WO2023002642A1 - 駆動装置及びその制御方法、並びにパラレルリンクロボット及びその制御方法 - Google Patents
駆動装置及びその制御方法、並びにパラレルリンクロボット及びその制御方法 Download PDFInfo
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- WO2023002642A1 WO2023002642A1 PCT/JP2021/044324 JP2021044324W WO2023002642A1 WO 2023002642 A1 WO2023002642 A1 WO 2023002642A1 JP 2021044324 W JP2021044324 W JP 2021044324W WO 2023002642 A1 WO2023002642 A1 WO 2023002642A1
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- 238000000034 method Methods 0.000 title claims description 32
- 238000012937 correction Methods 0.000 claims abstract description 195
- 239000012636 effector Substances 0.000 claims description 28
- 238000001356 surgical procedure Methods 0.000 claims description 10
- 238000010586 diagram Methods 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 13
- 238000012545 processing Methods 0.000 description 10
- 210000005252 bulbus oculi Anatomy 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000009509 drug development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 210000001525 retina Anatomy 0.000 description 1
- 210000003786 sclera Anatomy 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J11/00—Manipulators not otherwise provided for
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D3/00—Control of position or direction
Definitions
- the present invention relates to a driving device and its control method, and a parallel link robot and its control method.
- a robot that uses a parallel link has the advantage of being superior to a general serial link robot in terms of positioning accuracy and rigidity.
- the positioning error of each axis that constitutes the robot greatly affects the accuracy of the tip position of the robot arm, techniques for reducing such positioning error are being studied.
- Patent Document 1 a technique for correcting a positioning error of a movable part caused by friction or backlash when moving the movable part using a ball screw device that converts the rotation of a motor into linear motion
- Patent document 1 corrects the position error that occurs when the moving part of the machine tool reverses the direction of movement, but does not consider the lead error of the ball screw and the effects of cogging peculiar to the pulse motor. . If such an error were to be corrected by feedback control, the gain would have to be increased, which could make the system unstable. Further, the configuration of Patent Document 1 employs a drive mechanism using a servomotor and a rotary encoder instead of a parallel link mechanism. Servomotors have poor stability at rest, making it difficult to maintain accurate positioning of moving parts. Also, the use of a linear encoder in addition to the rotary encoder results in a complicated system configuration. Although Patent Document 2 is a technology of a parallel link mechanism, each link is simply feedback-controlled. Therefore, it is difficult to precisely position the tip of the end effector due to the lead error and cogging error described above.
- the present invention provides a driving device and a control method thereof, a parallel link robot, and a method of controlling the tip position of an end effector precisely and stably by reducing the correction amount of feedback control without complicating the structure.
- the object is to provide a control method.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable unit according to the correction signal, and a position sensor that detects the current position of the movable unit.
- the actuator has a nut connected to the movable portion, a ball screw shaft to which the nut is screwed, and a pulse motor for rotationally driving the ball screw shaft;
- the correction unit has a correction amount map in which a position correction amount for calibrating a predictable error due to the structure of the actuator is mapped for each position of the movable unit, and ideally moves the movable unit according to the command signal.
- a driving device that generates the correction signal by correcting the command signal so that the difference from the ideal movement position is reduced.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion; wherein the actuator has a nut connected to the movable part, a ball screw shaft to which the nut is screwed, and a pulse motor that rotationally drives the ball screw shaft.
- the correction unit has a correction amount map in which a position correction amount for calibrating a predictable error due to the structure of the actuator is mapped for each position of the movable unit, and the command signal causes the movable unit to a step of estimating an ideal movement position to be moved; a step of obtaining the position correction amount corresponding to the current position detected by the position sensor by referring to the correction amount map; and correcting the current position with the position correction amount. and generating the correction signal obtained by correcting the command signal so that the difference between the corrected current position and the ideal movement position is reduced.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion;
- a parallel link robot configured by using a plurality of drive devices and changing the position and orientation of a robot tip axis, wherein the actuator includes a nut connected to the movable part and a ball screw to which the nut is screwed. and a pulse motor that rotationally drives the ball screw shaft.
- Each correction unit estimates an ideal movement position to which the movable unit moves according to the command signal, refers to the correction amount map, and controls the position sensor finds the position correction amount corresponding to the detected current position, and corrects the command signal so that the difference between the corrected current position obtained by correcting the current position with the position correction amount and the ideal movement position becomes small.
- a parallel link robot that generates the correction signal.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion;
- a control method for a parallel link robot configured by using a plurality of driving devices provided with the actuator to change the position and orientation of a robot tip axis, wherein the actuator includes a nut connected to the movable part and a nut screwed together. and a pulse motor for rotationally driving the ball screw shaft, and the correction unit adjusts the position correction amount for calibrating a predictable error caused by the structure of the corresponding actuator.
- the position of the tip of the end effector can be precisely and stably controlled by reducing the correction amount of feedback control without complicating the structure.
- FIG. 1 is a front perspective view of a parallel link robot.
- FIG. 2 is a rear perspective view of the parallel link robot.
- FIG. 3 is a top view of the parallel link robot.
- FIG. 4 is an explanatory diagram schematically showing the configuration and operation of the parallel link robot.
- FIG. 5A is a diagram showing movement of the needle 25 when the first link portion 13 is driven.
- FIG. 5B is a diagram showing how the needle 25 moves when the first link portion 13 is driven in the direction opposite to that in FIG. 5A.
- FIG. 6 is an explanatory diagram schematically showing an example of end effector control during ophthalmic surgery.
- FIG. 7 is an explanatory diagram showing the influence of an actuator error, taking the first link portion as an example.
- FIG. 8 is a schematic configuration diagram of the driving device.
- FIG. 8 is a schematic configuration diagram of the driving device.
- FIG. 9 is a graph showing the error between the commanded position instructed to the actuator and the actual movement position for each commanded position.
- FIG. 10 is a control block diagram showing details of processing by the first control method.
- FIG. 11 is a control block diagram showing details of processing by the second control method.
- FIG. 12 is a control block diagram of the second integrated converter.
- FIG. 1 is a front perspective view of a parallel link robot.
- FIG. 2 is a rear perspective view of the parallel link robot.
- the parallel link robot 100 includes a first link portion 13 having a first drive device 11A and a second drive device 11B, and a second drive device 15A and a second drive device 15B having a third drive device 15A and a fourth drive device 15B. It includes a link portion 17 , a fifth driving device 19 , an end effector 21 for ophthalmic surgery provided on the fifth driving device 19 , and an integrated control portion 23 .
- the end effector 21 is provided with a needle (for example, a surgical instrument such as a cannula) 25 at its tip and is driven forward and backward by the fifth driving device 19 .
- a needle for example, a surgical instrument such as a cannula
- the first driving device 11A of the first link portion 13 advances and retreats the support plate 31A, which is the movable portion, toward the second link portion 17.
- the second drive device 11B advances and retreats the support plate 31B, which is a movable portion, toward the second link portion 17.
- Support portions 33A and 33B are fixed to the support plates 31A and 31B, respectively.
- a first connection member 35 is arranged facing the support plates 31A and 31B. Brackets 37A and 37B are fixed to the surface of the first connecting member 35 on the first link portion 13 side.
- the bracket 37A is rotatably connected to the support portion 33A of the support plate 31A, and the bracket 37B is rotatably connected to the support portion 33B of the support plate 31B.
- the third drive device 15A and the fourth drive device 15B of the second link portion 17 are fixed to the surface of the first connection member 35 opposite to the first link portion 13 side. As shown in FIG. 1, the third driving device 15A of the second link portion 17 advances and retreats the support plate 41A, which is the movable portion. Similarly, the fourth driving device 15B advances and retreats the support plate 41B, which is a movable portion. Support portions 43A and 43B are fixed to the support plates 41A and 41B, respectively.
- a second connection member 45 is arranged facing the support plates 41A and 41B.
- the second connection member 45 is a member having an L-shaped cross section, and brackets 47A and 47B are fixed to the surface of the second connection member 45 on the second link portion 17 side.
- the bracket 47A is rotatably connected to the support portion 43A of the support plate 41A, and the bracket 47B is rotatably connected to the support portion 43B of the support plate 41B.
- the brackets 47A and 47B are fixed to one side of the L-shaped cross section of the second connecting member 45, and the fifth driving device 19 is fixed to the other side.
- FIG. 3 is a top view of the parallel link robot 100.
- the forward and backward direction of the movable portion of the first link portion 13 is the X direction
- the forward and backward direction of the movable portion of the second link portion 17 is the Y direction
- the direction perpendicular to the X and Y directions is the Z direction.
- the forward/backward direction of the first link portion 13 is assumed to be the horizontal direction
- the Z direction is assumed to be the vertical direction.
- the first driving device 11A includes an actuator 53 that drives the rod 51 forward and backward, and a slider 55 that supports the actuator 53 so as to be slidable in one axial direction. A part of the slider 55 is fixed with the above-described support plate 31A. Although not shown, the second driving device 11B has the same configuration.
- the parallel link robot 100 is operated based on the actuators 53 of the first drive device 11A and the second drive device 11B.
- the actuator 53 is fixed to a fixed portion (not shown), and the slider 55 and the rod 51 slide in the X direction with respect to the actuator 53, forming a movable portion together with the support plate 31A.
- the third drive device 15A and the fourth drive device 15B have the same configuration, except that the actuator 53 is fixed to the first connection member 35 .
- FIG. 4 is an explanatory diagram schematically showing the configuration and operation of the parallel link robot 100.
- the first connecting member 35 is tilted about the axis L1 (arrow R1 direction) by the driving in the S1 direction by the first driving device 11A or the driving in the S2 direction by the second driving device 11B.
- the second connection member 45 is tilted about the axis L2 (arrow R2 direction) by driving in the S3 direction by the third driving device 15A or by driving in the S4 direction by the fourth driving device 15B.
- the needle 25 at the tip of the end effector 21 attached to the second connecting member 45 via the fifth driving device 19 can be moved in the R1 and R2 directions.
- the needle 25 can be moved in any three-dimensional direction.
- the end effector 21 is driven by the set of the first drive device 11A and the second drive device 11B and the set of the third drive device 15A and the fourth drive device 15B. It is possible to move the tip.
- the fifth driving device 19 enables the forward and backward movement of the distal end of the end effector 21 along the axial direction. With such a simple configuration, the end effector can be stably controlled.
- the independent operation of each driving device enables highly accurate independent position control, and fine control of the tip of the end effector 21 becomes possible.
- FIG. 5A is a diagram showing how the needle 25 moves when the first link portion 13 is driven.
- FIG. 5B is a diagram showing how the needle 25 moves when the first link portion 13 is driven in the direction opposite to that in FIG. 5A.
- the first driving device 11A of the first link portion 13 is driven in the direction of the arrow X1
- the first connection member 35 tilts, and the second link portion 17 fixed to the first connection member 35
- the fifth drive 19 and the end effector 12 tilt together.
- the second driving device 11B of the first link portion 13 is driven in the direction of the arrow X2
- the first connecting member 35 tilts in the direction opposite to that shown in FIG.
- the part 17, the fifth drive 19 and the end effector 21 tilt together.
- the tip position of the needle 25 can be swung at angles ⁇ 1 and ⁇ 2 from the vertical direction.
- the swing center can be adjusted appropriately by feeding out the needle 25 of the fifth driving device 19 .
- the parallel link robot 100 with this configuration, it is possible to operate with 5 to 6 degrees of freedom and high accuracy on the order of ⁇ m. Therefore, it can be applied to a robot for ophthalmic surgery, which requires so-called RCM (Remote Center of Motion) control to operate around a specific point located far from the actuator.
- RCM Remote Center of Motion
- FIG. 6 is an explanatory diagram schematically showing an example of end effector control during ophthalmic surgery.
- the needle 25 is controlled with the entrance 61 to the eyeball as the center of rotation.
- high positioning accuracy of each axis by the actuator is required.
- FIG. 7 is an explanatory diagram showing the influence of actuator error, using the first link portion 13 as an example.
- the tilting angles ⁇ 1 and ⁇ 2 of the first connecting member 35 are determined by the driving operations of the first driving device 11A and the second driving device 11B, and the position of the needle 25 is determined according to the tilting angles. Attitude is determined.
- an error of ⁇ L1 occurs in the actuator 53 of the first driving device 11A and an error of ⁇ L2 occurs in the actuator 53 of the second driving device 11B, even if the magnitudes of the errors ⁇ L1 and ⁇ L2 are minute, the The tilting angle of the one connecting member 35 changes greatly. Due to this angle variation, the error at the position O becomes ⁇ L3, and the error increases as the position is farther from the actuator 53 .
- the actuators 53 of the first link portion 13, the second link portion 17, and the fifth drive device 19 are independently controlled to prevent occurrence of positional errors.
- the first driving device 11A, the second driving device 11B, the third driving device 15A, the fourth driving device 15B, and the fifth driving device 19 have the same configuration, and are collectively referred to as the driving device 10 in the following description. explain.
- FIG. 8 is a schematic configuration diagram of the driving device 10.
- the drive device 10 includes a controller 65 that corrects an input command signal Sd to generate a correction signal Sc, an actuator 53 that advances and retreats a rod 51 that is a movable portion according to the correction signal Sc, and a rod that is a movable portion. and a position sensor 67 for detecting the current position of 51 .
- a position sensor 67 a linear encoder having a scale 67a and a reading portion 67b is used as the position sensor 67. By using a linear encoder, the movement of the movable part can be directly detected along the direction of movement, and highly accurate detection is possible.
- the controller 65 and the position sensor 67 may be arranged inside the housing 53a of the actuator 53, or may be arranged on the side of the housing 53a.
- the actuator 53 has a nut 69 connected to the rod 51, a ball screw shaft 71 to which the nut 69 is screwed, and a pulse motor 73 that drives the ball screw shaft 71 to rotate.
- the ball screw shaft 71 is rotatably supported and the nut 69 is moved.
- the nut may be rotatably fixed to the pulse motor and the ball screw shaft moved. In that case, the actuator can be made more compact.
- the pulse motor 73 is preferably a stepping motor.
- a stepping motor is more stable at rest than a servomotor, and does not require a rotary encoder for detecting the rotation of the servomotor, thereby simplifying the configuration.
- piezo actuators it can be driven at a low voltage suitable for medical equipment.
- the stationary state can be maintained by the frictional force between the ball screw shaft 71 and the nut 69 even when the power supply is turned off, and the posture of the robot can be stably maintained.
- FIG. 9 is a graph showing the error between the commanded position instructed to the actuator and the actual movement position for each commanded position. 9. The error representing the variation between the command position and the actual movement position shown in FIG. This is due to the fact that vibration of several ⁇ m is generated several tens to several hundred times at each time. In the case shown in FIG. 9, the error ⁇ S is approximately 20 ⁇ m.
- the error between the lead error of the ball screw device and the cogging of the pulse motor is an error that can be measured in advance.
- This error can be corrected by constructing a correction amount map based on the On the other hand, errors due to thermal expansion, wear, etc. of the ball screw device cannot be measured in advance.
- the command to the actuator is divided into pre-measurable errors and pre-measurable errors and corrected. That is, regarding the information of the target position indicated by the command signal, the error that can be measured in advance is referred to the correction amount map mapped, and the position correction value corresponding to the position information obtained from the position sensor 67 is obtained and fed forward. Correction is performed by control, and errors that cannot be measured in advance are corrected by feedback control.
- a pulse motor 73 included in the actuator 53 shown in FIG. 8 is driven by a correction signal Sc including a speed correction value Vc obtained by correcting the speed setting value Vdes of the command signal Sd input to the driving device 10 in a predetermined procedure.
- FIG. 10 is a control block diagram showing the details of processing by the first control method.
- the speed set value Vdes is corrected by feedforward control based on a speed correction value VFF from a first correction unit 81, details of which will be described later, and feedback control based on a speed correction value VFB from a second correction unit 83, details of which will be described later.
- a signal of the corrected speed correction value Vc is input to the controller 65 .
- the controller 65 drives the pulse motor 73 shown in FIG. 8 according to the input speed correction value Vc signal. As a result, the rod 51, which is a movable portion, moves via the ball screw shaft 71 and the nut 69. As shown in FIG. The controller 65 outputs the current position Xenc of the movable portion detected by the position sensor 67 of the movement of the rod 51 .
- the current position Xenc output from the controller 65 is input to the map section 85 .
- the map unit 85 has a correction amount map in which lead errors and errors due to cogging, which are errors that can be measured in advance, are mapped for each position of the movable part.
- the map unit 85 refers to the correction amount map and outputs the position correction amount Xerr corresponding to the current position Xenc.
- the position correction amount Xerr is input to the first correction unit 81 .
- the first correction unit 81 performs correction processing for the position correction amount Xerr, which is an error amount that is known to occur in advance, on the speed setting value Vdes. That is, the first correction unit 81 calculates the speed correction value VFF for adjusting the speed setting value Vdes so that the error represented by the position correction amount Xerr is zero. In other words, the first correction unit 81 adjusts the speed setting value Vdes according to the position correction amount Xerr by feedforward control.
- the speed set value Vdes input to the controller 65 is also input to the conversion unit 87 .
- the conversion unit 87 estimates the ideal movement position Xdes of the movable unit when the actuator is driven based on the input speed setting value Vdes.
- a corrected current position Xreal is obtained by correcting the current position Xenc of the movable part output from the controller 65 with the position correction amount Xerr corresponding to this current position Xenc.
- the second correction unit 83 adjusts the speed setting value Vdes so that the corrected current position Xreal obtained approaches the ideal movement position Xdes. That is, the second correction unit 83 outputs the speed correction value VFB for correcting the speed setting value Vdes so that the difference between the corrected current position Xreal and the ideal movement position Xdes is small, and adjusts the value of the speed setting value Vdes. do.
- the second correction unit 83 performs correction corresponding to errors such as thermal expansion and wear of the ball screw device that cannot be measured in advance. This correction adjusts the speed set value Vdes by feedback control so that there is no difference between the corrected current position Xreal and the ideal movement position Xdes.
- the corrected current position Xreal after the first correction unit 81 has corrected an error that can be measured in advance is corrected. becomes smaller.
- correction processing can be performed with a small gain, excessive adjustment such as overshoot and hunting is less likely to occur, and the speed setting value Vdes can be adjusted with high accuracy.
- the correction order of the speed setting value Vdes by the speed correction value VFF by the first correction unit 81 and the speed correction value VFB by the second correction unit 83 may be whichever comes first.
- position information of five axes is integrated for control.
- a procedure for determining a command signal to instruct each driving device 10 in order to move the end effector to a desired target position and orientation will be described. do.
- FIG. 11 is a control block diagram showing the details of processing by the second control method.
- the tip position Xtip and the tip speed Vtip of the needle 25 in the end effector 21 shown in FIG. 1 are instructed as the command signal Sd.
- the first integrated converter 89 obtains the speed set value Vact of the movable part of each driving device 10 according to these signals. Since the speed setting value Vact is the control of the five-axis parallel link robot 100 here, it is expressed as a five-dimensional matrix.
- the speed set value Vact is corrected to the corrected speed set value V Tc of the five-dimensional matrix by the speed correction value V TF from the first overall correction section 91 and the speed correction value V TB from the second overall correction section 93, which will be described later. and input to each driving device 10 of the parallel link robot 100 .
- each driving device 10 of the parallel link robot 100 drives the actuator according to the corresponding speed setting value from the inputted correction speed setting value V Tc , and the moving part detected by the position sensor 67 (FIG. 8). Output the current position.
- the parallel link robot 100 puts together the current positions XTa of the movable parts of the drive devices 10 and outputs them in a five-dimensional matrix.
- FIG. 12 is a control block diagram of the second integrated converter 95.
- a signal of the current position XTa of each driving device 10 is input to the overall map section 96 .
- the overall map unit 96 is a correction amount obtained by mapping the yawing direction error Yerr, the pitching direction error Perr, and the axial direction error Aerr in each driving device 10, which are the errors that can be measured in advance, for each position. Have a map.
- the overall map unit 96 refers to the correction amount map, and in accordance with the input current position XTa of the movable portion of each drive device 10, the yawing direction error Yerr and the pitching direction error Yerr in each corresponding drive device 10.
- the error Perr and the axial error Aerr are output to the first auxiliary converter 97 .
- the errors Yerr, Perr, and Aerr and information on the target position Xact output from the first overall conversion section 89 (FIG. 11) are input to the first auxiliary conversion section 97 .
- the second auxiliary conversion section 98 predicts the error of the tip position of the needle 25 in the end effector 21 from the input information, and outputs the error amount XTip to the second auxiliary conversion section 98 .
- the second auxiliary converter 98 receives the error amount XTip, the target position Xact output from the first overall converter 89 , and the axial error Aerr output from the overall map module 96 .
- the second auxiliary converter 98 outputs the feedforward control amount XTF of each driving device 10 from the input information.
- This feedforward control amount XTF is input to the first overall correction section 91 shown in FIG.
- the first overall correction section 91 obtains a speed correction value VTF corresponding to the input feedforward control amount XTF , and corrects the speed set value Vact output from the first overall conversion section 89 .
- a corrected current position XTreal is obtained by correcting the current position XTa of the movable portion output from the parallel link robot 100 by the axial error Aerr corresponding to the current position XTa .
- the second overall correction unit 93 adjusts the speed set value Vact so that the corrected current position XTreal approaches the target position Xact. That is, the second overall correction unit 93 corrects the velocity set value Vact so that the difference XTc between the corrected current position XTreal obtained by correcting the current position XTa with the error Aerr in the axial direction and the target position Xact becomes small. It outputs a speed correction value VTB to adjust the speed set value Vact.
- the parallel link robot 100 with this configuration can accurately grasp the position of the tip (needle tip) of the end effector 21 by grasping the tip position of the movable part by each driving device 10 .
- the attitude of the end effector can be controlled with an arbitrary point on the axis of the end effector 21 as the center of rotation by independent control of each driving device 10 .
- RCM Remote Center of Motion
- the present invention is applied to an ophthalmic surgical robot using a plurality of drive devices, but the application is not limited to this.
- the present invention can be suitably applied to various robots such as medical robots, drug development robots, processing robots, etc., which require high precision in the position of the tip of the end effector.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable unit according to the correction signal, and a position sensor that detects the current position of the movable unit.
- the actuator has a nut connected to the movable portion, a ball screw shaft to which the nut is screwed, and a pulse motor for rotationally driving the ball screw shaft;
- the correction unit has a correction amount map in which a position correction amount for calibrating a predictable error due to the structure of the actuator is mapped for each position of the movable unit, and ideally moves the movable unit according to the command signal.
- a driving device that generates the correction signal by correcting the command signal so that the difference from the ideal movement position is reduced.
- the input command signal is corrected for the predictable error caused by the structure of the actuator using the correction amount map, and then corrected so that the difference from the ideal movement position becomes small. , the amount of correction in the latter correction process can be reduced. Therefore, correction processing can be performed with a small gain, and high position accuracy can be stably obtained.
- the predictable error includes at least one of a lead error of the ball screw and a rotational error due to cogging of the pulse motor. According to this driving device, the lead error and the rotation error due to cogging can be corrected.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion; wherein the actuator has a nut connected to the movable part, a ball screw shaft to which the nut is screwed, and a pulse motor that rotationally drives the ball screw shaft.
- the correction unit has a correction amount map in which a position correction amount for calibrating a predictable error due to the structure of the actuator is mapped for each position of the movable unit, and the command signal causes the movable unit to a step of estimating an ideal movement position to be moved; a step of obtaining the position correction amount corresponding to the current position detected by the position sensor by referring to the correction amount map; and correcting the current position with the position correction amount. and generating the correction signal obtained by correcting the command signal so that the difference between the corrected current position and the ideal movement position is reduced.
- the input command signal is corrected for the predictable error caused by the structure of the actuator using the correction amount map, and then the difference from the ideal movement position is reduced. Since it is corrected, the amount of correction in the latter correction process can be reduced. Therefore, correction processing can be performed with a small gain, and high position accuracy can be stably obtained.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion;
- a parallel link robot configured by using a plurality of drive devices and changing the position and orientation of a robot tip axis, wherein the actuator includes a nut connected to the movable part and a ball screw to which the nut is screwed. and a pulse motor that rotationally drives the ball screw shaft.
- Each correction unit estimates an ideal movement position to which the movable unit moves according to the command signal, refers to the correction amount map, and controls the position sensor finds the position correction amount corresponding to the detected current position, and corrects the command signal so that the difference between the corrected current position obtained by correcting the current position with the position correction amount and the ideal movement position becomes small.
- a parallel link robot that generates the correction signal. According to this parallel link robot, the speed and position of the tip end of the movable portion can be accurately controlled by the independent control device of each link portion, so that the speed and position of the tip shaft can be reliably determined. In addition, fine speed and position adjustment of the tip axis of the robot is possible by driving the pulse motor with the correction signal, and stable stationary and driving can be realized.
- the plurality of driving devices include a first driving device and a second driving device arranged so that the forward and backward directions of the movable portions are parallel to each other, and the movable portions of the first driving device and the second driving device. are separated from each other and are tiltable by advancing and retracting the movable portion; and a fourth drive device, the third drive device and the movable portion of the fourth drive device are separated from each other and connected to each other, and a second connection member capable of tilting by advancing and retreating the movable portion, and the second connection member wherein the tilting axis of the first connecting member, the tilting axis of the second connecting member, and the advancing/retreating axis of the movable portion of the fifth driving device are orthogonal to each other.
- the parallel link robot according to (6). According to this parallel link robot, drive control of five orthogonal axes can be performed with high position accuracy and high stability.
- a correction unit that corrects an input command signal to generate a correction signal, an actuator that advances and retreats a movable portion according to the correction signal, and a position sensor that detects the current position of the movable portion;
- a control method for a parallel link robot configured by using a plurality of driving devices provided with the actuator to change the position and orientation of a robot tip axis, wherein the actuator includes a nut connected to the movable part and a nut screwed together. and a pulse motor for rotationally driving the ball screw shaft, and the correction unit adjusts the position correction amount for calibrating a predictable error caused by the structure of the corresponding actuator.
- the speed and position of the tip of the movable portion can be accurately controlled by the independent control device of each link, so that the speed and position of the tip axis can be reliably determined.
- fine speed and position adjustment of the tip axis of the robot is possible by driving the pulse motor with the correction signal, and stable stationary and driving can be realized.
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Abstract
Description
図1は、パラレルリンクロボットの正面斜視図である。図2は、パラレルリンクロボットの背面斜視図である。図1に示すように、パラレルリンクロボット100は、第一駆動装置11Aと第二駆動装置11Bとを有する第一リンク部13と、第三駆動装置15Aと第四駆動装置15Bとを有する第二リンク部17と、第五駆動装置19と、第五駆動装置19に設けられた眼科手術用のエンドエフェクタ21と、統括制御部23と、を備える。エンドエフェクタ21は、先端に針(例えばカニューレなどの手術用器具)25が設けられて第五駆動装置19によって進退駆動される。
図6は、眼科手術時のエンドエフェクタの制御例を模式的に示す説明図である。例えば、眼球57の強膜59に孔を開けて針25を眼球内に挿入し、眼底57aの一部に処置を行う場合、眼球への侵入口61を回転中心として針25を制御する。このような場合、アクチュエータによる各軸の高い位置決め精度が必要となる。また、手術時のエンドエフェクタ21の姿勢維持は非常に重要で、各軸が位置を安定して保持する必要がある。
次に、各アクチュエータ53の制御について説明する。上述した第一駆動装置11A、第二駆動装置11B、第三駆動装置15A,第四駆動装置15B、第五駆動装置19は同一の構成であり、以下の説明ではこれらを纏めて駆動装置10として説明する。
本パラレルリンクロボット100の第1の制御方法では、アクチュエータへの指令を、予め測定可能な誤差と、予め測定できない誤差とに分けて補正する。即ち、指令信号で指示する目標位置の情報を、予め測定可能な誤差については、マッピングした補正量マップを参照して、位置センサ67から得られる位置情報に応じた位置補正値を求めてフィードフォワード制御により補正し、予め測定できない誤差については、フィードバック制御により補正する。
次に、第2の制御方法について説明する。前述した第1の制御方法では、各軸の軸方向の精度は担保されるが、アクチュエータは軸方向だけでなくピッチング、ヨーイング運動しながら前後する(上下左右に揺れながら前後する)ため、その補正は単軸で行う第1の制御方法では行えない。また、軸方向の誤差ではないため、位置センサ67により検出できない誤差となる。そのため、ピッチング、ヨーイング運動により生じる誤差は、他の軸により補正させる必要がある。
11A 第一駆動装置
11B 第二駆動装置
13 第一リンク部
15A 第三駆動装置
15B 第四駆動装置
17 第二リンク部
19 第五駆動装置
21 エンドエフェクタ
23 統括制御部
25 針
31A,31B 支持プレート
33A,33B 支持部
35 第一接続部材
37A,37B ブラケット
41A,41B 支持プレート
43A,43B 支持部
45 第二接続部材
47A,47B ブラケット
51 ロッド
53 アクチュエータ
53a 筐体
55 スライダ
57 眼球
57a 眼底
59 強膜
61 侵入口
65 コントローラ
67 位置センサ
67a スケール
67b 読取り部
69 ナット
71 ボールねじ軸
73 パルスモータ
81 第一補正部
83 第二補正部
85 マップ部
87 変換部
89 第一統括変換部
91 第一統括補正部
93 第二統括補正部
95 第二統括変換部
96 統括マップ部
97 第一補助変換部
98 第二補助変換部
100 パラレルリンクロボット
Claims (10)
- 入力された指令信号を補正して補正信号を生成する補正部と、前記補正信号に応じて可動部を進退駆動するアクチュエータと、前記可動部の現在位置を検出する位置センサと、
を備える駆動装置であって、
前記アクチュエータは、前記可動部に接続されたナットと、前記ナットが螺合されるボールねじ軸と、前記ボールねじ軸を回転駆動するパルスモータと、を有し、
前記補正部は、前記アクチュエータの構造に起因した予測可能な誤差を校正する位置補正量が前記可動部の位置毎にマッピングされた補正量マップを有し、
前記指令信号により前記可動部が移動する理想移動位置を推定し、
前記補正量マップを参照して前記位置センサが検出した前記現在位置に対応する前記位置補正量を求め、
前記現在位置を前記位置補正量で補正した補正現在位置と、前記理想移動位置との差が小さくなるように前記指令信号を補正した前記補正信号を生成する、
駆動装置。 - 前記予測可能な誤差は、前記ボールねじのリード誤差と、前記パルスモータのコギングによる回転誤差との少なくとも一方を含む、請求項1に記載の駆動装置。
- 前記位置センサは、リニアエンコーダである、
請求項1又は2に記載の駆動装置。 - 前記パルスモータは、ステッピングモータである、
請求項1から3のいずれか1項に記載の駆動装置。 - 入力された指令信号を補正して補正信号を生成する補正部と、前記補正信号に応じて可動部を進退駆動するアクチュエータと、前記可動部の現在位置を検出する位置センサと、を備える駆動装置の制御方法であって、
前記アクチュエータは、前記可動部に接続されたナットと、前記ナットが螺合されるボールねじ軸と、前記ボールねじ軸を回転駆動するパルスモータと、を有し、
前記補正部は、前記アクチュエータの構造に起因した予測可能な誤差を校正する位置補正量が前記可動部の位置毎にマッピングされた補正量マップを有し、
前記指令信号により前記可動部が移動する理想移動位置を推定する工程と、
前記補正量マップを参照して前記位置センサが検出した前記現在位置に対応する前記位置補正量を求める工程と、
前記現在位置を前記位置補正量で補正した補正現在位置と、前記理想移動位置との差が小さくなるように前記指令信号を補正した前記補正信号を生成する工程と、
を有する、駆動装置の制御方法。 - 入力された指令信号を補正して補正信号を生成する補正部と、前記補正信号に応じて可動部を進退駆動するアクチュエータと、前記可動部の現在位置を検出する位置センサと、を備える駆動装置を複数用いて構成され、ロボット先端軸の位置及び姿勢を変更するパラレルリンクロボットであって、
前記アクチュエータは、前記可動部に接続されたナットと、前記ナットが螺合されるボールねじ軸と、前記ボールねじ軸を回転駆動するパルスモータと、それぞれを有し、
前記補正部は、対応する前記アクチュエータの構造に起因した予測可能な誤差を校正する位置補正量が前記可動部の位置毎にマッピングされた補正量マップをそれぞれ有しており、
前記補正部のそれぞれは、
前記指令信号により前記可動部が移動する理想移動位置を推定し、
前記補正量マップを参照して前記位置センサが検出した前記現在位置に対応する前記位置補正量を求め、
前記現在位置を前記位置補正量で補正した補正現在位置と、前記理想移動位置との差が小さくなるように前記指令信号を補正した前記補正信号を生成する、
パラレルリンクロボット。 - 複数の前記駆動装置は、
前記可動部の進退方向を互いに平行にして配置された第一駆動装置及び第二駆動装置と、
前記第一駆動装置と前記第二駆動装置の前記可動部とが互いに離れて接続され、当該可動部の進退によって傾動可能な第一接続部材と、
前記第一接続部材に設けられ、前記可動部の進退方向を互いに平行にして配置された第三駆動装置及び第四駆動装置と、
前記第三駆動装置と前記第四駆動装置の前記可動部とが互いに離れて接続され、当該可動部の進退によって傾動可能な第二接続部材と、
前記第二接続部材に設けられた第五駆動装置と、
を備え、
前記第一接続部材の傾動軸と、前記第二接続部材の傾動軸と、前記第五駆動装置の前記可動部の進退軸とが互いに直交している、
請求項6に記載のパラレルリンクロボット。 - 前記ロボット先端軸にエンドエフェクタが設けられた、
請求項7に記載のパラレルリンクロボット。 - 前記エンドエフェクタは、眼科手術用の処置具が装着される、
請求項8に記載のパラレルリンクロボット。 - 入力された指令信号を補正して補正信号を生成する補正部と、前記補正信号に応じて可動部を進退駆動するアクチュエータと、前記可動部の現在位置を検出する位置センサと、を備える駆動装置を複数用いて構成され、ロボット先端軸の位置及び姿勢を変更するパラレルリンクロボットの制御方法であって、
前記アクチュエータは、前記可動部に接続されたナットと、前記ナットが螺合されるボールねじ軸と、前記ボールねじ軸を回転駆動するパルスモータと、それぞれを有し、
前記補正部は、対応する前記アクチュエータの構造に起因した予測可能な誤差を校正する位置補正量が前記可動部の位置毎にマッピングされた補正量マップをそれぞれ有しており、
前記指令信号により前記可動部が移動する理想移動位置を推定する工程と、
前記補正量マップを参照して前記位置センサが検出した前記現在位置に対応する前記位置補正量を求める工程と、
前記現在位置を前記位置補正量で補正した補正現在位置と、前記理想移動位置との差が小さくなるように前記指令信号を補正した前記補正信号を生成する工程と、
を有する、パラレルリンクロボットの制御方法。
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JPH1110575A (ja) | 1997-06-26 | 1999-01-19 | Toshiba Mach Co Ltd | パラレルリンク機構 |
WO2001063730A1 (fr) * | 2000-02-25 | 2001-08-30 | Mitsubishi Denki Kabushiki Kaisha | Servomoteur cylindrique |
JP2006266999A (ja) * | 2005-03-25 | 2006-10-05 | Nsk Ltd | 角度位置検出装置及び方法 |
US20100331858A1 (en) * | 2008-01-30 | 2010-12-30 | The Trustees Of Columbia University In The City Of New York | Systems, devices, and methods for robot-assisted micro-surgical stenting |
JP2019028782A (ja) | 2017-07-31 | 2019-02-21 | オークマ株式会社 | 位置制御装置 |
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JPH1110575A (ja) | 1997-06-26 | 1999-01-19 | Toshiba Mach Co Ltd | パラレルリンク機構 |
WO2001063730A1 (fr) * | 2000-02-25 | 2001-08-30 | Mitsubishi Denki Kabushiki Kaisha | Servomoteur cylindrique |
JP2006266999A (ja) * | 2005-03-25 | 2006-10-05 | Nsk Ltd | 角度位置検出装置及び方法 |
US20100331858A1 (en) * | 2008-01-30 | 2010-12-30 | The Trustees Of Columbia University In The City Of New York | Systems, devices, and methods for robot-assisted micro-surgical stenting |
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