Automatic parameter adjustment device and link actuator

Abstract

The present invention provides an automatic parameter adjustment device and a link actuator that can improve the accuracy of parameter adjustment and reduce the amount of work required. [Solution] The link actuator 7 comprises a parallel link mechanism 9, a drive source 10 that drives the parallel link mechanism 9, and a control device Cu that controls the drive source 10. It also includes an automatic parameter adjustment device PU that automatically adjusts the control parameters of the link actuator 7. The automatic parameter adjustment device PU includes a vibration measuring unit 80 that measures the vibration frequency of the tip of the parallel link mechanism 9, a mass calculation unit 81 that calculates the mass of the workpiece W attached to the tip using the vibration frequency measured by the vibration measuring unit 80 and the spring constant of the parallel link mechanism 9 in a specific posture, and a load condition determination unit 82 that determines which of a plurality of preset load conditions the control parameters should be applied to according to the mass of the workpiece W calculated by the mass calculation unit 81.

Description

Technical Field

[0001] The present invention relates to a parameter automatic adjustment device and a link operating device, and more particularly to a technology capable of automatically adjusting control parameters of a robot such as a link operating device that requires a precise and wide operating range, such as medical equipment or industrial equipment.

Background Art

[0002] Conventionally, a control device has been proposed that determines the load condition acting on the tip member of a parallel link mechanism based on human judgment and manually switches a plurality of prepared control parameters (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, operation means such as physical buttons are used for the control parameter adjustment operation. However, since the adjustment of control parameters depends on the subjective judgment of the operator, the actual load condition at the tip of the parallel link mechanism may not match the assumed load condition of the operator. Therefore, a means for adjusting objective and appropriate control parameters is desirable.

[0005] Also, every time the load condition of the tip member changes, for example, in the case of changing the gripped workpiece, it is necessary to manually set the control parameters again, which takes a lot of labor for the operator.

[0006] An object of the present invention is to provide a parameter automatic adjustment device and a link operating device that can improve the accuracy of parameter adjustment and reduce the labor required.

Means for Solving the Problems

[0007] The parameter automatic adjustment device of the present invention is a parameter automatic adjustment device that automatically adjusts the control parameters of a robot, A vibration measuring unit 80 for measuring the vibration frequency of the tip of the arm in the robot, A mass calculation unit 81 calculates the mass of the workpiece W attached to the tip of the arm using the vibration frequency measured by the vibration measurement unit 80 and the spring constant in a specific posture of the robot. The system includes a load condition determination unit 82 that determines which of a plurality of preset load conditions to apply control parameters to, based on the mass of the workpiece W calculated by the mass calculation unit 81.

[0008] This configuration allows for more accurate setting of control parameters that match the actual load conditions, compared to conventional techniques where the operator anticipates load conditions based on the vibration level at the tip of the robot arm and sets the control parameters accordingly. This reduces vibration compared to conventional techniques and also reduces the amount of work required.

[0009] The automatic parameter adjustment device may be detachable from the robot. For a population where the workpiece mass does not vary significantly, rather than a population with large variations in workpiece mass, the load conditions can be initially estimated / determined and control parameters that match the load conditions can be applied. Subsequently, if the control parameters are to be used continuously, the automatic parameter adjustment device can be detached from the robot and used, for example, to adjust the control parameters of another robot. If there is variation in workpiece mass, the automatic parameter adjustment device can be operated while attached to the robot.

[0010] The robot control device Cu is A parameter storage unit 65a stores the control parameters for each load condition, The system may also include a parameter switching unit 65b that automatically switches to the control parameter that matches the load condition determined by the load condition determination unit 82 from among the multiple control parameters stored in the parameter storage unit 65a. In this case, the operator does not need to manually input the control parameter from the load condition, and the amount of work can be reduced.

[0011] The load condition determination unit 82 may determine the load condition based on a preset threshold value with respect to the mass of the workpiece W calculated by the mass calculation unit 81. The aforementioned threshold is determined by finding an appropriate value through, for example, testing and / or simulation. In this way, it becomes possible to automatically adjust the control parameters, and the accuracy of parameter adjustment can be improved.

[0012] The link actuator of the present invention comprises a parallel link mechanism 9, a drive source 10 for driving the parallel link mechanism 9, and a control device Cu for controlling the drive source 10, This link actuator is equipped with an automatic parameter adjustment device PU that automatically adjusts the control parameters of the link actuator. The parameter automatic adjustment device PU is A vibration measuring unit 80 for measuring the vibration frequency of the tip of the parallel link mechanism 9, A mass calculation unit 81 calculates the mass of the workpiece W attached to the tip of the parallel link mechanism 9 using the vibration frequency measured by the vibration measuring unit 80 and the spring constant of the parallel link mechanism 9 in a specific position, The system includes a load condition determination unit 82 that determines which of a plurality of preset load conditions to apply control parameters to, based on the mass of the workpiece W calculated by the mass calculation unit 81. The aforementioned specific posture is a posture arbitrarily determined by design, etc., and is, for example, determined to be an appropriate posture that matches the actual load conditions. The aforementioned control parameters are sometimes simply referred to as parameters or parameter values.

[0013] In this configuration, the vibration measurement unit 80 measures the vibration frequency of the tip of the parallel link mechanism 9. The mass calculation unit 81 uses the vibration frequency and the spring constant of the parallel link mechanism 9 in a specific orientation to calculate the mass of the workpiece W attached to the tip. The load condition determination unit 82 determines, based on the mass of the workpiece W, which of a plurality of preset load conditions the control parameters should match. When this automatic parameter adjustment device PU is applied, it is possible to set control parameters that more accurately match the actual load conditions than with conventional techniques where the operator sets control parameters by anticipating load conditions from the vibration level at the tip of the link mechanism. This reduces vibration compared to conventional techniques and also reduces the amount of work required.

[0014] The parallel link mechanism 9 connects the tip end link hub 13 to the base end link hub 12 via three or more sets of link mechanisms 14 so that its orientation can be changed. Each link mechanism 14 may have a base-side and a tip-side end link member 15, 16, each rotatably connected at one end to the base-side link hub 12 and the tip-side link hub 13, respectively, and a central link member 17, both ends rotatably connected to the other ends of these base-side and tip-side end link member 15, 16. In this case, vibration of the tip-side link hub 13 during settling and operation can be reduced without reducing the speed of the parallel link mechanism 9. [Effects of the Invention]

[0015] The parameter automatic adjustment device of the present invention is a parameter automatic adjustment device that automatically adjusts the control parameters of a robot, and includes a vibration measurement unit that measures the vibration frequency of the tip of the arm in the robot, the vibration frequency measured by this vibration measurement unit, and the spring constant in a specific posture of the robot. A mass calculation unit that calculates the mass of the workpiece attached to the tip of the arm using, and a load condition determination unit that determines which of a plurality of preset load conditions the control parameter to be applied matches according to the mass of the workpiece calculated by this mass calculation unit. Therefore, the accuracy of parameter adjustment can be improved, and the working hours can be reduced.

[0016] The link operating device of the present invention is a link operating device including a parallel link mechanism, a drive source that drives this parallel link mechanism, and a control device that controls this drive source, and includes a parameter automatic adjustment device that automatically adjusts the control parameters of this link operating device. The parameter automatic adjustment device measures the vibration frequency of the tip of the parallel link mechanism, the vibration frequency measured by this vibration measurement unit, and the spring constant in a specific posture of the parallel link mechanism. A mass calculation unit that calculates the mass of the workpiece attached to the tip of the parallel link mechanism using, and a load condition determination unit that determines which of a plurality of preset load conditions the control parameter to be applied matches according to the mass of the workpiece calculated by this mass calculation unit. Therefore, the accuracy of parameter adjustment can be improved, and the working hours can be reduced.

Brief Description of Drawings

[0017] [Figure 1] It is a block diagram schematically showing the overall configuration of the link operating device according to the first embodiment of the present invention. [Figure 2] It is a perspective view of the link operating device. [Figure 3] It is a front view of a simplified model in which two link mechanisms of the link operating device are omitted. [Figure 4] It is a partial sectional view taken along line IV-IV of FIG. 3. [Figure 5] This is a magnified view of a portion of Figure 4. [Figure 6] This diagram shows one of the link mechanisms of the link actuator as represented by straight lines. [Figure 7] This figure shows the maximum bending angle of the link actuator, etc. [Figure 8] This figure shows the relationship between workpiece mass and load conditions. [Figure 9] This is a block diagram of the control device and other components of the link actuator. [Figure 10] This is a block diagram schematically showing the overall configuration of a link actuator according to a second embodiment of the present invention. [Figure 11] This is a block diagram illustrating the overall configuration of the link actuator in the example proposal. [Figure 12] This figure shows an example of applying the parameter automatic adjustment device of the present invention to a vertical articulated robot. [Figure 13] This figure shows an example of applying the same automatic parameter adjustment device to a horizontally articulated robot. [Modes for carrying out the invention]

[0018] [First Embodiment] A link actuation device according to an embodiment of the present invention will be described with reference to Figures 1 to 9. The link actuation device as a robot is used, for example, in medical equipment or industrial equipment.

[0019] <Link Actuator> As shown in Figure 1, the link actuator 7 comprises a link actuator body 7A and an automatic parameter adjustment device PU. The automatic parameter adjustment device PU can also be applied to robots other than the link actuator 7 (as will be described later). The link actuator body 7A includes a parallel link mechanism 9, a drive source 10 that drives the parallel link mechanism 9, and a control device Cu that controls the drive source 10.

[0020] <Parallel link mechanism> As shown in Figure 2, the parallel link mechanism 9 connects the base link hub 12 to the tip link hub 13 via three sets of link mechanisms 14, allowing for attitude changes. The number of link mechanism sets 14 may be four or more. In Figure 3, only one set of link mechanism 14 is shown, and the remaining two link mechanisms are omitted.

[0021] Each link mechanism 14 has a base end link member 15, a tip end link member 16, and a central link member 17, forming a four-bar link mechanism consisting of four rotational pairs. As shown in Figure 2, the base and tip end link members 15 and 16 are L-shaped, with one end rotatably connected to the base link hub 12 and the tip link hub 13, respectively. The central link member 17 has the other ends of the base and tip end link members 15 and 16 rotatably connected to both ends.

[0022] As shown in Figure 3, the parallel link mechanism 9 is a structure that combines two spherical link mechanisms. The central axes of the rotational pairs of the base-side link hub 12 and the base-side end link member 15, and the central axes of the rotational pairs of the base-side end link member 15 and the central link member 17 intersect at the base-side spherical link center PA. Similarly, the central axes of the rotational pairs of the tip-side link hub 13 and the tip-side end link member 16, and the central axes of the rotational pairs of the tip-side end link member 16 and the central link member 17 intersect at the tip-side spherical link center PB.

[0023] Furthermore, the distance from the center of each rotational pair between the base-side link hub 12 and each end-side link member 15 to the base-side spherical link center PA (Figure 4) is the same. The distance from the center of each rotational pair between each end-side link member 15 and each central link member 17 to the base-side spherical link center PA (Figure 4) is the same. Similarly, the distance from the center of each rotational pair between the tip-side link hub 13 and each end-side link member 16 to the tip-side spherical link center PB is the same. The distance from the center of each rotational pair between each end-side link member 16 and each central link member 17 to the tip-side spherical link center PB is the same. The central axes of each rotational pair between the base-side and tip-side end-link members 15, 16 and the central link member 17 may have a certain intersection angle γ or may be parallel.

[0024] Figure 4 shows the relationship between the central axis O1 of each rotational pair between the base-side link hub 12 and the base-side end link member 15, and the spherical link center PA. The shape and positional relationship of the tip-side link hub 13 (Figure 3) and the tip-side end link member 16 (Figure 3) are the same as in Figure 4, although they are not shown. In Figure 4, the angle α formed by the central axis O1 of each rotational pair between the base-side link hub 12 and the base-side end link member 15, and the central axis O2 of each rotational pair between the base-side end link member 15 and the central link member 17 (Figure 5) is 90°. However, the angle α may be other than 90°.

[0025] The three sets of link mechanisms 14 have the same geometric shape. Geometrically identical shape means that, as shown in Figure 6, the geometric model in which each link member 15, 16, and 17 are represented by straight lines, that is, the model represented by each rotational pair and the straight lines connecting these rotational pairs, has a shape in which the base end portion and the tip end portion are symmetrical with respect to the central part of the central link member 17, regardless of the orientation. Figure 6 is a diagram in which one set of link mechanisms 14 is represented by straight lines. The parallel link mechanism 9 of this embodiment is of the rotationally symmetric type, and the positional relationship between the base end link hub 12 and the base end link member 15 and the tip end link hub 13 and the tip end link member 16 is configured to be rotationally symmetric with respect to the center line C of the central link member 17. The central part of each central link member 17 is located on a common orbital circle D.

[0026] The base-side link hub 12, the tip-side link hub 13, and three sets of link mechanisms 14 constitute a two-degree-of-freedom mechanism in which the tip-side link hub 13 can rotate freely around two orthogonal axes relative to the base-side link hub 12. In other words, the tip-side link hub 13 is a mechanism that allows for two degrees of rotation and change of orientation relative to the base-side link hub 12. This two-degree-of-freedom mechanism is compact while allowing for a wide range of motion of the tip-side link hub 13 relative to the base-side link hub 12.

[0027] For example, if the central axes QA and QB of the base and tip link hubs 12 and 13 are defined as straight lines passing through the base and tip spherical link centers PA and PB and intersecting the central axes O1 (Figure 4) of the respective rotational pairs of the base and tip link hubs 12 and 13 and the base and tip end link members 15 and 16 at right angles, then the maximum bending angle θ is the maximum value of the bending angle θ between the central axis QA of the base link hub 12 and the central axis QB of the tip link hub 13. maxThe angle can be set to approximately ±90°. Furthermore, the rotation angle φ of the tip-side link hub 13 relative to the base-side link hub 12 can be set within the range of 0° to 360°. The bending angle θ is the vertical angle at which the central axis QB of the tip-side link hub 13 is inclined relative to the central axis QA of the base-side link hub 12. On the other hand, the rotation angle φ is the horizontal angle at which the central axis QB of the tip-side link hub 13 is inclined relative to the central axis QA of the base-side link hub 12. The maximum bending angle θ is also shown. max It is acceptable for the angle to be 90° or greater.

[0028] The orientation change of the tip-side link hub 13 relative to the base-side link hub 12 is performed with the intersection point O of the central axis QA of the base-side link hub 12 and the central axis QB of the tip-side link hub 13 as the center of rotation. The solid line in Figure 7 shows the state where the central axis QA of the base-side link hub 12 and the central axis QB of the tip-side link hub 13 are on the same line, and the dashed line in Figure 7 shows the state where the central axis QB of the tip-side link hub 13 takes a certain operating angle (bending angle) with respect to the central axis QA of the base-side link hub 12. As shown in Figure 6, even if the orientation of the tip-side link hub 13 relative to the base-side link hub 12 changes, the distance L between the spherical link centers PA and PB of the base-side and tip-side links does not change.

[0029] As shown in Figures 4 and 6, in this parallel link mechanism 9, when all of the following conditions are met, the base-side link hub 12 and base-side end link member 15, and the tip-side link hub 13 and tip-side end link member 16 move in the same way due to geometric symmetry. Therefore, when the parallel link mechanism 9 transmits rotation from the base side to the tip side, the base side and the tip side rotate at the same angle and at a constant speed, functioning as a constant-velocity universal joint.

[0030] Condition 1: In each link mechanism 14, the angles α of the central axes O1 and O2 of the rotational pairs of the base and tip link hubs 12 and 13 and the base and tip end link members 15 and 16, as well as the lengths from the spherical link centers PA and PB on the base and tip sides to the centers of each rotational pair, are equal. Condition 2: The central axis O1 of the rotational pair between the base and tip end link hubs 12, 13 of each link mechanism 14 and the base and tip end link members 15, 16, and the central axis O2 of the rotational pair between the base and tip end link members 15, 16 and the central link member 17 intersect the base and tip end spherical link centers PA, PB at the base and tip ends. Condition 3: The geometric shapes of the base end link member 15 and the tip end link member 16 are equal. Condition 4: The geometric shapes of the base end portion and the tip end portion of the central link member 17 are equal. Condition 5: With respect to the plane of symmetry of the central link member 17, the angular positional relationship between the central link member 17 and the end link members 15 and 16 on the base and tip sides is the same on the base and tip sides.

[0031] As shown in Figure 2, the base end link hub 12 has a flat base member 6 and three rotating shaft connecting members 21 that are integrally provided with the base member 6. As shown in Figure 4, the base member 6 has a circular through hole 6a in its center, and the three rotating shaft connecting members 21 are arranged around this through hole 6a at equal intervals in the circumferential direction. The center of the through hole 6a is located on the central axis QA of the base end link hub 12 shown in Figure 3. A rotating shaft 22, shown in Figure 5, whose axis intersects the central axis QA of the base end link hub 12, is rotatably connected to each rotating shaft connecting member 21. One end of the base end link member 15 is connected to this rotating shaft 22.

[0032] The rotating shaft 22 has a large diameter section 22a, a small diameter section 22b, and a male threaded section 22c sequentially along its axial direction, and is rotatably supported by the rotating shaft connecting member 21 via two bearings 23 at the small diameter section 22b. The bearings 23 are ball bearings such as deep groove ball bearings and angular contact ball bearings. These bearings 23 are installed and fixed in a state where the outer ring surface is fitted into an inner diameter groove provided in the rotating shaft connecting member 21. The types and installation methods of bearings provided in other rotating paired parts are similar.

[0033] The rotating shaft 22 is positioned concentrically with the output shaft 52a of the reduction mechanism 52, described later, at its large-diameter portion 22a. One end of the base-side end link member 15 is connected to the rotating shaft 22 so as to rotate integrally with it. A notch 25 is formed at one end of the base-side end link member 15, and the portions on both sides of this notch 25 constitute a pair of inner and outer rotating shaft support portions 26 and 27. Through holes are formed in each of these pairs of rotating shaft support portions 26 and 27. The rotating shaft connecting member 21 is positioned within the notch 25, and the small-diameter portion 22b of the rotating shaft 22 is inserted through the through hole and the inner circumferential surface of the inner ring of the bearing 23. The male threaded portion 22c of the rotating shaft 22 protrudes inward from the inner rotating shaft support portion 27.

[0034] A spacer 28 is fitted around the outer circumference of the large-diameter portion 22a of the rotating shaft 22, and the end link member 15 on the base end side and the output shaft 52a of the reduction mechanism 52 are fixed together with a bolt 29 via this spacer 28. Furthermore, a nut is screwed onto the male threaded portion 22c of the rotating shaft 22. A spacer is interposed between the inner ring end face of the bearing 23 and a pair of rotating shaft support portions 26, 27, and preload is applied to the bearing 23 when the nut is screwed on.

[0035] A rotating shaft 35 is connected to the other end of the base-side end link member 15, and is rotatably connected to one end of the central link member 17. Similar to the rotating shaft 22 of the base-side link hub 12 (Figure 4), this rotating shaft 35 has a large-diameter portion 35a, a small-diameter portion 35b, and a male threaded portion 35c, and is rotatably supported at one end of the central link member 17 via two bearings 36 at the small-diameter portion 35b. A notch 37 is formed at the other end of the base-side end link member 15, and the portions on both sides of this notch 37 constitute a pair of inner and outer rotating shaft support portions 38 and 39. Through holes are formed in these rotating shaft support portions 38 and 39, respectively. The male threaded portion 35c protrudes inward from the inner rotating shaft support portion 39.

[0036] One end of the central link member 17 is positioned within the notch 37, and the small diameter portion 35b is inserted through the through hole and the inner circumferential surface of the inner ring of the bearing 36. Furthermore, a nut is screwed onto the male threaded portion 35c. A spacer is interposed between the inner ring end face of the bearing 36 and the pair of rotating shaft support portions 38 and 39, and preload is applied to the bearing 36 when the nut is screwed on.

[0037] As shown in Figure 2, the front-end link hub 13 has a flat end member 40 and three rotating shaft connecting members 41 provided equally spaced in the circumferential direction on the bottom surface of the end member 40. The center of the circumference on which each rotating shaft connecting member 41 is located is on the central axis QB (Figure 3) of the front-end link hub 13. A rotating shaft 43 whose axis intersects the central axis QB of the front-end link hub 13, as shown in Figure 7, is rotatably connected to each rotating shaft connecting member 41. As shown in Figure 2, one end of the front-end end link member 16 is connected to this rotating shaft 43. The other end of the front-end end link member 16 is connected to a rotating shaft 45 which is rotatably connected to the other end of the central link member 17.

[0038] The rotating shaft 43 of the tip-side link hub 13 and the rotating shaft 45 of the central link member 17 have the same shape as the rotating shaft 35 (Figure 5), and are rotatably connected to the other end of the rotating shaft connecting member 41 and the central link member 17, respectively, via two bearings (not shown).

[0039] <Power source> The drive source 10 is a rotary actuator consisting of a servo motor equipped with a reduction mechanism 52, and may be referred to as the attitude control actuator 10. The attitude control actuator 10 is mounted coaxially with the rotation shaft 22 shown in Figure 5 on the surface of the base member 6 of the base end link hub 12. The attitude control actuator 10 in Figure 4 and the reduction mechanism 52 shown in Figure 5 are provided as a single unit, and the reduction mechanism 52 is fixed to the base member 6 in Figure 4 by a motor fixing member 53. Note that the attitude control actuator 10 may also be equipped with a brake.

[0040] In this example, attitude control actuators 10 are provided on all three sets of link mechanisms 14. However, if attitude control actuators 10 are provided on at least two of the three sets of link mechanisms 14, the attitude of the tip-side link hub 13 (Figure 2) relative to the base-side link hub 12 can be determined.

[0041] The three attitude control actuators 10 are positioned so that their rotation axes 22 (Figure 5) are perpendicular to the central axis QA (Figure 3) of the base-side link hub 12, and the central position P is the intersection of the rotation axes 22 (Figure 5) of these attitude control actuators 10. 10 However, it lies on the central axis QA (Figure 3) of the base-side link hub 12. Also, of the three attitude control actuators 10, the angle bisector of the central axes O1, O1 of the rotation axes 22 (Figure 5) of two attitude control actuators 10 lies on the plane formed by the central axis O1 of the rotation axis 22 (Figure 5) of the remaining attitude control actuator 10 and the central axis QA (Figure 3) of the base-side link hub 12.

[0042] As shown in Figure 5, the reduction mechanism 52 has a flange output and a large-diameter output shaft 52a. The tip surface of the output shaft 52a is a planar flange surface 54 perpendicular to the center line of the output shaft 52a. The output shaft 52a is connected to the rotation shaft support portion 26 of the base end link member 15 via the spacer 28 by bolts 29. The large-diameter portion 22a of the rotation shaft 22, which constitutes the rotational pair between the base end link hub 12 (Figure 3) and the base end link member 15, is fitted into an inner diameter groove 57 provided on the output shaft 52a of the reduction mechanism 52.

[0043] As shown in Figure 3, the link actuator 7 rotates each attitude control actuator 10, thereby operating the parallel link mechanism 9. More specifically, when the attitude control actuator 10 is rotated, its rotation is reduced via the reduction mechanism 52 shown in Figure 5 and transmitted to the rotating shaft 22. As a result, the angle of the base end link member 15 relative to the base end link hub 12 shown in Figure 3 changes, and the attitude of the tip end link hub 13 relative to the base end link hub 12 can be arbitrarily changed. A workpiece can be detachably attached to the tip member 40 of the tip-side link hub 13, for example, via a hand (not shown).

[0044] <Control devices, etc.> As shown in Figures 2 and 9, the control device Cu controls each attitude control actuator 10 to change the attitude of the tip-side link hub 13 relative to the base-side link hub 12 from its current attitude to a target attitude provided by an external command means Ed to the control device Cu. The control device Cu is a computer-controlled numerical system and is mainly composed of attitude change control means 58. The attitude change control means 58 is composed of a servo driver or a programmable logic controller (PLC), and each attitude control actuator 10 is electrically connected to an individual control unit 59 within the control device Cu.

[0045] The attitude change control means 58, in order to change the attitude of the tip-side link hub 13 from its current attitude to the final target attitude, which is a target attitude given by the external command means Ed, usually calculates and registers several points (with different amounts of movement between points) to be passed along the way using a predetermined calculation, and then sequentially issues commands to move to each registered point. The point calculation means (not shown) that calculates and registers the multiple points is provided inside or outside the attitude change control means 58, above the command conversion unit 60 described later. Alternatively, the external command means Ed may command each point.

[0046] The attitude change control means 58 is a means for driving each attitude control actuator 10 by a command arm rotation angle from each rotation angle of the base end link member 15 when the current attitude is achieved to each rotation angle of the base end link member 15 when the target attitude is achieved. Specifically, the attitude change control means 58 comprises an initial parameter generation rule unit 65, a command conversion unit 60, a synchronization control unit 66, and an individual control unit 59. Of the attitude change control means 58, the command conversion unit 60, the synchronization control unit 66, and the individual control unit 59, excluding the initial parameter generation rule unit 65, are referred to as the control unit 58A (Figure 1).

[0047] The initial parameter generation rule unit 65 includes a parameter storage unit 65a and a parameter switching unit 65b. The parameter storage unit 65a stores control parameters for each load condition, and these control parameters are automatically adjusted by the automatic parameter adjustment device PU, which will be described later.

[0048] The parameter switching unit 65b automatically switches to a control parameter from among the multiple control parameters stored in the parameter storage unit 65a that matches the load condition determined by the load condition determination unit (described later). The parameter switching unit 65b retrieves the parameters corresponding to load conditions 1 to n commanded by the load condition determination unit from the parameter storage unit 65a and transmits them as rules to the initial parameter generation unit 60a of the command conversion unit 60. The initial parameter generation unit 60a generates control parameters according to the defined rules.

[0049] <Command conversion unit, etc.> The command conversion unit 60 is a means whose basic function is to convert a command B(θb,φb) of a target attitude given by an external command means Ed via the point calculation means or directly, in the form of a bending angle θ and a rotation angle φ, into a rotation angle β of the end link member 15 on the base end side of each link mechanism 14. The difference between the converted rotation angles βn(β1~β3) of each end link member 15 on the base end side and the current rotation angles α becomes the command arm rotation angle. The calculation to determine the rotation angle β of the end link member 15 on the base end side of each link mechanism 14 from the bending angle θ and the rotation angle φ is performed by inverse conversion using a defined relational expression.

[0050] From the above relationship, for attitudes A (θa, φa) and B (θb, φb) where the tip-side link hub 13 is located, the arm rotation angles corresponding to attitudes A and B are, respectively, the arm rotation angles for attitude A (β1a, β2a, β3a) and the arm rotation angles for attitude B (β1b, β2b, β3b).

[0051] In addition to the means having the basic functions described above, the command conversion unit 60 includes an initial parameter generation unit 60a and a judgment / modification unit 60b. The command arm rotation angle obtained by the command conversion unit 60 is provided to each individual control unit 59 corresponding to each attitude control actuator 10 via the synchronous control unit 66. In other words, the command conversion unit 60 generates initial parameters and performs predetermined judgments and modifications to pre-calculate the velocity between each point and the coordinates of each attitude control actuator (motor position).

[0052] The synchronous control unit 66 is a means for synchronously controlling the rotation of each end link member 15 on the base end side, and transmits hourly position commands to the individual control units 59, which are actuator drivers, in accordance with the synchronous timing. The individual control units 59 drive the corresponding attitude control actuators 10 according to the commands from the synchronous control unit 66. The synchronous control unit 66 has a parameter setting unit 66a and a position setting unit 66b, which set the parameters and positions to be specified to each individual control unit 59, respectively. The parameter setting unit 66a sets the control parameters initially generated by the command conversion unit 60, and when they are changed, it sets the changed control parameters. The position setting unit 66b sets the command arm rotation angle.

[0053] Each individual control unit 59 is a means for controlling the operation of the corresponding attitude control actuator 10 to rotate the end link member 15 on each base end from its current angle to a target angle, and includes a position control unit 59a consisting of a servo driver and a command execution means 59b. The synchronous control unit 66 provides operation commands to the position control unit 59a by pulse outputting or the like according to each control parameter and the arm command rotation angle, and the command execution means 59b drives the attitude control actuator 10. The position control unit 59a performs feedback control using the given operation command and the detected value of the encoder, which is a rotation angle detection means.

[0054] The initial parameter generation unit 60a of the command conversion unit 60 generates control parameters as initial values ​​for control parameters according to a defined rule, which control each end link member 15 on the base end side to start rotating and stop rotating simultaneously by the command arm rotation angle of each end link member 15 on the base end side given from a higher level. The initial parameter generation unit 60a sets the acceleration time and deceleration time, among the control parameters, to one period of the resonant frequency of the link actuator 7. The resonant frequency referred to here is the resonant frequency when all mounted components, such as end effectors, are installed on the tip-side link hub 13.

[0055] The judgment / modification unit 60b is a means for judging the control parameters generated by the initial parameter generation unit 60a according to a defined standard and changing them if it is determined that they should be changed. The judgment / modification unit 60b includes an operation time estimation means 60ba, a condition selection means 60bb, and a parameter modification means 60bc. The operation time estimation means 60ba estimates the operation time from the acceleration time, deceleration time, command speed, and command arm rotation angle of the attitude control actuator 10. The condition selection means 60bb is a means for comparing this estimated operation time with the sum of the acceleration time and deceleration time. The parameter modification means 60bc changes the initial value of the control parameters based on the result of the comparison by the condition selection means 60bb.

[0056] <Automatic parameter adjustment device> As shown in Figure 1, the automatic parameter adjustment device PU automatically adjusts the control parameters of the link actuator 7. <About control parameters> Examples of control parameters include acceleration time, deceleration time, maximum speed at commanded speed, filter time constant, moment of inertia, position loop gain, velocity loop gain, and velocity loop integral time constant, but are not limited to these examples. Multiple control parameters are linked to load conditions 1 to n. When the load conditions are switched, the numerical values ​​of the control parameters also switch, and a parameter switching command is also sent to the initial parameter generation rule unit 65 of the control device Cu shown in Figure 9.

[0057] The parameter automatic adjustment device PU in this example is independently traded on the market and is used by being electrically connected to the link actuator body 7A. The parameter automatic adjustment device PU is also detachable from the link actuator body 7A. For example, the parameter automatic adjustment device PU is detachably attached to the control device Cu in the link actuator body 7A using fasteners such as bolts. The parameter automatic adjustment device PU has a vibration measurement unit 80, a mass calculation unit 81, and a load condition determination unit 82. Specifically, in the link actuator 7, the workpiece W is attached to the tip-side link hub 13 (Figure 3), which is the tip of the parallel link mechanism 9. With the workpiece attached, the parallel link mechanism 9 is operated in a predetermined operating pattern.

[0058] Immediately after the parallel link mechanism 9 completes its operation, vibration occurs at the tip of the parallel link mechanism 9. The vibration measuring unit 80 measures the vibration frequency until the tip of the parallel link mechanism 9 settles down, using a measuring device 83 such as an acceleration pickup or displacement meter. The measuring device 83 is attached to the tip-side link hub 13 (Figure 3), which is the tip. The waveform of the acceleration, which is an analog signal, is input from the measuring device 83 to the vibration measuring unit 80, where it is converted into a vibration frequency signal. The measuring device 83 may also function as a vibration measuring unit 80 that converts the waveform of the acceleration, which is an analog signal, into a vibration frequency signal.

[0059] The mass calculation unit 81 uses the vibration frequency measured by the vibration measurement unit 80 and the spring constant of the parallel link mechanism 9 in a specific position to calculate the mass of the workpiece W attached to the tip of the parallel link mechanism 9 as follows. The specific position refers to the position of the parallel link mechanism 9 immediately after operating the parallel link mechanism 9 in a predetermined operating pattern while the workpiece is mounted. The mass calculation unit 81 converts the natural frequencies of the workpiece W and the tip of the parallel link mechanism from the measured vibration frequencies. Then, using the converted natural frequency f and the spring constant k of the parallel link mechanism 9 in a specific position, which has been measured in advance, the workpiece mass m is calculated using the following formula. m = k / 4π 2 f 2 …(k: spring constant, f: natural frequency)

[0060] The load condition determination unit 82 determines which of the preset load conditions to apply control parameters to, based on the mass of the workpiece W calculated by the mass calculation unit 81. At this time, the load condition determination unit 82 determines load conditions 1 to n (n: natural number) based on preset thresholds as shown in Figure 8, with respect to the mass of the workpiece W calculated by the mass calculation unit 81. The load in the load conditions refers to the mounted weight including the end effector such as the hand and the workpiece W attached to the end effector.

[0061] The load condition determination unit 82 in Figure 1 determines load condition 2 if, for example, the calculated mass of the workpiece W falls between threshold 1 and threshold 2 shown in Figure 8. Here, the intervals between the thresholds do not have to be equal. For example, the mass difference from threshold 2 to threshold 3 may be wider than the mass difference from threshold 1 to threshold 2.

[0062] <Effects and Effects> When applying the automatic parameter adjustment device PU shown in Figure 1, as described above, it is possible to set control parameters that more accurately match the actual load conditions than with conventional techniques where the operator sets control parameters by assuming load conditions from the vibration level of the tip of the link mechanism. This reduces vibration compared to conventional techniques and also reduces the amount of work required.

[0063] The automatic parameter adjustment device PU is detachable from the link actuator body 7A. In this case, the load conditions can be initially estimated / determined and control parameters that match the load conditions can be applied to a population where the mass of the workpiece W does not vary significantly, rather than a population where the mass of the workpiece W varies greatly. Subsequently, if the control parameters are to be used continuously, the automatic parameter adjustment device PU can be detached from the link actuator body 7A and used for adjusting the control parameters of other robots, for example. If there is variation in the mass of the workpiece W, the automatic parameter adjustment device PU can be operated while attached to the link actuator body 7A.

[0064] The control device Cu includes a parameter storage unit 65a that stores control parameters for each load condition, and a parameter switching unit 65b that automatically switches to the control parameter that matches the load condition determined by the load condition determination unit 82 from among multiple control parameters. In this case, the operator does not need to manually input the control parameters from the load conditions, and the amount of work can be reduced. The load condition determination unit 82 determines the load condition based on a preset threshold value relative to the mass of the workpiece W calculated by the mass calculation unit 81. In this way, it becomes possible to automatically adjust the control parameters and improve the accuracy of parameter adjustment.

[0065] As shown in Figure 2, the parallel link mechanism 9 connects the tip-side link hub 13 to the base-side link hub 12 via three sets of link mechanisms 14, allowing its orientation to be changed. Each link mechanism 14 has base-side and tip-side end link members 15 and 16, each rotatably connected at one end to the base-side link hub 12 and tip-side link hub 13, respectively, and a central link member 17, both ends rotatably connected to the other ends of these base-side and tip-side end link members 15 and 16. In this case, vibration of the tip-side link hub 13 during settling and operation can be reduced without reducing the speed of the parallel link mechanism 9.

[0066] <Regarding other embodiments> In the following description, parts corresponding to matters previously described in each embodiment will be denoted by the same reference numerals, and redundant explanations will be omitted. When only a part of the configuration is described, the other parts of the configuration will be the same as those in the previously described embodiment unless otherwise specified. Identical configurations will produce the same effects. Not only are combinations of the parts specifically described in each embodiment possible, but partial combinations of embodiments are also possible, provided that there are no particular problems with the combination.

[0067] [Second embodiment: Control device with automatic parameter adjustment device, Figure 10] As shown in Figure 10, the automatic parameter adjustment device PU may be provided on the control device Cu. In this case, when installing the link actuator 7, the effort of connecting the control device Cu and the automatic parameter adjustment device PU can be omitted, further reducing the amount of work required.

[0068] [Third Embodiment: Link Actuator with Operating Device] As shown in Figure 1 or Figure 10, the link actuator 7 may include an operating device Ou for manually setting the operating pattern of the end member 40 (Figure 2) and the control parameters. This operating device Ou may also have operating means for selecting and changing load conditions.

[0069] The load condition determination unit 82 may determine the load conditions not only based on the mass of the workpiece W, but also based on the bending angle θ, the swivel angle φ, the operating pattern, etc.

[0070] [Example of suggested method: Frequency measurement of parts other than the tip, Figure 11] As shown in Figure 11, for example, a measuring device 83 such as an acceleration pickup or displacement meter may be attached to the "movable part" of the parallel link mechanism 9, such as the end link member or the central link member at the tip. In this case, the link actuator 7 is represented as follows.

[0071] A link actuator 7 comprising a parallel link mechanism 9, a drive source 10 for driving the parallel link mechanism 9, and a control device Cu for controlling the drive source 10, This link actuator 7 is equipped with an automatic parameter adjustment device PU that automatically adjusts the control parameters. The parameter automatic adjustment device PU is A vibration measuring unit 80 for measuring the vibration frequency of the "movable part" of the parallel link mechanism 9, A mass calculation unit 81 calculates the mass of the workpiece W attached to the tip of the parallel link mechanism 9 using the vibration frequency measured by the vibration measurement unit 80 and the spring constant of the parallel link mechanism 9 in a specific position, A link actuator comprising: a load condition determination unit 82 that determines which of a plurality of preset load conditions to apply control parameters to, according to the mass of the workpiece W calculated by the mass calculation unit 81.

[0072] The vibration measuring unit 80 may detect the torque acting on the drive source 10 and calculate the vibration frequency until the tip of the parallel link mechanism 9 settles down.

[0073] [Fourth embodiment: Vertical articulated robot, Figure 12] As shown in Figure 12, the automatic parameter adjustment device PU may be applied to a vertical articulated robot Ra. A measuring device 83 is attached to the tip 13A of the arm Am in the robot Ra together with the workpiece W. The automatic parameter adjustment device PU is detachable from the robot Ra. For example, the automatic parameter adjustment device PU is detachably mounted on the control device Cu in the robot Ra using fasteners such as bolts. With the workpiece mounted, the robot Ra is operated according to a predetermined motion pattern. Hereafter, as in the first embodiment described above, the automatic parameter adjustment device PU can automatically adjust the control parameters of the robot Ra.

[0074] [Fifth embodiment: Horizontal articulated robot, Figure 13] As shown in Figure 13, the automatic parameter adjustment device PU may be applied to a horizontal articulated robot Rb. The measuring device 83 is attached to the tip 13A of the arm Am on the robot Rb together with the workpiece W. The automatic parameter adjustment device PU is detachable from the robot Rb. With the workpiece mounted, the robot Rb is operated in a predetermined motion pattern. Hereafter, as in the first embodiment described above, the automatic parameter adjustment device PU can automatically adjust the control parameters of the robot Rb.

[0075] While embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0076] 7...Link actuation device, 9...Parallel link mechanism, 10...Drive source, 12...Base end link hub, 13...Tip end link hub (tip section), 13A...Tip section, 14...Link mechanism, 15...Base end link member, 16...Tip end link member, 17...Central link member, 65a...Parameter storage unit, 65b...Parameter switching unit, 80...Vibration measurement unit, 81...Mass calculation unit, 82...Load condition discrimination unit, Am...Arm, Cu...Control device, PU...Automatic parameter adjustment device, Ra,Rb...Robot, W...Workpiece

Claims

1. A parameter automatic adjustment device for automatically adjusting the control parameters of a robot, A vibration measuring unit for measuring the vibration frequency of the tip of the arm in the robot, A mass calculation unit calculates the mass of a workpiece attached to the tip of the arm using the vibration frequency measured by this vibration measurement unit and the spring constant in a specific posture of the robot. A load condition determination unit determines which of a set of pre-set load conditions to apply control parameters to, based on the mass of the workpiece calculated by this mass calculation unit. An automatic parameter adjustment device having the following features.

2. An automatic parameter adjustment device according to claim 1, wherein the automatic parameter adjustment device is detachable from the robot.

3. In the automatic parameter adjustment device according to claim 1 or claim 2, the control device of the robot is: A parameter storage unit that stores the control parameters for each load condition, An automatic parameter adjustment device comprising: a parameter switching unit that automatically switches from a plurality of control parameters stored in the parameter storage unit to the control parameter that matches the load condition determined by the load condition determination unit.

4. An automatic parameter adjustment device according to claim 1 or claim 2, wherein the load condition determination unit determines the load condition based on a preset threshold value with respect to the mass of the workpiece calculated by the mass calculation unit.

5. A link actuator comprising a parallel link mechanism, a drive source for driving the parallel link mechanism, and a control device for controlling the drive source, This link actuator is equipped with an automatic parameter adjustment device that automatically adjusts the control parameters, and the automatic parameter adjustment device is A vibration measuring unit for measuring the vibration frequency of the tip of the parallel link mechanism, A mass calculation unit calculates the mass of a workpiece attached to the tip of the parallel link mechanism using the vibration frequency measured by the vibration measurement unit and the spring constant of the parallel link mechanism in a specific orientation. A load condition determination unit determines which of a set of pre-set load conditions to apply control parameters to, based on the mass of the workpiece calculated by this mass calculation unit. A link actuator having

6. In the link actuation device according to claim 5, the parallel link mechanism connects the tip end link hub, which is the tip end, to the base end link hub via three or more link mechanisms so that its orientation can be changed. Each of the aforementioned link mechanisms is a link actuation device having a base-side and a tip-side end link member, one end of which is rotatably connected to the base-side link hub and the tip-side link hub, respectively, and a central link member, both ends of which are rotatably connected to the other ends of these base-side and tip-side end link members.

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