JP2021125950A - Motor control method, motor drive device, control method of industrial robot, and industrial robot - Google Patents

Abstract

To stop motor rotation by open-loop control without causing motor stalling or vibration due to insufficient torque.SOLUTION: In the open-loop control, the method includes the steps of obtaining the torque required for a motor based on a position command value sent from a higher-level controller, obtaining a Q-axis current command value in accordance with the torque, and supplying the motor with a Q-axis current according to the Q-axis current command value and a D-axis current to draw in magnetic poles of a rotor magnet.SELECTED DRAWING: Figure 9

Description

The present invention relates to a motor control method, a motor drive device, a control method for an industrial robot, 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 Document 1, the motor is started by open loop control by forced commutation (current drawing method). At this time, the Q-axis current is maintained at zero while supplying a constant D-axis current to the motor. After that, when the angular velocity of the motor is increased until a sufficient induced voltage is obtained in the motor, the control method is changed from open loop control to sensorless vector control that estimates the rotation position of the motor based on the current detection value. Switch.

Japanese Unexamined Patent Publication No. 2008-11628

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

However, according to the experiment of the present inventor, it has been found that when the open loop control described in Patent Document 1 is used, the excess or deficiency of torque causes step-out or vibration of the motor.

Although the problems that occur when the motor control method is switched from the sensorless vector control to the open loop control have been described, the same problems may occur in the following configurations. That is, the control method is switched from feedback control that feeds back the detected value of the rotation position of the motor by an encoder or the like to open loop control.

The present invention has been made in view of the above background, and an object of the present invention is to provide the following motor control method, motor drive device, control method for industrial robot, and industrial robot. Is. That is, it is a motor control method that can stop the rotation of the motor by open loop control without causing step-out or vibration of the motor due to excess or deficiency of torque.

The first invention of the present application is a step of obtaining a torque required for a motor based on a rotation position command signal sent from a signal transmitting means in a motor control method for driving a motor by open loop control by a current drawing method, and the above-mentioned step. It includes a step of obtaining a Q-axis current command value corresponding to the torque, a step of supplying a Q-axis current corresponding to the Q-axis current command value, and a step of supplying a D-axis current for drawing the magnetic pole of the rotor magnet to the motor. This is a motor control method characterized by the above.

The second invention of the present invention is a motor driving device that controls the driving of a motor, and is a motor driving device characterized in that the driving of the motor is controlled by the motor control method of the first invention.

A third invention of the present application is a method for controlling an industrial robot in which the drive of a plurality of motors is individually controlled to change the position of an arm of the industrial robot, and the drive of each of the plurality of motors is controlled by the first invention. It is a control method of an industrial robot characterized by being controlled by the motor control method of the above.

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

According to these inventions, there is an excellent effect that the rotation of the motor can be stopped by open loop control without causing step-out or vibration of the motor due to excess or deficiency of torque.

The perspective view which shows the industrial robot which concerns on embodiment. Top view showing the industrial robot. It is a block diagram which shows the control composition of the motor drive device mounted on the industrial robot together with a motor and the like. It is a flowchart which shows the process flow of the mode value selection process executed by the control mode selection part of the motor drive apparatus. It is a block diagram which shows the open loop control electric angle generation part of the motor drive device. It is a graph which shows the relationship between the position command value and the actual rotation position of the hand part by the control corresponding to the position command value. It is a graph which shows the time change of various states in the conventional open loop control. It is a graph which shows the time change of various states in the method of determining the Q-axis current command value immediately after the start of open loop control based on the torque command value immediately before the start of open loop control. It is a block diagram which shows the control structure of the open loop control DQ axis current command generation part of the motor drive device. It is a graph which shows the relationship between the Q-axis current command value value and the D-axis current command value value in the motor drive device.

Hereinafter, embodiments of a motor drive device and an industrial robot using the motor control method according to the embodiment of the present invention will be described with reference to the drawings. In the drawings below, the actual structure and the scale and number of each structure may be different in order to make each configuration easy to understand.

First, the basic configuration of the industrial robot according to the embodiment will be described. FIG. 1 is a perspective view showing an industrial robot 1 according to an embodiment. FIG. 2 is a plan view showing the industrial robot 1. The industrial robot 1 is a robot for transporting a glass substrate, and includes an arm 2, a gantry 3, and an elevating part 4. The elevating part 4 is held by the gantry 3 and elevates and elevates in the vertical direction (in the direction of the arrow in FIG. 1) by driving an elevating 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 the elevating portion 4.

The shoulder joint 2D, which is the connection portion of the upper arm portion 2C with the elevating portion 4, can be rotated along the horizontal direction by the drive of the first motor 22A. Specifically, the rotational driving force of the first motor 22A is transmitted to the shoulder joint 2D via the first belt 2E, so that the shoulder joint 2D rotates in the horizontal direction. Further, the elbow joint 2F, which is a connecting portion between the upper arm portion 2C and the forearm portion 2B, can be rotated along the horizontal direction by the drive of the second motor 22B. Specifically, the rotational driving force of the second motor 22B is transmitted to the elbow joint 2F via the second belt 2G, so that the elbow joint 2F rotates in the horizontal direction. Further, the wrist joint, which is the connecting portion between the forearm portion 2B and the hand portion 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 hand portion 2A straight in the direction of the arrow along the trajectory shown by the alternate long and short dash line in FIG. 2, the angle between the shoulder joint 2D and the elbow joint 2F is set to a ratio of 1: 2. 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 rotation positions of the first motor 22 and the second motor 22B, the balance of the driving amounts of both motors is lost and the hand portion 2A deviates from the trajectory indicated by the alternate long and short dash line. It will stop at the position. Then, there is a possibility that the hand portion 2A may hit the surrounding structure or device.

Next, a motor drive device using the motor control method according to the embodiment will be described.
FIG. 3 is a block diagram showing a 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. The industrial robot 1 rotates the motor drive device 20 for rotating the shoulder joint 2D of the arm 2, the elbow joint 2F of the arm 2, and the wrist joint as the motor drive device 20 shown in FIG. The motor drive device 20 for raising and lowering the elevating unit 4 and the motor drive device 20 for raising and lowering the elevating unit 4 are provided.

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

The industrial robot 1 includes a host controller 100 that sends commands to three motor drive devices 20. The host controller 100 transmits a position command value (rotation position command signal) to each of the three motor drive devices 20 based on the control program stored in the storage medium. Each of the three motor drive devices 20 executes control to rotate the rotor of the motor 22 to a rotation 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 above-mentioned control program.

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

The motor drive 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, a DQ inverse conversion unit 27, a PWM control unit 28, and The inverter 29 is provided. The motor 22 driven by the motor driving device 20 is the above-mentioned 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 generation unit 33, a third selector 34, a position estimation unit 35, and an open loop control electric angle generation unit 36. Further, 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 host controller 100 is input to the position speed control unit 23 of the motor drive device 20 and the open loop control electric angle generation unit 36.

The motor 22 that is the driving source for the turning motion (rotation of the shoulder joint 2D), the joint bending / stretching motion (rotation of the shoulder joint 2D, the elbow joint 2F, and the wrist joint), or the lifting motion of the arm 2 of the industrial robot 1. Consists of a three-phase (U-phase, V-phase, W-phase) AC PM (Permanent Joint) motor. The rotary encoder 30 as a rotation position detector mounted on the motor 22 detects the rotation 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 rotation position as a position detection value (rotation position signal). The output position detection value is input to the encoder communication abnormality determination unit 38 and the control mode selection unit 21. The position detection value is also input to the position / speed control unit 23 via the second selector 32.

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

The encoder communication abnormality determination unit 38 detects the presence or absence of an abnormality in the position detection value sent from the rotary encoder 30, and if an abnormality is detected, transmits an abnormality occurrence signal to the control mode selection unit 21 and the host controller 100. do. As an example of the method of detecting the abnormality of the position detection value by the encoder communication abnormality determination unit 38, when the time change amount of the position detection value exceeds a predetermined threshold value (or is equal to or more than the threshold value), it is detected as an abnormality. The method can be mentioned. However, the method is not limited to this method. As a method of detecting the abnormality of the position detection value, a method of detecting the abnormality of the rotary encoder 30 as the abnormality of the position detection value may be adopted.

The control mode selection unit 21 calculates the angular velocity of the motor 22 based on the amount of change in the position detection value sent from the rotary encoder 30 per unit time, and is based on the calculation result and the presence or absence of an abnormality in the position detection value. Select the control mode value and output it.

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

On the other hand, when the abnormality 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 higher than a predetermined value (or whether or not it exceeds a predetermined value). (S3). When the angular velocity is equal to or higher than a predetermined value (Y in S3), "1" is selected as the control mode value and output from the control mode selection unit 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 output from the control mode selection unit 21. Hereinafter, the above-mentioned predetermined value may be expressed as a lower limit value.

As described above, in the control mode value selection process, "0" is selected as the control mode value when no abnormality has occurred in the position detection value. If an abnormality in the position detection value occurs and the angular velocity is equal to or higher than the predetermined value, "1" is selected as the control mode value, and if an abnormality occurs in the position detection value and the angular velocity is not equal to or higher than the predetermined value. "2" is selected as the control mode value.

The above-mentioned predetermined value is, for example, 10% of the rated angular velocity of the motor 22.

When an abnormality occurrence signal is sent from the motor drive device 20, the host controller 100 transfers the position command values to be transmitted to the three motor drive devices 20 while moving the arm 2 on a predetermined orbit, and the arm 2 and the motor 22. Is changed in a pattern that decelerates and stops. As a result, the arm 2 stops while decelerating on a predetermined orbit.

In FIG. 3, the control mode values output from the control mode selection unit 21 are the first selector 25, the second selector 32, and the third selector 34 (hereinafter, these are collectively three selectors (25, 32, 34)). It is also entered in each of). Each of the three selectors (25, 32, 34) has a 0th input terminal, a 1st input terminal, and a 2nd input terminal, and outputs based on the control mode value sent from the control mode selection unit 21. Switch signals. Specifically, each of the three selectors (25, 32, 34) outputs a signal input to the 0th input terminal when the control mode value is "0", and when it is "1". Outputs the signal input to the 1st input terminal, and outputs the signal input to the 2nd input terminal when it is "2".

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

Of the above three control methods, first, the detection position feedback control will be described.
If 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 the 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 input to the position speed control unit 23 and the vector control electric angle generation unit 33 as the position feedback value. .. The position / speed control unit 23 calculates the 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 the torque command value for vector control DQ axis current command. Output to the generation unit 24. Further, the vector control electric angle generation unit 33 generates an electric angle based on the position feedback value. This electric angle is input to the DQ conversion unit 39 via the third selector 34.

The vector-controlled DQ-axis current command generator 24 has a D-axis current required to generate the same torque as the input torque value, a D-axis current command value for generating the Q-axis current in the motor 22, and a D-axis current command value. A Q-axis current command value (hereinafter, these are also referred to as a DQ-axis current command value) is generated. The D-axis current is a component of the current flowing through the motor 22 that is parallel to the magnetic flux of the permanent magnet. The Q-axis current is a component of the current flowing through the motor 22 that is orthogonal to the magnetic flux of the permanent magnet.

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. When the detection position feedback control is executed (control mode value = 0) and when the sensorless vector control is executed (control mode value = 1), the DQ generated by the vector control DQ axis current command generation unit 24 The shaft current command value is output from the first selector 25. This DQ axis current command value is input to the current control unit 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 electric angle sent from the third selector 34, and is a current control unit. Output to 26. At the time of sensorless vector control, which will be described later, the DQ conversion unit 39 has a DQ axis based on the electric angle sent from the third selector 34 and the three-phase current detection value sent from the current detection unit 31. Generate 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. Output to the DQ inverse conversion unit 27.

The DQ inverse conversion unit 27 receives the required D-axis current and Q-axis current based on the electric angle sent from the third selector 34 and the DQ-axis voltage command value sent from the current control unit 26. Is generated and output as 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) for generating the current in the motor 22. The three-phase voltage command value output from the DQ inverse conversion unit 27 is input to the PWM control unit 28. The PWM control unit 28 is a U composed of a PWM signal for outputting the U-phase voltage, the V-phase voltage, and the W-phase voltage indicated by the U-phase voltage command value, the V-phase voltage command value, and the W-phase voltage command value from the inverter 29. A phase gate signal, a V phase gate signal, and a W phase gate signal are generated. The inverter 29 supplies the U-phase gate signal, the V-phase gate signal, the U-phase voltage based on the W-phase gate signal, the V-phase voltage, and the W-phase voltage 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 (hereinafter, these are also referred to as three-phase currents) flowing from the inverter 29 to the motor 22, and the detection results are the U-phase current detection value and V. It is output as a phase current detection value and a W phase current detection value (hereinafter, also referred to as a three-phase current detection value). Instead of detecting the current value of the three phases, only the current value of the two phases is detected among the three phases, and the current value of the remaining one phase is based on the detection result of the current value of the two phases. May be calculated.

If 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 position detection value and the angular velocity of the motor 22 immediately before the abnormality occurs is equal to or greater than a predetermined value (or exceeds a predetermined value) (control mode value = 1). Drives the motor 22 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 electric 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. do. 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.

The position estimation unit 35 has a position estimation value and an electric 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. And ask. Then, the position estimation unit 35 outputs the position estimation value to the first input terminal of the second selector 32, and outputs the electric angle estimation value to the first input terminal of the third selector.

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 via the second selector 32. The position / speed control unit 23 outputs a torque command value in the same manner as the detected position feedback control except that the position estimated value is used as the position feedback value. The processing until the U-phase gate signal, the V-phase gate signal, and the W-phase gate signal are input to the inverter 29 based on the torque command value is the same as the detection position feedback control. That is, in the sensorless vector control, the detected position feedback control is performed except that the position estimated value based on the induced voltage generated in the motor 22 is fed back to the position speed control unit 23 as the position feedback value instead of the position detected value. The same process is performed.

In the sensorless vector control, the motor drive device 20 lowers the control loop gain of the position speed control as compared with the detection position feedback control. As an example of the method of lowering the control loop gain, there is a method of lowering the control loop gain by a command of the host controller 100. In order to maintain the trajectory of the arm 2 with high accuracy, it is desirable to reduce not only the motor drive device 20 in which the abnormality of the position detection value has occurred but also the control loop gain of the position speed control of the other motor drive device 20. According to the command of the host controller 100, it is possible to appropriately reduce the control loop gain of the position speed control in all the motor drive devices 20.

As another example of reducing the control loop gain of the position / speed control of the motor drive device 20, the control loop gain of the position / speed control of the motor drive device 20 by the processing of the motor drive device 20 that caused the abnormality of the position detection value. There is a way to reduce only. As an example of the processing of this method, there is a method of reducing each of the speed loop gain, the position loop gain, and the speed loop integrated gain in the configuration in which the rotation position and the angular velocity are controlled by P-PI control. Further, as another example, in a configuration in which the rotation position and the angular velocity are controlled by RPP control as described in JP-A-2002-229604, for example, a method of reducing _{ω 2} gain, ω ₁ gain, and ω _{q gain.} Can be mentioned. Further, as another example, there is a method of lowering the inertial nominal set value in a configuration in which the rotation position and the angular velocity are controlled by RPP control. By reducing the inertia nominal setpoint, it is possible to reduce omega _{2 gain,} the omega ₁ gain approximately. According to this method, the control loop gain can be appropriately reduced without constructing a dedicated program for reducing the control loop gain.

Next, open loop control will be described. When open loop control is executed, that is, when there is an abnormality in the position detection value and the angular velocity of the motor 22 is less than (or less than or equal to) the predetermined value (control mode value = 2), the following The motor 22 is driven in this way. That is, the open loop control electric angle generator 36 calculates and opens the rotation position (hereinafter referred to as the forced synchronization position command value) that attracts the magnetic poles of the motor 22 based on the position command value sent from the host controller 100. Output to the loop control DQ axis current command generation unit 37. Further, the estimated electric angle value is calculated based on the position command value and output to the third selector 34.

When switching the control method to detection position feedback control or sensorless vector control, the electric angle of the motor 22 is switched from the angle indicated by the position detection value or the position estimation value to the initial angle for performing open loop control. Suppose. At this time, if the direction of the DQ-axis current vector flowing through the motor 22 is instantaneously switched from the Q-axis direction to the positive direction in the D-axis direction, the following problems will occur. That is, the torque for moving the drive target machine (the entire arm 2, the hand 2A, the forearm 2B, or the upper arm 2C) using the motor 22 as the drive source cannot be obtained, causing the motor 22 to step out or vibrate greatly. It will occur.

Therefore, the open-loop control electric angle generation unit 38 shown in FIG. 3 generates an electric angle so that the rotation position of the motor 22 changes with time in the same manner as when the detection position feedback control is executed.

FIG. 5 is a block diagram showing an open loop control electric angle generation unit 36. The open-loop control electric angle generation unit 36 includes a controller 36a, an electric / mechanical model 36b, and an electric 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. 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 generation unit 36a2 shown in FIG. 5 executes the same processing as the vector control DQ axis current command generation unit 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. The DQ inverse conversion unit 36a4 shown in FIG. 5 executes the same processing as the DQ inverse conversion 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 unit 36a6 shown in FIG. 5 executes the same processing as the DQ conversion unit 39 shown in FIG.

The electrical / mechanical model 36b includes a model of the inverter 36b1, a model of the motor 36b2, and a model of the load machine 36b5 for the motor. These models show how the rotation position of the motor 22 and the current value flowing through the motor 22 when the gate signal changes from the value before the change to the value after the change for each of the U phase, the V phase, and the W phase. It is equipped with an algorithm that simulates whether it changes to. 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, the electric angle calculation unit 36c, and the open loop control DQ axis current command generation unit 37 in FIG. Is entered in.

The electric angle calculation unit 36c in FIG. 5 calculates the electric angle of the motor 22 based on the position simulation value, and outputs the result to the DQ inverse conversion unit 27 and the DQ conversion unit 39 in FIG.

Control method when an abnormality occurs in the position detection value. After switching from the detection position feedback control or the sensorless vector control to the open loop control, it is possible to operate the motor in the same behavior as when the position detection value is performed. Therefore, according to the motor control method according to the embodiment, it is possible to suppress the occurrence of step-out and vibration of the motor due to a sudden change in the electric angle after the control method is switched to the open loop control.

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, the position / speed control unit 36a1 executes a process of obtaining the required torque command value based on the position command value and the position simulation value, and inputs the obtained torque command value to the mechanical model 36b for position simulation. Just get the value.

Further, instead of simulating the rotation position of the motor, the motor after responding to the position detection value when the position command value is virtually detected and the position feedback control is executed by the position control response transfer function G (s). It may be converted to the rotation 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 determines what kind of delay and what kind of rotation position the position command value is reflected in the actual control. Obtained as a position conversion value by G (s). The obtained position conversion value may be output to the DQ inverse conversion unit 27 and the DQ conversion unit 39 shown in FIG. 3 and output to the open loop control DQ axis current command generation unit 37 as the forced synchronization position command value. .. Further, the electric angle may be calculated based on the position conversion value.

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

It is desirable to obtain the position conversion value using this basic formula, but the position command value may be converted into the position conversion value by the following formula obtained by modifying the right side of the basic formula.

By using a simple position control response transfer function G (s) containing only ω _{2 among ff 1} , ff ₂ , ω ₁ , and ω ₂ , a high-speed and expensive arithmetic unit (for example, a 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), the position conversion value of the motor 22 can be obtained with an appropriate value if the motor is controlled in the following aspects. That is, ff ₁ takes a value close to 1, and ff ₂ takes a value close to 0.

In the above-described embodiment, after the control method of the motor 22 is switched from the detection position feedback control or the sensorless vector control to the open loop control, the motor is operated in the same manner as in the case of performing the position feedback control. It is possible. Therefore, it is possible to suppress the occurrence of step-out and vibration of the motor 22 after switching the control method to open-loop control, and to appropriately obtain the position conversion value by an inexpensive arithmetic unit.

As a method of bringing the electric angle of the motor 22 closer to the position command value, a method of using a first-order lag filter that gradually converges the position deviation to zero with the position deviation immediately before switching to the open loop control as the initial value is also conceivable. However, in this method, since the position deviation is reduced regardless of the position command value, the hand portion 2A cannot be moved along the desired trajectory.

FIG. 6 is a graph showing the relationship between the position command value and the actual rotation position of the hand portion 2A by the control in response to the position command value. Focusing on the graph showing the relationship between the rotation 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 the command. In the detection position feedback control and the sensorless vector control, the trajectory of the hand 2A is set by setting the position control gain so as to uniformly delay the actual rotation position with respect to the position command value of the motor of each joint of the industrial robot 1. Ensure accuracy. On the other hand, in open-loop control, when the method of converging the position deviation to zero only on a specific axis by the above-mentioned first-order lag filter is used, as shown in the figure, the change in the actual rotation position is different from that in the detection position feedback control. different. As a result, there is a difference in the delay of the position of each axis with respect to the position command value, and the position of the hand portion 2A deviates from the target trajectory. On the other hand, in the method using the simulation value as in the open loop control according to the embodiment, as shown in the figure, the actual rotation position is the same as when the detection position feedback control is executed with respect to the change in the position command value. (The hand 2A can be moved along the target trajectory).

FIG. 7 is a graph showing time changes of various states in the conventional open loop control. In FIG. 7, after the motor 22 is started by the detection position feedback control, before the angular velocity of the rotation of the motor 22 reaches the lower limit value of the sensorless vector control, the conventional open-loop control is performed due to the occurrence of an abnormality in the position detection value. Shows an example in which the motor 22 is stopped. In this example, after the motor 22 is started, the Q-axis current command value is increased by the detection position feedback control to increase the angular velocity of the motor 22. After that, when the control method is switched to open loop control in order to stop the motor 22 due to the occurrence of an abnormality in the position detection value, the Q-axis current command value is reduced to zero by filter processing, and then the rotation of the motor 22 is started. The Q-axis current command value is maintained at zero until it is stopped.

However, it has been found that the change in the Q-axis current command value as described above causes step-out or vibration of the motor 22 due to excess or deficiency of torque. This is because it is necessary to supply the Q-axis current to the motor 22 in order to generate the required torque. Specifically, as shown in FIG. 7, assuming that the motor 22 is stopped by the detection position feedback control in the normal state, the Q-axis current command value first decreases to zero in a sine curve shape, and then It increases in the minus direction again, and returns to zero through a sine curve-like fluctuation 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 drive device 20 according to the embodiment, after obtaining the torque required for the motor 22 based on the position command value, the Q-axis current command value corresponding to the torque is obtained, and the Q corresponding to the Q-axis current command value is obtained. A shaft current and a D-axis current for drawing in the magnetic poles of the rotor magnet are supplied to the motor. According to this configuration, by supplying a Q-axis current of a value corresponding to the torque required for the motor 22 to the motor, open loop control is performed without causing step-out or vibration of the motor 22 due to excess or deficiency of torque. The drive of the motor 22 can be stopped.

As a method of obtaining the torque required to rotate the motor 22 to the position commanded by the position command value, the angular acceleration when the detection position feedback control is virtually executed based on the position command value is estimated and obtained. A method of obtaining the required torque based on the estimated angular acceleration value can be mentioned. This makes it possible to obtain the torque required to rotate the motor 22 at a desired angular velocity.

Further, as another method for 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 angular velocity estimated value and the angular acceleration estimated value. Can be mentioned. More specifically, the torque required for acceleration or deceleration is obtained based on the estimated angular acceleration value, and the required viscous resistance and the torque for compensating at least one of the Coulomb frictions are obtained based on the estimated angular velocity speed. ..

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 to cause the following problems in the experiment by the present inventor. .. That is, when the sensorless vector control is switched to the open loop control, the motor 22 vibrates greatly depending on the timing of occurrence of the abnormality of the position detection value.

FIG. 8 is a graph showing time changes of various states in the method of determining the Q-axis current command value immediately after the start of open loop control based on the torque command value immediately before the start of open loop control. In FIG. 8, a series of various states by the detection position feedback control is also shown in the time zone after the abnormality of the position detection value occurs. It shows how the state changes.

In the example shown in FIG. 8, after the motor 22 is activated by the detection position feedback control, the position when the angular velocity of rotation of the motor 22 rises to a value slightly higher than the lower limit value (threshold value) of the sensorless vector control. An error in the detected 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 an abnormality, as shown in the figure, the rotation of the motor 22 becomes unstable due to the transient phenomenon of the rotation position estimation by the current detection immediately after the switching. Therefore, the angular velocity estimated value based on the current detection value fluctuates greatly. Since the angular velocity of the motor 22 was slightly higher than the lower limit of the sensorless vector control when the position detection value was abnormal, the sensorless vector control was executed only for a short time. Therefore, the control method shifts to open-loop control before the vibration of the position estimated value based on the current detected value converges and the angular velocity estimated value stabilizes. Since the Q-axis current value is calculated by multiplying the estimated angular velocity by a constant, the torque command value immediately before the control method switches from sensorless vector control to open loop control depends on the torque required to execute open loop control. It may be far from the value. If a torque command value of such a value is used, the motor 22 may vibrate significantly. Hereinafter, the phenomenon in which the motor 22 vibrates significantly as described above is referred to as vibration of the motor 22 when the open loop control is switched due to insufficient position estimation response of the sensorless vector control.

If an abnormality occurs in the position detection value while the motor 22 is rotating at a sufficient angular velocity in the detection position feedback control, the sensorless vector control is executed for a sufficient time after the estimated angular velocity value is stabilized. The control method switches to open loop control. Then, in the open loop control, the torque command value immediately after the control method is switched from the sensorless vector control to the open loop control can be obtained with an appropriate value, so that the motor 22 is not vibrated significantly.

In the motor drive device 20 according to the embodiment, the rotational position estimated value of the motor 22 after responding to the position command value is obtained, and the angular acceleration estimated value is obtained based on the obtained rotational position estimated value. The rotation position estimated value is obtained as a forced synchronization position command value by the open loop control DQ axis electric angle generation unit 36.

FIG. 9 is a block diagram showing a control configuration of the open loop control DQ axis current command generation unit 37. The open-loop control DQ-axis current command generation unit 37 includes a Q-axis current command generation unit 37A and a D-axis current command generation unit 37B.

The Q-axis current command generation unit 37A includes a plurality of delay elements, a first numerical differentiation unit 37A1, a first low-pass filter 37A9, a second numerical differentiation unit 37A2, a second low-pass filter 37A4, and a nominal value of the moment of inertia (hereinafter, inertial gain). It is equipped with 37A5 and the like. Further, the Q-axis current command generation unit 37A includes a torque constant dividing unit 37A8, a sign function unit 37A3, a viscosity coefficient nominal value (hereinafter referred to as viscosity gain) 37A6, and a Coulomb friction force nominal value (hereinafter referred to as Coulomb friction gain). It is equipped with 37A7 and the like.

Ｊ：慣性モーメント
θ：モータ角度 The process executed by the Q-axis current command generation unit 37A will be described.
The forced synchronization position command value sent from the open-loop control electric angle generation unit (36 in FIG. 3) is sequentially input to the first numerical differentiation unit 37A1 and the first low-pass filter 37A9 to obtain an angular velocity estimation value. This angular velocity estimated value is input to the second numerical differentiation unit 37A2 and the second low-pass filter 37A4 in order to obtain the angular acceleration estimated value, and then is input to the inertial gain 37A5. The inertial 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

Ｄ：粘度係数 The above-mentioned angular velocity estimate is also input to the viscosity gain 37A6. The viscous gain 37A6 outputs a viscous torque compensation value (viscosity resistance). This is equivalent to calculating the torque for compensating the viscous resistance based on the following equation.

D: Viscosity coefficient

Ｃ：クーロン摩擦 The above-mentioned angular velocity estimated value is also input to the sign function unit 37A3. A value having a sign opposite to the estimated angular velocity value is output from the sign function unit 37A3 and input to the Coulomb friction gain 37A7. The Coulomb friction gain 37A17 outputs the Coulomb friction torque compensation value (Coulomb friction force). This is equivalent to calculating the torque for compensating for 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 up to form a torque command value and input to the torque constant division unit 37A8. The torque constant division unit 37A8 outputs the result of dividing the torque command value by the torque constant Kt (the result of multiplying the reciprocal of the torque constant) as the Q-axis current command value. The Q-axis current command value is input to the current control unit (26 in FIG. 3) and the D-axis current command generation unit 37B. By including the torque constant of the motor 22 in each of the inertial gain, the viscosity gain, the Coulomb friction compensation value, and the gravity compensation value, the torque constant division unit 37A8 may be omitted.

As shown in FIG. 8, which determines the Q-axis current command value immediately after the start,

After the control method is switched from sensorless vector control to open loop control, it takes about ten and several [μsec] until the estimated angular acceleration value is obtained. During that time, if the estimated angular acceleration value 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, the acceleration estimated value is obtained based on the position command value during the execution of the sensorless vector control.

Specifically, as shown in FIG. 3, the position command value transmitted from the host controller 100 is input to the open loop control electric angle generation unit 36 without going through the separator. Further, the forced synchronization 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 going through the separator. Therefore, the flow until the position command value becomes the DQ axis current command value via the open loop control electric angle generation unit 36 and the open loop control DQ axis current command generation unit 37 and is input to the first selector 25 is It is executed regardless of the control method. That is, the above-mentioned flow is executed even during the execution of the sensorless vector control.

As shown in FIG. 5, the open-loop control electric angle generation unit 36 generates a position simulation value based on the position command value, and outputs this to the DQ axis current command generation unit 37 as a forced synchronization position command value. Further, as shown in FIG. 9, the open loop control DQ axis current command generation unit 37 obtains an angular velocity estimated value based on the forced synchronization position command value, and obtains an angular acceleration estimated value based on the obtained angular velocity estimated value. Ask. Therefore, the motor drive device 20 obtains an acceleration estimated value based on the position command value during execution of the sensorless vector control.

In such a configuration, immediately after switching the control method from sensorless vector control to open loop control, it is possible to obtain the required torque using the angular acceleration estimated value obtained immediately before. Therefore, immediately after switching from the sensorless vector control to the open loop control, the Q-axis current command value corresponding to the required torque is obtained, and the vibration of the motor 22 is generated by supplying an inappropriate Q-axis current at the time of switching. It can be suppressed.

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).
FIG. 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. Further, the current value b is the lower limit value of the DQ axis norm current, but in the example of FIG. 10, this value is used as the rated current value of the motor 22. However, it does not have to be the rated current value. The current value a is a value obtained by dividing the lower limit of the DQ-axis norm current by the Q-axis norm change rate gain. Further, the current value d is the upper limit value of the DQ axis norm current, and in the example shown in FIG. 10, this value is used as the instantaneous maximum current specification value of the motor 22. However, it does not have to be the instantaneous maximum current specification value. 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 the line segment connecting 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 and the origin. Is.

Hereinafter, the torque region obtained by the 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 having a current value a or more and a current value less than c is referred to as a medium torque region. Further, the torque region obtained by the Q-axis current value of the current value c or more 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 mode in which the norm of the DQ-axis current vector is made constant in the low torque region. For this calculation, as an algorithm for obtaining the D-axis current command value, an algorithm is used in which the D-axis current command value is set to a value lower than the Q-axis current command value and the value is decreased as the Q-axis current command value increases. In such a configuration, heat generation of the motor 22 can be suppressed by suppressing the magnitude of the current to the rated current value or less.

When the D-axis current command value decreases in the low torque region, it eventually 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). The torque region is the medium torque region. The open-loop control DQ-axis current command generation unit 37 obtains the D-axis current command value by an algorithm that increases the D-axis current command value as the Q-axis current command value increases 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 is obtained by making the D-axis current value higher than the D-axis current value in the low torque region. Can be done. In addition, by increasing the D-axis current command value as the torque increases, the required torque calculation error and restoring force against disturbance are obtained, and the motor 22 is controlled by open loop without stepping out or vibrating. The drive of the can be stopped.

As the D-axis current command value increases in the medium torque region, the DQ-axis norm current value eventually reaches the DQ-axis norm current upper limit value, 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 by an algorithm that lowers the D-axis current command value as the Q-axis current command value increases in a high torque region. In the high torque region, where higher torque is required than in the medium torque region, the Q-axis current value decreases as the torque increases, weakening the force that attracts the magnetic poles of the rotor magnet, and the current exceeds the maximum allowable value. It can be suppressed.

The process executed by the D-axis current command generation unit 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 saturation unit 37B3, a first square calculation unit 37B4, a second square calculation 37B5, and a square root calculation unit. It is equipped with 37B6.

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

The output from the saturation unit 37B3 is converted into a square value by the first square calculation unit 37B4, and then input to the adder as a positive value. 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. By the above processing, the D-axis current command value changes according to the characteristics shown in the graph of FIG.

<Action and effect of industrial robot 1>
<Structure 1>
Configuration 1 is a motor control method in which the motor 22 is driven by open-loop control by a current drawing method. Configuration 1 includes a step of obtaining the torque (for example, the torque command value in FIG. 9) required for the motor 22 based on the position command value (rotation position command signal) sent from the host controller 100 (signal transmitting means). do. Further, in the configuration 1, the step of obtaining the Q-axis current command value corresponding to the required torque (for example, the torque constant dividing unit 37A8 in FIG. 9), the Q-axis current corresponding to the Q-axis current command value, and the magnet of the rotor It is provided with a step (for example, the D-axis current command generation unit 37B in FIG. 9) for supplying the D-axis current for drawing the magnetic poles of the above to the motor.

<Action and effect of configuration 1>
According to the configuration 1, by supplying a Q-axis current having a value corresponding to the torque required for the motor 22 to the motor 22, the drive of the motor 22 is stopped by open loop control without causing the motor 22 to step out or vibrate. Can be made to.

<Structure 2>
In the configuration 2, the step of obtaining the torque in the configuration 1 is based on the step of obtaining the estimated angular acceleration value of the motor 22 (for example, the estimated angular velocity in FIG. 9) after responding to the position command value and the estimated angular acceleration value. It includes a step of obtaining a torque (for example, a torque command value in FIG. 9).

<Action and effect of configuration 2>
According to the configuration 2, by supplying the Q-axis current corresponding to the torque required to rotate the motor 22 to the motor 22, it is possible to suppress the supply of an unnecessary Q-axis current to the motor 22.

<Structure 3>
In the configuration 3, the steps for obtaining the torque in the configuration 2 are the step for obtaining the angular velocity estimated value (for example, the angular velocity estimated value in FIG. 9) of the motor 22 after responding to the position command value, the angular velocity estimated value, and the angular acceleration estimation. It includes a step of obtaining torque based on a value.

<Action and effect of configuration 3>
According to the configuration 3, the required torque can be obtained more accurately by obtaining the torque based on the estimated value of the angular velocity in addition to the estimated value of the angular acceleration.

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

<Action and effect of configuration 4>
According to the configuration 4, by obtaining the estimated angular acceleration value of the motor 22 based on the position simulation value, it is possible to avoid the occurrence of vibration of the motor 22 when the open loop control is switched due to the insufficient execution time of the sensorless vector control. can.

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

<Action and effect of configuration 5>
According to the configuration 5, the Q-axis current corresponding to the inertial force of the drive mechanical system can be supplied to the motor 22.

<Structure 6>
In the configuration 6, in the step of obtaining the torque in the configuration 5, the estimated angular velocity of the motor 22 after responding to the position command value is obtained, and the force for compensating the viscous resistance of the drive mechanical system based on the estimated angular velocity is obtained. Find the moment as part of the torque.

<Action and effect of configuration 6>
According to the configuration 6, in addition to the moment of the force required for accelerating and decelerating the drive mechanical system, the viscous resistance of the drive mechanical system is also obtained as the required torque. As a result, it is possible to suppress the occurrence of excess or deficiency of the torque of the motor 22 as compared with the case where only the moment of the force required for acceleration and deceleration is obtained as the required torque.

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

<Action and effect of configuration 7>
According to the configuration 7, in addition to the moment of the force required for acceleration and deceleration of the drive mechanical system, gravity is also obtained as the required torque, so that only the moment of the force required for acceleration and deceleration is obtained as the required torque. Compared with the above, it is possible to suppress the occurrence of excess or deficiency of the torque of the motor 22.

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

<Action and effect of configuration 8>
According to the configuration 8, in addition to the moment of the force required for accelerating and decelerating the drive mechanical system, the Coulomb friction force is also obtained as the required torque. As a result, it is possible to suppress the occurrence of excess or deficiency of the torque of the motor 22 as compared with the case where only the moment of the force required for acceleration and deceleration is obtained as the required torque.

<Structure 9>
The configuration 9 includes, in any of the configurations 5 to 8, a step of obtaining a D-axis current command value corresponding to the Q-axis current command value. Further, in the configuration 9, in the step of supplying the Q-axis current corresponding to the Q-axis current command value and the D-axis current for drawing the magnetic pole of the rotor magnet to the motor, the D-axis corresponding to the D-axis current command value is provided. Supply current to the motor.

<Action and effect of configuration 9>
According to the configuration 9, the motor is prevented from burning, and the heat generation of the motor is suppressed as compared with the configuration in which a constant value of the D-axis current is passed as in the conventional configuration, and the required torque calculation error and restoration against disturbance are suppressed. You can gain power.

<Structure 10>
In the configuration 10, in the step of obtaining the D-axis current command value in the 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.

<Action and effect of configuration 10>
According to the configuration 10, by increasing the D-axis current command value as the Q-axis current command value increases, a required torque calculation error and a restoring force against disturbance can be obtained without causing the motor 22 to step out or vibrate. The drive of the motor 22 can be stopped by the open loop control.

<Structure 11>
In the configuration 11, in the step of obtaining the D-axis current command value in the configuration 10, the D-axis current command value is obtained by the following algorithm. That is, the D-axis current command value is obtained in a manner that makes the norm of the front DQ-axis current vector constant in a predetermined low torque region. Further, in the medium torque region higher than the low torque region, the D-axis current command value is increased as the Q-axis current command value increases.

<Action and effect of configuration 11>
According to the configuration 11, in the low torque region where it is not necessary to strongly draw the magnetic pole of the rotor magnet, the magnitude of the current is rated by obtaining the D-axis current value in a manner of keeping the norm of the DQ-axis current vector constant. The heat generation of the motor 22 can be suppressed by suppressing the current value to or less than that.
Further, according to the configuration 11, in the medium torque region where the Q-axis current value generally exceeds the rated current value, it is necessary to make the D-axis current value higher than the D-axis current value in the low torque region. The drive of the motor 22 can be stopped by the open loop control without stepping out or vibrating the motor 22 by obtaining the torque calculation error and the restoring force against the disturbance.

<Structure 12>
Configuration 12 is an algorithm that reduces the D-axis current command value as the Q-axis current command value increases in a high torque region higher than the medium torque region in the step of obtaining the D-axis current command value in configuration 11. Obtain the shaft current command value.

<Action and effect of configuration 12>
According to the configuration 12, in the high torque region where a higher torque than the medium torque region is required, the force for attracting the magnetic poles of the rotor magnet is weakened by lowering the D-axis current value as the torque increases, and the current is generated. Can be prevented from exceeding the maximum allowable value.

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

<Action and effect of configuration 13>
In configuration 13, if an abnormality occurs in the position detection value while the motor 22 is rotating at a relatively high speed, the induced voltage that is satisfactorily generated in the motor 22 is estimated by sensorless vector control. Then, the rotation position of the motor 22 is estimated from the estimated induced voltage, and the motor 22 is driven based on the estimation result to appropriately control the rotation operation of the motor 22. After that, when the angular velocity of the motor 22 is reduced to the extent that a sufficient induced voltage is not generated in the motor 22 by the sensorless vector control, the drive control of the motor 22 is switched from the sensorless vector control to the open loop control. In open loop control, the rotational operation of the motor 22 is appropriately controlled by the current drawing method. In such a configuration, when an abnormality occurs in the position detection value when the motor 22 is rotating at a relatively high angular velocity, sensorless vector control and open loop control are performed to appropriately rotate the motor 22. While controlling, the motor 22 is gradually decelerated and stopped.
Further, in the configuration 13, if 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 such a configuration 13, it is possible to avoid the occurrence of improper operation of the hand portion 2A (operated body) by immediately forcibly stopping the motor 22 when an abnormality occurs in the position detection value. In addition, after switching the control method to open loop control, it is possible to operate the motor in the same manner as when performing detection position feedback control, so it is possible to suppress the occurrence of step-out and vibration of the motor after switching. Can be done.

When an abnormality occurs in the position detection value, the pattern of the position command value sent from the upper controller 100 (upper device) to stop the operation of the hand 2A simply decelerates and stops the drive of the motor 22. Not limited to patterns. Depending on the structure of the arm 2, it may be possible to stop the hand portion 2A along an appropriate trajectory by the following pattern. That is, first, the drive of the motor 22 is stopped by the sensorless vector control and the open loop control. Immediately after that, the motor 22 is rotated in the reverse direction by the open loop control, then accelerated and decelerated in the opposite direction by the sensorless vector control, and then the motor 22 is decelerated and stopped by the open loop control.

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

<Action and effect of configuration 14>
In the configuration 14, immediately after switching from the sensorless vector control to the open loop control, the Q-axis current command value corresponding to the required torque is obtained based on the angular acceleration estimated value obtained immediately before the switching. As a result, according to the configuration 14, it is possible to suppress the occurrence of vibration of the motor 22 due to the supply of an inappropriate Q-axis current at the time of switching.

<Structure 15>
Configuration 15 is a motor driving device 20 that controls the driving of the motor 22, and controls the driving of the motor 22 by the motor control method according to any one of configurations 1 to 14.

<Action and effect of configuration 15>
According to the configuration 15, by using the motor control method according to any one of the configurations 1 to 15, the drive of the motor 22 can be stopped by open loop control without causing the motor 22 to step out or vibrate.

<Structure 16>
Configuration 16 is a control method for an industrial robot 1 that individually controls the drive of a plurality of motors 22 to change the position of the arm 2 of the industrial robot 1. Further, the configuration 16 controls each drive of the plurality of motors 22 by the motor control method according to any one of the configurations 1 to 14.

<Structure 17>
Configuration 17 is an industrial robot 1 that individually controls the drive of a plurality of motors 22 to change the position of the arm 2, and controls each drive of the plurality of motors 22 by the motor drive device 20 of the configuration 15. do.

<Actions and effects of configurations 16 and 17>
In configurations 16 and 17, when an abnormality in the position detection value occurs in at least one of the motors 22, the driving of the motor 22 is stopped by open loop control without stepping out or vibrating the motor 22. be able to.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications and modifications can be made within the scope of the gist thereof. The embodiments are included in the scope and gist of the invention, and at the same time, are included in the invention described in the claims and the equivalent scope thereof.

1: Industrial robot, 2: Arm, 20: Motor drive, 21: Control mode selection unit, 22: Motor, 23: Position speed control unit, 24: Vector control DQ axis current command generation unit, 25: First selector , 26: Current control unit, 27: DQ reverse conversion unit, 28; PWM control unit, 29: Inverter, 30: Rotary encoder (rotation position detector), 31: Current detector, 32: Second selector, 33: Vector Control electric angle generation unit, 34: 3rd selector, 35: position estimation unit, 36: open loop control electric angle generation unit, 37: open loop control DQ axis current command generation unit, 38 encoder communication abnormality determination unit, 39: DQ Conversion unit, 100: Upper controller

Claims (17)

In the motor control method in which the motor is driven by open loop control by the current drawing method,
A step of obtaining the torque required for the motor based on the rotation position command signal sent from the signal transmitting means, a step of obtaining the Q-axis current command value corresponding to the torque, and a Q corresponding to the Q-axis current command value. A motor control method comprising a step of supplying an axial current and a D-axis current for drawing in a magnetic pole of a rotor magnet to a motor. The step for obtaining the torque includes a step for obtaining an estimated angular acceleration value of the motor after responding to the rotation position command signal, and a step for obtaining the torque based on the estimated angular acceleration value. The motor control method according to claim 1. The step of obtaining the torque includes a step of obtaining an estimated angular velocity of the motor after responding to the rotation position command signal, and a step of obtaining the torque based on the estimated angular velocity and the estimated angular acceleration. The motor control method according to claim 2, wherein the motor control method is characterized. The step of obtaining the torque includes a step of obtaining an estimated value of the rotation position of the motor after responding to the said rotation position command signal and a step of obtaining the estimated value of the angular acceleration based on the estimated value of the rotation position. The motor control method according to claim 2 or 3, wherein the motor control method is characterized. In the step of obtaining the torque, the moment of the force required for acceleration and deceleration of the drive mechanical system obtained by multiplying the estimated angular acceleration value by a coefficient corresponding to the moment of inertia is obtained as the torque or a part of the torque. The motor control method according to any one of claims 2 to 4, wherein the motor control method is characterized. In the step of obtaining the torque, the angular velocity estimated value of the motor after responding to the rotation position command signal is obtained, and the moment of the force for compensating the viscous resistance force of the drive mechanical system is calculated based on the angular velocity estimated value. The motor control method according to claim 5, wherein the motor control method is obtained as a part of the above. The motor control method according to claim 5 or 6, wherein in the step of obtaining the torque, a moment of force for compensating for gravity is obtained as a part of the torque. In the step of obtaining the torque, the angular velocity estimated value of the motor after responding to the rotation position command signal is obtained, and the moment of the force for compensating the Coulomb friction force based on the angular velocity estimated value is used as a part of the torque. The motor control method according to any one of claims 5 to 7, wherein the motor control method is obtained. A step of obtaining a D-axis current command value corresponding to the Q-axis current command value is provided, and the Q-axis current corresponding to the Q-axis current command value and the D-axis current for drawing the magnetic pole of the rotor magnet are applied to the motor. The motor control method according to any one of claims 5 to 8, wherein a D-axis current corresponding to the D-axis current command value is supplied to the motor in the supply step. The ninth aspect of the present invention, wherein in the step of obtaining the D-axis current command value, 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. Motor control method. 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 value is set as the Q-axis current command value increases. A claim characterized in that the D-axis current command value is obtained by an algorithm that lowers the current and increases the D-axis current command value as the Q-axis current command value increases in a medium torque region higher than the low torque region. Item 10. The motor control method according to Item 10. In the step of obtaining the D-axis current command value, the D-axis current command is an algorithm that lowers the D-axis current command value as the Q-axis current command value increases in a high torque region higher than the medium torque region. The motor control method according to claim 11, wherein a value is obtained. A step of detecting an abnormality in a rotation position signal transmitted from a rotation position detector for detecting the rotation position of a motor is provided.
When the abnormality is not detected, the motor is driven by feedback control based on the rotation position signal.
When the abnormality is detected and the angular velocity of the motor at the time of detection is not less than or less than a predetermined threshold value, the motor is operated by sensorless vector control that feeds back an estimated rotation position based on the current flowing through the motor. Drive and
Any one of claims 5 to 12, wherein 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, the driving of the motor is stopped by open loop control. The motor driving method described in the section. The motor control method according to claim 13, wherein during the execution of the sensorless vector control, a step of obtaining an estimated angular acceleration value of the motor based on the rotation position command value is executed. A motor drive device that controls the drive of a motor.
A motor driving device, characterized in that the driving of the motor is controlled by the motor control method according to any one of claims 1 to 14. It is a control method for an industrial robot that changes the position of the arm of the industrial robot by individually controlling the drive of multiple motors.
A control method for an industrial robot, wherein each drive of a plurality of motors is controlled by the motor control method according to any one of claims 1 to 14. An industrial robot that individually controls the drive of multiple motors to change the position of the arm.
An industrial robot characterized in that the drive of each of a plurality of motors is controlled by the motor drive device according to claim 15.

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