Motor Control Device
The motor control device addresses torque and speed ripples by transitioning from speed to torque control with a speed limit function, enabling smooth and high-speed pressing operations without shocks.
Patent Information
- Application Number
- JP2020168643
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2020-10-05
- Publication Date
- 2025-02-03
- Estimated Expiration
- 2040-10-05
AI Technical Summary
Existing motor control systems face challenges in smoothly increasing torque and preventing shocks during pressing operations due to torque and speed ripples, making it difficult to perform precise and high-speed pressing control.
A motor control device that integrates a speed detection unit, a speed limit function, and a torque command restriction mechanism to smoothly transition from speed control to torque control, ensuring stable torque application without overshoot.
Enables smooth and high-speed pressing control by suppressing overshoot and ensuring stable torque application, preventing shocks during pressing operations.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to a motor control device having a press-fit control function. [Background technology]
[0002] The pressing control is used for pressing the probe of an automatic inspection machine, pressing for gripping a workpiece with a hand in a handling operation of a robot hand, screwing caps, press-fitting devices, etc. Patent Document 1 is an example of an implementation of such pressing control. Patent Document 1 describes an automatic pressing method in which a motor is driven to move a movable member, the movable member is brought into contact with a contacted member, and then the motor is increased in power to press the movable member against the contacted member, the speed of the movable member and the torque of the motor are kept below an allowable value until the movable member comes into contact with the contacted member, the contact of the movable member with the contacted member is detected by a change in the current flowing through the motor or a change in the speed of the rotor of the motor, and then the motor is controlled to generate an increased torque in the motor, thereby pressing the movable member against the contacted member.
[0003] In this way, in the method of Patent Document 1, the contact of the moving member with the object to be contacted is detected by a change in the current flowing through the motor or a change in the speed of the motor rotor, and then the motor is controlled to generate increased torque. However, motors have torque ripples and speed ripples, making it difficult to detect the contact by a small change in the current flowing through the motor or a small change in the speed of the motor rotor, and there is a problem that the detection level cannot be reduced. If the contact is detected by a large change in the current flowing through the motor or a large change in the speed of the motor rotor, a large torque is already output from the motor at the time of detection, and the force applied to the object cannot be smoothly increased, and impacts are applied to the object, making it difficult to smoothly tighten or press the screw. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2001-62765 A Summary of the Invention [Problem to be solved by the invention]
[0005] The present invention has been made to solve the problems described above, and its purpose is to provide a motor control device equipped with a pressing control function that can smoothly increase the motor torque (force applied to an object) when the movable part comes into contact with the object without detecting that the movable part has come into contact with the object, and at the same time suppresses overshooting when transitioning from position control or speed control to torque control with a speed limiting function, thereby enabling high-speed control. [Means for solving the problem]
[0006] The present invention is a motor control device that controls the torque of a motor while limiting the speed based on a torque command and a speed limit command, the motor control device having a speed detection unit that detects the speed of the motor, and a speed limiting unit that calculates a speed command based on a torque command based on the torque command, and outputs a motor speed command after applying a limit to the speed command based on the torque command, the speed limiting unit being characterized in that it comprises a torque command limiter that limits the torque command based on a speed limited state in which the speed command based on the torque command is limited by the speed limit command, and outputs a torque command after the limiter, a change adjuster for smoothly changing the torque command after the torque command limiter, a speed deviation calculator that calculates a speed deviation based on the torque command after the change adjuster, an adder that adds the speed deviation based on the torque command and the speed of the motor to obtain the speed command based on the torque command, and a speed limiter that limits the speed command based on the torque command by the speed limit command. Effect of the Invention
[0007] According to the present invention, it is possible to provide a motor control device equipped with a pressing control function that can smoothly increase the motor torque (force applied to an object) when the movable part comes into contact with the object without detecting that the movable part has come into contact with the object, and that can quickly transition from position control or speed control to torque control with a speed limiting function while suppressing overshoot. [Brief description of the drawings]
[0008] [Figure 1] FIG. 1 is a block diagram illustrating one embodiment of a motor control device and method. [Diagram 2] FIG. 2 is a block diagram illustrating another embodiment of a motor control device and method. [Diagram 3] FIG. 3 is a diagram showing a simulation result of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The following describes in detail the embodiments of the motor control device and method according to the present invention with reference to the drawings. Note that the scope of the present invention is not limited by the description of the embodiments, and any embodiment is included in the scope of the present invention as long as it falls within the technical scope of the invention according to each claim of the claims. FIG. 1 illustrates one embodiment of a motor control device and method.
[0010] As described in the Background Art section above, a motor control device and a control method having a press-fit control function are well known, and therefore a detailed description thereof will be omitted. However, an embodiment of the present invention is as follows.
[0011] The motor control device A of the present invention, which controls the motor torque and speed of the motor 21, is roughly composed of an encoder EN23, a speed detection unit 25 which obtains the speed by differentiating the position of the encoder EN23, a torque command limiter 1, a change adjuster 3, a speed deviation calculator 5, an adder 7, a speed limiter 9, a subtractor 11, a speed controller 15, a motor torque controller 17, etc. The change adjuster 3 is, for example, a low-pass filter. Of these, the torque command limiter 1, the change adjuster 3, the speed deviation calculator 5, the adder 7, and the speed limiter 9 are collectively referred to as a speed limiting unit B.
[0012] (First embodiment) The embodiment shown in Fig. 1 shows a configuration example in which pressing control is performed by contacting an object in a speed-limited state. The functions of each part of the motor control device A are as follows.
[0013] Torque command T C The torque command T output from the torque command limiter 1 is TC Input the torque command T after the change regulator CT The torque controller 3 outputs the torque command T C The speed deviation S based on the torque command is calculated by passing it through the speed deviation calculator 5, which takes the input DT The speed deviation S based on the torque command is calculated. DT and speed V to obtain the speed command S based on the torque command. TC Request.
[0014] Speed command S based on torque command TC The speed limiter 9 issues a speed limit command S LC The motor speed command S is limited based on MC The motor speed command S MC Specifically, the speed V is calculated by differentiating the position of the encoder EN23 attached to the motor 21. MCを Subtract the speed V to get the speed deviation S D is calculated and passed through the speed controller 15 to generate the motor torque command T MT Calculate the motor torque command T MT Based on this, the motor torque controller 17 outputs a motor torque command TMT A torque based on this is output from the motor 21. The torque output from the motor 21 is converted into a linear motion by a ball screw or the like, and drives a movable part.
[0015] The position rotated by the torque output from the motor 21 is detected by the encoder EN23, and the speed is controlled so that the speed coincides with the motor speed command. The speed controller 15 is composed of a proportional-integral controller, and depending on the control state, the proportional controller 15a alone is operated, or both the proportional controller 15a and the integral controller 15b are operated. The speed command S based on the torque command TC When the speed limiter 9 is in the ON state, proportional-integral control is performed, and when the speed limit state is released, the speed controller 15 is switched to proportional control, and torque control is performed as follows.
[0016] If the gain of the proportional controller 15a in the speed controller 15 is G, the speed command S based on the torque command TC would be as follows: Speed deviation S based on torque command DT = Torque command after the change regulator T CT / G Speed command S based on torque command TC = Speed deviation based on torque command S DT +speed V Then, the speed command S based on the obtained torque command is TC Speed limit command S LC The speed is limited based on the motor speed command S MC Request. Motor speed command S MC When the motor speed is controlled according to the above, the result is as follows. Motor torque command T MT = speed deviation S D ×G = (Motor speed command S MC -Speed V)×G
[0017] If the speed limit is not reached, the motor speed command S MC = Speed command S based on torque command TC Therefore, it is as follows: Motor torque command T MT = (speed command based on torque command S TC -speed V) × G = {(speed deviation based on torque command S DT +Speed V)-Speed V}×G = (Speed deviation based on torque command S DT ) × G = Torque command T after the change regulator CT / G×G = Torque command T after the change regulator CT Therefore, the motor torque command T MT is the torque command T after the change regulator CT This motor torque command T MT Torque control is performed based on this, and the motor torque according to the motor torque command is output from the motor 21.
[0018] Speed limit command S LC is set to a low value within the acceptable range of impact when the moving part hits the object, and the speed command S based on the torque command is TC is the speed limit command S LC If the speed is limited based on the torque command limiter 1, the torque command T C is limited to a small value (e.g. 1 / 10). C When is limited to a small value, the speed deviation S based on the torque command DT Since the value of becomes small, the speed command S based on the torque command TC becomes a slightly larger value with respect to the velocity V.
[0019] When the movable part is moving to the object in the speed limited state, the speed controller 15 is configured as a proportional integral controller and performs proportional integral control of the speed, so that the steady-state deviation of the speed becomes 0 and the speed V is equal to the speed limit command S LC In this state, when the moving part comes into contact with the object, the speed deviation S based on the torque command DT The speed limit state is released with a very slight decrease in speed corresponding to CTincreases smoothly according to the time constant of the change regulator, and when the effect of the change regulator 3 ends, the torque command T C The motor torque is output as follows.
[0020] As described above, in the embodiment of the present invention, the torque command T C The torque command T after the change regulator is inserted into the output when the speed limit state is released. CT The torque command T C By limiting the speed deviation S based on the torque command, DT can be set to a small value, so that the speed limit state can be released with only a slight decrease in speed when the robot touches the object. The robot moves at the speed limit and the torque command T C Torque command T after the change adjuster when performing pressing control based on CT The increase in the temperature can be made smooth.
[0021] Instead of the change adjuster 3, a function that increases the torque command at a constant gradient or any other function required during pressing may be used. The present invention can also be applied to a linear motor. In that case, the torque can be treated as a thrust force.
[0022] (Second Example) A second embodiment of the present invention is shown in Fig. 2. The second embodiment shows a configuration example in which the movable part moves under position control to approach an object, automatically transitions to a speed-limited state, and contacts the object in the speed-limited state to perform pressing control.
[0023] Position command L C Subtract the position P from the position deviation P D Calculate the position deviation P D is passed through the position controller 18 to obtain the speed command S PC Also, the torque command T C is passed through the torque command limiter 1, the change regulator 3, and the speed deviation calculator 5 to obtain the speed deviation S based on the torque command.DT The speed deviation S based on the torque command is calculated. DT and speed V to obtain the speed command S based on the torque command. TC The speed command S based on the torque command is calculated. TC The speed limiter 9 issues a speed limit command S LC The speed command S after the limiter is limited based on CL The speed limiter 9 calculates the speed command S based on the torque command. TC is the speed limit command S LC If the speed is limited based on the torque command limiter 1, the torque command T C Limit.
[0024] In this pressing control, first, the movable part is brought close to the object by position control, and when it approaches the object, the upper controller enables automatic control mode switching and gives the torque value required for pressing control as a torque command. When automatic control mode switching is enabled, the control mode switching unit 16 outputs an automatic control mode switching ON signal M C Based on this, the speed command S from the position controller PC and the speed command S after the limiter CL and the speed command S from the position controller 18 is PC is the speed command S after limiting CL If it is larger, the position control mode remains, and the speed command S from the position controller PC is the speed command S after the limiter CL When the control mode is the position control mode, the speed command selection unit 10 selects the speed command S PC If the control mode is torque control mode with speed limit function, the speed command S after the limiter is selected. CL Select the motor speed command S MC This motor speed command S MC The motor speed is controlled based on the above.
[0025] Specifically, the speed V is calculated by differentiating the position of the encoder EN23 attached to the motor 21. MCSubtract the speed V from to get the speed deviation S D is calculated and passed through the speed controller 15 to generate the motor torque command T MT Calculate the motor torque command T MT Based on this, the motor torque controller 17 outputs torque based on the motor torque command from the motor 21. The torque output from the motor 21 is converted into linear motion by a ball screw or the like to drive a movable part. The position rotated by the torque output from the motor 21 is detected by the encoder EN23, and the motor speed command S MC Speed control is performed so that the speed V coincides with the speed V. The speed controller 15 is composed of a proportional and integral controller, and depending on the control state, only the proportional controller 15a is operated, or both the proportional controller 15a and the integral controller 15b are operated. When the position control mode is selected as the control mode M in the control mode switching unit 16, both the proportional controller 15a and the integral controller 15b are operated to perform proportional and integral control. When the torque control mode with speed limiting function is selected as the control mode M in the control mode switching unit 16, and a speed command S based on a torque command is TC When the speed limit state is released, the speed controller 15 switches to proportional control and performs torque control in the same manner as in the first embodiment.
[0026] Speed limit command S LC is set to a low value within the acceptable range of the impact when the moving part hits the object, and when the motor is driven at high speed in the position control mode, the speed V is high, so the speed command S after the limiter CL When the control mode switching unit 16 switches from the position control mode to the torque control mode with speed limit function, the motor speed command S MC is the speed command S from the position controller PC Speed command S after the limiter CL and the speed limit command S LC The motor speed is controlled based on the speed limit command S LC The speed V is proportional-integral controlled.
[0027] In addition, the speed command S based on the torque commandTC When the speed limiter 9 is used to limit the speed, the speed limiter 9 outputs a speed limit state, and the torque command is limited to a small value (for example, 1 / 10) by the torque command limiter 1 based on the speed limit state (torque command T TC When the torque command is limited to a small value, the speed deviation S based on the torque command DT Since the speed command S based on the torque command also becomes a small value, TC becomes a value that is slightly larger than the speed V. When the movable part is moving to the object in the speed limited state, the speed controller 15 is configured as a proportional integral controller and performs proportional integral control of the speed V, so that the steady-state error of the speed V becomes 0 and the speed V is controlled by the speed limit command S LC In this state, when the moving part comes into contact with the object, the speed deviation S based on the torque command DT The speed limit state is released with a very slight decrease in speed corresponding to CT increases smoothly according to the time constant of the change regulator 3, and when the effect of the change regulator 3 ends, the torque command T C The motor torque is output as follows. C When pressure is applied by the pressure adjusting device, the automatic control mode switching is disabled.
[0028] Figure 3 shows the simulation results for the second embodiment. The horizontal axis is time. The vertical axis is the value shown at the top of the figure. Waveform A is the velocity command S from the position controller. PC FIG. Waveform B is the torque command T C , the torque command after the change regulator T CT 11A and 11B are diagrams showing changes in load torque over time. Waveform C shows the speed limited state (1: limited state). Waveform D is the speed command S after the limiter. CL FIG. Waveform E is the motor speed command S MC FIG. Waveform F shows the change in motor speed V over time. Waveform G is the motor torque command T MT FIG. The horizontal axis is the same for all waveforms.
[0029] When the pushing target is approached in position control, the automatic control mode switching is enabled, and the speed command S from the position controller shown in waveform A PC The speed command S after the limiter shown in waveform D CL When the speed becomes lower than this, the torque control mode is switched to the torque control mode with the speed limit function, and the speed command selection unit 10 selects the speed command S after the limiter shown by the waveform D. CL Select the motor speed command S shown by waveform E. MC is the speed limit command S LC The speed limit value set by (300 min -1 ) (see around t=0.12). The control mode is switched, and the motor speed command S shown by waveform E MC When the speed V becomes a constant speed limit command value after deceleration, the speed limit state is temporarily released while an overshoot occurs in the speed V, and the torque command T after the change regulator shown in waveform B is CT It can also be seen that the overshoot of velocity V shown by waveform F is suppressed by increasing the
[0030] Then, when the moving part approaches the object at the limited speed and abuts against the object, the speed limit state is released with only a slight decrease in speed, and the torque command T after the change regulator shown by waveform B is CT increases according to the time constant of the change regulator 3, and when the effect of the change regulator 3 ends, the torque command T C Motor torque command T MC (Waveform G) presses the object to be pressed. Torque command T C The operation is smooth and does not impact the object being pressed (around t = 0.14).
[0031] As described above, in this embodiment, normal position control is performed until the movable part approaches the pressing object, and when the movable part approaches the pressing object, automatic control mode switching is enabled. When automatic control mode switching is enabled, the control mode switching unit 16 switches the speed command S from the position controller to the PC and the speed command S after the limiter CL and the speed command S from the position controller PC is the speed command S after the limiter CL If the torque control with the speed limit function is selected and the torque control with the speed limit function is performed, the torque control with the speed limit function is selected and the torque control with the speed limit function is performed.
[0032] If a speed overshoot occurs when switching, the speed limit state is temporarily released, so the speed overshoot can be suppressed, and the speed after switching is quickly set to the speed limit command value and the pressing object is contacted. When the pressing object is contacted, the speed limit state is released with only a slight decrease in speed V, and the torque command T C The limit on the torque command T after the change regulator is released. CT rises with the time constant of the change regulator 3, and when the effect of the change regulator 3 ends, the torque command T C Motor torque command T MT The torque command T C The torque control with speed limit function of this control method automatically switches from the speed limit state to the torque control state, and furthermore, it is possible to smoothly increase the torque after contact with the pressing object, even without detecting contact with the pressing object.
[0033] In this way, the torque command can be smoothly increased when the pressing object is pressed, so pressing control can be achieved without giving any shock to the controlled object. In addition, since the shock when the pressing object is pressed is small, the speed limit command can be set to a higher value, so pressing control can be performed in a shorter time. Note that speed control may be performed instead of position control until the motor approaches the pressing object. In that case, the speed command from the position controller becomes the speed command during speed control.
[0034] (Effects of the Invention) As described above, in the present invention, a torque command limiter and a change adjuster are provided in a torque command input section, a speed command based on a torque command is calculated based on a torque command after the change adjuster, a speed limit is performed to obtain a speed command after the limit, and if the speed is limited, the torque command is limited by the torque command limiter. Then, the motor speed is controlled according to the speed command after the limit, thereby realizing press-fit control. This makes it possible to provide a motor control device equipped with a press-fit control function that suppresses speed overshoot when shifting from position control or speed control to torque control with a speed limit function to increase the operation speed, and smoothly increases the motor torque (force applied to the object) when the moving part comes into contact with the object without detecting that the moving part has come into contact with the object, thereby preventing a shock to the object.
[0035] Each of the above-mentioned embodiments shows one embodiment of the present invention, and the present invention itself is not limited to the specific configurations shown by those embodiments. The scope of the present invention includes everything that a person skilled in the art can imagine based on the matters described in the claims. [Explanation of symbols]
[0036] A Motor Control Device P position V speed 1 Torque command limiter 3. Change Adjuster 5 Speed deviation calculator 7 Adder 9 Speed Limiter 10 Speed command selection section 11 Subtractor 15 Speed Controller 15a Proportional Controller 15b Integral Controller 16 Control mode switching section 17 Motor torque controller 18 Position Controller 21 Motor 23 Encoder L C position command PD position deviation S CL Speed command after the limiter S MC Motor Speed Command S D speed deviation S DT Speed deviation based on torque command S LC Speed limit command S TC Speed command based on torque command S MC Motor Speed Command T TC Torque command after the limiter T C Torque Command T MT Motor Torque Command
Claims
1. A motor control device A controls the torque of a motor 21 while limiting the speed based on a torque command Tc and a speed limit command SLC, The motor control device A includes: a speed detection unit 25 for detecting a speed V of the motor; a speed limiting unit B that calculates a speed command STC based on a torque command based on the torque command Tc, and calculates and outputs a motor speed command SMC after limiting the speed command STC based on the torque command with a speed limiting command SLC; a subtractor 11 that subtracts the speed V of the motor 21 detected by the speed detection unit 25 from the motor speed command SMC and outputs the result as a speed deviation SD; A speed controller 15 that calculates a motor torque command TMT based on the speed deviation SD; having The speed controller 15 is a proportional controller 15a that multiplies the speed deviation SD by a gain G to calculate and output a proportional motor torque command; the integral controller 15b which integrates the speed deviation SD to calculate and output an integral motor torque command; a speed adder that calculates and outputs the motor torque command TMT by adding the proportional motor torque command and the integral motor torque command, The speed limiting unit B is a torque command limiter 1 which, when a speed command STC based on the torque command is in a speed limited state limited by the speed limit command SLC, limits the torque command Tc by a torque command limiter 1, calculates and outputs a torque command TTC after the torque command limiter, and, when the speed limit state is not in the speed limited state, outputs the torque command Tc as it is as the torque command TTC after the torque command limiter; a change adjuster 3 that calculates the torque command TTC output from the torque command limiter so as to smoothly change the torque command TTC output from the torque command limiter in either case, and outputs a torque command TCT output from a change adjuster; a speed deviation calculator 5 for calculating a speed deviation SDT based on a torque command obtained by dividing the torque command TCT after the change regulator 3 by the gain G and outputting the speed deviation SDT; an adder 7 for calculating and outputting a speed command STC based on the torque command by adding the speed deviation SDT based on the torque command and the motor speed V; a speed limiter 9 that calculates and outputs the motor speed command SMC by limiting a speed command STC based on the torque command by the speed limit command SLC; A motor control device comprising:
2. A motor control device A controls a motor 21 in a control mode M of either a torque control mode or a position control mode, controls a position of the motor 21 in the position control mode, and controls a torque of the motor 21 while limiting a speed in the torque control mode, The motor control device A includes: a position detection unit that detects a position of the motor; a speed detection unit 25 for detecting a speed V of the motor 21 from the position of the motor; a speed controller 15 for controlling the speed of the motor based on a motor speed command SMC; a speed limiting unit B that calculates a speed command STC based on a torque command, and calculates and outputs a speed command SCL after a speed limiter by applying a limit to the speed command STC based on the torque command; having The speed limiting unit B is a torque command limiter 1 that limits a torque command TC based on a speed limit state in which a speed command STC based on the torque command is limited by a speed limit command SLC, and outputs a torque command TTC after the torque command limiter; a change adjuster 3 that calculates the torque command TTC outputted from the torque command limiter so as to smoothly change the torque command TTC outputted from the torque command limiter and outputs a torque command TCT outputted from a change adjuster; a speed deviation calculator 5 for calculating and outputting a speed deviation SDT based on a torque command by dividing a torque command TCT of the change regulator by the gain G; an adder 7 for calculating and outputting a speed command STC based on the torque command by adding the speed deviation SDT based on the torque command and the motor speed V; a speed limiter 9 that limits a speed command STC based on the torque command by the speed limit command SLC and outputs a speed command SCL after the speed limiter; Equipped with The motor control device A includes: a subtractor that calculates and outputs a position deviation PD by subtracting the position P of the motor 21 from a position command LC; a position controller 18 that calculates and outputs a speed command SPC from the position controller based on the position deviation PD; a control mode switching unit 16 that operates when a control mode automatic switching signal MC becomes effective and automatically switches between the position control mode and the torque control mode; a speed command selection unit 10 which selects a speed command SPC from the position controller in the position control mode and selects a speed command SCL after the speed limiter in the torque control mode according to the control mode M switched by the control mode switching unit 16, and outputs the motor speed command SMC; having The control mode switching unit 16 When the control mode automatic switching signal MC is valid, the speed command SPC from the position controller is compared with the speed command SCL after the speed limiter, and if the value of the speed command SPC from the position controller is greater than the value of the speed command SCL after the speed limiter, the position control mode is selected, and if the value of the speed command SPC from the position controller is equal to or less than the value of the speed command SCL after the speed limiter, the torque control mode is selected. Motor control device.
3. The control mode switching unit 16 activates the control mode automatic switching signal MC when the position of the member driven by the motor 21 reaches a predetermined position. The motor control device according to claim 2 .
4. The speed controller 15 is If the speed is not limited by the speed limiter 9, proportional control is performed.
4. The motor control device according to claim 3, wherein when the speed is limited by the speed limiter 9, proportional-integral control is performed.
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