connected in a deviated state. be able to. As a result, the two arm bodies are restrained from being forcibly connected in a shifted state, and the deformation force generated on the workpiece 40 and each of the arm bodies 21 to 26 can be suppressed.

  FIG. 6 is a flowchart showing a control procedure of each of the sub-controllers 31A to 31C in the host controller 32. The calculation unit of the host controller 32 reads the control program stored in the storage unit and gives an operation command to each sub-controller 31 according to the control program.

  First, in step b0, as a preparation process, the host controller 32 receives a moving program necessary for moving the workpiece 40 via the input unit. The movement program includes, for example, a plurality of teaching positions through which the workpiece 40 passes, information indicating the types of movement paths connecting the teaching positions, the movement speed and acceleration of the workpiece 40, a waiting time, and the like. The input movement program is stored in the storage unit. When the work 40 gripped by the articulated arms 30A to 30C is in a movable state and a movement command for the work 40 is given by an operator or the like, the process proceeds to step b1 to each of the sub controllers 31A to 31C. Start command operation.

  In step b1, the moving program stored in the storage unit is read, and the process proceeds to step b2. In step b2, the calculation unit decodes the instruction indicated in the read movement program, calculates the position and orientation of the workpiece that changes per unit time of the workpiece 40, and proceeds to step b3. In step b3, the calculation unit calculates the position and orientation of each hand unit 27 that changes per unit time based on the calculation result calculated in step b2, and proceeds to step b4.

  In step b4, the calculation unit transmits a workpiece movement command to the sub-controllers 31A to 31C. Next, signals indicating the movement position and posture of each hand unit 27 calculated in step b3 are sequentially transmitted to the corresponding sub-controllers 31A to 31C, and the process proceeds to step b5. In step b5, the arithmetic unit transmits a movement end signal indicating the last hand movement position and posture, and then transmits an end signal indicating that each hand unit 27 has reached the end position to each of the sub-controllers 31A to 31C. The process proceeds to step b6. In step b6, the calculation unit ends the command operation to each of the sub-controllers 31A to 31C.

  In the present embodiment, the movement program for the workpiece 40 is stored in the storage unit. However, the movement program for the one hand unit 27 of interest may be stored in the storage unit. In this case, in step b2, the movement position and posture of one hand unit 27 of interest are sequentially calculated, and in step b3, the movement positions of the remaining hand units 27 are determined based on the relationship of the work gripping positions of the hand units 27. And the posture may be calculated sequentially. As described above, in the present embodiment, the host controller 32 that calculates the command value of the position and orientation of the hand unit 27, and the sub-controllers 31A to 31C that perform the inverse transformation calculation based on the movement position and orientation of each hand unit 27. This makes it possible to share the computational load on one controller and to smoothly operate each articulated arm.

  As described above, the positioning robot 20 according to the present embodiment is a robot that conveys and positions the workpiece 40 in a state where one workpiece 40 is gripped cooperatively by the plurality of articulated arms 30A to 30C. By cooperatively gripping the workpiece 40 with the plurality of multi-joint arms 30A to 30C, each of the multi-joint arms 30A to 30C can be reduced in size as compared with the case where the workpiece 40 is gripped with one multi-joint arm. Further, by cooperatively gripping the workpiece 40 with the respective hand portions 27 of the plurality of multi-joint arms 30A to 30C, the workpiece can be stably gripped as compared with the case where the workpiece is gripped by one multi-joint arm. it can.

  According to the present embodiment, the plurality of multi-joint arms 30A to 30C each have a non-drive joint portion. By providing the non-drive joint portion, even if various errors occur and the two arm bodies are displaced, it is possible to prevent the two arm bodies from being forcibly connected in a displaced state, and the workpiece 40 and each arm. The deformation force generated in the body can be suppressed, and damage to the workpiece 40 and the positioning robot 20 can be prevented. For example, even when the gripping position of the hand portion 27 with respect to the workpiece varies, it is possible to prevent the workpiece 40 and the like from being damaged by suppressing the deformation force applied to the workpiece 40 and the like.

  Further, for example, even when each hand unit 27 does not accurately pass through a predetermined movement route, the deformation force generated on the workpiece 40 or the like can be suppressed. Therefore, even if the sub-controller 31 obtains an approximate solution, not an analytical solution, and determines the displacement position of each arm body based on the approximate solution in the inverse transformation calculation process, the work 40 gripped in cooperation is moved. be able to. In other words, since the displacement position of the arm body can be obtained by the approximate solution in the inverse transformation calculation, the three joints on the hand side or the base side such as the multi-joint arms 30A to 30C as in the present embodiment. Even when the rotation axes of the portions do not intersect at one point, it is possible to smoothly move the workpiece 40 even when analytical derivation in the inverse transformation calculation is difficult.

  Further, since the driving means such as the servo motor 41 and the speed reducer 55 can be unnecessary in the non-drive joint part, the structure of the positioning robot can be improved compared to the case where all of the joint parts are drive joint parts. It can be simplified and the manufacturing cost can be reduced. Moreover, in this Embodiment, by providing one or more non-drive joint parts in each articulated arm 30A-30C, the deformation force given to each articulated arm 30A-30C can be suppressed, and each articulated arm Damage to the arms 30A to 30C can be prevented more reliably. Here, each multi-joint arm 30 may have a non-drive joint part, and any one multi-joint arm 30 may have. Moreover, the non-drive joint part which one multi-joint arm has can be set to an arbitrary number within a range in which the work 40 gripped in cooperation can be positioned.

  In the present embodiment, each sub-controller 31 switches the brake 42 to the engaged state after the workpiece is moved. As a result, the relative displacement of the two arm bodies connected to the non-drive joint can be prevented, and the lack of rigidity of the positioning robot due to the use of the non-drive joint can be compensated. Thus, after positioning the workpiece 40 at the target position and target posture, the rigidity of the positioning robot 30 can be increased and the workpiece 40 can be supported more stably. For example, when machining is performed on the workpiece 40 while the workpiece 40 is supported, it is possible to prevent the workpiece from shifting during machining and perform suitable machining.

  Further, when the non-joint joint portions are provided in the multi-joint arms 30A to 30C, respectively, as shown in FIGS. 4 (1) to 4 (3), depending on the selection mode of the non-drive joint portion and the drive joint portion, There is a risk that the cooperative gripping of the workpiece 40 becomes unstable. On the other hand, in the present embodiment, each driving joint unit supports each articulated arm with each other via a work 40 that holds the joints in a state where the relative displacements of the two arm bodies to be connected are fixed. As a result, it is selected as a joint part that prevents deformation of each multi-joint arm. The workpiece 40 can be stably held at the time of workpiece cooperative holding, and the workpiece 40 can be reliably positioned even if the non-joint joint portions are provided in the multi-joint arms 30A to 30C, respectively. Further, since each joint portion of the positioning robot 30 is realized by either a tilt joint portion or a coaxial joint portion, in most cases where the workpiece 40 is moved, the cooperatively gripped workpiece 40 is undesirably displaced. Therefore, the position and posture of the workpiece can be kept constant. In the present embodiment, three articulated arms 30A to 30C are provided and their bases 28 are arranged so as not to be arranged in a straight line, so that compared to the case where two articulated arms 30 are provided. Further, it is possible to further prevent the work 40 gripped in cooperation from being undesirably displaced.

  Each multi-joint arm 30A-30C has six degrees of freedom and six or more drive joints are provided, whereby the position and posture of the workpiece 40 can be aligned, and the workpiece 40 can be positioned in advance. Positioning to a target posture can be performed, and convenience can be improved. In addition, by providing six or more non-drive joints, the workpiece 40 can be gripped in an arbitrary position and arbitrary posture with respect to the target position and target posture.

  The drive joint is set to the joint on the base 28 side from among a plurality of joints that can be selected as the drive joint. As a result, the servo motor 41 can be disposed on the base side of the multi-joint arm, and the hand-side shape of the multi-joint arm 30 can be further reduced. Here, the joint part that can be selected as the drive joint part is a joint part that is at least necessary to enable the work held in cooperation to be moved to an arbitrary position.

  Further, in the case of a comparative positioning robot in which all the joint portions provided in each of the multi-joint arms 30A to 30C are drive joint portions, six degrees of freedom are controlled by 18 drive joint portions. It is necessary to perform coordinated control with strict synchronization. On the other hand, in the present embodiment, since the six degrees of freedom are controlled by the nine drive joint portions provided in each of the multi-joint arms 30A to 30C, each multi-joint is compared with the positioning robot of the comparative example. There is no need to strictly synchronize the arms, and cooperative control can be simplified.

  FIG. 7 is a flowchart showing the positioning control operation of the hand unit 27 by the sub-controller 31A. In the present embodiment, each of the multi-joint arms 30A to 30C is configured such that the hand unit 27 can be independently positioned at an arbitrary position by controlling the servo motor 41 provided in the drive joint unit by the sub-controller 31. It becomes a single drive articulated arm.

  Each multi-joint arm 30 proceeds to step a0 shown in FIG. 5 in a state in which the hand unit 27 is moved to the workpiece gripping position and the workpiece 40 is gripped in cooperation by the hand unit 27. The multi-joint arm 30 moves the workpiece to the gripping position independently without borrowing human power or the power of another robot by the operation shown in FIG.

  Since each of the sub-controllers 31A to 31C performs the same operation, the first sub-controller 31A will be described, and the description of the remaining sub-controllers 31B and 31C will be omitted. The arithmetic unit of the first sub-controller 31A controls the servo motor 41 and the brake 42 by reading the hand unit positioning control program stored in the storage unit and executing the control program.

  First, in step c0, when a hand unit positioning command is given from the host controller 32 or the like in a state where the sub controller 31 can angularly displace each arm body connected to each drive joint unit, the calculation unit 27 starts the positioning control operation, and proceeds to step c1.

  In step c1, the calculation unit gives a release command to the brake 42 provided in one notable driving joint through the output unit. Further, a fastening command is given to the brakes 42 provided in the remaining joint portions. The brake 42 to which the release command is given cancels the inhibition of the relative displacement of the corresponding arm body. Further, the brake 42 to which the engagement command is given prevents the relative displacement of the corresponding arm body. Thus, if a calculating part gives instruction | command to the brake 42 provided in each joint part, it will progress to step c2.

  In step c2, the computing unit gives a drive command to the servo motor 41 provided in one or a plurality of drive joints via the output unit. As a result, the direction in which gravity is applied to the arm body connected to the non-drive joint to be noticed is changed, and the process proceeds to step c3. Since the arm body to which the non-drive joint portion is coupled is in a state where displacement is permitted, the arm body is angularly displaced in accordance with a change in the direction of application of gravity. In the present embodiment, the arm body connected to the drive joint portion is relatively moved by the servo motor 42 so that the arm body connected to the non-drive joint portion moves to a preset relative angle by gravity. In this case, the arm body connected to the non-drive joint portion is angularly displaced by gravity and stops in a state where the set relative angle is reached.

  In step c3, the calculation unit confirms that the arm body connected to the non-drive joint unit has reached the set relative angle based on the detection result of the encoder 42 provided in the target non-drive joint unit via the input unit. If it judges, it will progress to step c4. In step c4, the calculation unit gives an engagement command to the brake 42 provided in the target non-drive joint through the output unit, and the process proceeds to step c5. As a result, the arm body connected to the focused non-drive joint is prevented from being angularly displaced in a state where the set relative angle is reached.

  In step c5, the calculation unit determines whether or not the arm bodies connected to all the non-drive joints have been prevented from being angularly displaced by a set relative angle set individually. If it is determined that there is an arm body connected to the non-drive joint that does not prevent angular displacement at the set relative angle, the non-drive joint is reset as the target non-drive joint, and the process returns to step c2. If it is determined that the angular displacements of the arm bodies connected to all the non-drive joints are set relative angles, the process proceeds to step c6.

  In step c6, the calculation unit gives a drive command to the servo motor 41 provided in the drive joint, and angularly displaces the arm body connected to the drive joint to the set relative angle. When the angle is displaced, an engagement command is given to the brake 42 provided at the drive joint, and the process proceeds to step c7. Accordingly, the relative angle of each arm body can be positioned at a predetermined angular position. In step c7, the calculation unit ends the positioning control operation of the hand unit.

  As described above, in the present embodiment, when the arm body connected to the non-drive joint portion reaches a predetermined set angle in a state where the arm body connected to the non-drive joint portion is relatively displaced by an external force, Prevent body displacement. Thereby, even if it is a non-drive joint part in which the servo motor 41 is not provided, the two arms to be connected can be positioned at a set angle. Each articulated arm 30A-30C can move the hand part 27 to the workpiece gripping position by itself without borrowing human power or the power of other devices, and can further improve convenience. In such a single operation multi-joint arm, it is preferable that at least one or a plurality of joints closest to the base 28 is set as a drive joint. Accordingly, the remaining joint portion on the hand side can be displaced by gravity. Further, considering that the single-operation multi-joint arm is operated alone, the joint portion to which gravity does not easily act, and the vertical joint portions such as the first joint portion Jt1 and the sixth joint portion Jt6 in FIG. It is better not to. Further, in a state where the multi-joint arm is linearly deformed, it is preferable that the joint portion parallel to the other non-drive joint portion, for example, the third joint portion Jt3 with respect to the second joint portion Jt2 is not a non-drive joint portion.

  Further, after each multi-joint arm 30A-30C is operated alone and each hand unit 27 is moved to the work gripping position and the work 40 is gripped cooperatively, the sub-controllers 31A as shown in FIG. ˜31C controls the servo motor 41 provided in each of the multi-joint arms 30A to 30C, thereby moving the work 40 to be cooperatively held to an arbitrary position in a state where the brake 42 of the non-driven joint portion is released. be able to.

  In the present embodiment, the arm body connected to the non-drive joint portion is angularly displaced by changing the direction of gravity generated in the arm body connected to the non-drive joint portion. For example, the arm body connected to the non-driving joint may be angularly displaced by rotating the servo motor to apply an inertial force to the arm body. Also, since the positioning robot is used as a jig robot that supports and fixes the workpiece, high-speed positioning is rarely required, and even if it takes time to position the hand portion of the articulated arm at a set angle, It can be suitably used as a jig robot.

  Further, in the present embodiment, the servo motor 41 is rotated and the arm body connected to the non-drive joint portion is fixed at the set angle, but the present invention is not limited to this. For example, instead of the operation of the servo motor 41 in step c2, an external force is applied to the hand unit 27 manually or by another robot, and the remaining steps c1, c3 to c7 are performed to guide the hand unit 27 to the gripping position. Also good. Further, if the angle of the arm body connected to the non-drive joint portion is determined quantitatively by defining the operation amount of the servo motor 41, the encoder 43 may not be provided. Even if the grip position of the hand portion 27 is slightly shifted, the shift of the grip position can be absorbed by providing the non-drive joint portion as described above.

  FIG. 8 is a block diagram showing a positioning robot 120 according to the second embodiment of the present invention. FIG. 9 is a diagram showing a workpiece 140 that is gripped in cooperation with the positioning robot 120. The positioning robot 120 according to the second embodiment has a configuration corresponding to the positioning robot 20 according to the first embodiment. About the corresponding structure, the reference code | symbol which added 100 to the reference code of the structure shown by the positioning robot 20 of 1st Embodiment is attached | subjected. The positioning robot 120 of the second embodiment has the same configuration as that of the positioning robot 120 of the first embodiment except that the types of joints are different, and the description of the same configuration is omitted.

  A calculation result in the case where there is an error in positioning of the drive joint using the positioning robot 120 is shown below. The positioning robot 120 has three articulated arms 130A to 130C, and each is configured identically. Each articulated arm 130A to 130C includes six arm bodies 121 to 126 arranged in series, six joint parts Jt2 to Jt7 that rotatably connect two adjacent arm bodies, a hand part 127, and a base 128. Including. Each arm body 121 to 126 constitutes an arm structure 129 that is connected and extends in series.

  The second joint portion Jt2 serves as a drive tilt joint portion, and connects the first arm body 121 and the second arm body 122 fixed to the base 128. The third joint portion Jt3 is a non-driven inclined joint portion, and connects the second arm body 122 and the third arm body 122. The fourth joint portion Jt4 serves as a drive tilt joint portion, and connects the third arm body 123 and the fourth arm body 124. The fifth joint portion Jt5 is a non-drive coaxial joint portion, and connects the fourth arm body 124 and the fifth arm body 125. Further, the sixth joint portion Jt6 becomes a non-drive inclined joint portion, and connects the fifth arm body 125 and the sixth arm body 126. The seventh joint portion Jt7 is a non-drive coaxial joint portion, and connects the sixth arm body 126 and the hand portion 127.

  In a state where the axes of the arm bodies 121 to 126 are arranged in a straight line, the rotation axes A2 and A3 of the second joint part Jt2 and the third joint part Jt3 extend in parallel, and the third joint part Jt3 and the fourth joint The rotation axes A3 and A4 with the part Jt4 extend vertically. Each of the inclined joint portions Jt2, Jt3, Jt4, and Jt6 has rotation axes A2, A3, A4, and A6 inclined at 45 from the axis of the arm body to be connected. In the present embodiment, the rotation axes A5, A6, and A7 of the fifth joint portion Jt5, the sixth joint portion Jt6, and the seventh joint portion Jt7 are set to be the sixth joint portion so that the inverse transformation calculation can be easily performed. Cross at the 3-axis intersection Pw set to Jt6.

  As shown in FIG. 9, in the present embodiment, the workpiece 140 is formed in a regular triangular plate shape. It is assumed that each hand unit 127 holds the three vertex positions of the workpiece 140 and also holds the workpiece 140 perpendicular to the triangular plane of the workpiece 140.

  The base 128 of each of the articulated arms 130A to 130C is arranged on a plane including a predetermined world coordinate system X-axis and Y-axis, and is on a circumference that goes around the world origin P0 around the Z-axis of the world coordinate system. Are arranged at equal intervals. When each of the articulated arms 130A to 130C is deformed so that the axis of the arm structure 129 extends in a straight line, the axis extends in parallel to the Z axis of the world coordinate system.

  A base coordinate system is set on the base 128 of each articulated arm 130A to 130C. In the base coordinate system, a point where the axis of the arm structure 129 deformed so as to extend in a straight line and a plane including the X axis and the Y axis of the world coordinate system is set as the base origin PB. The Z axis of the world coordinate system and the Z axis of the base coordinate system extend parallel to each other. A plane including the X axis and Y axis of the world coordinate system and a plane including the X axis and Y axis of the base coordinate system are located in the same plane.

  When the position and orientation of the workpiece 140 with respect to the world coordinate system are designated, the three-axis intersection point Pw of the articulated arms 130A to 130C in the world coordinate system can be determined. Further, by performing coordinate system conversion between the world coordinate system and the base coordinate system, it is possible to determine the three-dimensional position of the three-axis intersection point Pw in the base coordinate system set for each multi-joint arm 130A to 130C.

A three-dimensional position (Pwxα _k , Pwyα _k , Pwzα _k ) ^T of the three-axis intersection Pwα _k in the base coordinate system of the k-th multi-joint arm, and the second joint portion Jt2 _k to the fourth joint portion Jt4 of the k-th multi-joint arm. the the angle _q2 k to Q4 _k of _k, have the relationship shown in the following equation (1)

Here, the subscript k is a symbol indicating the k-th multi-joint arm. For example, Pwxα ₁ indicates the X coordinate position of the three-axis intersection Pw of the first articulated arm 130A in the base coordinate system. Further, q2 ₁ represents the angle of the second joint portion Jt2 of the first multi-joint arm 130A. Here, when a state in which the axis of the arm structure 129 extends in a straight line is a reference state, q2 _k is an angle at which the second arm body 122 is displaced relative to the first arm body 121 in the reference state. . Further, q3 is an angle at which the third arm body 123 is displaced relative to the second arm body 122 in the reference state. Further, q4 is an angle at which the fourth arm body 124 is displaced relative to the third arm body 123 in the reference state. Thus, the relative angle of the arm body may be referred to as the angle of the joint portion.

  L1 is the distance from the base origin to the second joint part Jt2, and L2 is the distance from the second joint part Jt2 to the third joint part Jt3. L3 is a distance from the third joint part Jt3 to the fourth joint part Jt4, and L4 is a distance from the fourth joint part Jt4 to the sixth joint part Jt6.

When the three-dimensional position and orientation of the workpiece 140 are determined, the three-axis intersection point Pw of each multi-joint arm in the base coordinate system can be obtained, and the obtained three-axis intersection point Pw is substituted into the equation (1). The angles of the second to fourth joint portions of each multi-joint arm can be obtained. In the present embodiment, L1 = 280 mm, L2 = 290 mm, L4 = 290 mm, L3 = 160 mm, L5 = 180 mm, Lb = 408 mm, and Lh = 433 mm. Here, Lb is a distance from the world origin P0 to each base 128, and Lh is a half value of the length of one side of the workpiece 140 (= 2 · Lh). Further, the three-dimensional position (Pgx, Pgy, Pgz) ^T in the world coordinate system of the center position of the workpiece 140 that is cooperatively held at the holding position is (0, 0, 910) ^T [mm]. The three-dimensional posture (PgRx, PgRy, PgRz) is (0, 0, 46.225) [deg]. In this case, the angles q2 ₁ , q2 ₂ , q2 ₃ of the second joint portions of each multi-joint arm are 60 degrees, respectively. Further, the angles q3 ₁ , q3 ₂ , and q3 ₃ of the third joint portion are −60 degrees, respectively. Further, the angles q4 ₁ , q4 ₂ , q4 ₃ of the fourth joint portion are 120, respectively.

The three-dimensional position (Pwxβ _k , Pwyβ _k , Pwzβ _k ) ^T of the three-axis intersection Pwβ _k in the world coordinate system of the k-th multi-joint arm has a relationship shown in the following equation (2).

Here, when the first articulated arm, that is, k = 1, θ = 0. For the second articulated arm, ie k = 2, θ = 120. In the third articulated arm, that is, k = 3, θ = 240. In addition, (Pwxα _k , Pwyα _k , Pwzα _k ) ^T is obtained by substituting the angles q2 _{k to} q4 _k of the second to fourth joints in the k-th multi-joint arm into the equation (1). This is a three-dimensional position of the three-axis intersection point Pwα of the k-th multi-joint arm, and is a function including the angles q2 _{k to} q4 _k of the second to fourth joint portions in the k-th multi-joint arm as variables.

  In addition, as each hand unit 27 set on the first articulated arm 130A holds the workpiece 140 in cooperation, the condition of the above-described expression (2) is constrained to satisfy the relationship of the following expression (3). The

Here, the left term in the formula (a) is C ₃ , the left term in the formula (b) is C ₁ , the left term in the formula (c) is C ₂ , and the following (4) Each term shown in Formula and Formula (5) is defined.

  Assuming that the workpiece 140 is a rigid body, the distance between the hand portions is unchanged even if any of the multi-joint arms is deformed. From this, the following equation (6) is established.

For (6), for each articulated arm, variation and Derutaq3 _k angles passive joint portion, variation Derutaq2 k of angle of the drive _joint, by separating into a Derutaq4 _k, the following (7) Can be transformed into a formula.

From equation (7), it is possible to calculate the absorption amount of the error of the non-drive joint when there is an error in the positioning of the drive joint. Substituting the shape (L1 to L4) of each articulated robot described above and the angles q2 _k , q3 _k , and q4 _{k of the} joints in the workpiece cooperative gripping state, Jl is obtained as follows ( 8) Equation is obtained.

For example, among the angles q2 _k, q4 _k of the drive joint, the angle of the first multi-joint angle q2 ₁ of the second joint portion Jt2 arm moves shifted once for command value, remaining drive joint When q2 ₂ , q2 ₃ , q4 ₁ , q4 ₂ , q4 ₃ move strictly to the command value, the angle (q3 ₁ , q3 ₂ , q3 ₂ ) ^T of the non-driven joint is calculated from the angle to be moved by (− 1.14923, 0.2555486, -0.265846) The error occurs by ^T [deg] and moves to the position. Thus the third joint portion angle q3 ₁ of the first articulated arm, with respect to the angle to be moving (= -60 °), the error angle (= -1.14923 degrees) above minute shift.

At this time, the three-dimensional position (Pgx, Pgy, Pgz) ^T of the center position of the workpiece 140 in the world coordinate system is (0.650269, 1.67466, −0.852597) ^T [mm] with respect to the command value. The three-dimensional posture of the workpiece 140 is inclined by 0.537118 [deg] with respect to the plane perpendicular to the Z axis.

Center position of the workpiece determines the three-dimensional position of the 3-axis intersections Pwβk of each articulated arm (Pwxβk, Pwyβk, ^Pwzβk) center-of-gravity position Pwβ of _{^{T 0 (= (Pwβ1 + Pwβ2}} + Pwβ3) / 3). Next, three axes intersection Pwβk of each articulated arm, obtains a direction vector with respect to a horizontal plane, with respect to the center of gravity position Pwbeta _0, by adding the L5 in the direction of the direction vector, determining the center position of the workpiece 140 Can do.

  As described above, in the positioning robot 120 according to the second embodiment, the third joint portion Jt3 of each multi-joint arm 130A to 130C is set as each non-drive joint portion, so that an error occurs in the angle of the drive joint portion. Even if this occurs, the angle of the non-drive joint changes following the error. Accordingly, the expression (6) can be satisfied, the work 140 can be gripped cooperatively without deformation of each arm body and work, and damage to the work 140 and arm body can be avoided. .

  In addition, it was explained that the angle of the non-drive joint part changes following the angle deviation of the drive joint part, but servo errors, workpiece gripping errors, arm body and workpiece shape errors, placement errors of each multi-joint arm, etc. This is the same even when the error occurs, and the angle of the non-drive joint portion changes following the error. Further, the error absorption by the non-drive joint has been described using the positioning robot 120 of the second embodiment, but the error is also caused by the non-drive joint by the positioning robot 20 of the first embodiment shown in FIG. Can be absorbed.

  Further, the positioning robot 120 of the second embodiment can obtain the same effects as those of the first embodiment. Furthermore, the positioning robot 120 controls six degrees of freedom with the six drive joints provided in each of the multi-joint arms 130A to 130C, eliminating the need for cooperative control. Accordingly, it is possible to prevent the synchronization of the articulated arms 130A to 130C from being exactly the same, and the workpiece can be moved more easily. In addition, since the rotation axes A5 to A7 of the fifth to seventh joints intersect at the three-axis intersection Pw, the inverse transformation calculation can be easily performed.

  FIG. 10 is a diagram for explaining the self-supporting condition of the positioning robot 120. As shown in FIG. 10, the self-supporting condition of the positioning robot 120 including three multi-joint arms 130 </ b> A to 130 </ b> C each having six joint portions is obtained below. It is assumed that the total number of joint portions of each of the multi-joint arms 130A to 130C is 18, of which 6 are the drive joint portions and 12 are the non-drive joint portions.

A matrix representing the position and orientation of the workpiece 140 is a workpiece matrix W. The work matrix W is a 1-by-6 column (Wx, Wy, Wz) having six variables including a three-dimensional position (Wx, Wy, Wz) of the work 140 and a three-dimensional posture (WRx, WRy, WRz) of the work 140. Wz, WRx, WRy, WRz) A matrix of ^T. A matrix representing the angles of the joints of the first articulated arm 130A among the three articulated arms 130A to 130C is defined as a first arm angle matrix Q1. The k-th arm matrix Qk has 1 row and 6 columns (q1 _k , q2 _k) having six variables including angles q1 _{k to} q6 _k of the joint portions Jt1 _{k to} Jt6 _k of the K-th multi-joint arms 130A to 130C. , Q3 _k , q4 _k , q5 _k , q6 _k ) ^T matrix. In this case, the following relational expression is satisfied.

W = F1 · Q1 (9)
W = F2 / Q2 (10)
W = F3 ・ Q3 (11)

  Here, F1 to F3 are 6 × 6 determinants obtained from the types of joint portions and arm lengths of the multi-joint arms, and are transformation matrices obtained based on the forward transformation equations.

  Since the first multi-joint arm 130A, the second multi-joint arm 130B, and the third multi-joint arm 130C are rigidly coupled by the hand portion 127, C2 and C3 in the following constraint condition are zero. It becomes.

C2 = F1 · Q1−F2 · Q2 (12)
C3 = F1 / Q1-F3 / Q3 (13)

  In addition, regarding the work matrix W, a matrix representing a minute change amount of the position and orientation of the work 140 is dW. Further, regarding the k-th arm angle matrix Qk, a matrix representing the minute change amount of each angle of the k-th multi-joint arm is defined as dQk. In addition, the minute changes of C2 and C3 represented by the equation (10) are dC2 and dC3. In this case, the following Jacobian matrices J1, J2, and J3 are defined. Each Jacobian matrix J1-J3 is a function with each element in () as a variable.

dW = J1 (dQ1) (14)
dC2 = J2 (dQ1, dQ2) (15)
dC3 = J3 (dQ1, dQ3) (16)
Six variables out of a total of 18 variables q1 _{1 to} q6 ₁ , q1 _{2 to} q6 ₂ , q1 _{3 to} q6 ₃ of the first to third arm angle matrices Q1 to Q3 are used as variables indicating the angle of the driving joint. Qa is a matrix of 1 row and 6 columns selected from them. Further, the remaining 12 are selected as variables indicating the angles of the non-drive joints, and a 1 × 12 matrix having these as elements is defined as Qp. Also, a matrix indicating a minute change in Qa is dQa, and a matrix indicating a minute change in Qp is dQp. If (14), (15), and (16) are modified simultaneously, the following expression can be obtained.

dW = Ja · dQa (17)
dQp = Jp · dQa (18)
Here, Ja is a 6 × 6 matrix, and Jp is a 12 × 6 matrix.

The state in which the workpiece 140 moves despite the positioning of the driving joint, that is, the state in which it cannot stand independently is that dW is not zero even though dQa is zero in the equation (17). It corresponds to. This phenomenon occurs when the inverse matrix Ja ⁻¹ of the Jacobian matrix Ja becomes zero. Thus, the state where the determinant of the inverse Jacobian matrix Ja ⁻¹ becomes zero means that the work reaches a position called “think point”.

  The state that reaches the singular point where the determinant of the Jacobian matrix Ja is zero exists in both the open-loop link system and the closed-loop link system, whereas the state that reaches the thought point is a closed-loop having a non-driven joint portion. Only a link system can exist. In addition, the singular point can be easily escaped even if it reaches the point of control, but the thought point may not return to the original form once it reaches, and the work becomes the point of thought. You should avoid reaching. This can be said for the entire positioning robot of the present embodiment.

Therefore, as a method of selecting six drive joints from all 18 joints, the determinant of the inverse Jacobian matrix Ja ^{−1 in} the equation (17) is the entire space, the target work movement space, or the work movement path. In the above, a drive joint that does not become zero may be selected. The same applies to the case where there are 1 articulated robot having n drive joints and m non-drive joints. Here, n, m, and l are arbitrary integers. In addition to an articulated robot having an inclined joint, for example, a positioning robot having a vertical articulated arm is the same, and the determinant of the inverse Jacobian matrix Ja ⁻¹ does not become zero. This is an independence condition that prevents the deformation of the workpiece.

The host controller stores a functional expression that can calculate the determinant of the inverse Jacobian matrix Ja ⁻¹ shown in Expression (17), and based on each displacement amount given from the drive joint, the inverse Jacobian matrix Ja ^−1. The determinant may be calculated at any time. When the collaboratively gripped work 140 is moved by test using the multi-joint arms 130A to 130C during teaching or the like, if the determinant of the inverse Jacobian matrix Ja- ¹ reaches a predetermined value near zero, the output means Information indicating that the workpiece 140 is approaching the thought point may be notified, and a robot operation stop command may be given to the servo controller. As a result, each articulated arm can be prevented from becoming unable to stand on its own.

Moreover, you may display the angle rotation direction of the joint part by which the absolute value of the determinant of inverse Jacobian matrix Ja- ¹ becomes large with an output means. In this case, the designated drive joint is moved in the plus direction and the minus direction from the current position, and the rotation direction in which the absolute value of the determinant of the inverse Jacobian matrix Ja- ¹ is increased is output. As a result, the operator can easily determine that the workpiece 140 moves away from the thought point, and convenience can be improved.

In this way, the host computer or the sub computer executes a predetermined program, thereby controlling the articulated arm so as to avoid the thought point, and the absolute value of the determinant of the inverse Jacobian matrix Ja ⁻¹ is obtained. A calculating unit for calculating, a determining unit for determining whether an absolute value of a determinant of the inverse Jacobian matrix Ja ⁻¹ is equal to or less than a predetermined set value, and a determinant of the inverse Jacobian matrix Ja ^{−1 in} the determining unit Is determined to be smaller than the set value, a control unit that angularly displaces the angle of the drive joint so that the absolute value of the determinant of the inverse Jacobian matrix Ja ⁻¹ is greater than the set value. A computer including the above is also included in the present invention. In addition, when moving the workpiece, the present invention also includes controlling the angle of the drive joint so as to avoid a thought point by repeating the calculation step by the calculation unit, the determination step by the determination unit, and the control step by the control unit.

  FIG. 11 is a perspective view showing a positioning robot 220 according to the third embodiment of the present invention. The positioning robot 220 according to the third embodiment has a configuration corresponding to the positioning robot 20 according to the first embodiment. About the corresponding structure, the reference code | symbol which added 200 to the reference code | symbol of the structure shown by the positioning robot 20 of 1st Embodiment is attached | subjected. The positioning robot 220 of the third embodiment shows the same configuration as the positioning robot 120 of the first embodiment, except that each multi-joint arm is formed in a vertical articulated type having 6 degrees of freedom. Will not be described.

  Each multi-joint arm 230A to 230C is provided with the first to sixth joint portions Jt1 to Jt6 arranged in order as the arm bodies 221 to 226 progress in the series direction from the base 228 toward the hand portion 227. The first joint portion Jt1 is a coaxial joint portion, the second joint portion Jt2 is a vertical joint portion, and the third joint portion Jt3 is a vertical joint portion. The fourth joint portion Jt4 is a coaxial joint portion, the fifth joint portion Jt5 is a vertical joint portion, and the sixth joint portion Jt6 is a coaxial joint portion.

  In the present embodiment, the first to third joint portions Jt1 to Jt3 are drive joint portions, and the fourth to sixth joint portions are non-drive joint portions. In addition, a triangle is formed by line segments connecting the bases 228 of the articulated arms 230A to 230C. The driving joint unit fixes the relative displacements of the two arm bodies to be connected to each other, so that the multi-joint arms 230A to 230C are supported by each other via the work 240 to be gripped in cooperation, whereby the multi-joint arms 230A to 230A are supported. It is selected as a joint portion where deformation of 230C is prevented.

  When the third joint portion Jt3 and the fifth joint portion Jt5 of each of the multi-joint arms 230A to 230C extend in parallel, the workpiece 240 can move in the vertical direction if each is a non-drive joint portion. End up. Further, when the first joint portion Jt1 and the sixth joint portion Jt6 of each of the multi-joint arms 230A to 230C extend in parallel, the workpiece 240 can move in the horizontal direction if they are non-drive joint portions. End up. On the other hand, in this embodiment, as described above, the third joint portion Jt3 and the fifth joint portion Jt5 serve as drive joint portions, thereby preventing the workpiece 240 from being undesirably displaced. it can.

  Even with the positioning robot 220 of the third embodiment, the same effects as those of the positioning robots 20 and 120 of the first and second embodiments can be obtained. That is, when the cooperatively gripped work 240 is moved, the non-driving joint portion is provided, so that the deformation force applied to the work 240 and the positioning robot 220 caused by the error can be suppressed. Damage to the robot 220 can be prevented. Even in the positioning robot 220 of the third embodiment, the drive joint portion is selected and the movable region or the movement path of the workpiece 240 is determined so as to satisfy the above-described independence condition. preferable.

  Each of the above-described embodiments is merely an example of the present invention, and the configuration can be changed within the scope of the invention. For example, the present invention is applicable when the workpiece 40 is gripped cooperatively by a plurality of multi-joint arms and at least one joint portion of the multi-joint arm is a non-driven joint. For example, the present invention includes a positioning robot that cooperatively grips a workpiece with a multi-joint arm in which all joint portions are drive joint portions and a multi-joint arm in which all joint portions are non-drive joint portions. Moreover, the non-drive joint part which a multi-joint arm has can be set to an arbitrary number.

  In addition, it is preferable that the workpiece is cooperatively gripped by three or more multi-joint arms, but a positioning robot that cooperatively grips the workpiece by two multi-joint arms is also included in the present invention. Further, the workpiece may be gripped cooperatively by different types of articulated robots. Further, a configuration in which the brake 41 and the encoder 42 are not provided in the non-drive joint portion is also included in the present invention. In this embodiment, the sub-controller 32 and the host controller 31 are used. However, each servo motor 41 may be controlled by one controller that performs these operations.

It is a block diagram which shows the positioning robot 20 which is 1st Embodiment of this invention. It is a perspective view which shows the state which hold | gripped the workpiece | work 40 by each articulated arm 30A-30C in cooperation. It is sectional drawing which shows 1st-4th joint part Jt1-Jt4 among the multi-joint arms 30A. It is a figure which shows the deformation | transformation conditions of the articulated arm which hold | gripped the workpiece | work 40 cooperatively. It is a flowchart which shows the workpiece movement control procedure of the articulated arm 30A by sub controller 31A. 4 is a flowchart showing a control procedure of sub controllers 31A to 31C in the host controller 32. It is a flowchart which shows the positioning control operation | movement of the hand part 27 by 31 A of sub controllers. It is a block diagram which shows the positioning robot 120 which is 2nd Embodiment of this invention. It is a figure which shows the workpiece | work 140 hold | gripped by the positioning robot 120 in cooperation. It is a figure for demonstrating the independence conditions of a positioning robot. It is a perspective view which shows the positioning robot 220 which is 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Positioning robot 21-26 Arm body 27 Base 28 Hand part 30A-30C Articulated arm 31A-31C Subcontroller 32 Host controller 40 Work 41 Servo motor 42 Brake 43 Encoder Jt1-Jt6 Joint part

Claims (5)

A positioning robot capable of positioning a workpiece to be cooperatively held by a plurality of articulated arms at a target position,
(A) a plurality of articulated arms,
(A1) a plurality of arm bodies arranged in series,
(A2) a plurality of joint portions that connect two adjacent arm bodies so as to be capable of relative displacement, and a plurality of joint portions including a drive joint portion that can drive relative displacement between the two arm bodies ;
(A3) a hand unit that is connected to an arm body at one end in the series direction and grips a workpiece;
(A4) a plurality of articulated arms each having a base portion connected to the arm body at the other end in the series direction and fixed at a fixed position;
(B) the respectively provided on each drive dynamic joints, and a plurality of driving means for relative displacement drive two arms body driving joint portion is connected,
(C) A relative displacement position of each arm body to be moved to a target position for a work that is cooperatively gripped by a plurality of multi-joint arms is calculated, and each drive unit is set so that each arm body is relatively displaced according to the calculation result. and a control means for controlling each viewing including,
At least one of each multi-joint arm has the drive joint part and the non-drive joint part that the two arm bodies to be connected are passively relatively displaced but cannot be actively displaced relatively Driving articulated arm,
Among each joint part, each driving joint part fixes each relative displacement of the two arm bodies to be connected to each other so that each multi-joint arm is supported by each other through a work to be held in cooperation. A positioning robot characterized in that it is selected as a joint that prevents deformation of the arm . (D) further including a displacement prevention means that can be switched between a fastening state that prevents the relative displacement of the two arm bodies to which each joint portion is connected and an open state that allows the relative displacement;
The positioning robot according to claim 1, wherein the control means controls the displacement prevention means. The single drive articulated arm is:
Displacement preventing means switchable between a fastening state that prevents relative displacement of the two arm bodies connected to the non-drive joint portion and an open state that allows relative displacement;
Detecting means for detecting a relative displacement position of the two arm bodies to which the non-driving joint portion is connected;
3. The positioning robot according to claim 1, wherein the control means switches the state of the corresponding displacement prevention means based on the detection result of the detection means. Each joint part rotates about the rotation axis which inclines with respect to the axis line of the coaxial joint part and each arm body which connect two arm bodies to be connected to the axis line of one arm body rotatably. 4. The positioning robot according to any one of claims 1 to 3 , wherein the positioning robot is realized by any one of inclined joint portions that are freely connected. Each articulated arm has six degrees of freedom, the driving joints, the positioning robot according to any one of claims 1-4, characterized in that it is provided more than six.

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