KR102567726B1 - Motor control method, motor driving device, industrial robot control method, and industrial robot - Google Patents

Abstract

The rotation of the motor is stopped by open-loop control without generating motor out-of-phase or vibration due to lack of torque.
In open-loop control, a step for obtaining a torque required for a motor based on a position command value sent from a host controller, a step for obtaining a command value for Q-axis current according to the torque, a step for obtaining a command value for Q-axis current according to the Q-axis current command value, and and a step for supplying a D-axis current to the motor for drawing magnetic poles of the magnets of the rotor.

Description

Motor control method, motor drive device, industrial robot control method and industrial robot

The present invention relates to a motor control method, a motor driving device, an industrial robot control method, and an industrial robot.

Conventionally, a motor control method for driving a motor by open-loop control is known.

For example, in the motor control method described in Patent Literature 1, the motor is started by open-loop control by forced current (current drawing method). At this time, while supplying a constant D-axis current to the motor, the Q-axis current is maintained at zero. Then, when the angular velocity of the motor is raised until a sufficient induced voltage is obtained in the motor, the control method is switched from open-loop control to sensorless vector control in which the rotational position of the motor is estimated based on the current detection value. do.

Japanese Unexamined Patent Publication No. 2008-11628

Patent Literature 1 does not specifically describe how to stop the rotation of the motor. In the motor control method described in Patent Literature 1, since the rotational position of the motor is controlled by sensorless vector control during normal driving of the motor, the rotation is decelerated while controlling the rotational position of the motor when the motor is stopped. It is thought to stop Specifically, the rotation of the motor is decelerated by sensorless vector control until a sufficient induced voltage is not obtained in the motor, and then the control method is switched to open-loop control to stop the rotation.

By the way, according to the experiment of the present inventor, it has been found that using the open loop control described in Patent Document 1 causes motor out-of-regulation and vibration due to excessive or insufficient torque.

In addition, the problems that occur when switching the control method of the motor from sensorless vector control to open-loop control have been described, but the same problems may also occur in the following configuration. That is, it is a configuration in which the control method is switched from feedback control in which the detection value of the rotational position of the motor by an encoder or the like is fed back to open-loop control.

The present invention has been made in view of the above background, and its object is to provide the following motor control method, motor drive device, industrial robot control method, and industrial robot. That is, a motor control method capable of stopping rotation of a motor by open-loop control without generating motor out-of-control or vibration due to excessive or insufficient torque.

The first invention of the present application is a motor control method for driving a motor by open-loop control using a current drawing method, comprising the steps of obtaining a torque required for a motor based on a rotational position command signal sent from a signal transmission means; A step of obtaining a Q-axis current command value according to the torque, and a step of supplying the Q-axis current according to the Q-axis current command value and the D-axis current for drawing in the magnetic pole of the magnet of the rotor to the motor motor control method.

A second invention of the present application is a motor driving device for controlling driving of a motor, and a motor driving device characterized in that the driving of the motor is controlled by the motor control method of the first invention.

The third invention of the present application is an industrial robot control method for individually controlling the driving of a plurality of motors to change the position of an arm of the industrial robot, wherein each driving of the plurality of motors is controlled by the motor of the first invention. It is a control method of an industrial robot characterized in that it is controlled by the method.

The fourth invention of the present application is an industrial robot that individually controls driving of a plurality of motors to change the position of an arm, and controls each driving of the plurality of motors by the motor driving device of the second invention. It is an industrial robot characterized by

According to these inventions, there is an excellent effect that the rotation of the motor can be stopped by open-loop control without causing the motor to run out or vibrate due to excessive or insufficient torque.

1 is a perspective view showing an industrial robot according to an embodiment.
Fig. 2 is a plan view showing the industrial robot;
Fig. 3 is a block diagram showing the control configuration of the motor driving device mounted on the industrial robot together with a motor and the like.
Fig. 4 is a flowchart showing the processing flow of the mode value selection process executed by the control mode selection section of the same motor drive device.
Fig. 5 is a block diagram showing an open-loop controlled electrical angle generation unit of the motor drive device.
6 is a graph showing a relationship between a position command value and an actual rotational position of a hand part by control in response to the position command value.
7 is a graph showing time changes of various states in the conventional open loop control.
8 is a graph showing time changes of various states in a method for determining a Q-axis current command value immediately after open-loop control starts based on a torque command value immediately before open-loop control starts.
Fig. 9 is a block diagram showing the control configuration of the open-loop controlled DQ-axis current command generation unit of the same motor drive device.
10 is a graph showing the relationship between the Q-axis current command value and the D-axis current command value in the same motor drive device.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the motor drive apparatus and industrial robot using the motor control method concerning embodiment of this invention is described, referring drawings. In the following drawings, in order to make each configuration easy to understand, the actual structure and the scale and number of each structure may be different in some cases.

First, the basic configuration of the industrial robot according to the embodiment will be described. 1 is a perspective view showing an industrial robot 1 according to an embodiment. 2 is a plan view showing the industrial robot 1 . The industrial robot 1 is a robot for conveying a glass substrate, and is provided with an arm 2, a mount 3, and an elevation part 4. The elevation part 4 is held by the mount 3 and moves up and down in the up-and-down direction (in the direction of the arrow in FIG. 1) by driving an elevation motor (not shown). The arm 2 includes a hand portion 2A on which a glass substrate is placed, a forearm portion 2B, and an upper arm portion 2C, and is held by a lifting portion 4 .

The shoulder joint 2D, which is a connecting portion with the elevation part 4 in the upper arm part 2C, can rotate along the horizontal direction by driving the 1st motor 22A. Specifically, when the rotational driving force of the first motor 22A is transmitted to the shoulder joint 2D via the first belt 2E, the shoulder joint 2D rotates in the horizontal direction. Further, the elbow joint 2F, which is a connecting portion between the upper arm 2C and the forearm 2B, can rotate along the horizontal direction by driving the second motor 22B. Specifically, the elbow joint 2F rotates in the horizontal direction when the rotation driving force of the second motor 22B is transmitted to the elbow joint 2F via the second belt 2G. Further, the wrist joint, which is a connecting portion between the forearm 2B and the arm 2A, can rotate along the horizontal direction by receiving the driving force of the second motor 22B via the belt.

In the industrial robot 1, in order to move the arm 2A straight in the direction of the arrow along the trajectory indicated by the dashed-dotted line in FIG. Therefore, it is necessary to rotate both joints. For that purpose, it is necessary to drive the first motor 22A and the second motor 22B with different driving amounts. When both motors are stopped without controlling the respective rotational positions of the first motor 22 and the second motor 22B, the balance of the drive amounts of both motors is disrupted and the hand portion 2A is moved from the trajectory indicated by the chain dotted line. Stop at the wrong position and throw it away. Then, there is a possibility that the receiving portion 2A may collide with a surrounding structure or device.

Next, a motor drive device using the motor control method according to the embodiment will be described.

3 is a block diagram showing the control configuration of the motor drive device 20 mounted on the industrial robot 1 according to the embodiment together with the motor 22 and the like. In addition, the industrial robot 1 is a motor drive device 20 shown in FIG. 3, a motor drive device 20 for rotating the shoulder joint 2D of the arm 2, an elbow joint of the arm 2 ( 2F) and a motor driving device 20 for rotating the wrist joint and a motor driving device 20 for moving the elevation unit 4 up and down.

Each of the three motor drive devices 20 can switch and execute three of detection position feedback control, sensorless vector control, and open loop control as a control method for driving the motor 22 . The detection position feedback control is control that feeds back the result of detecting the rotational position of the motor to command generation of the rotational position.

The industrial robot 1 includes a host controller 100 that sends commands to three motor drive devices 20 . The upper controller 100 transmits a position command value (rotational position command signal) to each of the three motor drive devices 20 based on a control program stored in a storage medium. Each of the three motor drive devices 20 executes control to rotate the rotor of the motor 22 to a rotational position corresponding to the position command value sent from the host controller 100 . By this control, the arm 2 of the industrial robot 1 performs an operation based on the control program described above.

The configurations of the three motor driving devices 20 are the same as each other. Therefore, the configuration of only one of the three motor drive devices 20 will be described in detail below.

The motor driving device 20 includes a control mode selection unit 21, a position speed control unit 23, a vector control DQ axis current command generation unit 24, a first selector 25, a current control unit 26, and a DQ inverse conversion. section 27, a PWM controller 28 and an inverter 29. The motor 22 driven by the motor drive device 20 is the above-described first motor 22A, second motor 22B, or third motor. The motor drive device 20 includes a current detection unit 31, a second selector 32, a vector control electric angle generator 33, a third selector 34, a position estimation unit 35, and an open loop control electric angle. A generator 36 is provided. In addition, the motor drive device 20 includes an open loop control DQ axis current command generation unit 37, an encoder communication abnormality determination unit 38, and a DQ conversion unit 39. The motor unit includes a motor 22 and a rotary encoder 30 .

The position command value output from the upper controller 100 is input to the position speed controller 23 and the open-loop control electrical angle generator 36 of the motor drive device 20 .

of the arm 2 of the industrial robot 1 (rotation of the shoulder joint 2D), joint bending and extension operation (rotation of the shoulder joint 2D, elbow joint 2F, and wrist joint), or lifting operation The motor 22 as a driving source is composed of a PM (Permanent Magnet) motor of three-phase (U-phase, V-phase, W-phase) alternating current. The rotary encoder 30 as a rotational position detector mounted on the motor 22 detects the rotational position of the rotor of the motor 22 by a well-known technique. Then, the rotary encoder 30 outputs the information of the detection result of the rotational position as a position detection value (rotational position signal). The outputted position detection value is input to the encoder communication failure determination unit 38 and the control mode selection unit 21. In addition, the position detection value is also input to the position speed controller 23 through the second selector 32 .

Hereinafter, rotation of the rotor of the motor 22 may be expressed as rotation of the motor 22 .

The encoder communication abnormality determination unit 38 detects the presence or absence of an abnormality with respect to the position detection value sent from the rotary encoder 30, and when an abnormality is detected, an abnormality occurrence signal is sent to the control mode selection unit 21 and the upper controller ( 100). As an example of a method for detecting an abnormality in the positional detection value by the encoder communication abnormality determination unit 38, a method of detecting as anomaly when the amount of time change in the positional detection value exceeds a predetermined threshold value (or is greater than or equal to the threshold value) can be heard However, it is not limited to this method. As a method of detecting an abnormality in the position detection value, a method of detecting an abnormality in the rotary encoder 30 as an abnormality in the position detection value may be employed.

The control mode selector 21 calculates the angular velocity of the motor 22 based on the amount of change per unit time of the position detection value sent from the rotary encoder 30, and the calculation result and whether or not the position detection value is abnormal Based on this, the control mode value is selected and output.

FIG. 4 is a flowchart showing the processing flow of the mode value selection process executed by the control mode selection unit 21. As shown in FIG. In the mode value selection process, first, it is determined whether or not an abnormality generation signal transmitted as necessary from the encoder communication abnormality determining unit 38 has been received (S (step) 1). Then, when the abnormal occurrence signal is not received (N in S1), "0" is selected as the control mode value and outputted from the control mode selector 21 (S2). After that, the processing flow returns to S1.

On the other hand, when an abnormal occurrence signal is received (Y in S1), it is then determined whether or not the angular velocity of the motor 22 is equal to or greater than a predetermined value (or whether it exceeds a predetermined value) (S3). Then, when the angular velocity is equal to or greater than the predetermined value (Y in S3), "1" is selected as the control mode value and outputted from the control mode selector 21 (S4). On the other hand, if it is not equal to or greater than the predetermined value (or does not exceed the predetermined value) (N in S3), "2" is selected as the control mode value and outputted from the control mode selector 21. Hereinafter, the above predetermined value may be expressed as a lower limit value.

As described above, in the control mode value selection process, when no abnormality has occurred in the position detection value, "0" is selected as the control mode value. In addition, when an abnormal position detection value occurs and the angular velocity exceeds the predetermined value, "1" is selected as the control mode value, and when an abnormal position detection value occurs and the angular velocity does not exceed the predetermined value, the control mode value As "2" is selected.

In addition, the above predetermined value is 10 [%] of the rated angular velocity of the motor 22, for example.

When an abnormal occurrence signal is sent from the motor drive device 20, the host controller 100 transmits a position command value to the three motor drive devices 20 while moving the arm 2 on a predetermined trajectory. 2) and the motor 22 are changed to a decelerating and stopping pattern. As a result, the arm 2 stops while decelerating on a predetermined trajectory.

3, the control mode value output from the control mode selector 21 is a first selector 25, a second selector 32, and a third selector 34 (hereafter, these are collectively referred to as three selectors). Also referred to as (25, 32, 34)). Each of the three selectors 25, 32, 34 has an input terminal No. 0, an input terminal No. 1, and an input terminal No. 2, and based on the control mode value sent from the control mode selector 21, outputs switch the signal Specifically, each of the three selectors 25, 32, 34 outputs a signal input to input terminal 0 when the control mode value is "0", and outputs a signal input to input terminal 1 when it is "1". In the case of "2", the signal input to the second input terminal is output.

The following signals are output from each of the three selectors 25, 32 and 34 having this structure. That is, detection position feedback for rotating the motor 22 from the position indicated by the position detection value to the position indicated by the position command value when no abnormality has occurred in the position detection value (control mode value = 0). A signal for executing the control is output. Further, when an abnormal position detection value occurs and the angular velocity of the motor 22 is equal to or greater than a predetermined value (or exceeds a predetermined value) (control mode value = 1), the sensorless vector control described later causes the motor to A signal for driving (22) is output. Further, when an abnormal position detection value occurs and the angular velocity of the motor 22 is less than a predetermined value (or less than or equal to a predetermined value) (control mode value = 2), the motor 22 is operated by the open-loop control described later. A signal for driving is output.

Among the three control methods described above, first, detection position feedback control will be described.

When there is no abnormality in the position detection value output from the rotary encoder 30, the motor drive device 20 drives the motor 22 by detection position feedback control. Specifically, when there is no abnormality in the position detection value, the position detection value is output from the second selector 32 and is input to the position speed control section 23 and the vector control electric angle generation section 33 as a position feedback value. do. The position speed control unit 23 calculates a torque value required to rotate the motor 22 from the position indicated by the position feedback value to the position indicated by the position command value, and uses the result as a torque command value for vector control DQ axis current. output to the command generator 24. Also, the vector control electrical angle generator 33 generates an electrical angle based on the position feedback value. This electrical angle is input to the DQ conversion section 39 through the third selector 34.

The vector control DQ-axis current command generation unit 24 includes a D-axis current command value and a Q-axis current command value for generating D-axis current and Q-axis current required to generate the same torque as the input torque value in the motor 22 Generates current command values (hereinafter, these are also referred to as DQ-axis current command values). The D-axis current is a component parallel to the magnetic flux of the permanent magnet among currents flowing through the motor 22 . In addition, the Q-axis current is a component orthogonal to the magnetic flux of the permanent magnet among the currents flowing through the motor 22 .

The DQ-axis current command value output from the vector control DQ-axis current command generation unit 24 is input to the 0th input terminal and the 1st input terminal of the first selector 25 . The DQ axis generated by the vector control DQ axis current command generation section 24 when detection position feedback control is executed (control mode value = 0) and when sensorless vector control is executed (control mode value = 1). A current command value is output from the first selector 25 . This DQ-axis current command value is input to the current controller 26.

The DQ conversion unit 39 generates a D-axis current feedback value and a Q-axis current feedback value (hereinafter, also referred to as a DQ-axis current feedback value) based on the electrical angle sent from the third selector 34, and the current controller ( 26) is output. In the case of sensorless vector control described later, the DQ conversion unit 39 uses the electrical angle sent from the third selector 34 and the three-phase current detection value sent from the current detection unit 31 to determine the DQ axis. Generates a current feedback value.

The current control unit 26 generates a DQ-axis voltage command value based on the DQ-axis current command value sent from the first selector 25 and the DQ-axis current feedback value sent from the DQ conversion unit 39, and generates a DQ-axis voltage command value. It is output to the inverse transform unit 27.

The DQ inverse conversion unit 27 converts the required D-axis current and Q-axis current to the motor 22 based on the electrical angle sent from the third selector 34 and the DQ-axis voltage command value sent from the current control unit 26. ), a U-phase voltage command value, a V-phase voltage command value, and a W-phase voltage command value (hereinafter also referred to as a three-phase voltage command value) are generated and output. The three-phase voltage command value output from the DQ inverse conversion unit 27 is input to the PWM control unit 28. The PWM controller 28 converts the U-phase voltage, V-phase voltage, and W-phase voltage indicated by the U-phase voltage command value, V-phase voltage command value, and W-phase voltage command value into PWM signals for outputting from the inverter 29 A U-phase gate signal, a V-phase gate signal, and a W-phase gate signal are generated. The inverter 29 supplies the U-phase voltage, V-phase voltage, and W-phase voltage based on the U-phase gate signal, V-phase gate signal, and W-phase gate signal to the motor 22 to rotate the motor 22. .

The current detection unit 31 detects the U-phase current, the V-phase current, and the W-phase current flowing from the inverter 29 to the motor 22 (hereinafter, these are also referred to as three-phase currents), and outputs the detection result as the U-phase current. It is output as a detected value, a V-phase current detected value, and a W-phase current detected value (hereinafter also referred to as a three-phase current detected value). In addition, instead of detecting the three-phase current values, only the two-phase current values may be detected, and the remaining one-phase current values may be calculated based on the two-phase current value detection results.

When there is no abnormality in the position detection value output from the rotary encoder 30, the motor 22 is driven by the detection position feedback control as described above.

Next, sensorless vector control will be described. When sensorless vector control is executed, that is, when there is an abnormality in the detected position value and the angular velocity of the motor 22 immediately before the occurrence of the abnormality is equal to or greater than a predetermined value (or exceeds a predetermined value) (control mode value = 1) Then, the motor 22 is driven as follows. That is, the three-phase current detection value output from the current detection unit 31 is input to the DQ conversion unit 39 . The DQ conversion unit 39 generates and outputs a DQ-axis current feedback value based on the three-phase current detection value and the electrical angle sent from the third selector 34 . The output DQ-axis current feedback value is input to the current control unit 26 and the position estimation unit 35.

The current control unit 26 generates and outputs a DQ-axis voltage command value based on the DQ-axis current command value sent from the first selector 25 and the DQ-axis current feedback value sent from the DQ conversion unit. The position estimation unit 35 estimates the rotational position of the motor 22 based on the DQ-axis voltage command value sent from the current control unit 26 and the DQ-axis current feedback value sent from the DQ conversion unit 39. do.

The position estimation unit 35 obtains a position estimation value and an electrical angle estimation value based on the DQ-axis current feedback value sent from the DQ conversion unit 39 and the DQ-axis voltage command value sent from the current control unit 26. . Then, the position estimation unit 35 outputs the position estimation value to the first input terminal of the second selector 32 and also outputs the electrical angle estimation value to the first input terminal of the third selector 32 .

The position estimation value output from the position estimation unit 35 is input to the position speed control unit 23 as a position feedback value through the second selector 32 . The position speed controller 23 outputs a torque command value in the same manner as the detection position feedback control except for using the estimated position value as the position feedback value. Processing up to input to the inverter 29 as a U-phase gate signal, a V-phase gate signal, and a W-phase gate signal based on this torque command value is the same as the detection position feedback control. That is, in the sensorless vector control, instead of the position detection value, the position estimation value based on the induced voltage generated in the motor 22 is fed back to the position speed controller 23 as a position feedback value, and the detected position feedback control The same processing as is performed.

Further, in the sensorless vector control, the motor drive device 20 lowers the control loop gain of the position velocity control compared to the detection position feedback control. As an example of a method of lowering the control loop gain, a method of lowering the control loop gain by a command from the upper controller 100 may be mentioned. In order to maintain the trajectory of the arm 2 with high precision, it is desirable to reduce the control loop gain of not only the motor drive device 20 where the abnormality in the position detection value occurred, but also the position and speed control of the other motor drive devices 20. . According to the command of the upper controller 100, it is possible to appropriately lower the control loop gain of the position velocity control in all the motor drive devices 20.

As another example of reducing the control loop gain of the position and speed control of the motor drive device 20, the position and speed control of the motor drive device 20 is performed by processing the motor drive device 20 that causes an abnormal position detection value. A method of lowering only the control loop gain of . An example of the processing of this method is a method of lowering each of the velocity loop gain, the position loop gain, and the velocity loop integral gain in a configuration in which the rotational position and angular velocity are controlled by P-PI control. In addition, as another example, in the configuration in which the rotational position and angular velocity are controlled by RPP control as described, for example, in Japanese Unexamined Patent Publication No. 2002-229604, ω ₂ gain, ω ₁ gain, and ω _q gain There are ways to lower it. Further, as another example, in a configuration in which the rotational position and angular velocity are controlled by RPP control, a method of lowering the inertia nominal set value may be mentioned. By lowering the set value of the inertia nominal, it is possible to approximately reduce the ω ₂ gain and the ω ₁ gain. According to this method, the control loop gain can be appropriately lowered without constructing a dedicated program for lowering the control loop gain.

Next, open loop control will be described. When open-loop control is executed, that is, when there is an error in the detected position value and the angular velocity of the motor 22 is less than (or less than or equal to) a predetermined value (control mode value = 2), the motor (22) is driven. That is, the open-loop controlled electrical angle generating unit 36 has a rotational position at which the magnetic poles of the motor 22 are pulled based on the position command value sent from the upper controller 100 (hereinafter, referred to as a forced synchronous position command value). Calculate and output to the open loop control DQ axis current command generation unit 37. In addition, an estimated electrical angle is calculated based on the position command value and output to the third selector 34 .

When the control method is switched to detection position feedback control or sensorless vector control, the electrical angle of the motor 22 is changed from an angle indicated by a position detection value or a position estimation value to an initial angle for performing open loop control. make it converted At this time, if the direction of the DQ-axis current vector to flow through the motor 22 is instantly switched from the Q-axis direction to the positive D-axis direction, the following problem will arise. That is, torque for moving the machine to be driven (the entire arm 2, the arm 2A, the forearm 2B, or the upper arm 2C) using the motor 22 as a driving source is not obtained, and the motor 22 ) and causes large vibrations.

Therefore, the open-loop control electrical angle generation unit 38 shown in FIG. 3 generates an electrical angle so that the rotational position of the motor 22 is time-varying similarly to the time of execution of the detection position feedback control.

Fig. 5 is a block diagram showing the open-loop controlled electric angle generator 36. This open-loop controlled electrical angle generation unit 36 includes a controller 36a, an electrical/mechanical system model 36b, and an electrical angle calculation unit 36c.

The controller 36a includes a position speed control unit 36a1, a vector control DQ axis current command generation unit 36a2, a current control unit 36a3, a DQ inverse conversion unit 36a4, a PWM control unit 36a5, and a DQ conversion unit 36a6. to provide The position-speed control unit 36a1 shown in FIG. 5 executes the same processing as the position-speed control unit 23 shown in FIG. The vector control DQ-axis current command generator 36a2 shown in FIG. 5 executes the same processing as the vector control DQ-axis current command generator 24 shown in FIG. The current control unit 36a3 shown in FIG. 5 executes the same processing as the current control unit 26 shown in FIG. 3 . The DQ inverse transform unit 36a4 shown in FIG. 5 executes the same processing as the DQ inverse transform unit 27 shown in FIG. The PWM control unit 36a5 shown in FIG. 5 executes the same processing as the PWM control unit 28 shown in FIG. The DQ conversion section 36a6 shown in FIG. 5 executes the same processing as the DQ conversion section 39 shown in FIG.

The electric/mechanical model 36b includes a model of the inverter 36b1, a model of the motor 36b2, and a model of the load machine 36b5 relative to the motor. These models show how the rotational position of the motor 22 and the current value flowing through the motor 22 are affected when the gate signal changes from the value before the change to the value after the change for each of the U phase, V phase, and W phase. It has an algorithm that simulates whether it changes. The position simulation value obtained by the simulation is output from the model of the rotary encoder 36b4, and the position-speed control unit 36a1 of the controller 36a and the electrical angle calculation unit 36c and the open-loop control in FIG. It is input to the DQ axis current command generation unit 37.

The electrical angle calculation unit 36c in FIG. 5 calculates the electrical angle of the motor 22 based on the position simulation value, and the DQ inverse conversion unit 27 and the DQ conversion unit 39 in FIG. 3 calculate the result. ) is output to

When an abnormal position detection value occurs, after switching the control method from detection position feedback control or sensorless vector control to open loop control, it is possible to operate the motor with the same behavior as in the case of performing position detection values. do. Therefore, according to the motor control method according to the embodiment, it is possible to suppress out-of-phase or vibration of the motor due to a sudden change in the electrical angle after the control method is switched to the open-loop control.

Further, instead of simulating the rotational position of the motor 22 and the current value supplied to the motor 22, only the rotational position of the motor 22 may be simulated. In this case, a process of obtaining a required torque command value based on the position command value and the position simulation value is executed by the position speed controller 36a1, and the obtained torque command value is input to the mechanical system model 36b to obtain the position simulation value. should get

Further, instead of simulating the rotational position of the motor, the motor after responding to the position detection value in the case where the position command value is virtually executed by the position control response transfer function G(s) and the detection position feedback control is executed. You may convert it to the rotational position of (22). In the method of obtaining the position conversion value using the position control response transfer function G(s), the position control response transfer function G(s) determines which rotational position is reflected at what delay in actual control with respect to the position command value. It is obtained as a position conversion value by If the obtained position conversion value is output to the DQ inverse conversion unit 27 and the DQ conversion unit 39 shown in FIG. 3, and also outputted as a forced synchronous position command value to the open-loop control DQ axis current command generation unit 37, do. Further, the electrical angle may be calculated based on the position conversion value.

The basic expression of the position control response transfer function G(s) is represented by the following expression.

Although it is preferable to obtain a position conversion value using this basic expression, the right side of the basic expression may be modified and then the position command value may be converted into a position conversion value by the following expression.

Among ff ₁ , ff ₂ , ω ₁ and ω ₂ , by using a simple position control response transfer function G(s) including only ω ₂ , a high-speed and expensive computing device (eg, CPU) is not used, It is possible to obtain the position conversion value of the motor 22 at high speed. Even with a simple position control response transfer function G(s), it is possible to obtain an appropriate value for the position conversion value of the motor 22 if the motor control is in the following aspect. That is, ff ₁ takes a value close to 1, and ff ₂ takes a value close to 0.

In the above aspect, after switching the control method of the motor 22 from detection position feedback control or sensorless vector control to open loop control, operating the motor in the same behavior as in the case of performing position feedback control possible. For this reason, it is possible to suppress out-of-regulation and occurrence of vibration of the motor 22 after the control system is switched to open-loop control, and the position conversion value can be appropriately obtained with an inexpensive arithmetic unit.

In addition, as a method of bringing the electrical angle of the motor 22 closer to the position command value, a first-order delay filter is used that sets the position deviation immediately before switching to open-loop control as an initial value and gradually converges the position deviation to zero. You can think of ways. However, in this method, the hand portion 2A cannot be moved along a desired trajectory in that the position deviation is reduced regardless of the position command value.

Fig. 6 is a graph showing the relationship between the position command value and the actual rotational position of the hand part 2A by control in response to the position command value. If we pay attention to the graph showing the relationship between the rotational position and time, the change in the actual position is delayed with respect to the change in the position command value. This is because it takes time to change the actual position in response to a command. In the detection position feedback control and sensorless vector control, the position control gain is set so that the actual rotational position is uniformly delayed with respect to the position command value of the motor of each joint of the industrial robot 1, so that the trajectory accuracy of the hand part 2A is achieved. to secure On the other hand, in the open-loop control, if the method of converging the position deviation of only a specific axis to zero by the above-described first-order delay filter is used, as shown in the figure, the change in the actual rotation position is different from the detection position feedback control. different. As a result, a difference occurs in the delay of the position command value of the position of each axis, and the position of the receiving part 2A deviates from the target trajectory. In contrast, in the method using simulated values, such as the open loop control according to the embodiment, as shown in the figure, the actual rotational position is changed in response to a change in the position command value to be the same as when the detection position feedback control is executed. (The receiver 2A can be moved along the trajectory of the target).

Fig. 7 is a graph showing time changes of various states in conventional open loop control. In Fig. 7, after the motor 22 is started by the detection position feedback control, and before the angular velocity of rotation of the motor 22 reaches the lower limit value of the sensorless vector control, due to the occurrence of an abnormality in the position detection value, the conventional open An example in which the motor 22 is stopped by loop control is shown. In this example, after starting the motor 22, the angular velocity of the motor 22 is increased by increasing the Q-axis current command value by the detection position feedback control. Then, when the control method is switched to open-loop control in order to stop the motor 22 due to the occurrence of an abnormal position detection value, after reducing the Q-axis current command value to zero by filtering, the motor 22 ), maintain the Q-axis current command value at zero.

However, it has been found that, in the change of the Q-axis current command value as described above, excessive or insufficient torque causes out-of-regulation or vibration of the motor 22 . This is because supply of the Q-axis current to the motor 22 is required to generate the required torque. Specifically, as shown in FIG. 7 , assuming that the motor 22 is stopped by normal detection position feedback control, the Q-axis current command value first decreases to zero in a sine curve shape, and then returns again. It increases in the minus direction and returns to zero through fluctuations on the sine curve on the minus side. In order to stop the motor 22 while obtaining the required torque, it is necessary to change the Q-axis current command value as described above.

Therefore, in the motor driving device 20 according to the embodiment, after obtaining the torque required for the motor 22 based on the position command value, obtaining the Q-axis current command value according to the torque, and obtaining the Q-axis current command value according to the Q-axis current command value. The D-axis current for drawing in the axis current and the magnetic pole of the rotor magnet is supplied to the motor. According to this configuration, by supplying the Q-axis current of a value corresponding to the torque required for the motor 22 to the motor, the motor 22 does not run out of phase or vibrate due to excessive or insufficient torque, and the motor is controlled by open-loop control. (22) can be stopped.

As a method of obtaining torque required to rotate a motor (22) to a position commanded by a position command value, angular acceleration when virtually detected position feedback control is executed based on the position command value is estimated, and the obtained angular acceleration estimate value Based on this, the required torque can be obtained. Thus, it is possible to obtain torque required to rotate the motor 22 at a desired angular velocity.

In addition, as another method of obtaining the required torque, a method of estimating the required angular velocity and angular acceleration based on the position command value and obtaining the required torque based on the obtained estimated angular velocity and estimated angular acceleration values may be mentioned. More specifically, torque necessary for acceleration or deceleration is obtained based on the estimated angular acceleration value, and torque for compensating for at least one of viscous resistance and Coulomb friction necessary is obtained based on the estimated angular velocity value.

Further, in the open-loop control, the method of estimating the required torque based on the position command value and the immediately preceding torque command value has been found through experiments by the present inventors to cause the following problems. That is, when switching from sensorless vector control to open-loop control, it is a defect that the motor 22 vibrates greatly depending on the timing of occurrence of an abnormal position detection value.

8 is a graph showing time changes of various states in a method for determining a Q-axis current command value immediately after the start of open-loop control based on a command value of torque immediately before the start of open-loop control. In FIG. 8, a sequence of various states by detection position feedback control is described even in the time zone after the occurrence of an abnormality in the position detection value, but the sequence shows how the state changes when it is assumed that the abnormality does not occur. there is.

In the example shown in FIG. 8 , after the motor 22 is started by the detection position feedback control, when the angular velocity of rotation of the motor 22 rises to a value only slightly higher than the lower limit (threshold) of the sensorless vector control, An error in the position detection value has occurred.

When the control direction is switched from the detection position feedback control to the sensorless vector control based on the occurrence of the above, as shown in the figure, the rotation of the motor 22 is unstable due to the transient phenomenon of rotational position estimation by current detection immediately after the change as shown in the figure. It is determined, and the angular velocity estimation value based on the current detection value fluctuates greatly. Since the angular velocity of the motor 22 was only slightly higher than the lower limit of the sensorless vector control at the time of occurrence of an abnormal position detection value, the sensorless vector control is executed only for a short time. For this reason, before the oscillation of the position estimation value based on the current detection value converges and the angular velocity estimation value is stabilized, the control system shifts to open-loop control. Since the Q-axis current value is calculated by multiplying the estimated angular velocity value by a constant, the torque command value immediately before the control method is switched from the sensorless vector control to the open-loop control depends on the torque required to execute the open-loop control. It is possible that it is far from the value. If such a torque command value is used, there is a risk of vibrating the motor 22 greatly. Hereinafter, the phenomenon in which the motor 22 vibrates greatly as described above is referred to as vibration of the motor 22 when switching to open-loop control due to lack of position estimation responsiveness of sensorless vector control.

Further, in the detection position feedback control, when an abnormality in the position detection value occurs while the motor 22 is rotating at a sufficient angular velocity, the sensorless vector control is executed for a sufficient time to stabilize the angular velocity estimation value, and then the control method is open loop. switch to control Then, in the open loop control, since it is possible to obtain an appropriate value for the torque command value immediately after switching the control method from the sensorless vector control to the open loop control, the motor 22 does not vibrate greatly.

In the motor drive device 20 according to the embodiment, an estimated value of the rotational position of the motor 22 after responding to the position command value is obtained, and an estimated value of angular acceleration is obtained based on the obtained estimated value of the rotational position. The rotational position estimation value is obtained as a forced synchronous position command value by the open-loop control DQ-axis electrical angle generator 36.

Fig. 9 is a block diagram showing the control configuration of the open-loop control DQ-axis current command generating section 37. The open-loop control DQ-axis current command generator 37 includes a Q-axis current command generator 37A and a D-axis current command generator 37B.

The Q-axis current command generator 37A includes a plurality of delay elements, a first numerical differentiator 37A1, a first low-pass filter 37A9, a second numerical differentiator 37A2, and a second low-pass filter 37A4. ), a nominal value of the moment of inertia (hereinafter referred to as an inertia gain) 37A5, and the like. In addition, the Q-axis current command generation unit 37A includes a torque constant division unit 37A8, a sign function unit 37A3, a nominal value of the viscous coefficient (hereinafter referred to as a viscous gain) 37A6, and a nominal value of the Coulomb friction force. (hereinafter referred to as a Coulomb friction gain) 37A7 and the like.

The processing executed by the Q-axis current command generator 37A will be described.

The forced synchronous position command value sent from the open-loop controlled electrical angle generating unit (36 in FIG. 3) is sequentially input to the first numerical differentiation unit 37A1 and the first low-pass filter 37A9, and becomes an angular velocity estimation value. This angular velocity estimated value is sequentially input to the second numerical derivative unit 37A2 and the second low-pass filter 37A4 to become an angular acceleration estimated value, and then input to the inertia gain 37A5. The inertia gain 37A5 outputs an inertial torque compensation value (inertial force). This is equivalent to calculating the torque required for inertial acceleration based on the following equation.

J: moment of inertia

θ: motor angle

The angular velocity estimation value described above is also input to the viscous gain 37A6. The viscous gain 37A6 outputs a viscous torque compensation value (viscous resistance force). This is equivalent to calculating the torque for compensating the viscous resistive force based on the following equation.

D: viscosity coefficient

The angular velocity estimation value described above is also input to the code function unit 37A3. The sign function section 37A3 outputs a value with the opposite sign of the angular velocity estimation value, and is input to the Coulomb friction gain 37A7. The Coulomb friction gain 37A17 outputs a Coulomb friction torque compensation value (Coulomb friction force). This is equivalent to calculating the torque for compensating the Coulomb frictional force based on the following equation.

C: Coulomb friction

The gravity compensation value shown in FIG. 9 is a constant. The inertial torque compensation value, the viscous torque compensation value, the Coulomb friction compensation value, and the gravity compensation value are added together to form a torque command value, which is input to the torque constant divider 37A8. The torque constant divider 37A8 outputs the result of dividing the torque command value by the torque constant Kt (the result of multiplying by the reciprocal of the torque constant) as the Q-axis current command value. This Q-axis current command value is input to the current controller (reference numeral 26 in Fig. 3) and the D-axis current command generator 37B. Further, the torque constant divider 37A8 may be omitted by including the torque constant of the motor 22 in each of the inertia gain, the viscous gain, the Coulomb friction compensation value, and the gravity compensation value.

As shown in FIG. 8 for determining the Q-axis current command value immediately after starting,

After the control method is switched from the sensorless vector control to the open loop control, it takes about several tens [μs] of time until an angular acceleration estimation value is obtained. In the meantime, if the estimated value of angular acceleration cannot be obtained, an appropriate Q-axis current cannot be supplied to the motor.

Therefore, in the motor drive device 20 according to the embodiment, as shown in Figs. 3, 5 and 9, an estimated acceleration value is obtained based on the position command value during execution of the sensorless vector control.

Specifically, as shown in FIG. 3 , the position command value transmitted from the upper controller 100 is input to the open-loop control electric angle generator 36 without passing through a separator. In addition, the forced synchronous position command value output from the open-loop control electric angle generation unit 36 is input to the open-loop control DQ-axis current command generation unit 37 without passing through a separator. Therefore, until the position command value becomes the DQ-axis current command value through the open-loop control electrical angle generator 36 and the open-loop control DQ-axis current command generator 37 and is input to the first selector 25 A flow is executed regardless of the control method. That is, the above flow is executed even during execution of sensorless vector control.

As shown in FIG. 5 , the open-loop controlled electrical angle generation unit 36 generates a position simulation value based on the position command value, and sends this to the DQ-axis current command generation unit 37 as a forced synchronous position command value. print out In addition, as shown in FIG. 9, the open-loop control DQ-axis current command generation unit 37 obtains an angular velocity estimation value based on the forced synchronous position command value, and obtains an angular acceleration estimation value based on the obtained angular velocity estimation value. Therefore, the motor drive device 20 obtains an estimated acceleration value based on the position command value during execution of the sensorless vector control.

In this configuration, immediately after switching the control method from sensorless vector control to open-loop control, it becomes possible to obtain the required torque using the angular acceleration estimation value obtained immediately before. Therefore, immediately after switching from sensorless vector control to open-loop control, it is possible to suppress vibration of the motor 22 by obtaining a Q-axis current command value according to the required torque and supplying an inappropriate Q-axis current at the time of switching. can

In the motor drive device 20 according to the embodiment, the D-axis current value (D-axis current command value) is changed according to the Q-axis current value (Q-axis current command value).

10 is a graph showing the relationship between the Q-axis current command value and the D-axis current command value in the motor drive device 20 according to the embodiment. In Fig. 10, the Q-axis norm change rate gain is √2, but this value is an example. In addition, the current value b is the DQ-axis norm current lower limit value, but in the example of FIG. 10 , this value is used as the rated current value of the motor 22 . However, it may not be a rated current value. The current value a is a value obtained by dividing the DQ-axis norm current lower limit by the Q-axis norm change rate gain. In addition, the current value d is the DQ-axis norm current upper limit value, but in the example shown in FIG. 10 , this value is used as the instantaneous maximum current specification value of the motor 22 . However, it may not be the instantaneous maximum current specification value. Further, the current value c is a value obtained by dividing the upper limit of the DQ-axis norm current by the Q-axis norm change rate gain. The DQ-axis norm current value is a current value corresponding to the length of a line segment connecting the origin and the intersection of the Q-axis current value and the D-axis current value in the two-dimensional coordinates of the Q-axis current value and the D-axis current value.

Hereinafter, a torque region obtained at a Q-axis current value less than the current value a is referred to as a low torque region. Further, a torque region obtained by a Q-axis current value equal to or greater than the current value a and less than the current value c is referred to as a medium torque region. Further, a torque region obtained with a Q-axis current value equal to or greater than the current value c is referred to as a high torque region.

The open-loop control DQ-axis current command generation unit 37 calculates the D-axis current command value in a manner in which the norm of the DQ-axis current vector is constant in the low torque region. For this calculation, as an algorithm for obtaining the D-axis current command value, an algorithm that sets the D-axis current command value to a value lower than the Q-axis current command value and lowers the value as the Q-axis current command value increases is used. . In this configuration, heat generation of the motor 22 can be suppressed by suppressing the magnitude of the current to the rated current value or less.

In the low torque region, as the D-axis current command value decreases, it immediately becomes the same value as the Q-axis current value (the DQ-axis norm current value becomes the same value as the DQ-axis norm current lower limit value), and the torque region moves to the mid-torque region. becomes The open-loop control DQ-axis current command generation unit 37 obtains the D-axis current command value using an algorithm that increases the D-axis current command value according to the increase of the Q-axis current command value in the medium torque region. In the illustrated example, the Q-axis current command value and the D-axis current command value are in a proportional relationship. In the medium torque region where the Q-axis current command value generally exceeds the rated current value (b), the required torque can be obtained by making the D-axis current value higher than the D-axis current value in the low torque region. In addition, by increasing the D-axis current command value in accordance with the increase in torque, a necessary torque calculation error or restoring force against disturbance is obtained, and the motor 22 is operated by open-loop control without out-of-phase or vibration of the motor 22. drive can be stopped.

In the medium torque region, as the D-axis current command value increases, the DQ-axis norm current value finally reaches the upper limit of the DQ-axis norm current, and the torque region becomes the high torque region. The open-loop control DQ-axis current command generation unit 37 obtains the D-axis current command value using an algorithm that lowers the D-axis current command value according to the increase in the Q-axis current command value in the high torque region. In the high torque region where a higher torque is required than in the medium torque region, by reducing the Q-axis current value in accordance with the increase in torque, the force that attracts the magnetic poles of the magnets of the rotor is weakened to suppress the current from exceeding the maximum allowable value. can do.

The processing executed in the D-axis current command generator 37B shown in Fig. 9 will be described.

The D-axis current command generation unit 37B includes a Q-axis-norm current change rate gain 37B1, an absolute value calculation unit 37B2, a saturating unit 37B3, a first square calculation unit 37B4, and a second square calculation. 37B5 and a square root calculation unit 37B6.

The Q-axis current command value generated by the Q-axis current command generation unit 37A is converted into a squared value by the second square operation unit 37B5 and then input as a negative value to the adder. In addition, the Q-axis current command value is gained by the Q-axis-norm current change rate gain 37B1, converted into an absolute value by the absolute value calculation unit 37B, and input to the saturation unit 37B3. In the saturating section 37B3, when the input value is less than the lower limit of the DQ-axis norm current, it is converted into the lower limit of the DQ-axis norm current, and when the input value exceeds the upper limit of the DQ-axis norm current, it is converted into the upper limit of the DQ-axis norm current. do.

The output from the saturating section 37B3 is converted into a squared value by the first square calculation section 37B4, and then inputted as a positive value to the adder. The square root calculation unit 37B6 converts the output value from the adder into a square root value and outputs the value as a D-axis current command value. Through the above processing, the D-axis current command value changes to the characteristic shown in the graph of FIG. 10 .

<Operation effect of industrial robot 1>

<Configuration 1>

Configuration 1 is a motor control method in which the motor 22 is driven by open-loop control by the current drawing method. Configuration 1 is the torque required for the motor 22 based on the position command value (rotational position command signal) sent from the host controller 100 (signal transmission means) (for example, the torque command value in FIG. 9) It is provided with a step for obtaining Configuration 1 includes a step for obtaining a Q-axis current command value according to the required torque (for example, the torque constant divider 37A8 in FIG. 9 ), a Q-axis current according to the Q-axis current command value, and A step (for example, the D-axis current command generator 37B in FIG. 9 ) for supplying the D-axis current to the motor for drawing in the magnetic poles of the magnets of the rotor is provided.

<Operation effect of configuration 1>

According to configuration 1, by supplying the Q-axis current of a value corresponding to the torque required for the motor 22 to the motor 22, the motor 22 is driven by open-loop control without out-of-phase or vibration of the motor 22. can stop

<Configuration 2>

Configuration 2 is based on the step of obtaining an angular acceleration value (for example, the estimated angular velocity value in FIG. 9) of the motor 22 after the step of obtaining torque in configuration 1 responds to the position command value, and the estimated angular acceleration value. A step for obtaining torque (for example, the torque command value in FIG. 9 ) is provided.

<Operation effect of composition 2>

According to configuration 2, supply of unnecessary Q-axis current to the motor 22 can be suppressed by supplying the Q-axis current corresponding to the torque required to rotate the motor 22 to the motor 22 .

<Configuration 3>

In configuration 3, the step for obtaining torque in configuration 2 includes a step for obtaining an estimated angular velocity of the motor 22 (for example, an estimated angular velocity value in FIG. 9) after responding to a position command value, an estimated angular velocity value, and an estimated angular acceleration value. A step for obtaining a torque based on is provided.

<Operation effect of composition 3>

According to Configuration 3, the required torque can be more accurately obtained by obtaining the torque based on the estimated angular velocity value as well as the estimated value of the angular acceleration.

<Configuration 4>

In configuration 4, the torque calculation step in configuration 2 or 3 is a step for obtaining a simulated position value (rotational position estimation value) of the motor 22 after responding to the position command value (for example, in FIG. 5 ). and a step of obtaining an angular acceleration estimation value (for example, a torque command value in FIG. 9 ) based on the electric system/mechanical system model) and the position simulation value.

<Operation effect of configuration 4>

According to Configuration 4, by obtaining an estimated value of the angular acceleration of the motor 22 based on the position simulation value, generation of vibration of the motor 22 at the time of switching the open-loop control due to insufficient execution time of the sensorless vector control can be avoided. there is.

<Configuration 5>

In configuration 5, in the step of obtaining any of the torques of configurations 2 to 4, the acceleration and deceleration of the driving mechanical system obtained by multiplying the estimated value of angular acceleration by a coefficient corresponding to the moment of inertia (for example, the inertia gain 37A5 in FIG. 9) The moment of the force required for this is obtained as a torque or a part of the torque.

<Operation effect of composition 5>

According to Configuration 5, the Q-axis current according to the inertial force of the driving mechanical system can be supplied to the motor 22.

<Configuration 6>

In configuration 6, in the step of obtaining torque in configuration 5, an estimated angular velocity value of the motor 22 after responding to the position command value is obtained, and based on the estimated angular velocity value, a moment of force for compensating for the viscous resisting force of the driving mechanical system. as part of the torque.

<Operation effect of configuration 6>

According to configuration 6, in addition to the moment of force required for acceleration and deceleration of the driving mechanical system, the viscous resistance of the driving mechanical system is also obtained as the necessary torque. This makes it possible to suppress the occurrence of excessive or insufficient torque of the motor 22 compared to the case where only the moment of force necessary for acceleration and deceleration is obtained as the necessary torque.

<Configuration 7>

In configuration 7, in the step of obtaining torque in configuration 5 or 6, a moment of force for compensating for gravity is obtained as a part of the torque.

<Operation effect of configuration 7>

According to configuration 7, in addition to the moment of force required for acceleration and deceleration of the driving mechanical system, gravity is also obtained as a required torque, compared to the case where only the moment of force required for acceleration and deceleration is obtained as the required torque. The occurrence of excessive or insufficient torque can be suppressed.

<Configuration 8>

In configuration 8, in the step of obtaining torque in any of configurations 5 to 7, an estimated value of the angular velocity of the motor 22 after responding to the position command value is obtained, and a moment of force for compensating the Coulomb frictional force based on the estimated angular velocity value as part of the torque.

<Operation effect of configuration 8>

According to configuration 8, in addition to the moment of force required for acceleration and deceleration of the driving mechanical system, the Coulomb friction force is also obtained as the required torque. This makes it possible to suppress the occurrence of excessive or insufficient torque of the motor 22 compared to the case where only the moment of force necessary for acceleration and deceleration is obtained as the necessary torque.

<Configuration 9>

Configuration 9 includes a step of obtaining a D-axis current command value according to the Q-axis current command value in any one of configurations 5 to 8. In addition, configuration 9, in the step of supplying the Q-axis current according to the Q-axis current command value and the D-axis current for drawing in the magnetic pole of the magnet of the rotor to the motor, the D-axis current according to the D-axis current command value supply to the motor.

<Operation effect of composition 9>

According to configuration 9, burnout of the motor is prevented, and compared to a configuration in which a constant value of D-axis current flows as in the conventional configuration, heat generation of the motor can be suppressed, and restoring force against a required torque calculation error or disturbance can be obtained. there is.

<Configuration 10>

In configuration 10, in the step of obtaining the D-axis current command value in configuration 9, the D-axis current command value is obtained by an algorithm that increases the D-axis current command value as the Q-axis current command value increases.

<Operation effect of configuration 10>

According to configuration 10, by increasing the D-axis current command value in accordance with the increase in the Q-axis current command value, the necessary torque calculation error or restoring force against disturbance is obtained, and open-loop control is performed without out-of-phase or vibration of the motor 22. By this, the driving of the motor 22 can be stopped.

<Configuration 11>

In configuration 11, in the step of obtaining the D-axis current command value in configuration 10, the D-axis current command value is obtained by the following algorithm. That is, in a predetermined low torque region, the D-axis current command value is obtained in such a way that the norm of all DQ-axis current vectors is constant. Further, in the medium torque region higher than the low torque region, the D-axis current command value is increased according to the increase in the Q-axis current command value.

<Operation effect of configuration 11>

According to configuration 11, in the low torque region where it is not necessary to strongly draw in the magnetic poles of the magnets of the rotor, the value of the D-axis current is obtained in such a way that the norm of the DQ-axis current vector is constant, so that the magnitude of the current is the rated current value It is possible to suppress the heat generation of the motor 22 by suppressing it to or less than that.

Further, according to configuration 11, in the medium torque region where the Q-axis current value generally exceeds the rated current value, the D-axis current value is set higher than the D-axis current value in the low torque region, thereby reducing the calculation error of required torque. The driving of the motor 22 can be stopped by the open loop control without obtaining a restoring force against external disturbance and without causing the motor 22 to go out of tune or vibrate.

<Configuration 12>

Configuration 12 is an algorithm that, in the step of obtaining the D-axis current command value in Configuration 11, decreases the D-axis current command value as the Q-axis current command value increases in the high torque region higher than the medium torque region, Get the D-axis current command value.

<Operation effect of configuration 12>

According to configuration 12, in the high torque region where a higher torque is required than in the medium torque region, the D-axis current value is lowered as the torque increases, thereby weakening the force that attracts the magnetic poles of the magnets of the rotor, so that the current reaches the maximum allowable value. can be prevented from exceeding

<Configuration 13>

Configuration 13 is a step for detecting an abnormality in the position detection value (rotational position signal) transmitted from the rotary encoder 30 (rotational position detector) that detects the rotational position of the motor 22 in any one of configurations 5 to 12. to provide Further, configuration 13 drives the motor 22 by detection position feedback control based on the position detection value, when abnormality is not detected. Configuration 13 also drives the motor 22 by sensorless vector control when an abnormality is detected and the angular velocity of the motor 22 at the time of detection is not less than a predetermined lower limit value (below or below the threshold value). do. In sensorless vector control, an estimated position value (estimated rotational position value) based on the current flowing through the motor 22 is fed back. Configuration 13 stops driving of the motor 22 by open-loop control when an abnormality is detected and the angular velocity of the motor at the time of detection is less than the lower limit value.

<Operation effect of composition 13>

In configuration 13, when an abnormality occurs in the position detection value while the motor 22 is rotating at a relatively high speed, an induced voltage that is generated satisfactorily in the motor 22 is estimated by sensorless vector control. . Then, the rotational position of the motor 22 is estimated from the estimated induced voltage, the motor 22 is driven based on the estimation result, and the rotational operation of the motor 22 is appropriately controlled. Thereafter, when the angular velocity of the motor 22 is lowered by the sensorless vector control to such an extent that a sufficient induced voltage is not generated in the motor 22, the drive control of the motor 22 is changed from the sensorless vector control. Switch to open loop control. In the open-loop control, the rotational operation of the motor 22 is appropriately controlled by the current drawing method. In this configuration, when an abnormality occurs in the position detection value while the motor 22 is rotating at a relatively high angular velocity, sensorless vector control and open-loop control are performed to appropriately control the rotational operation of the motor 22. While doing so, the motor 22 is gradually decelerated and stopped.

Further, in configuration 13, when an abnormality occurs in the position detection value while the motor 22 is rotating at a relatively low angular velocity, the drive of the motor 22 is stopped by open-loop control.

According to this configuration 13, occurrence of inappropriate operation of the hand part 2A (operated object) by forcibly stopping the motor 22 immediately when an abnormality in the position detection value occurs can be avoided. In addition, after switching the control method to open loop control, it is possible to operate the motor in the same behavior as in the case of performing the detection position feedback control, so that the occurrence of out-of-phase or vibration of the motor after switching can be suppressed.

In addition, when an abnormal position detection value occurs, the change pattern of the position command value sent from the host controller 100 (host device) to stop the operation of the receiving unit 2A makes driving the motor 22 simple. It is not limited to the pattern of slowing down and stopping. Depending on the structure of the arm 2, there may be cases where the arm 2A can be stopped along an appropriate trajectory by the following pattern. That is, first, the driving of the motor 22 is stopped by sensorless vector control and open loop control. Immediately after that, the motor 22 is rotated in reverse by open-loop control, then acceleration and deceleration are performed in the reverse direction by sensorless vector control, and then the motor 22 is decelerated and stopped by open-loop control. .

<Configuration 14>

Configuration 14 executes a step of obtaining an estimated angular acceleration value of the motor 22 based on a position command value (rotational position command value) during execution of the sensorless vector control of the configuration.

<Operation effect of composition 14>

In Configuration 14, the Q-axis current command value corresponding to the required torque is obtained based on the estimated angular acceleration value obtained immediately after switching from sensorless vector control to open-loop control and immediately before switching. Thus, according to configuration 14, generation of vibration of the motor 22 caused by supplying inappropriate Q-axis current at the time of switching can be suppressed.

<Configuration 15>

Configuration 15 is the motor drive device 20 that controls the drive of the motor 22, and the drive of the motor 22 is controlled by any of the motor control methods of the configurations 1 to 14.

<Operation effect of composition 15>

According to configuration 15, by using any of the motor control methods of configurations 1 to 15, the drive of the motor 22 can be stopped by open-loop control without causing the motor 22 to go out of tune or vibrate.

<Configuration 16>

Configuration 16 is a control method of the industrial robot 1 in which the position of the arm 2 of the industrial robot 1 is changed by individually controlling driving of the plurality of motors 22 . Further, configuration 16 controls each drive of the plurality of motors 22 by any one of the motor control methods of configurations 1 to 14.

<Configuration 17>

Configuration 17 is an industrial robot 1 that changes the position of the arm 2 by individually controlling the drive of a plurality of motors 22, and each drive of the plurality of motors 22 is configured as of Configuration 15. It is controlled by the motor drive device 20.

<Operation and effect of components 16 and 17>

In the configurations 16 and 17, when an abnormal position detection value occurs in at least one of the motors 22, the motor 22 is driven by open-loop control without causing the motor 22 to step out or vibrate. can stop

As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to embodiment, Various deformation|transformation and change are possible within the scope of the summary. Embodiment is included in the range of the invention described in the claim, and its equality while being included in the scope and summary of an invention.

1: industrial robots
2: Cancer
20: motor drive unit
21: control mode selection unit
22: motor
23: position speed controller
24: vector control DQ axis current command generation unit
25: first selector
26: current controller
27: DQ inverse transform unit
28; PWM control
29: Inverter
30: rotary encoder (rotational position detector)
31: current detection unit
32: second selector
33: vector control electric angle generator
34: third selector
35: position estimation unit
36: open loop control electrical angle generator
37: open loop control DQ axis current command generation unit
38: encoder communication abnormal determination unit
39: DQ conversion unit
100: upper controller

Claims (17)

A motor control method for driving a motor by open-loop control by a current drawing method,
a step of obtaining a torque required for the motor based on a rotational position command signal transmitted from the signal transmission means;
A step of obtaining a Q-axis current command value according to the torque;
and supplying a Q-axis current according to the Q-axis current command value and a D-axis current for drawing in magnetic poles of a magnet of a rotor to the motor to stop driving the motor. The motor according to claim 1, wherein the step of obtaining the torque includes a step of obtaining an estimated value of angular acceleration of the motor after responding to the rotational position command signal, and a step of obtaining the torque based on the estimated value of the angular acceleration. control method. The method of claim 2 , wherein the step of obtaining the torque includes a step of obtaining an estimated angular velocity of the motor after responding to the rotational position command signal, and a step of obtaining the torque based on the estimated angular velocity and the estimated angular acceleration. Characterized motor control method. 3. The method of claim 2 , wherein the step of obtaining the torque includes a step of obtaining an estimated value of the rotational position of the motor after responding to the rotational position command signal, and a step of obtaining an estimated value of the angular acceleration based on the estimated value of the rotational position. motor control method. The method according to claim 2, wherein in the step of obtaining the torque, a moment of force required for acceleration and deceleration of the driving mechanical system, which is obtained by multiplying the estimated angular acceleration value by a coefficient corresponding to the moment of inertia, is regarded as the torque or a part of the torque. A motor control method characterized in that obtaining. The method according to claim 5, wherein in the step of obtaining the torque, an estimated angular velocity value of the motor after responding to the rotational position command signal is obtained, and a moment of force for compensating the viscous resistance of the driving mechanical system is determined based on the estimated angular velocity value. A method of controlling a motor characterized in that it is obtained as a part of torque. The motor control method according to claim 5, wherein in the step of obtaining the torque, a moment of force for compensating for gravity is obtained as a part of the torque. The method of claim 5 , wherein in the step of obtaining the torque, an estimated angular velocity value of the motor after responding to the rotational position command signal is obtained, and a moment of force for compensating for a Coulomb frictional force based on the estimated angular velocity value is regarded as a part of the torque. A motor control method characterized in that obtaining. The method of claim 5, further comprising a step of obtaining a D-axis current command value according to the Q-axis current command value, wherein the Q-axis current according to the Q-axis current command value and the D-axis current for drawing in the magnetic pole of the rotor magnet In the step of supplying to the motor, the motor control method characterized in that for supplying the D-axis current according to the D-axis current command value to the motor. 10. The method of claim 9 , wherein in the step of obtaining the D-axis current command value, the D-axis current command value is obtained using an algorithm that increases the D-axis current command value according to an increase in the Q-axis current command value. motor control method. 11. The method of claim 10, wherein in the step of obtaining the D-axis current command value, the D-axis current command value is set to a value lower than the Q-axis current command value in a predetermined low torque region, and the Q-axis current command value Calculating the D-axis current command value with an algorithm that decreases the value according to an increase in , and increases the D-axis current command value according to an increase in the Q-axis current command value in the mid-torque region higher than the low-torque region. Characterized motor control method. 12. The method of claim 11, wherein the step of obtaining the D-axis current command value is an algorithm that lowers the D-axis current command value according to an increase in the Q-axis current command value in a high torque region higher than the medium torque region, Motor control method characterized in that for obtaining the D-axis current command value. The method according to claim 5, comprising a step of detecting an abnormality in a rotational position signal transmitted from a rotational position detector that detects the rotational position of the motor,
When the abnormality is not detected, the motor is driven by feedback control based on the rotational position signal;
When the abnormality is detected and the angular velocity of the motor at the time of detection is equal to or less than a predetermined threshold value, the motor is operated by sensorless vector control that feeds back an estimated rotational position value estimated based on a current flowing through the motor. driving,
A motor control method characterized in that, when the abnormality is detected and the angular velocity of the motor at the time of detection is equal to or less than the threshold value or less than the threshold value, driving of the motor is stopped by open-loop control. 14. The motor control method according to claim 13, wherein a step of obtaining an estimated angular acceleration value of the motor based on the rotational position command signal is performed during execution of the sensorless vector control. A motor driving device that controls the driving of a motor,
A motor driving device characterized in that driving of the motor is controlled by the motor control method according to any one of claims 1 to 14. A control method of an industrial robot that individually controls driving of a plurality of motors to change the position of an arm of the industrial robot,
An industrial robot control method characterized in that each drive of a plurality of motors is controlled by the motor control method according to any one of claims 1 to 14. It is an industrial robot that changes the position of an arm by individually controlling the driving of a plurality of motors.
An industrial robot characterized in that each drive of a plurality of motors is controlled by the motor drive device according to claim 15.

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