JP2011224745A - Robot teaching device and controller for the same, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such the problem that a teaching operator has to manually operate a programming pendant while shifting a hand from a teaching arm to the programming pendant in order to operate a robot so that a teaching tool reaches an operation point where the teaching tool is taught when the teaching tool does not reach the desired operation point since the teaching arm exceeds its movable range when the teaching tool of the teaching arm is moved to the operation point where the teaching tool is taught, in the robot teaching device of the conventional technique in which the teaching arm is used.SOLUTION: For example, there is provided a robot teaching device which calculates the degree of allowance related to the allowance of the teaching arm attached to the robot and which controls the operation of the robot so that the allowance is not reduced.

Description

  One embodiment of the present invention relates to an apparatus and program for teaching the position and orientation of an end effector of a robot in a teaching playback type industrial robot using a teaching arm.

Currently, there are several methods for teaching the position and orientation of the end effector in the teaching playback type industrial robot.
There is a method that mainly uses a box-type operation device called a programming pendant. In this method, the teaching worker pushes the axis operation switch on the programming pendant to move the robot as desired, and moves the end effector to the work position of the work object to set the position and posture of the end effector to the robot. It was stored in the controller. However, operating the robot by pushing the axis operation switch in this way requires skill, and no matter how much you are skilled in operation, you can change the movement speed of the end effector or move the end effector to the correct work position. There was the difficulty that it took time to do. Furthermore, there is a problem that the robot is hit against the work object by mistakenly pressing the switch.

  There is a technique called direct teaching in which teaching is performed by a teaching worker directly holding the tip of the robot and moving the tip to a working position. However, this method requires an expensive force sensor to measure the operating force of the teaching worker. A large operating force must be applied to achieve stable force control, and precise position adjustment is required. However, it was difficult.

  There is a technique in which a teaching worker holds an indicating rod and teaches by measuring the position of the tip of the indicating rod with a three-dimensional distance sensor or the like. However, this method is accurate because various errors such as error due to sensor resolution, sensor installation error, and robot installation error occur during coordinate conversion from the coordinate system of the three-dimensional distance sensor to the robot coordinate system. However, it was difficult to measure the position, and in order to remove these errors, a complicated calibration was required.

  As a technique for overcoming these difficulties, there is a technique for attaching a detachable teaching arm to the tip of the robot and teaching the position and orientation of the end effector with the pointing tool of the teaching arm (for example, Patent Document 1 or 2). reference). FIG. 9 is a diagram showing a conventional robot teaching apparatus. In FIG. 9, reference numeral 1 denotes a robot, and a teaching arm 4 is attached to the tip 1b of the robot. In this method, the teaching worker directly grips and moves the teaching arm 4 and determines the position and orientation of the end effector of the robot 1 during actual work based on the position and orientation of the pointing tool 48 of the teaching arm 4 during teaching. Teaching.

JP-A-7-276275 (FIG. 1, item 4) Japanese Patent Laid-Open No. 3-19782 (FIG. 1)

  However, in the robot teaching apparatus of the prior art using the teaching arm, when the instruction tool of the teaching arm is moved to the work point to be taught, the movable range of the teaching arm is exceeded. If the pointing tool does not reach the desired work point, the teaching worker once releases the teaching arm and moves it to the programming pendant to operate the robot so that the pointing tool reaches the working point to be taught. After manually operating the programming pendant, it was necessary to have the teaching arm again, which was troublesome. In order to minimize such shifts, it is only necessary to use a teaching arm with a wide movable range, that is, a large teaching arm. However, the large teaching arm has poor operability and is difficult to attach and detach. In reality, the teaching arm cannot be made too large.

  One embodiment of the present invention is a robot teaching device that teaches the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot, and has the following features It is.

  The teaching arm has at least one rotary joint and at least two links, and two links are connected to each of the rotary joints of the teaching arm, and the two links rotate around the rotary joint. The angle formed by the two links has an upper limit and a lower limit, and one of the links of the teaching arm has an instruction unit for instructing the position and orientation of the end effector. Then, the position and orientation of the end effector is taught by storing the position and orientation of the instruction unit, the instruction unit moves in response to an external force being applied to the link having the instruction unit, and the instruction unit moves. As a result, at least one of the links of the teaching arm rotates.

  The robot has at least one rotary joint or linear motion joint and at least two links, and two links are connected to each of the rotary joint or linear motion joint of the robot, Two connected links are rotated around the rotary joint by a motor, one of the two links connected to the linear motion joint of the robot is expanded and contracted by a motor, and each of the links of the robot is In response to an external force being applied, the robot is prevented from rotating and expanding and contracting, and one of the robot links has a teaching arm mounting portion for mounting a teaching arm, As the at least one of them rotates or expands and contracts, the teaching arm mounting portion moves.

And the device
For each of the rotary joints of the teaching arm, the margin of the rotary joint, which is a function of the current angle formed by the two links connected to the rotary joint, the small margin being the current angle And a margin of the rotary joint indicating that a difference between an upper limit angle and a lower limit angle of the two links is small, and the rotation of at least one rotary joint of the teaching arm The margin of the link, which is a function of the current angle formed by the two links connected to the joint, and the small margin means that the current angle and the two links when the two links are aligned. The margin of the link indicating that the difference between two links is small is obtained, and the margin of the teaching arm is obtained by multiplying the obtained margin of the rotary joint and the margin of the link. It means for determining,
Means for determining a direction in which the pointing unit has moved based on a difference between a current position of the pointing unit and a position before a predetermined time when a margin of the teaching arm is equal to or less than a desired threshold;
Means for generating the signal to be input to the motor of the robot and for moving the teaching arm mounting portion in the direction obtained.

  The teaching arm may further include at least one linear motion joint. In this case, two links are connected to each of the linear motion joints, and one of the two links can expand and contract, and the length of the link that changes by expanding and contracting is the upper limit. And at least one of the links of the teaching arm rotates or expands and contracts as the pointing unit moves.

  Further, in this case, the means for obtaining the margin is further a function that is a function of the length of one of the links connected to the linear motion joint for each of the linear motion joints of the teaching arm. The margin of the dynamic joint, where the margin is small indicates the margin of the linear joint indicating that the difference between the current length of the link and the upper limit or the lower limit of the link length is small. The margin of the teaching arm is obtained by multiplying the obtained margin of the rotary joint, the obtained margin of the link and the obtained margin of the linear motion joint.

  The means for generating the signal may generate the signal when a margin of the teaching arm is equal to or less than the desired threshold value. The means further includes a speed for moving the teaching arm mounting portion based on the obtained direction and the obtained margin of the teaching arm, the magnitude of the speed being a margin of the teaching arm. It is also possible to obtain the speed that increases as the signal becomes smaller, and to generate the signal based on the speed.

  Another embodiment of the present invention is a controller of a robot teaching apparatus that teaches the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot. This controller includes the above-described means.

  Another embodiment of the present invention is a program for teaching the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot. When this program is executed on the computer, the computer functions as the above-described means.

  According to one embodiment of the present invention, when the instruction portion of the teaching arm attached to the robot is moved, if the margin of the teaching arm falls below a certain threshold, the teaching arm attachment portion of the robot is set to the teaching arm. It will automatically move in the direction you moved. Therefore, even if you want to move the instruction unit to a work point that does not reach unless you move the teaching arm attachment unit, you can continue to move the instruction unit to that work point without changing to the programming pendant. Troublesome operations can be omitted, and the teaching time can be shortened.

1 is an external view of a system including a robot teaching apparatus according to an embodiment of the present invention. The figure which shows the example of the arm for teaching in the robot teaching apparatus which concerns on one Embodiment of this invention The figure which shows operation | movement of a robot when the robot teaching apparatus which concerns on one Embodiment of this invention is used. The block diagram of the controller in the robot teaching apparatus which concerns on one Embodiment of this invention The figure which shows the example calculation method of the margin of a rotation joint The figure which shows the example calculation method of the margin of a linear motion joint Diagram showing an exemplary calculation method for link margins Diagram showing an exemplary alternative calculation method for link margins Schematic diagram of prior art robot teaching device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external view of a system including a robot teaching apparatus according to an embodiment of the present invention. The “robot teaching device” is a device used when teaching the operation of the robot (at the time of teaching) in order to set the operation of the robot at the time of work. In the following description, the term “the robot teaching device according to this embodiment” is used to mean “a device including a part of the controller 200, the programming pendant 300, and the teaching arm 400”. There is no intention to limit what the robot teaching apparatus includes. An example of teaching “robot operation” is teaching “end effector position / posture” described later.

  A “robot” is an apparatus that performs some work on behalf of a person. The robot 100 used in the robot teaching apparatus according to this embodiment teaches an operation after teaching the operation using the robot teaching apparatus. It is assumed that the robot is an industrial robot of a method (teaching playback method) that performs an automatic operation by reproducing the operation. However, another device that performs some work instead of a person may be used as the robot 100. In the robot teaching apparatus according to this embodiment, the teaching operator can teach the position and orientation during work of an end effector (not shown) attached to the robot 100 using the teaching arm 400. The “end effector” is a device that performs some work on the work target of the industrial robot, such as a hand (gripper) for grasping an object or a grinder for deburring. The end effector only needs to be attached to the robot 100 during work, and can be removed during teaching. “At work” means when the end effector actually performs some work on the work object.

The robot 100 has at least one rotary joint or linear motion joint and at least two links. Two links are connected to each of the rotary joint and the linear joint of the robot 100. In the case of a rotary joint, the two links connected to the rotary joint of the robot 100 are rotated around the rotary joint by a motor. An angle detection sensor such as an encoder for detecting the rotation angle of the link around the joint (hereinafter referred to as “joint angle”) can be attached to the axis of the rotary joint. The angle detection sensor outputs an angle detection signal indicating the detected joint angle. The output angle detection signal is input to the controller 200. Based on this angle detection signal, an angle formed by two links connected to the joint can be obtained for a rotary joint of the robot 100.
On the other hand, in the case of a linear joint, one of the two links connected to the linear joint of the robot 100 is expanded and contracted by a motor. A length detection sensor for detecting the length of the link that changes as it expands and contracts can be attached to the axis of the linear motion joint. The length detection sensor outputs a length detection signal indicating the length of the detected link. The output length detection signal is input to the controller 200.
The motor is controlled by a controller (control device) 200. The motor may have a joint. Further, each link of the robot 100 is configured not to rotate or expand or contract in response to an external force being applied. One of the links of the robot 100 has a teaching arm attachment part 130 for attaching the teaching arm 400 (see FIG. 3). In the robot teaching apparatus shown in FIG. 1, the link having the teaching arm attachment unit 130 is the robot tip link 110 that is the link closest to the tip of the robot among the links provided in the robot 100. Here, the teaching arm 400 is attached in the direction 111 of the axis serving as the center of rotation of the robot tip link 110, but it may be attached in a direction perpendicular to this axis. Further, it is not always necessary to attach to the tip portion, and for example, it may be attached to the root portion of the robot tip link 110. The teaching arm attachment unit 130 moves as at least one of the links of the robot 100 rotates or expands and contracts. In the robot teaching apparatus according to this embodiment, the robot 100 has a 6-degree-of-freedom configuration.

  The “programming pendant” is a device that includes one or both of a display for displaying information and a plurality of buttons for inputting information, and transmits and receives signals based on the information. The programming pendant has a function for manually operating the robot using the display or button, a function for changing the mode in the robot teaching device, a function for checking and editing the operation of the taught robot, and the like. Yes. Examples of modes include a mode for teaching a robot operation (mode at teaching), a mode for checking and editing the taught operation, and a mode for reproducing the taught operation (mode at work). Can be mentioned. Examples of editing a taught action include using the above buttons to modify part of the taught action, duplicating or deleting part of the taught action, and one of the taught actions. For example, a conditional branch may be set between a part and a part. The programming pendant 300 in the robot teaching apparatus according to this embodiment is connected to the controller 200 and inputs / outputs the above signals to / from the controller 200. The programming pendant 300 may further have a function of changing parameters in the robot teaching apparatus using the buttons. As examples of parameters, a threshold value E0 of a margin for teaching arm described later, Amin_i, Amax_i, a1_i, and a2_i related to the margin of a rotary joint, Bmin_k, Bmax_k, b1_k related to a margin of a linear motion joint, And b2_k, and w1 and w2 related to the margin of the link.

  The “teaching arm” is a device that is attached to a robot at the time of teaching and is operated by a teaching worker to teach the operation of the robot at the time of working. The teaching arm 400 in the robot teaching apparatus according to this embodiment has at least one rotary joint and at least two links. Two links are connected to each of the rotary joints of the teaching arm 400. These two links can rotate around the rotary joint. However, the angle formed by these two links has an upper limit and a lower limit. The teaching arm 400 may further include at least one linear motion joint. Two links are connected to each of the linear joints of the teaching arm 400. One of these two links can expand and contract. However, the length of the link that changes by expanding and contracting has an upper limit and a lower limit. One of the links of the teaching arm 400 has an instruction unit 430 for instructing the position and orientation of the end effector (see FIG. 2). The position and orientation of the end effector are taught by storing the position and orientation of the instruction unit 430. Note that the postures of the end effector and the instruction unit are determined based on the direction in which they are facing, and can be, for example, a three-dimensional angle of these directions. In response to an external force being applied to the link having the instruction unit 430, the instruction unit moves. The link having the instruction unit 430 can further include a gripping unit 410 (see FIG. 2), and an external force can be applied to the link by the teaching operator gripping and moving the gripping unit. As the instruction unit 430 moves, at least one of the links of the teaching arm 400 rotates or expands and contracts. The rotary joint and the linear joint of the teaching arm 400 can also include an angle detection sensor and a length detection sensor as described above with respect to the robot 100.

  FIGS. 2A and 2B are diagrams showing an example of the teaching arm 400. 2A shows an example of a serial link type arm, and FIG. 2B shows an example of a parallel link type arm. In FIG. 2, reference numerals J1 to J6 indicate possible rotation directions of the link. Both of these arm examples use a 6-degree-of-freedom configuration, but the teaching arm 400 may use other degrees of freedom, such as 3 or 4 degrees of freedom, depending on the robot's work application. And a different degree of freedom configuration than the robot 100 can be used. The teaching worker can grasp and operate the grasping unit 410 to instruct the position and posture of the end effector of the robot when working by the position and posture of the instruction unit 430. In addition, in these examples of the arm, the instruction unit 430 is located at the tip of the arm, but the instruction unit 430 may be located in another place of the arm. Further, as shown in FIG. 2, the wrist mechanism in the examples of these arms is designed so that the possible rotation directions J4 to J6 of the links relating to the joints constituting the wrist mechanism are orthogonal to each other. If it is designed, it is difficult to become a unique posture and operability is generally good. The teaching arm 400 can be attached to the robot 100 via the attachment jig 120. At this time, a mechanism that can be accurately attached with a positioning pin or the like so as to minimize the attachment error may be used. When the teaching worker presses the switch 420, the controller 200 can store the position and orientation of the instruction unit 430 when the switch is pressed. In the following description, the robot teaching apparatus according to this embodiment uses a serial link type arm shown in FIG.

  Here, with reference to FIG. 3, the operation of the robot 100 when using the robot teaching apparatus according to the embodiment of the present invention will be described. The robot 100 and the teaching arm 400 shown in FIG. 3 schematically show the robot 100 shown in FIG. 1 and the teaching arm 400 shown in FIG. First, it is assumed that the robot 100 and the teaching arm 400 are in the state shown in FIG. Next, it is assumed that the teaching operator holds the grip portion 410, moves the grip portion in the direction of the arrow 411, and the teaching arm 400 is in the state shown in FIG. At this time, in the robot teaching device of the prior art, if the teaching operator further moves the gripping part 410 in the direction of the arrow 411, the robot 100 does not operate, so the teaching arm 400 finally reaches the movable limit, and the gripping part 410 could not be moved in this direction. Note that the fact that the teaching arm 400 reaches the movable limit means that the link has reached the limit for at least one of the joints of the arm. More specifically, when the at least one joint is a rotary joint, the angle formed by the two links connected to the rotary joint has reached the upper limit or the lower limit of the angle, or the two links are formed. The angle means an angle when the two links are in a straight line, for example, 180 degrees, and when the joint is a linear joint, the length of the link connected to the linear joint is It means that the upper limit or the lower limit of the length has been reached. Therefore, in the prior art robot teaching apparatus, when it is desired to teach a work point that is farther from the instruction unit 430 when the teaching arm 400 reaches the movable limit, the instruction unit 430 reaches the work point. In order to operate the robot 100, the teaching operator needs to change the teaching arm 400 to the programming pendant 300 and manually operate the pendant.

  However, in the robot teaching apparatus according to this embodiment, even in such a case, the teaching operator does not need to change the teaching arm 400 to the programming pendant 300. This is because in the robot teaching apparatus according to this embodiment, since the robot 100 automatically operates so that the teaching arm 400 does not reach the movable limit, the teaching operator can continue to move the gripper 410. is there. Note that the robot 100 may be automatically operated when the teaching arm 400 reaches the movable limit, and in this case, the teaching operator can continue to move the gripper 410. More specifically, in the robot teaching apparatus according to this embodiment, when the robot 100 has a small margin to the movable limit of the teaching arm 400 (hereinafter, referred to as “teaching arm margin”), for example, When the teaching arm 400 is in the state shown in FIG. 3B, the teaching arm mounting portion 130 is moved in the direction of the arrow 131 so that the margin is increased in this embodiment so that the margin is not further reduced. That is, it automatically operates so as to move the gripper 410 in the same direction as the arrow 411 that has been moved. The robot 100 and the teaching arm 400 are brought into the state shown in FIG. The margin of the teaching arm in FIG. 3C is larger than the margin of the teaching arm in FIG. FIG. 3C is an exemplary diagram when the teaching worker stops the gripper 410 at the time when the automatic operation of the robot 100 is started. In the robot teaching apparatus according to this embodiment, the teaching operator can continue to move the gripper 410 regardless of the start of the automatic operation of the robot 100. Note that the robot 100 may be automatically operated so that the margin of the teaching arm is kept constant. Further, when there is no more margin for the teaching arm, that is, when the teaching arm 400 reaches the movable limit, the robot 100 may be automatically operated so that the margin is increased. Hereinafter, the “operation for preventing the margin of the teaching arm from becoming small” as described above will be referred to as “movable limit avoidance operation” of the robot 100.

  FIG. 4 is a block diagram of the controller 200 according to an embodiment of the present invention. The controller 200 includes teaching processing means 210 and 220, means 230 to 250 related to an automatic movement limit avoiding operation, and a motor control means 260. Further, the controller 200 can be a computer including a calculation device such as a CPU, a storage device such as a memory, and an input / output device for transmitting and receiving a desired signal. Here, the desired signal may include a signal used in serial communication with the motor, the sensor, the programming pendant 300, or the like. This computer can function as the above means by using a program. More specifically, when the calculation device executes the program stored in the storage device, the input / output device receives a signal, the calculation device calculates a value based on the received signal, and the storage device calculates The value can be stored. The input / output device can further transmit a signal based on the calculated value.

  When the teaching worker operates with the gripper 410, the angle detection sensor for each axis of the robot 100 and the angle detection sensor for each axis of the teaching arm 400 are used to detect the position and orientation of the instruction unit 430. The angle detection signal is taken into the tip position / orientation calculation means 210. When one or both of the robot 100 and the teaching arm 400 include a linear motion joint, a length detection signal is further captured. The tip position / orientation calculation means 210 obtains the joint angles and link lengths of the robot 100 and the teaching arm 400 based on the acquired angle detection signal and length detection signal for each control cycle of the controller 200. Position and orientation data for indicating the position and orientation of the instruction unit 430 is calculated and stored from the joint angle and the link length by forward kinematics calculation. The position / posture data includes, for example, coordinates (X, Y, Z) indicating the position of the instruction unit 430 and posture angles (α, β, γ) indicating the posture, coordinates (X, Y, Z) indicating the position, and A 3 × 3 posture matrix (R) indicating the posture is included. When the teaching worker presses the storage switch 420, the calculated position / orientation data is sent as teaching data to the teaching position / orientation storage means 220, and the teaching position / orientation storage means 220 stores the teaching data. The programming pendant 300 can read the stored teaching data from the teaching position and orientation storage means 220 and display it.

Next, a method for causing the robot 100 to automatically perform the movable limit avoidance operation, which is a feature of the controller 200 according to an embodiment of the present invention, will be described.
In the controller 200, first, the margin calculation means 230 obtains the margin of the teaching arm related to the margin of the teaching arm attached to the robot 100. In the controller 200, the margin of the teaching arm ranges from 0 to 1, and when the margin of the teaching arm is sufficiently large, 1 approaches 0 as the margin decreases, and when the margin does not exist, for example, 0 when the link cannot rotate any more at a certain joint of the teaching arm 400, when the link cannot be expanded or contracted any more, or when the link is fully extended at a certain joint. To take.

  Next, the robot position change speed calculation unit 240 and the robot position change command generation unit 250 allow the robot 100 to prevent the teaching arm margin from being reduced based on the teaching arm margin obtained by the margin calculation unit 240. To control the operation. More specifically, the robot position change speed calculation unit 240 compares the margin calculated by the margin calculation unit 230 with a predetermined desired threshold value. A margin greater than the threshold indicates that the robot 100 may remain stationary. That the margin is less than or equal to the threshold value indicates that the robot 100 must perform the movement limit avoidance operation. If the margin falls below a certain threshold, the robot position change speed calculation means 240 calculates the movement direction and movement speed of the teaching arm attachment unit 130 so that the margin of the teaching arm is not further reduced. . Then, in accordance with the movement direction and movement speed calculated by the robot position change speed calculation means 240, the robot position change command generation means 250 sets the movement destination position of the teaching arm attachment unit 130 (hereinafter referred to as “target position”). ) Is calculated to generate a command for moving the portion to the target position. Thereafter, this command is passed to the motor control means 260, and a signal input to the motor of the robot 100 is generated based on this command. When this signal is actually sent to the motor, the robot 100 is operated, and the position of the teaching arm mounting portion 130 is updated.

According to such a method, as described with reference to FIG. 3, when the margin of the teaching arm becomes small, the robot 100 automatically performs the movable limit avoiding operation, so that the teaching arm 400 reaches the movable limit. There is no. Therefore, the teaching worker can continue to move the gripper 410 until the instruction unit 430 reaches the work point to be taught. In this embodiment, the movement direction, the movement speed, and the target position are calculated for the teaching arm attachment unit 130. However, with respect to another place of the robot 100 so that the teaching arm 400 does not reach the movable limit. These can be calculated. Further, the threshold value E0 may be set to 0, for example, so that the robot 100 automatically operates when the teaching arm 400 reaches the movable limit. The gripper 410 can continue to move until it reaches the work point to be taught.
Here, an exemplary calculation method of the margin of the teaching arm by the margin calculation means 230 will be described with reference to FIGS.

  With reference to FIG. 5, the 1st calculation method of the margin of a teaching arm is demonstrated. In this calculation method, the margin of the teaching arm is calculated by calculating the margin related to the rotation of the link related to a certain rotating joint, for example, the margin of the rotating joint indicating the margin until the link cannot be rotated. The The margin of the rotary joint can be a function of the current angle formed by the two links connected to the rotary joint. The margin can be expressed as a numerical value in a certain range, for example, as a value from 0 to 1, and the smaller the value, the less the margin, that is, the upper limit or lower limit of the angle formed by the current angle and the two links. It can be shown that the difference from the angle is small. FIG. 5A shows two links 451 and 452 connected to a rotary joint i450 among the links of the teaching arm 400. The margin Es_i of the rotary joint 450 can be the following function based on the angle θi formed by the link 451 and the link 452.

FIG. 5B shows a graph of this function. This function can be defined based on the parameters Amin_i and Amax_i indicating the lower and upper limit angles and the parameters a1_i and a2_i. Here, the parameters Amin_i and Amax_i may be values corresponding to the structural limits of the rotary joint and the link, or may be desired values instead. In this function, the margin Es_i of the rotary joint 450 is 0 when the angle θi exceeds the joint angle limit of each axis (Amin_i> θi or Amax_i <θi), and is within the limit (Amin_i ≦ θi ≦ Amax_i). In this case, a value from 0 to 1 is taken according to the angle θi. Desired values can be set in advance for the parameters a1_i and a2_i. These parameters a1_i and a2_i are for providing a dead zone, and the presence of this dead zone can prevent a jerky movement that the robot always keeps moving. The margin Es_i of the rotary joint 450 can be set as the margin of the teaching arm. Moreover, the margin of a plurality of rotary joints can be defined as the product of the margin of each rotary joint, and this product can be used as the margin of the teaching arm. For example, when the teaching arm 400 includes six rotary joints, the margin Es of the entire joint can be obtained by the following equation.

Es = Es_1 x Es_2 x Es_3 x Es_4 x Es_5 x Es_6
Such a margin Es of the entire joint can be set as a margin of the teaching arm.
With reference to FIG. 6, the second calculation method of the margin of the teaching arm will be described. In this calculation method, it is assumed that the teaching arm includes a linear joint, and the margin of the teaching arm is a margin related to the expansion and contraction of the link related to a certain linear motion joint, for example, the link cannot expand and contract. It is calculated by calculating the margin of the linear joint indicating the margin up to. The margin of the linear motion joint can be a function of the current length of one of the links connected to the joint. The margin can be expressed as a numerical value in a certain range, for example, as a value from 0 to 1, and the smaller the value, the less the margin, that is, the upper limit or the lower limit of the current length and the link length. It can be shown that the difference is small. FIG. 6A shows two links 461 and 462 connected to a linear motion joint k460 among the links of the teaching arm 400. The margin Ed_k of the linear motion joint 460 can be the following function based on the length δk of the link 462.

FIG. 6B shows a graph of this function. As shown in FIG. 6B, this function can be defined based on the parameters Bmin_k and Bmax_k indicating the lower and upper limit lengths, and the parameters b1_k and b2_k. Here, the parameters Bmin_k and Bmax_k may be values corresponding to the structural limits of the linear motion joint and the link, or may be desired values instead. In the function shown in FIG. 6B, the margin Ed_k of the linear motion joint 460 is 0 when the distance δk exceeds the joint distance limit of each axis (Bmin_k> δk or Bmax_k <δk), and within the limit ( In the case of Bmin_k ≦ δk ≦ Bmax_k), a value from 0 to 1 is taken according to the distance δk. Desired values can be set in advance for the parameters b1_k and b2_k. These parameters b1_k and b2_k are for providing a dead zone as described above regarding the margin of the rotary joint. The margin Ed_k of the linear motion joint 460 can be set as the margin of the teaching arm. Further, the product of the margins of the respective linear motion joints can be used as the margin of the teaching arm, similarly to the margin of the rotary joint. Of course, the product of the margin of the rotary joint and the margin of the linear motion joint may be used as the margin of the teaching arm.

  With reference to FIG. 7, a third method for calculating the margin of the teaching arm will be described. In this calculation method, the margin of the teaching arm is calculated by calculating a margin of a link indicating a margin until two links connected to a certain joint are fully extended. The link margin can be a function of the current angle formed by the two links connected to the rotary joint. The margin can be expressed as a numerical value in a certain range, for example, as a value from 0 to 1, and the smaller the value, the less the margin, that is, when the current angle and the two links are in a straight line. It can be shown that the difference from the angle formed by the two links is small. Note that the fact that the two links are in a straight line means that the two links are fully extended. Further, “the angle formed by the two links when the two links are in a straight line” is 180 degrees in this embodiment, but it is practically used to indicate that the two links are fully extended. If sufficient, the angle may deviate from 180 degrees, such as 179.9 degrees or 180.1 degrees, and in some cases 170 degrees or 190 degrees. Needless to say, these angles are merely examples. Hereinafter, this calculation method will be described by taking the margin of the link related to the joint 440 in the serial link type arm shown in FIG. 2A as an example. Needless to say, the link margin may be calculated for another joint. FIG. 7 (a) shows two links 442 and 443 connected to the joint 440. Since the joint 440 and the joint 441 of the arm can be regarded as a human elbow joint and a shoulder joint, respectively, the link 442 is hereinafter referred to as a forearm and the link 443 is referred to as an upper arm. The link margin Ew can be a function of the angle θ formed by the forearm 442 and the upper arm 443. This function can be defined based on the desired parameter w1. The link margin Ew can be obtained according to the following equation.

FIG. 7B shows a graph of this function. Note that “180” in the above expression is “an angle formed by the two links when the two links are in a straight line”, that is, a value representing 180 degrees in this embodiment. Again, this value may be a value representing an angle deviating from 180 degrees if practically sufficient. In this embodiment, θ = 180 indicates that the forearm 442 and the upper arm 443 are aligned, that is, the forearm 442 and the upper arm 443 are fully extended. The parameter w1 is for providing a dead zone. The margin of this link can be made the margin of the teaching arm. Further, the product of the margins of links related to a plurality of joints can be used as the margin of the teaching arm, similarly to the margin of joints.

With reference to FIG. 8, the 4th calculation method of the margin of a teaching arm is demonstrated. This calculation method is an alternative calculation method for the link margin. This alternative calculation method will also be described by taking as an example the margin of the link related to the joint 440 in the serial link type arm shown in FIG. In FIG. 8A, a point 444 indicates a rotation axis in the rotation direction J3 in the arm, and a point 445 indicates a crossing point of rotation axes in the rotation directions J4, J5, and J6 in the arm. A point 446 indicates an intersection of a straight line passing through the point 444 and perpendicular to the upper arm 443 and a straight line passing through the point 445 and parallel to the upper arm 443. Here, L is a distance from point 444 to point 445, h is a distance from point 445 to point 446, and w is a distance from point 446 to point 444.
w ² = L ² −h ² = 0
At this time, the upper arm 443 and the forearm 442 are fully extended. Accordingly, the link margin Ew can be obtained according to the following equation.

FIG. 8B shows a graph of this function. Set an appropriate value for w2 as a parameter in advance. This parameter is also for providing a dead zone. Note that L in the above equation can be obtained based on the design of the teaching arm, and h and w can be obtained based on the angle detection signal from the joint.

In the above, several exemplary methods for calculating the margin of the teaching arm have been described. However, the calculation method for the margin of the teaching arm is not limited to the above calculation method. For example, the margin of the teaching arm may be obtained by combining the margin shown here and multiplying the margin of the rotary joint by the margin of the link. In this case, the margin of the teaching arm is
E = Es × Ew
E calculated according to Furthermore, the margin of the teaching arm can be calculated using various methods, for example, using a well-known index such as manipulability. In this embodiment, E described above is used as the margin of the teaching arm.

Next, a method for calculating the moving direction and moving speed of the teaching arm attachment unit 130 by the robot position changing speed calculating unit 240 in the controller 200 according to this embodiment will be described in more detail. The robot position change speed calculation unit 240 first acquires the margin E of the teaching arm from the margin calculation unit 230 for each control cycle of the controller 200 and compares it with a threshold value E0 which is a desired value. The calculation of the moving direction and moving speed in the controller 200 is performed for each control period only when the margin E of the teaching arm is equal to or less than the threshold value E0. In this embodiment, the moving direction is calculated by obtaining the moving direction unit vector z = (zx, zy, zz) ^T. The moving direction unit vector z is calculated based on an angle detection signal acquired at each control period from the angle detection sensors of the robot 100 and the teaching arm 400. Of the coordinates (X, Y, Z) of the position of the instruction unit 430 calculated by the tip position / orientation calculation means 210, the coordinates calculated in the current control cycle and a past control cycle, for example, one control of the current control cycle The coordinates calculated in the control cycle before the cycle are acquired from the means, and the difference ΔX = (Δx, Δy, Δz) ^T is calculated. Further, the moving direction unit vector z is calculated based on the difference ΔX. To do. In the controller 110, the moving direction unit vector z is calculated according to the following equation.

Further, the moving speed V = (Vx, Vy, Xz) can be calculated based on the moving direction unit vector z, and the magnitude thereof is a value that increases as the margin E of the teaching arm decreases. Can do. In the controller 200, the robot position change speed calculation means 240 calculates the movement speed V according to the following formula based on the maximum movement speed VL, the ratio K, and the operation direction unit vector z.

V = (VL × K) z
In the above equation, the maximum movement speed VL is a parameter of the maximum speed related to the robot operation at the time of teaching set in advance. The ratio K is calculated by the robot position change speed calculation means 240 based on the threshold value E0 and the margin E, so that the moving speed V increases as the margin E of the teaching arm decreases. It is a parameter to make. This ratio K is calculated in the controller 200 according to the following equation.

K = (E0−E) / E0
This mathematical formula is calculated only when E0 ≧ E.
Next, a method for calculating the target position of the teaching arm attachment unit 130 by the robot position change command generation unit 250 in the controller 200 according to this embodiment will be described in more detail. The robot position change command generation means 250 first determines whether the movement direction and the movement speed are calculated by the robot position change speed calculation means 240 for each control cycle of the controller 200. The calculation of the target position in the controller 200 is performed for each control cycle only when the moving direction and the moving speed are calculated. In this embodiment, the target position is calculated by calculating coordinates Xr indicating the target position. The robot position change command generation unit 250 stores the coordinates of the position of the teaching arm attachment unit 130 for each control cycle. As the coordinates to be stored, the coordinates Xr of the calculated target position described below can be used as they are, or the coordinates calculated based on the angle detection signal acquired from the angle detection sensor of the robot 100 through a path (not shown) can be used. It can also be used. The coordinate Xr of the target position is determined by the moving speed V calculated in the current control cycle by the robot position change speed calculation means 240 and the teaching arm in the past control cycle, for example, the control cycle one control cycle before the current control cycle. Based on the coordinate X0 of the position of the attachment portion 130 and a time related to the control cycle, for example, a time Ts of one control cycle, the calculation is performed according to the following formula.

Xr = X0 + V × Ts
The motor control unit 260 controls each axis motor of the robot 100 so as to move the teaching arm mounting portion 130 to the coordinate Xr of the target position, and operates the robot. The coordinate Xr of the target position is obtained only when the moving direction and moving speed are calculated as described above, that is, only when the margin E is equal to or less than the threshold value E0. The movement of the unit 130 is automatically stopped when the margin E becomes larger than the threshold value E0. In this embodiment, each means included in the controller 200 operates on the basis of the control cycle of the controller 200 as described above, but may operate on the basis of another control cycle. The period time and the start timing of the period may be different.

  According to such a method, the robot 100 automatically operates so that the teaching arm attachment unit 130 moves at an appropriate speed in the same direction as the direction in which the teaching operator moves the gripping unit 410. . Therefore, the margin of the teaching arm can be prevented from becoming any smaller. Accordingly, the robot 100 automatically operates so as to avoid the teaching arm 400 from reaching the movable limit. Therefore, the teaching worker does not care about the movable limit of the teaching arm 400, for example, the link cannot rotate. The teaching work can be continued without worrying about the state or the state where the link is fully extended. As a result, the teaching work time can be shortened, and the burden on the worker can be reduced. Even when the robot 100 automatically operates when the teaching arm 400 reaches the movable limit, the teaching operator can perform teaching at an appropriate speed in the same direction as the direction in which the teaching operator moves the gripping portion 410. The movement of the arm attachment portion 130 is the same.

DESCRIPTION OF SYMBOLS 100 Robot 110 Robot tip link 111 Direction of the axis used as the center of rotation of a robot tip link 120 Teaching arm attachment jig 130 Robot teaching arm attachment part 131 Example of moving direction of robot teaching arm attachment part 200 Controller 210 Tip position and orientation calculation means 220 Teaching position and orientation storage means 230 Margin degree calculation means 240 Robot position change speed calculation means 250 Robot position change command generation means 260 Motor control means 300 Programming pendant 400 Teaching arm 410 Teaching arm gripping part 411 Teaching Example of movement direction of gripping portion of arm for teaching 420 Memory switch 430 for teaching arm Instruction portion 440 for teaching arm Joint 441 that can be regarded as an elbow joint Joint 442 that can be regarded as a shoulder joint 442 Connected to a joint that can be regarded as an elbow joint A link 443 that can be regarded as a forearm, and a link 450 that can be regarded as an upper arm connected to a joint that can be regarded as an elbow joint.
451 Link 45 connected to rotational joint i Link 460 connected to rotational joint i A linear motion joint k
461 Link connected to linear joint k 462 Link connected to linear joint k

Claims (5)

A robot teaching device that teaches the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot,
The teaching arm has at least one rotary joint and at least two links, and two links are connected to each of the rotary joints of the teaching arm, and the two links rotate around the rotary joint. The angle formed by the two links has an upper limit and a lower limit, and one of the links of the teaching arm has an instruction unit for instructing the position and orientation of the end effector. Then, the position and orientation of the end effector is taught by storing the position and orientation of the instruction unit, the instruction unit moves in response to an external force being applied to the link having the instruction unit, and the instruction unit moves. And at least one of the teaching arm links rotates,
The robot has at least one rotary joint or linear motion joint and at least two links. Two links are connected to each of the rotary joint or linear motion joint of the robot, and are connected to the rotary joint of the robot. The two links are rotated about the rotary joint by a motor, one of the two links connected to the linear motion joint of the robot is expanded and contracted by the motor, and each of the links of the robot has an external force. In response to being applied, the link of the robot does not rotate, and one of the links of the robot has a teaching arm attachment for attaching a teaching arm, and at least one of the links of the robot The teaching arm attachment moves as one rotates or expands and contracts,
The device is
For each of the rotary joints of the teaching arm, the margin of the rotary joint, which is a function of the current angle formed by the two links connected to the rotary joint, the small margin being the current angle And a margin of the rotary joint indicating that a difference between an upper limit angle and a lower limit angle of the two links is small, and the rotation of at least one rotary joint of the teaching arm The margin of the link, which is a function of the current angle formed by the two links connected to the joint, and the small margin means that the current angle and the two links when the two links are aligned. The margin of the link indicating that the difference between two links is small is obtained, and the margin of the teaching arm is obtained by multiplying the obtained margin of the rotary joint and the margin of the link. It means for determining,
Means for determining a direction in which the pointing unit has moved based on a difference between a current position of the pointing unit and a position before a predetermined time when a margin of the teaching arm is equal to or less than a desired threshold;
A robot teaching apparatus, comprising: a signal that is input to the motor of the robot and that generates the signal for moving the teaching arm mounting portion in the direction obtained. The teaching arm further includes at least one linear motion joint, two links being connected to each of the linear motion joints, and one link of the two links can be expanded and contracted, The length of the link that changes by expanding and contracting has an upper limit and a lower limit, and at least one of the links of the teaching arm rotates or expands and contracts as the pointing unit moves.
The means for determining the margin further includes, for each of the linear motion joints of the teaching arm, a margin of the linear motion joint that is a function of the length of one of the links connected to the linear motion joint. The margin of the linear motion joint indicating that the margin is small means that the difference between the current length of the link and the upper limit or the lower limit of the length of the link is small. The margin of the teaching arm is obtained by multiplying the margin of the rotary joint, the margin of the obtained link and the margin of the obtained linear motion joint.
The robot teaching apparatus according to claim 1.   The means for generating the signal generates the signal when a margin of the teaching arm is equal to or less than the desired threshold, and the means further includes the determined direction and the determined direction of the teaching arm. Based on the margin, the speed at which the teaching arm mounting portion is moved, and the magnitude of the speed increases as the margin of the teaching arm decreases, and the signal is calculated based on the speed. The robot teaching apparatus according to claim 1 or 2, wherein: A robot teaching device controller that teaches the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot,
The teaching arm has at least one rotary joint and at least two links, and two links are connected to each of the rotary joints of the teaching arm, and the two links rotate around the rotary joint. The angle formed by the two links has an upper limit and a lower limit, and one of the links of the teaching arm has an instruction unit for instructing the position and orientation of the end effector. Then, the position and orientation of the end effector is taught by storing the position and orientation of the instruction unit, the instruction unit moves in response to an external force being applied to the link having the instruction unit, and the instruction unit moves. And at least one of the teaching arm links rotates,
The robot has at least one rotary joint or linear motion joint and at least two links. Two links are connected to each of the rotary joint or linear motion joint of the robot, and are connected to the rotary joint of the robot. The two links are rotated about the rotary joint by a motor, one of the two links connected to the linear motion joint of the robot is expanded and contracted by the motor, and each of the links of the robot has an external force. In response to being applied, the link of the robot does not rotate, and one of the links of the robot has a teaching arm attachment for attaching a teaching arm, and at least one of the links of the robot The teaching arm attachment moves as one rotates or expands and contracts,
The controller is
For each of the rotary joints of the teaching arm, the margin of the rotary joint, which is a function of the current angle formed by the two links connected to the rotary joint, the small margin being the current angle And a margin of the rotary joint indicating that a difference between an upper limit angle and a lower limit angle of the two links is small, and the rotation of at least one rotary joint of the teaching arm The margin of the link, which is a function of the current angle formed by the two links connected to the joint, and the small margin means that the current angle and the two links when the two links are aligned. The margin of the link indicating that the difference between two links is small is obtained, and the margin of the teaching arm is obtained by multiplying the obtained margin of the rotary joint and the margin of the link. It means for determining,
Means for determining a direction in which the pointing unit has moved based on a difference between a current position of the pointing unit and a position before a predetermined time when a margin of the teaching arm is equal to or less than a desired threshold;
A controller for a robot teaching apparatus, comprising: a signal that is input to the motor of the robot and that generates the signal for moving the teaching arm mounting portion in the direction obtained. A program for teaching the position and orientation of an end effector attached to a robot during work using a teaching arm attached to the robot,
The teaching arm has at least one rotary joint and at least two links, and two links are connected to each of the rotary joints of the teaching arm, and the two links rotate around the rotary joint. The angle formed by the two links has an upper limit and a lower limit, and one of the links of the teaching arm has an instruction unit for instructing the position and orientation of the end effector. Then, the position and orientation of the end effector is taught by storing the position and orientation of the instruction unit, the instruction unit moves in response to an external force being applied to the link having the instruction unit, and the instruction unit moves. And at least one of the teaching arm links rotates,
The robot has at least one rotary joint or linear motion joint and at least two links. Two links are connected to each of the rotary joint or linear motion joint of the robot, and are connected to the rotary joint of the robot. The two links are rotated about the rotary joint by a motor, one of the two links connected to the linear motion joint of the robot is expanded and contracted by the motor, and each of the links of the robot has an external force. In response to being applied, the link of the robot does not rotate, and one of the links of the robot has a teaching arm attachment for attaching a teaching arm, and at least one of the links of the robot The teaching arm attachment moves as one rotates or expands and contracts,
When the program is executed on a computer, the computer
For each of the rotary joints of the teaching arm, the margin of the rotary joint, which is a function of the current angle formed by the two links connected to the rotary joint, the small margin being the current angle And a margin of the rotary joint indicating that a difference between an upper limit angle and a lower limit angle of the two links is small, and the rotation of at least one rotary joint of the teaching arm The margin of the link, which is a function of the current angle formed by the two links connected to the joint, and the small margin means that the current angle and the two links when the two links are aligned. The margin of the link indicating that the difference between two links is small is obtained, and the margin of the teaching arm is obtained by multiplying the obtained margin of the rotary joint and the margin of the link. It means for determining,
Means for determining a direction in which the pointing unit has moved based on a difference between a current position of the pointing unit and a position before a predetermined time when a margin of the teaching arm is equal to or less than a desired threshold;
A program that functions as a signal that is input to the motor of the robot and that generates the signal for moving the teaching arm mounting portion in the direction obtained.