JP2013202725A - Operating device for link actuation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operating device specifying a desired distal end orientation in an orthogonal coordinate system to thereby performing teaching intuitively in a link actuation device in which control of an actuator for changing a distal end orientation is handled in an angle coordinate system.SOLUTION: A link actuation device 51 couples a distal-end-side link hub 3 via three or more sets of link mechanisms 4 so that the orientation is changeable with respect to a proximal-end-side link hub 2, and arbitrarily changes the distal end orientation, which is the orientation of the distal-end-side link hub 3 with respect to the proximal-end-side link hub 2, by an actuator 53 provided to two or more sets of link mechanisms 4. An operating device 55 includes: an orientation specifying means 53a for specifying, by manual operation, the desired distal end orientation at a coordinate position in the orthogonal coordinate system; an orientation acquiring means 53b for acquiring the distal end orientation represented in the angle coordinate system by calculation from the specified coordinate position; and an orientation information imparting means 53c for presenting information on the acquired distal end orientation to a control device 54 controlling the actuator 53.

Description

  The present invention relates to an operating device for a link operating device that requires a precise and wide operating range, such as medical equipment and industrial equipment.

  An example of a working device having a link mechanism main body is disclosed in Patent Document 1, and an example of a link actuating device used for medical equipment, industrial equipment, and the like is disclosed in Patent Document 2, respectively.

  Since the link mechanism main body of patent document 1 has a small operating angle of each link, in order to set the operating range of a traveling plate large, it is necessary to lengthen a link length. Thereby, there existed a problem that the dimension of the whole mechanism became large and an apparatus became large. Further, when the link length is increased, the rigidity of the entire mechanism is reduced. For this reason, there is a problem that the weight of the tool mounted on the traveling plate, that is, the transportable weight of the traveling plate is limited to a small one. For these reasons, it is difficult to use in a medical device or the like that requires a precise and wide range of operation while having a compact configuration.

  On the other hand, the link actuating device of Patent Document 2 has a configuration in which a distal end side link hub is connected to a proximal end side link hub via three or more sets of three-joint linkage mechanisms so that the posture can be changed. As a result, it is possible to operate in a precise and wide range of operation while having a compact configuration. The distal end posture, which is the posture of the distal end side link hub with respect to the proximal end side link hub, is determined by defining the states of two or more sets of link mechanisms among the three or more sets of link mechanisms. “Defining the state of the link mechanism” means, for example, defining the rotation angle of the link connected to the link hub on the base end side of the link mechanism with respect to the link hub on the base end side.

JP 2000-94245 A US Pat. No. 5,893,296

  In general, a link operating device provided with three or more sets of three-link linkage mechanisms determines the tip posture by a folding angle and a turning angle, calculates a rotation angle of the link from the folding angle and the turning angle, The operating position of the actuator to be rotated is positioned. For this reason, conventionally, when the tip posture is changed, the target tip posture is specified by inputting the folding angle and the turning angle. The bend angle is a vertical angle in which the central axis of the link hub on the distal end side is inclined with respect to the central axis of the link hub on the proximal end side, and the turning angle is relative to the central axis of the link hub on the proximal end side. This is a horizontal angle at which the central axis of the link hub on the tip side is inclined.

  On the other hand, when the end effector is installed on the link hub on the distal end side and the link actuating device is actually used, the coordinate position of the work piece on which the end effector works is often handled in an orthogonal coordinate system. For this reason, it has been difficult to intuitively operate the link operating device in specifying the tip posture by the bending angle and the turning angle. For example, when the link hub on the tip side is positioned in a certain tip posture and the tip posture is changed so that the end effector moves from the tip posture by the amount of movement specified in the Cartesian coordinate system, the operator The amount of operation of the actuator must be determined by converting the movement in the Cartesian coordinate system into the movement in the angle coordinate system represented by the bending angle and the turning angle. For this reason, it was difficult to operate the link actuating device, requiring experience and special training.

  An object of the present invention is to provide an operating device capable of teaching intuitively by designating a target tip posture in an orthogonal coordinate system in a link actuator in which control of an actuator for changing the tip posture is handled in an angular coordinate system. That is.

The operation device of the link actuating device of the present invention connects the link hub on the distal end side to the link hub on the proximal end side so that the posture can be changed via three or more sets of link mechanisms, The proximal end and distal end end link members, one end of which is rotatably connected to the proximal end link hub and the distal end link hub, and the other ends of the proximal end and distal end end link members And each link mechanism has a geometric model expressing the link mechanism as a straight line, a proximal end portion and a distal end with respect to a central portion of the central link member. The side portion has a symmetrical shape, and two or more sets of the three or more sets of link mechanisms may have any distal end posture that is the posture of the distal end side link hub with respect to the proximal end side link hub. Turn into An actuator for controlling the actuator is provided, and the control device for controlling the actuator is configured such that the distal end posture is bent at a vertical angle in which the central axis of the distal link hub is inclined with respect to the central axis of the proximal link hub. It is provided in a link actuating device defined by an angle and a turning angle that is a horizontal angle at which the central axis of the distal end side link hub is inclined with respect to the central axis of the proximal end side link hub.
The operating device has the origin on the extension axis of the central axis of the link hub on the base end side, and the target tip at a coordinate position on a two-dimensional orthogonal coordinate system orthogonal to the extension axis of the central axis Posture specifying means for specifying the posture by human operation, posture acquiring means for acquiring the tip posture expressed by the bending angle and the turning angle by calculation from the coordinate position specified by the posture specifying means, and the posture acquisition Posture information giving means for giving information on the tip posture acquired by the means to the control device.

  According to this configuration, the target tip posture is designated by the coordinate position of the orthogonal coordinate system by human operation by the posture designation means. The posture acquisition means acquires the tip posture represented by the bending angle and the turning angle by calculation from the designated coordinate position. Information on the tip posture is given to the control device by the posture information adding means. Then, the control device controls the actuator using information on the tip posture represented by the bending angle and the turning angle. In this way, since the target tip posture is designated by the coordinate position on the orthogonal coordinate system, the link actuator can be operated intuitively even when the coordinate position of the work piece is handled in the orthogonal coordinate system. it can.

The posture acquisition means can use, for example, a convergence calculation by a least square method as a calculation for acquiring the tip posture represented by the bending angle and the turning angle.
According to the least square method, an appropriate folding angle and turning angle representing the tip posture can be obtained by a simple calculation.

The control device may calculate the command operation amount of each actuator as follows. That is, the rotation angle of the end link member on the base end side with respect to the link hub on the base end side is βn, the connecting end shaft of the central link member rotatably connected to the end link member on the base end side, The angle formed by the connecting end shaft of the central link member rotatably connected to the end link member on the front end side is γ, and the end link members on the base end side with respect to the reference end link member on the base end side When the separation angle in the circumferential direction is δn, the folding angle is θ, and the turning angle is φ,
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
By inversely transforming the expression represented by the following equation, the rotation angle of each base end side end link member in the target distal end posture is obtained, and the obtained rotation angle and the current distal end posture are The command operation amount of each actuator is calculated from the difference from the rotation angle of the end link member on each base end side.
According to this method, the command operation amount can be easily obtained, and the control of the actuator is simplified.

Further, the control device may calculate the command operation amount of each actuator as follows. That is, the rotation angle of the end link member on the base end side with respect to the link hub on the base end side is βn, the connecting end shaft of the central link member rotatably connected to the end link member on the base end side, The angle formed by the connecting end shaft of the central link member rotatably connected to the end link member on the front end side is γ, and the end link members on the base end side with respect to the reference end link member on the base end side When the circumferential separation angle is δn, the bending angle is θ, and the turning angle is φ,
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
A table indicating the relationship between the distal end posture and the rotation angle of the end link member on each proximal end side is created by inversely transforming the expression represented by the equation, and this table is used as a target. The rotation angle of the end link member on the base end side in the distal end posture is obtained, and from the difference between the calculated rotation angle and the rotation angle of the end link member on the base end side, Calculate the command operation amount of the actuator.
According to this method, the calculation time of the command operation amount using the above formula can be shortened by tabulating the relationship between the tip posture and the rotation angle of each proximal end link in advance, The actuator can be controlled at a higher speed.

  For example, the posture designating unit designates a coordinate position on the orthogonal coordinate system by numerical input. In that case, the designation of the coordinate position on the orthogonal coordinate system may be a numerical input of an absolute coordinate with respect to a predetermined reference point, or a numerical input of a difference from the current coordinate position to the target coordinate position. It may be.

  The posture designating unit may designate the coordinate position on the orthogonal coordinate system with an operation amount determined according to an operation time or the number of operations. In this case, the relationship between the operation and the coordinate position is easy to understand sensuously.

  It is preferable that the posture acquisition means obtains the bending angle by searching in order from the vicinity with the current coordinate position as a reference by the convergence calculation by the least square method. Thereby, the number of calculations can be reduced.

The control device may convert the tip posture information given from the posture designation means into an operation amount of the actuator by a predetermined conversion formula, and operate the actuator by the operation amount.
Thus, by converting the information on the tip posture into the operation amount of the actuator, the actuator can be easily controlled.

  The operation device of the link actuating device of the present invention connects the link hub on the distal end side to the link hub on the proximal end side so that the posture can be changed via three or more sets of link mechanisms, The proximal end and distal end end link members, one end of which is rotatably connected to the proximal end link hub and the distal end link hub, and the other ends of the proximal end and distal end end link members And each link mechanism has a geometric model expressing the link mechanism as a straight line, a proximal end portion and a distal end with respect to a central portion of the central link member. The side portion has a symmetrical shape, and two or more sets of the three or more sets of link mechanisms may have any distal end posture that is the posture of the distal end side link hub with respect to the proximal end side link hub. Turn into An actuator for controlling the actuator is provided, and the control device for controlling the actuator is configured such that the distal end posture is bent at a vertical angle in which the central axis of the distal link hub is inclined with respect to the central axis of the proximal link hub. An operating device in a link actuating device defined by an angle and a turning angle that is a horizontal angle at which a central axis of the distal link hub is inclined with respect to a central axis of the proximal link hub, The origin is located on the extension axis of the center axis of the link hub on the end side, and the target tip posture is specified manually by a coordinate position on a two-dimensional orthogonal coordinate system orthogonal to the extension axis of the center axis. Posture specifying means for performing, posture acquiring means for acquiring the tip posture represented by the folding angle and the turning angle by calculation from the coordinate position specified by the posture specifying means, and the posture acquiring means And a posture information providing means for providing the control device with the information on the tip posture acquired in the above-mentioned manner, in a link actuator in which the control of the actuator for changing the tip posture is handled in an angle coordinate system, the target tip posture is set. Specify in the Cartesian coordinate system for intuitive teaching.

It is the front view which abbreviate | omitted a part of one Embodiment of the link actuating device provided with the operating device of this invention. It is the front view which abbreviate | omitted a part which shows one state of the link mechanism main body of the link actuating device. It is the front view which abbreviate | omitted one part which shows the different state of the link mechanism main body of the same link actuator. It is the perspective view which represented the link mechanism main body of the link actuating device three-dimensionally. It is the figure which expressed one link mechanism of the link actuating device with a straight line. It is a fragmentary sectional view of the link mechanism main part of the link actuator. It is a flowchart of the convergence calculation by the least square method which calculates | requires a bend angle. It is a figure which shows an example of the operation part of an operating device. It is a figure which shows the example from which the operation part of an operating device differs. It is a figure which shows schematic structure of the working apparatus provided with the link actuating device. It is the front view which abbreviate | omitted a part of other embodiment of the link actuating device provided with the operating device of this invention. It is a fragmentary sectional view of the link mechanism main part of the link actuator. It is the elements on larger scale of FIG.

  An embodiment of a link actuating device provided with an operating device of the present invention will be described with reference to FIGS. As shown in FIG. 1, the link operating device 51 includes a link mechanism main body 1, a plurality of actuators 53 (the same number as the link mechanism 4 described later) for operating the link mechanism main body 1, and a control device 54 for controlling these actuators 53. And an operation device 55 for inputting an operation command to the control device 54. In this example, both the control device 54 and the operation device 55 are provided in the controller 56, but the control device 54 may be provided separately from the controller 56. In this example, the link mechanism main body 1 is installed in a suspended state on the base member 52.

  The link mechanism main body 1 will be described. 2 and 3 are front views showing different states of the link mechanism main body 1. The link mechanism main body 1 has three sets of link mechanisms 4 in which the link hub 3 on the distal end side is linked to the link hub 2 on the proximal end side. It is connected so that the posture can be changed via. 2 and 3, only one set of link mechanisms 4 is shown.

  FIG. 4 is a perspective view showing the link mechanism body 1 three-dimensionally. Each link mechanism 4 includes a base end side end link member 5, a front end side end link member 6, and a central link member 7, and forms a three-joint link mechanism including four rotating pairs. The end link members 5 and 6 on the base end side and the front end side are L-shaped, and the base ends are rotatably connected to the link hub 2 on the base end side and the link hub 3 on the front end side, respectively. The central link member 7 is rotatably connected to the distal ends of the end link members 5 and 6 on the proximal end side and the distal end side at both ends.

  The end link members 5 and 6 on the base end side and the front end side have a spherical link structure, and the spherical link centers PA and PB (FIGS. 2 and 3) in the three sets of link mechanisms 4 coincide with each other, and the spherical surfaces thereof The distance d from the link centers PA and PB is the same. The central axis of each rotational pair of the end link members 5 and 6 and the central link member 7 may have a certain crossing angle γ or may be parallel.

  That is, the three sets of link mechanisms 4 have the same geometric shape. The geometrically identical shape is a geometric model in which the link members 5, 6, and 7 are expressed by straight lines, that is, a model that is expressed by each rotation pair and a straight line connecting these rotation pairs. The base end side part and the front end side part with respect to the center part of the are said to have a symmetrical shape. FIG. 5 is a diagram representing a set of link mechanisms 4 in a straight line.

  The link mechanism 4 of this embodiment is a rotationally symmetric type, and the positions of the proximal-side link hub 2 and the proximal-side end link member 5, the distal-side link hub 3 and the distal-side end link member 6. The relationship is a position configuration that is rotationally symmetric with respect to the center line C of the central link member 7. 2 shows a state where the central axis QA of the link hub 2 on the proximal end side and the central axis QB of the link hub 3 on the distal end side are on the same line, and FIG. 3 shows the central axis of the link hub 2 on the proximal end side. A state in which the central axis QB of the link hub 3 on the distal end side takes a predetermined operating angle with respect to QA is shown. Even if the posture of each link mechanism 4 changes, the distance d between the spherical link centers PA and PB on the base end side and the tip end side does not change.

  The link hub 2 on the proximal end side, the link hub 3 on the distal end side, and the three link mechanisms 4 allow the distal link hub 3 to move in the two orthogonal directions relative to the link hub 2 on the proximal end side. A degree mechanism is configured. In other words, it is a mechanism that can freely change the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side with two degrees of freedom of rotation. This two-degree-of-freedom mechanism is based on the intersection P between the center axis QA of the link hub 2 on the proximal end side, the center axis QB of the link hub 3 on the distal end side, and the center line C of the center link member 7. The link hub 3 on the distal end side changes the posture with respect to the link hub 2.

  Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side can be widened. For example, the maximum value (maximum folding angle) of the bending angle θ between the central axis QA of the link hub 2 on the proximal end side and the central axis QB of the link hub 3 on the distal end side can be set to about ± 90 °. Further, the turning angle φ of the distal end side link hub 3 with respect to the proximal end side link hub 2 can be set in a range of 0 ° to 360 °. The bending angle θ is a vertical angle in which the central axis QB of the distal end side link hub 3 is inclined with respect to the central axis QA of the proximal end side link hub 2, and the turning angle φ is the proximal end side link hub. This is a horizontal angle at which the central axis QB of the link hub 3 on the distal end side is inclined with respect to the central axis QA of the second axis.

  In this link mechanism body 1, the angle and length of the shaft member 13 (FIG. 6) of the end link members 5 and 6 of each link mechanism 4 are equal, and the end link member 5 on the proximal end side and the distal end side link member 5 are on the distal end side. When the geometrical shape of the end link member 6 is equal and the shape of the central link member 7 is the same at the proximal end side, the central link member 7 and the end of the central link member 7 are symmetrical with respect to the symmetry plane of the central link member 7. If the angular positional relationship with the base link members 5 and 6 is the same between the base end side and the tip end side, the base end side link hub 2 and the base end side end link member 5 from the geometric symmetry, The distal end side link hub 3 and the distal end side end link member 6 move in the same manner. For example, when the rotation hubs are provided coaxially with the center axes QA and QB on the link hubs 2 and 3 on the proximal end side and the distal end side, and rotation is transmitted from the proximal end side to the distal end side, the proximal end side and the distal end side are It becomes a constant velocity universal joint that rotates at the same speed at the same rotation angle. The plane of symmetry of the central link member 7 when rotating at a constant speed is referred to as a uniform speed bisector.

  Therefore, by arranging a plurality of link mechanisms 4 having the same geometric shape sharing the base side link hub 2 and the tip side link hub 3 on the circumference, the plurality of link mechanisms 4 can move without contradiction. The central link member 7 is limited to movement only on the equal speed bisector. Thereby, even if the proximal end side and the distal end side have arbitrary operating angles, the proximal end side and the distal end side rotate at a constant speed.

  The link hub 2 on the base end side and the link hub 3 on the front end side have a donut shape in which a through hole 10 is formed in the center portion along the axial direction and the outer shape is a spherical shape. The center of the through hole 10 coincides with the central axes QA and QB of the link hubs 2 and 3. The proximal end link member 5 and the distal end link member 6 rotate at equal intervals in the circumferential direction of the outer peripheral surface of the proximal link hub 2 and distal link hub 3 respectively. It is connected freely.

  FIG. 6 is a cross-sectional view showing a rotational pair of the proximal-side link hub 2 and the proximal-side end link member 5 and a rotational end of the proximal-side end link member 5 and the central link member 7. In the link hub 2 on the base end side, radial communication holes 11 that communicate the axial through hole 10 and the outer peripheral side are formed at three locations in the circumferential direction, and two bearings provided in each communication hole 11. 12, shaft members 13 are rotatably supported. The outer end of the shaft member 13 protrudes from the link hub 2 on the base end side, and the end link member 5 on the base end side is coupled to the protruding screw portion 13 a and is fastened and fixed by a nut 14.

  The bearing 12 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted to the inner circumference of the communication hole 11, and an inner ring (not shown) is the outer circumference of the shaft member 13. Is fitted. The outer ring is retained by a retaining ring 15. Further, a spacer 16 is interposed between the inner ring and the end link member 5 on the base end side, and the tightening force of the nut 14 is transmitted to the inner ring via the end link member 5 and the spacer 16 on the base end side. Thus, a predetermined preload is applied to the bearing 12.

  The rotating pair of the end link member 5 and the center link member 7 on the base end side is provided with two bearings 19 in communication holes 18 formed at both ends of the center link member 7. A shaft portion 20 at the tip of the end link member 5 is rotatably supported. The bearing 19 is fastened and fixed by a nut 22 via a spacer 21.

  The bearing 19 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted to the inner circumference of the communication hole 18, and an inner ring (not shown) is the outer circumference of the shaft portion 20. Is fitted. The outer ring is retained by a retaining ring 23. A tightening force of the nut 22 screwed to the tip screw portion 20a of the shaft portion 20 is transmitted to the inner ring through the spacer 21 to apply a predetermined preload to the bearing 19.

  The rotation pair of the base end side link hub 2 and the base end side end link member 5 and the base end side end link member 5 and the central link member 7 have been described above. The rotation pair of the hub 3 and the end link member 6 on the front end side and the rotation pair of the end link member 6 and the center link member 7 on the front end side have the same configuration (not shown).

  Thus, the four rotation pairs in each link mechanism 4, that is, the rotation pair of the link hub 2 on the proximal end side and the end link member 5 on the proximal end side, the link hub 3 on the distal end side and the end link on the distal end side Bearings 12 and 19 are provided on the rotational pair of the member 6, the end link member 5 and the central link member 7 on the base end side, and the rotational pair of the end link member 6 and the central link member 7 on the distal end side. By adopting the structure, it is possible to reduce the rotational resistance by suppressing the frictional resistance at each rotational pair, and to ensure smooth power transmission and improve the durability.

  In the structure in which the bearings 12 and 19 are provided, by applying a preload to the bearings 12 and 19, the radial gap and the thrust gap can be eliminated, and shakiness of the rotation pair can be suppressed. The rotational phase difference between the link hub 3 side on the side and the distal end side is eliminated, and the constant velocity can be maintained and the occurrence of vibration and abnormal noise can be suppressed. In particular, by setting the bearing clearance between the bearings 12 and 19 to be a negative clearance, backlash generated between input and output can be reduced.

  By providing the bearing 12 embedded in the link hub 2 on the proximal end side and the link hub 3 on the distal end side, the outer shape of the entire link mechanism body 1 is not increased, and the link hub 2 on the proximal end side and the distal end side link hub 2 are The outer shape of the link hub 3 can be enlarged. Therefore, it is easy to secure a mounting space for mounting the proximal-side link hub 2 and the distal-side link hub 3 to other members.

  In FIG. 1, the link mechanism main body 1 is in a state in which the base end side link hub 2 is fixed to the lower surface of the base member 52 and the front end side link hub 3 is suspended. On the upper surface of the base member 52, the same number of actuators 53, that is, three actuators 53, which are rotary actuators, are installed. The output shaft 53a of the actuator 53 protrudes downward through the base member 52, and is a fan-shaped cap attached to the bevel gear 57 attached to the output shaft 53a and the shaft member 13 (FIG. 6) of the link hub 2 on the proximal end side. The gear 58 is meshed.

  When the actuator 53 is rotated, the rotation is transmitted to the shaft member 13 via a pair of bevel gears 57 and 58, and the angle of the end link member 5 on the base end side with respect to the link hub 2 on the base end side changes. By controlling the operation amount of each actuator 53 and adjusting the angle of the end link member 5 on the base end side for each link mechanism 4, the attitude of the link hub 3 on the front end side with respect to the link hub 2 on the base end side ( Hereinafter, “tip posture” is determined. The operation of each actuator 53 is controlled by the control device 54 based on an operation command from the operation device 55.

The operation device 55 includes posture designation means 55a, posture acquisition means 55b, and posture information provision means 55c.
The posture designation means 55a is a means for manually designating a target tip posture, and designates the tip posture at a coordinate position on a two-dimensional orthogonal coordinate system. As shown in FIG. 4, the orthogonal coordinate system is an XY in which the origin O is defined at an arbitrary position on the extension axis QA ′, which is orthogonal to the extension axis QA ′ of the center axis QA of the link hub 2 on the base end side. An orthogonal coordinate system 100 is shown. The target tip posture is represented by target coordinates T (X, Y) which are the coordinates of the point where the center axis QB of the link hub 3 on the tip side intersects the XY orthogonal coordinate system 100. A method for specifying the target coordinate T will be described later.

  The posture acquisition unit 55b converts the tip posture represented by the coordinate position of the XY orthogonal coordinate system 100 designated by the posture designation unit 55a into the tip posture represented by the bending angle θ and the turning angle φ of the angle coordinate system. Means. The principle of conversion will be described.

また、角度座標系での原点Ｏと目標座標Ｔとの距離ｒ´は、式２を用いて求められる。
ｒ´＝ｈ´×tanθ ・・・（式２） A distance r between the origin O and the target coordinate T in the XY coordinate system 100 is obtained using Equation 1.

Further, the distance r ′ between the origin O and the target coordinate T in the angular coordinate system is obtained using Equation 2.
r ′ = h ′ × tan θ (Formula 2)

Here, h ′ is the height from the intersection point P which is the rotation center of the posture change of the link hub 3 on the distal end side to the target coordinate T. If the distance between the spherical link centers PA and PB is d and the height from the spherical link center PA of the proximal end side link hub 2 to the target coordinate T is h, h ′ is obtained from Equation 3. By substituting h ′ obtained by Equation 3 into Equation 2, the distance r ′ between the origin O and the target coordinate T in the angular coordinate system is obtained. D and h are fixed values determined by the dimensions of the link mechanism main body 1 and the dimensions of the device on which the link actuating device 51 is mounted.

The distance r between the origin O and the target coordinate T in the XY coordinate system 100 thus obtained is compared with the distance r ′ between the origin O and the target coordinate T in the angle coordinate system, and the difference is minimum. Search for the bending angle θ. The search for the bending angle θ is performed by using a convergence calculation by the least square method, for example, as shown in Expression 4.
dr = (r−r ′) ² (Expression 4)

  The convergence calculation by the least square method is performed in the order shown in the flowchart of FIG. First, in S1, the calculation of the distance r by Equation 1 and the setting of the initial value of the comparison value A are performed. The comparison value A is a comparison value with dr, and a value sufficiently larger than the value of dr calculated in the search process is set as an initial value.

Next, assuming that θ = 0 ° in S2, r ² and dr are calculated in S3. In S4, if dr is smaller than A, dr is substituted for A, and θ at that time is substituted for Ans θ. If dr is larger than A, A and Ans are left as they are. Furthermore, in S5, θ is compared with a maximum value Maxθ of a predetermined angle range. If it is smaller, a predetermined value is added as S = θ + Δθ in S6.

  The operations of S3, S4 and S6 are repeated until θ reaches the maximum value Maxθ of a set angle range. In S7, the finally obtained Ans θ is set as a bending angle θ.

とする。 The turning angle φ is obtained using the bending angle θ obtained by the search. At that time, if θ = 0,
φ = 0 (Formula 5)
And if θ ≠ 0,

And

  The target tip posture is defined by the bending angle θ obtained by the operation shown in the flowchart of FIG. 7 and the turning angle φ obtained by the calculation of Expression 5 or 6. As described above, the number of computations can be reduced by performing the convergence calculation by the least square method to obtain the bending angle θ by sequentially searching from the vicinity of the current coordinate position as a reference.

  The posture information giving unit 55c gives the control device 54 information on the tip posture acquired by the posture acquiring unit 55b, that is, the bending angle θ and the turning angle φ.

  The control device 54 is of a numerical control type by a computer, and the target rotation of the end link member 5 on the base end side is determined in accordance with the tip posture information given from the posture information giving means 55c of the operation device 55. The angle βn (FIG. 4) is obtained, and each actuator 53 is feedback-controlled so that the actual rotation angle βn detected by the posture detection means 59 (FIG. 1) becomes the target rotation angle βn.

The rotation angle βn is obtained, for example, by inversely transforming the following equation (7). The inverse transformation is a transformation for calculating the rotation angle βn from the bending angle θ and the turning angle φ. The bending angle θ, the turning angle φ, and the rotation angle βn are mutually related, and the other value can be derived from one value.
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
(N = 1, 2, 3) (Expression 7)
Here, γ (FIG. 4) is rotatably connected to the connecting end shaft of the central link member 7 rotatably connected to the end link member 5 on the base end side and the end link member 6 on the tip end side. The angle formed by the connecting end axis of the central link member 7. δn is a circumferential separation angle of each base end side end link member 5 with respect to the base end side end link member 5 serving as a reference.

  Although the rotation angle βn may be obtained by inversely transforming Equation 7 for each command, a table showing the relationship between the tip position / posture and the rotation angle βn as shown in Table 1 may be created in advance. In the case of a table, if there is a command to change the tip posture, the target rotation angle βn can be obtained immediately using the table. For this reason, the actuator 53 can be controlled at a higher speed. In addition, when command patterns are registered in advance and operated in the order of registration, a table storage area can be saved by registering a table indicating the relationship between the tip position and orientation and the rotation angle βn at the time of pattern registration as shown in Table 2. .

  FIG. 8 shows an example of the operation unit of the operation device 55. This operation unit is a method of designating a coordinate position by numerical input, and present value display units 101 and 102 for displaying the X coordinate value and Y coordinate value of the current coordinate position, respectively, and the target X coordinate value and Y coordinate. Target value display sections 103 and 104 for displaying values, a numerical value input button 105 including 10 keys for inputting the target X coordinate value and Y coordinate value to the target value display sections 103 and 104, an operation execution button 106, Is provided. The designation of the coordinate position on the XY Cartesian coordinate system is a method of numerically inputting absolute coordinates with respect to a predetermined reference point (for example, the origin O), and a method of numerically inputting a difference from the current coordinate position to the target coordinate position. Any of these may be used.

  When the target X coordinate value and Y coordinate value are input using the numerical value input button 105, the values are displayed on the target value display sections 103 and 104. At the same time, the target X- and Y-coordinate values, the distance from the link hub 3 on the distal end side to the work surface of the work piece (not shown), the dimensions of each part of the link mechanism body 1, and the like The bending angle θ and the turning angle φ of the tip posture are calculated. Further, the operation amount of each actuator 53 is calculated from the tip posture. When the operation execution button 106 is pressed, each actuator 53 is driven, and the tip posture is changed so that the input X coordinate value and Y coordinate value are obtained. In this way, since the target tip posture is specified by the coordinate position on the XY rectangular coordinate system 100, the link actuator 51 is operated intuitively even when the coordinate position of the work piece is handled by the rectangular coordinate system. can do.

  FIG. 9 shows a different example of the operation unit of the operation device 55. This operation unit is a method of designating a coordinate position by an operation amount, and is a current value display unit 101 and 102 for displaying the X coordinate value and the Y coordinate value of the current coordinate position, respectively, and a push operation for changing the tip posture. Buttons 107-110. When the push operation button 107 is pressed, the posture is changed to the side where the X coordinate value is increased. When the push operation button 108 is pressed, the posture is changed to the side where the X coordinate value is decreased. When the push operation button 109 is pressed, the Y coordinate value is increased. The posture is changed to the side where the Y coordinate value is decreased when the push operation button 110 is pressed.

  The degree of the posture change varies depending on the time or the number of times the push operation buttons 107 to 110 are pushed. In this example, each of the push operation buttons 107 to 110 includes a low speed button 107a, 108a, 109a, 110a in which the posture change is performed at a low speed, and a high speed button 107b, 108b, 109b, 110b in which the posture change is performed at a high speed. Therefore, the posture can be changed in two stages, low speed and high speed.

  In the case of the operation device 55, the X coordinate value and the Y coordinate value are sequentially changed by the operation of the push operation buttons 107 to 110, and the target folding angle θ and turning angle φ are calculated each time, and the actuator 53 corresponding thereto is calculated. It is a system that determines the amount of movement. That is, the tip posture continues to change only while the push operation buttons 107 to 110 are being pressed. For this reason, the relationship between the operation and the coordinate position is easy to understand intuitively.

The control device 54 used in combination with the operation device 55 converts the tip posture information given from the posture designation means 55c of the operation device 55 into an operation amount of the actuator 53 by a predetermined conversion formula, and the operation thereof. The actuator 53 is controlled to be operated by the amount. Specifically, when the tip posture represented by the bending angle θ and the turning angle φ is given to the control device 54 from the posture specifying means 55c, the control device 54 uses the equation 7 to calculate the bending angle θ and the turning angle φ. The rotation angle βn of the end link member 5 on each proximal end side is obtained by inverse conversion, and the operation amount Rn of each actuator 53 is calculated by calculating Expression 8 using the obtained rotation angle βn. .
Rn = βn × k; (n = 1, 2, 3) (Equation 8)
Here, k is a coefficient determined by a reduction ratio of a reduction gear (not shown) attached to the actuator 53. In this way, when the tip posture information is converted into the operation amount of the actuator 53 by the conversion formula, the actuator 53 can be easily controlled.

  The amount of movement of the actuator 53 and the change speed of the tip posture cannot be changed in stages, but the amount of movement of the actuator 53 and the change speed of the tip posture per operation of the push operation buttons 107 to 110 can be arbitrarily changed. You may do it. Further, as in this example, the operation may be performed with one operation means such as a joystick, instead of operating with the plurality of push operation buttons 107 to 110.

  FIG. 10 shows a working device provided with the link actuating device 51. In this working device 120, the base end-side link hub 2 is fixed to a base member 52 that constitutes the ceiling portion of the work chamber 121, and the link mechanism main body 1 is installed in a suspended state. An end effector 122 is mounted on the link hub 3 on the distal end side. The end effector 122 is, for example, a painting machine.

  Below the end effector 122, a moving mechanism 123 that moves the work W in the XY-axis direction is installed. The moving mechanism 123 includes an X-axis rail 124 that is long and fixed along the X-axis direction that is fixedly installed on the floor surface, and a Y-axis rail 125 that can move forward and backward along the X-axis rail 124 and that is long along the Y-axis direction. And a work table 126 on which the work piece can be placed on the upper surface so as to be movable back and forth along the Y-axis rail 125. The Y-axis rail 125 and the work table 126 are moved in the X-axis direction and the Y-axis direction, respectively, by driving a drive source (not shown).

  When the end effector 122 is a coating machine, the work place 126 by the moving mechanism 123 is moved back and forth in the X-axis and Y-axis directions, so that the coating location of the work W is positioned at the tip of the paint spraying port 122a of the coating machine. . Further, by changing the tip posture of the link actuating device 51 and changing the direction of the end effector 122, the paint spraying port 122a is always adjusted to face the painted surface of the work W.

  Figures 11 to 13 show different embodiments of the link actuating device. As shown in FIG. 11, the link actuating device 61 is provided with a link mechanism body 1 suspended from a base member 62. That is, the link mechanism main body 1 has a base end side link hub 2 fixed to the base member 62 via a base member 62, and a front end side link hub 3 mounted with a front end mounting member 63 for attaching various instruments and the like. ing.

  As shown in FIGS. 12 and 13, the link mechanism main body 1 includes bearings 31 that rotatably support the end link members 5 and 6 with respect to the link hub 2 on the proximal end side and the link hub 3 on the distal end side. Outer ring rotation type. The rotation pair of the link hub 2 on the base end side and the end link member 5 on the base end side will be described as an example. Shaft portions 32 are formed at three locations in the circumferential direction of the link hub 2 on the base end side. The inner rings (not shown) of the two bearings 31 are fitted to the outer periphery of the portion 32, and the outer ring (not shown) of the bearing 31 is fitted to the inner periphery of the communication hole 33 formed in the end link member 5 on the proximal end side. Are mated. The bearing 31 is a ball bearing such as a deep groove ball bearing or an angular ball bearing, for example, and is fixed in a state where a predetermined preload is applied by tightening with a nut 34. The rotating pair of the distal end side link hub 3 and the distal end side end link member 6 has the same structure as described above.

  Further, the bearing 36 provided at the rotation pair of the end link member 5 on the base end side and the central link member 7 is connected to the outer ring on the inner periphery of the communication hole 37 formed at the front end of the end link member 5 on the base end side. (Not shown) is fitted, and an inner ring (not shown) is fitted to the outer periphery of the shaft portion 38 integrated with the central link member 7. The bearing 36 is, for example, a ball bearing such as a deep groove ball bearing or an angular ball bearing, and is fixed in a state where a predetermined preload is applied by tightening with a nut 39. The rotational pair of the end link member 6 and the center link member 7 on the front end side has the same structure as described above.

  All of the three sets of link mechanisms 4 of the link mechanism main body 1 have an actuator 70 for arbitrarily changing the distal end position and posture by rotating the end link member 5 on the proximal end side, and the operation amount of this actuator 70 as the proximal end. A speed reduction mechanism 71 that decelerates and transmits to the side end link member 5 is provided. The actuator 70 is a rotary actuator, more specifically a servo motor with a speed reducer 70 a, and is fixed to the base member 62 by a motor fixing member 72. The speed reduction mechanism 71 includes a speed reducer 70 a of the actuator 70 and a gear type speed reduction unit 73.

  The gear type reduction unit 73 is connected to the output shaft 70 b of the actuator 70 through a coupling 75 so as to be able to transmit rotation, and is fixed to the end link member 5 on the proximal end side and is connected to the small gear 76. It is comprised with the large gear 77 which meshes | engages. In the illustrated example, the small gear 76 and the large gear 77 are spur gears, and the large gear 77 is a sector gear in which teeth are formed only on a sector-shaped peripheral surface. The large gear 77 has a larger pitch circle radius than the small gear 76, and the rotation of the output shaft 70 b of the actuator 70 is transferred to the end link member 5 on the base end side, and the link hub 2 on the base end side and the end link on the base end side. It is decelerated and transmitted to the rotation around the rotation axis O1 of the rotation pair with the member 5. The reduction ratio is 10 or more.

  The pitch circle radius of the large gear 77 is set to ½ or more of the arm length L of the end link member 5 on the base end side. The arm length L is determined from the axial center point P1 of the central axis O1 of the rotational pair of the base end side link hub 2 and the base end side end link member 5 to the base end side end link member 5 and the center. An axial center point P1 of the axial center point P2 of the center axis O2 of the rotational pair with the link member 7 is orthogonal to the rotational pair axis O1 of the base end side link hub 2 and the base end side end link member 5. The distance to the point P3 projected on the plane passing through. In the case of this embodiment, the pitch circle radius of the large gear 77 is not less than the arm length L. Therefore, it is advantageous to obtain a high reduction ratio.

  The small gear 76 has shaft portions 76 b protruding on both sides of a tooth portion 76 a meshing with the large gear 77, and both shaft portions 76 b are two bearings provided on a rotation support member 79 installed on the base member 62. 80 are rotatably supported by each. The bearing 80 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. In addition to arranging ball bearings in double rows as in the illustrated example, roller bearings or sliding bearings may be used. A shim (not shown) is provided between the outer rings (not shown) of the two bearings 80, and a preload is applied to the bearing 80 by tightening a nut 81 screwed into the shaft portion 76b. The outer ring of the bearing 80 is press-fitted into the rotation support member 79.

  In the case of this embodiment, the large gear 77 is a member separate from the end link member 5 on the base end side, and is detachably attached to the end link member 5 on the base end side by a coupler 82 such as a bolt. ing. The large gear 77 may be integrated with the end link member 5 on the base end side.

  The rotation axis O3 of the actuator 70 and the rotation axis O4 of the small gear 76 are located on the same axis. The rotation axes O3 and O4 are parallel to the rotation pair axis O1 of the base end side link hub 24 and the base end side end link member 5 and have the same height from the base member 62.

  The link actuating device 61 also includes in the controller 86 a control device 84 that controls the actuator 70 and an operation device 85 that inputs an operation command to the control device 84. The control device 84 and the operation device 85 have the same configuration as that of the above embodiment, and the same operation and effect as described above can be obtained. The operation device 85 includes a posture designation unit, a posture acquisition unit, and a posture information addition unit, as in the above embodiment, but these are not shown.

  This link actuating device 61 can be controlled so that the backlash of the link mechanism main body 1 and the speed reduction mechanism 71 is reduced by providing the actuator 70 and the speed reduction mechanism 71 in all of the three sets of link mechanisms 4. The positioning accuracy of the link hub 3 on the side can be improved, and the link actuator 61 itself can be made highly rigid.

  The gear-type reduction unit 73 of the reduction mechanism 71 is a combination of a small gear 76 and a large gear 77, and a high reduction ratio of 10 or more can be obtained. If the reduction ratio is high, the positioning resolution of the encoder or the like is increased, so that the positioning resolution of the link hub 3 on the distal end side is improved. Also, a low output actuator 70 can be used. In this embodiment, the actuator 70 with the reduction gear 70a is used. However, if the reduction ratio of the gear-type reduction gear 73 is high, the actuator 70 without the reduction gear can be used, and the actuator 70 can be downsized. it can.

By setting the pitch circle radius of the large gear 77 to ½ or more of the arm length L of the end link member 5 on the base end side, the bending moment of the end link member 5 on the base end side due to the tip load is reduced. . Therefore, it is not necessary to increase the rigidity of the entire link operating device 61 more than necessary, and the weight of the end link member 5 on the base end side can be reduced. For example, the end link member 5 on the base end side can be changed from stainless steel (SUS) to aluminum. Further, since the pitch circle radius of the large gear 77 is relatively large, the surface pressure of the tooth portion of the large gear 77 is reduced, and the rigidity of the entire link actuator 61 is increased.
Further, when the pitch circle radius of the large gear 77 is equal to or greater than ½ of the arm length, the large gear 77 is installed on the rotating pair of the base end side link hub 2 and the base end side end link member 5. Since the diameter is sufficiently larger than the outer diameter of the bearing 12, a space is formed between the tooth portion of the large gear 77 and the bearing 12, and the large gear 77 can be easily installed.

  In particular, in the case of this embodiment, the pitch circle radius of the large gear 77 is equal to or greater than the arm length L. Therefore, the pitch circle radius of the large gear 77 is further increased, and the above-described action and effect appear more remarkably. In addition, the small gear 76 can be installed on the outer diameter side of the link mechanism 4. As a result, an installation space for the small gear 76 can be easily secured, and the degree of freedom in design increases. Further, interference between the small gear 76 and other members is less likely to occur, and the movable range of the link actuator 61 is widened.

  Since the small gear 76 and the large gear 77 are spur gears, they are easy to manufacture and have high rotation transmission efficiency. Since the small gear 76 is supported by the bearings 80 on both sides in the axial direction, the support rigidity of the small gear 76 is high. As a result, the angle holding rigidity of the end link member 5 on the proximal end side due to the distal end load is increased, and the rigidity and positioning accuracy of the link actuator 61 are improved. Further, the rotational axis O3 of the actuator 70, the rotational axis O4 of the small gear 76, and the central axis O1 of the rotational pair of the base-side link hub 2 and the base-side end link member 5 are on the same plane. Therefore, the overall balance is good and the assemblability is good.

  Since the large gear 77 is detachable with respect to the end link member 5 on the base end side, the reduction ratio of the gear-type reduction portion 73 and the operation of the link hub 3 on the front end side with respect to the link hub 2 on the base end side. It becomes easy to change the specifications such as the range, and the mass productivity of the link actuating device 61 is improved. In other words, the same link actuating device 61 can be applied to various uses by simply changing the large gear 77. Also, maintainability is good. For example, when a failure occurs in the gear-type reduction unit 73, it is possible to deal with it by replacing only the reduction unit 73.

2 ... Base end side link hub 3 ... Front end side link hub 4 ... Link mechanism 5 ... Base end side end link member 6 ... Front end side end link member 7 ... Central link members 51, 61 ... Link actuator 53, 70 ... Actuators 54, 84 ... Control devices 55, 85 ... Operation devices 55a ... Posture specifying means 55b ... Posture acquisition means 55c ... Posture information giving means 100 ... Orthogonal coordinate system O ... Origin QA ... Proximal end link hub Center axis QA '... Extension shaft QB ... Center axis θ of the link hub on the tip side ... Bending angle φ ... Swivel angle

Claims (10)

The link hub on the distal end side is connected to the link hub on the proximal end side through three or more sets of link mechanisms in such a manner that the posture can be changed, and each of the link mechanisms includes a link hub on the proximal end side and a link hub on the distal end side. End link members on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a center on which both ends are rotatably connected to the other ends of the end link members on the base end side and the tip end side, respectively. Each of the link mechanisms is a geometric model in which the link mechanism is represented by a straight line, and the base end side portion and the tip end side portion are symmetrical with respect to the center portion of the center link member, Among the three or more sets of link mechanisms, two or more sets of link mechanisms are provided with actuators that arbitrarily change the tip posture, which is the posture of the tip side link hub with respect to the base side link hub. The control device for controlling the actuator includes a bending angle that is a vertical angle in which a central axis of the distal-side link hub is inclined with respect to a central axis of the proximal-side link hub; An operating device in a link actuating device defined by a turning angle which is a horizontal angle at which the central axis of the link hub on the distal end side is inclined with respect to the central axis of
The origin is located on the extension axis of the central axis of the link hub on the base end side, and the target tip posture is artificially operated at a coordinate position on a two-dimensional orthogonal coordinate system orthogonal to the extension axis of the central axis. The posture designation means designated by
Posture acquisition means for acquiring the tip posture represented by the bending angle and the turning angle by calculation from the coordinate position specified by the posture specification means;
Posture information giving means for giving information on the tip posture acquired by the posture acquisition means to the control device;
An operating device for a link actuating device, comprising:   2. The operating device for a link operating device according to claim 1, wherein the posture acquisition means uses a convergence calculation by a least square method as a calculation for acquiring the tip posture expressed by the bending angle and the turning angle. 2. The control device according to claim 1, wherein a rotation angle of the base end side end link member with respect to the base end side link hub is βn, and the center is rotatably connected to the base end side end link member. The angle formed by the connecting end shaft of the link member and the connecting end shaft of the central link member rotatably connected to the end link member on the distal end side is γ, and each angle relative to the reference end link member on the base end side When the separation angle in the circumferential direction of the end link member on the proximal end side is δn, the bending angle is θ, and the turning angle is φ,
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
By inversely transforming the expression represented by the following equation, the rotation angle of each base end side end link member in the target distal end posture is obtained, and the obtained rotation angle and the current distal end posture are An operating device for a link operating device that calculates a command operation amount of each actuator from a difference from a rotation angle of an end link member on each base end side. 2. The control device according to claim 1, wherein a rotation angle of the base end side end link member with respect to the base end side link hub is βn, and the center is rotatably connected to the base end side end link member. The angle formed by the connecting end shaft of the link member and the connecting end shaft of the central link member rotatably connected to the end link member on the distal end side is γ, and each angle relative to the reference end link member on the base end side When the separation angle in the circumferential direction of the end link member on the proximal end side is δn, the bending angle is θ, and the turning angle is φ,
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
A table indicating the relationship between the distal end posture and the rotation angle of the end link member on each proximal end side is created by inversely transforming the expression represented by the equation, and this table is used as a target. The rotation angle of the end link member on the base end side in the distal end posture is obtained, and from the difference between the calculated rotation angle and the rotation angle of the end link member on the base end side, An operating device for a link actuating device that calculates a command operation amount of an actuator.   3. The operating device for a link operating device according to claim 1, wherein the posture designating unit designates a coordinate position on the orthogonal coordinate system by numerical input.   6. The operating device for a link operating device according to claim 5, wherein the posture specifying means specifies the coordinate position on the orthogonal coordinate system by inputting numerical values of absolute coordinates with respect to a predetermined reference point.   6. The operation device for a link operating device according to claim 5, wherein the posture designation means designates a coordinate position on the orthogonal coordinate system by inputting a numerical value from a current coordinate position to a target coordinate position. .   3. The operating device for a link operating device according to claim 1, wherein the posture specifying means specifies a coordinate position on the orthogonal coordinate system with an operation amount determined according to an operation time or the number of operations.   3. The operating device for a link operating device according to claim 2, wherein the posture acquisition means searches for the bending angle by sequentially searching from the vicinity of the current coordinate position based on a convergence calculation by the least square method.   2. The link operation according to claim 1, wherein the control device converts the tip posture information given from the posture designation unit into an operation amount of the actuator by a predetermined conversion formula, and operates the actuator by the operation amount. Device operating device.

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