JP2009177881A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a plurality of shaft control parts intend to use information of a single full-closed position sensor, a gain reduction in a position control loop occurs caused by delay in relaying of a signal between the shaft control parts, or the semi-closed position feedback gain for every motor is lowered under the influence of the upper limit of a full-closed loop gain since the full-closed loop gain at a position to be set is different due to the difference in a mechanical transfer mechanism between a drive motor and the sensor. <P>SOLUTION: In the motor controller, a speed command based on the full-closed position feedback is transferred from the first shaft control part to the other shaft control part, and the other shaft control part adjusts to use the speed command based on the semi-closed position feedback obtained from each shaft motor position and a speed command obtained from the first shaft control part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tandem control type motor control device that uses a plurality of motors to control the position and speed of one movable part, and separately from position sensors that detect the position of each motor, The present invention is applied to a control object including a single position sensor for directly detecting the position.

  In machine tool tables, etc., when the mass of the movable part is large and sufficient acceleration cannot be obtained with one motor during acceleration / deceleration, tandem control to drive one movable part using multiple motors is possible. Done. An apparatus configured to perform control so that thrust applied to the movable part is equalized by passing control parameters between the position and speed control parts of the master axis and slave axis that operate in tandem (for example, Patent Documents) 1) and a device that makes the torque command of the slave motor asymptotically approach the low frequency component of the master shaft motor command torque with the above-described configuration (for example, Patent Document 2) is known.

  When torque transmission between the motor and the moving part is performed via a ball screw or gear, as in the case of driving with a single motor, in order to avoid the influence of backlash and lost motion of the transmission mechanism, A sensor for full closed loop position control that directly measures the position of the moving part is used. An example of dandem control according to the prior art in a system in which only one sensor is attached to a movable part, which is a subject of the present invention, will be described below.

  FIG. 2 is a block diagram showing a configuration example of a system in which the position sensor 10 for full closed loop position control is attached to only one position of the movable portion 9. The movable portion 9 is configured to move by rotating each of the ball screw 5 connected to the master shaft motor 3 and the ball screw 8 connected to the slave shaft motor 6, and detects the rotational position of each motor in multiple rotations. The signals of the semi-closed loop position control sensors 4 and 7 are connected to the master axis control unit 1 and the slave axis control unit 2, respectively. Further, the position command coordinates P * of the movable part 9 given from the host control device are inputted to both controllers simultaneously.

  Inside the master axis control unit 1, the read value Pf from the position sensor 10 of the movable unit 9 is input to the position feedback arbitration unit 101, and the value is transmitted to the slave axis control unit 2 using communication means. . The position feedback arbitration unit 101 subtracts the semi-closed position detection value Pm from the master axis position control sensor 4 from the read value Pf using the subtractor 101a, and then passes through the low-frequency pass filter 101b. Again, adder 101c adds to Pm. As a result, the output of the position feedback mediation unit 101 gradually approaches the low frequency component to Pf and the high frequency component to Pm. The output of the position feedback arbitration unit 101 is subtracted from P * by the subtracter 102, the position deviation from the target is obtained, and the speed command Vmdiff corresponding to the position deviation is multiplied by the speed command coefficient KV1 in the position control unit 103. Is calculated. The feed forward speed component differentiated by the differentiator 104 of the position command P * is added to Vmdiff by the adder / subtractor 106 to obtain a speed command, and the motor speed Vm obtained by calculating the difference of Pm is subtracted to obtain the master. Calculate the speed deviation of the axis. The speed control unit 107 performs a proportional and integral calculation according to the speed deviation to calculate a torque command Tm for the master shaft. The Tm is input to the current control unit 108 and transmitted to the slave axis control unit 2 using communication means. The current control unit 108 performs feedback control so that the output current of the voltage inverter 109 that supplies current to the master shaft motor 3 matches the output torque of the master shaft motor 3.

  The slave axis control unit 2 uses the movable part position Pf sent from the master axis control unit 1 to calculate a motor torque command Tsh * for the slave axis from the speed control unit 207 in exactly the same way as on the master axis side, thereby generating torque. Input to the arbitration unit 211. On the other hand, as described in Patent Document 2, the torque command Tm sent from the master shaft is matched with the mechanical torque transmission polarity of the drive mechanism by the polarity calculation unit 210, and is then sent to the torque arbitration unit 211. The slave shaft command torque Ts * is controlled such that the high frequency component approaches Tsh * and the DC component approaches Tm *, and the current of the slave shaft motor 6 is controlled using this torque command.

  In the conventional motor control device, the master axis control unit 1 passes the detection value of the position sensor 10 for full closed loop position control to the slave controller side by communication means or the like. If the correction calculation is not performed, there is a problem that the time command P * from the upper level and the time shift occur, and if the time correction is performed, the control timing between the controllers is shifted. In addition, since the absolute position is handed over, the communication data size between both controllers tends to be large and the delay time itself tends to be large. In order to prevent this, the output of the position sensor 10 for full-closed loop position control may be divided into two on the electric circuit and read by each controller, but the sensors are connected by high-speed serial communication. If this is the case, distribution becomes difficult, and the configuration described above must be taken.

  On the other hand, in a system using only one position sensor 10 for full-closed loop position control, the sensor is placed at a position where the mechanical transfer functions from either the ball screw 5 on the master side or the ball screw 8 on the slave side are almost equal. It is often difficult to place. In this case, the gain of the position control unit 203 is lower than that of the master side position control unit 103 on the shaft on the side where the rigidity of the mechanical transmission path and the lost motion are large, and in FIG. Cannot be set. However, considering the disturbance in the motor shaft rotation system at the time of start-up and reversal, there has been a problem that it is preferable that the position feedback gain of the semi-closed loop is set to be high for both axes.

JP 2002-95290 A JP 2003-79180 A

  In the present invention, in a tandem control system control device that operates a single movable unit using a plurality of motors, the master axis control unit 1 uses the slave axis control to detect the detection value of the position sensor 10 for full closed loop position control. Realize a motor control device that prevents deterioration of controllability due to communication delay time passed to the unit. When the setting upper limit of the fully closed position feedback gain of both shaft control units differs depending on the mounting position of the position sensor 10, the semi-closed loop position feedback gain on the motor shaft side is not directly affected by the mounting position, It is to realize a motor control device that can be set.

  In order to solve the above-described conventional problems, the present invention provides a first axis control unit that controls the position and speed of the first motor to a second and subsequent axis control units that control other motors. A speed command for semi-closed position control calculated based on the motor position to be controlled is configured so as to transmit the speed command for full-closed position feedback calculated by one axis control unit. And the transmitted full-closed position feedback speed command, and use the former for the high-frequency speed command and the latter for the low-frequency speed command to determine the motor speed of the shaft control unit. Configure to control.

  Since the speed command value, not the position detection value, is transmitted from the first axis control unit, the data size for communication is reduced to about ½, and the transmission delay time is reduced. In addition, since the first axis control unit has completed the position error calculation of the fully closed loop, the second axis control unit does not need to correct the timing of the position error calculation, and the high frequency component of this command is Because it is not used, the communication delay time hardly affects the control performance. Moreover, since the gain of the fully closed position feedback and the gain of the semi-closed position control back in the second axis control unit can be set as independent constants, the position control loop of the semi-closed loop of the first and second controllers can be set. The gain setting on the high frequency side can be made substantially the same, and the followability at the time of starting and reversing the motor shaft can be improved.

  An example of the embodiment is shown in FIG. 2. Prior Art Embodiment Since parts having the same functions as those in FIG. 2 are given the same reference numerals, only the differences will be described. In the configuration of FIG. 1, the master axis control unit 1 includes a subtractor 112 for obtaining a position deviation between the detection position Pf from the fully closed position detector 10 and the position command P * of the movable part, and the position deviation. A position control unit 103 that multiplies the speed command coefficient KV1 and calculates a speed command Vf * for full-closed position control according to the position deviation is added. Since the calculated Vf * is a unit system of speed, a position change amount with a time period of less than 1 ms is generally used. For this reason, the data size is reduced to about ½ as compared with the position detection value Pf delivered in the embodiment of the prior art.

  The speed command Vf * for full closed position control is transmitted to the slave axis control unit 2 using the communication means, and is input to the newly added speed command arbitration unit 214. The speed command arbitration unit 214 calculates the speed command Vsc * for semi-closed position control by multiplying the position command P * and the position deviation between the slave axis position control sensor 7 by the speed command coefficient KV2. And input to the speed command arbitration unit 214. The difference between the two signals is obtained by the subtractor 211a, and is added to Vsc * by the adder 214c through the low-pass filter 214b to be the slave axis speed command Vs *. Thereafter, the speed of the slave shaft motor 6 is controlled as in the embodiment of FIG.

  In the position feedback loop on the slave axis side, the gain of the fully closed position control loop depends on the coefficient Kv3 of the position control unit 113, and the gain of the semi-closed position control loop depends on the coefficient Kv2 of the position control unit 203. Even if the oscillation limit of the full-closed position control loop on the slave side is different, the gain on the high-frequency side of the semi-closed position control loop can be adjusted independently. For this reason, the semi-closed loop gain can be set higher than that of the conventional motor shaft on the side where the oscillation limit of the fully closed position control loop is low, and the transient response delay at the time of start-up and reversal can be reduced.

It is a block diagram which shows an example of embodiment of this invention. It is a block diagram which shows an example of the conventional control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Master axis control part, 2 Slave axis control part, 3 Master axis motor, 4,7 Position control sensor, 6 Slave axis motor, 5,8 Ball screw, 9 Movable part, 10 Position sensor, 101,201 Position feedback arbitration part, 211 torque arbitration unit, 214 speed command arbitration unit, 104, 105, 201, 206 differentiator, 103, 201, 113 position control unit, 107, 207 speed control unit, 106, 206 adder / subtractor, 108, 208 current control unit, 109, 209 Voltage source inverter, 210 Polarity calculation unit, 101a, 201a, 211, 214b Low-pass filter, 102, 101a, 112, 202, 201a, 211a Subtractor, 101c, 201b, 211c, 214c Adder.

Claims (1)

In a motor control device having a position sensor for one fully closed loop that directly detects the position of a movable object while controlling the position and speed of the movable part using a plurality of motors,
From the first axis control unit that reads the value of the position sensor for the fully closed loop and controls the position and speed of the first motor to the second and subsequent axis control units that control other motors, the first Configured to transmit the speed command for fully closed position feedback calculated by the axis controller of
The second and subsequent axis control units arbitrate the semi-closed position control speed command calculated based on the motor position to be controlled and the transmitted full-closed position feedback speed command,
A motor control device configured to control the motor speed of the shaft control unit using the former for a high-frequency speed command and the latter for a low-frequency speed command.

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