JP4003741B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device.

  2. Description of the Related Art Conventionally, servo motors and servo amplifiers are often used because FA system devices such as semiconductor manufacturing devices, robots, and various machine tools require high-precision positioning. The servo motor is connected to a rotor with an encoder and a resolver for detecting rotation information of the motor, and has a resolution of 10,000 or more per rotation. The servo amplifier drives the servo motor in accordance with a command from a host controller, such as a sequencer, and performs an operation of controlling the servo motor so that position information fed back from the encoder or resolver matches the command from the host controller. The command from the host controller is generally a command by a pulse, and the number of cases where the motor is driven by a pulse exceeding 500 Mbps or more than 1 Mbps is recently increasing in order to increase the speed of the apparatus. As the speed increases, the FA system apparatus is reduced in size and cost, so that the machine rigidity is reduced and a resonance frequency exists in the control region, which is a cause of hindering the speeding up.

As a measure to improve this, there is a method of reducing the gain although the response is lowered. By reducing the gain, the peak due to resonance can be lowered, but the frequency response is lowered, so that the machine tact time becomes longer. There are drawbacks. As a technique for suppressing vibration without lowering the frequency response, there is a method of inserting a notch filter in the torque command. The notch filter has a frequency characteristic as shown in FIG. 5, for example, and the resonance peak can be suppressed by matching the resonance frequency with the frequency at which the gain of the notch filter attenuates (see, for example, Patent Document 1). ). However, a multi-joint robot such as a robot arm has a two-inertia characteristic and has a frequency characteristic as shown in FIG. 6, so that the vibration on the load side increases due to the gain peak at the anti-resonance frequency. In the above-described notch filter, it is difficult to suppress this vibration. Therefore, in recent years, there is a technique for suppressing vibration by vibration suppression control as a technique for actively removing vibration components from the position command. This is a technique of suppressing a gain peak due to an anti-resonance frequency by inserting a damping filter having a frequency characteristic similar to that of a notch filter into a position command (see, for example, Patent Document 2).
JP-A-1-230109 Japanese Patent Laid-Open No. 10-56790

  The problem to be solved is that the anti-resonance frequency changes depending on the expansion / contraction of the arm of the robot and the loading / unloading of the object with the transfer machine. Then, vibration occurs and settling time becomes longer, and the effect of shortening the total machine tact time is reduced.

  In order to solve the above-described problems, the present invention provides a command output device that outputs a position command, a vibration suppression filter that generates a command in which a vibration component is removed from the command from the command output device, and a motor that receives a command from the vibration suppression filter. Control means for following the motor, power conversion means for driving the motor in response to a command from the control means, command direction detection means for detecting the direction of rotating the motor from the command from the command output device, and first from the command direction And a filter switching means for switching between the second damping filter and the second damping filter.

  Or, a command output device that outputs a position command, a damping filter that creates a command from which a vibration component has been removed from a command from the command output device, a control unit that causes the motor to follow the command from the damping filter, and a control unit Comprising a power conversion means for driving the motor in response to a command from the rotation direction detection means for detecting the rotation direction of the motor, and a filter switching for switching the first damping filter and the second damping filter from the rotation direction of the motor. Means.

  According to the motor control device of the present invention, the rigidity of the robot arm is automatically changed to detect the change of the anti-resonance frequency caused by the expansion / contraction of the robot arm and the loading / unloading of the object by the transfer machine. Vibrations can be suppressed even for low machines, and the settling time can be shortened.

  A command output device that outputs a position command, a vibration control filter that creates a command from which a vibration component has been removed from the command from the command output device, a control unit that causes the motor to follow the command from the vibration suppression filter, Command direction detecting means for detecting a direction in which the motor is rotated from a command from the command output device, and a first damping filter and a second damping filter from the command direction. And a filter switching means for switching between.

  A motor control apparatus according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a block diagram of a motor control system in Embodiment 1 of the present invention. Reference numeral 1 denotes a command output device, 2 denotes a motor control device, 7 denotes a motor, 8 denotes an encoder, and 10 denotes a load having characteristics of two inertia systems such as a robot arm.

  The command output device 1 shows a host controller connected to a servo amplifier such as a sequencer, and generally outputs two signals of PULS and SIGN. The command output method is a method in which PULS and SIGN give a pulse having a phase difference of 90 degrees, a method in which a pulse is given to the PULS side when turning in the CCW direction, a pulse in the SIGN side when turning in the CW direction, a pulse to the PULS And switching between CCW and CW with the sign of SIGN is often used. The number of pulses given here is the amount of rotation of the motor, and the amount of movement of the motor by one pulse is determined by the resolution per rotation of the encoder and the frequency division / multiplication processing by software. The pulse command diagram shown in FIG. 2 shows an example in which a command in the CCW direction is given when a pulse is given to PULS, and a command in the CW direction is given when a pulse is given to SIGN.

  The motor control device 2 drives the motor 7 based on the command from the command output device 1, detects the signal from the encoder 8 as a feedback signal, and controls the motor 7 so that the command value matches the feedback signal. To do.

  The encoder 8 serves to feed back information such as the rotor position, rotation speed, and rotation position of the motor 7 to the motor control device.

  For example, assuming that the resolution of the command pulse and the resolution of the encoder are the same in the motor control device 2 and the resolution per rotation of the encoder is 10,000, when the command pulse of 10,000 pulses is input from the command output device 1 to the motor control device 2, the motor 7 Is driven one revolution.

  The inertial load 10 is, for example, a load such as a robot arm, and has a peak point of frequency characteristics at a resonance point and an antiresonance point as shown in FIG. 6, and the load side induces vibration due to the peak of the antiresonance frequency on the motor side. Is done.

  Next, details of the motor control device 2 will be described.

  The motor control device 2 includes a damping filter 3, filter switching means 9, control means 5, power conversion means 6, and command direction detection means 4.

  The control means 5 is generally a position control and a speed control, and the position control is often constituted by P control (proportional control) and the speed control is constituted by PI control (proportional / integral control). In the position control, the speed command is output by multiplying the difference between the position command determined by the number of pulses given from the command output device 1 and the rotor position obtained from the feedback signal from the encoder 8 by the position proportional gain. In speed control, PI control is performed so that the speed command output from the position control is equal to the rotational speed of the rotor that can be detected from the feedback signal from the encoder, and a torque command value is output.

  The power conversion means 6 is composed of an IGBT, a MOSFET or the like, and applies a voltage to the motor winding based on the torque command value output from the control means 5. In the case of a three-phase motor, it is often composed of six IGBTs.

  Like the notch filter, the damping filter 3 is a filter having frequency characteristics in which the gain decreases in a certain frequency band (damping frequency) as shown in FIG. 5, and the first damping filter 3a and the second damping filter The configuration is such that two filters 3b can be set. The pulse command 21 output from the command output device 1 passes through the first damping filter 3a or the second damping filter 3b, and outputs the first pulse command 23a or the second pulse command 23b.

  The command direction detecting means 4 detects whether the pulse command 21 from the command output device 1 is a command to drive the motor 7 in CCW / CW and outputs a command direction 22a.

  Here, the filter switching means 9 functions to switch the pulse command according to the signal in the command direction 22a. For example, the first pulse command 23a is used for a command in the CCW direction, and the second pulse command is used in the command in the CW direction. 23b is selected and a pulse command is given to the control means 5. FIG. 2 shows a state where the damping filter 3 is switched by the command direction 22a. Since the pulse commands that have passed through the damping filter 3 remove the frequency components set by the first damping filter 23a and the second damping filter 23b, respectively, the anti-resonance frequency of the FA system device and the damping filter By adjusting the set frequency, vibration can be reduced.

  With the above configuration, it is possible to automatically cope with a change in the anti-resonance frequency of the FA system device. For example, a robot that transports an object often makes a fixed movement such as a CCW direction when an object is mounted and a CW direction when the object is not mounted. In such a case, vibration can be reduced by adopting a configuration in which the damping filter is automatically switched according to the command direction.

  In addition, although two damping filters can be set, two or more damping filters may be set. In this case, selection can be made by combining an external switching signal and the command direction 22a.

  A second embodiment of the present invention will be described with reference to FIGS.

  What is different from the first embodiment is a method for switching the damping filter 3, which will be described.

  Based on the signal output from the encoder 8, the rotation direction detection means 11 detects the rotation direction of the motor 7. The first pulse command 23a or the second pulse command 23b is switched depending on the detected motor rotation direction 22b. FIG. 4 shows a state where the damping filter 3 is switched by the motor rotation direction 22b.

  With the above configuration, it is possible to automatically cope with a change in the anti-resonance frequency of the FA system apparatus. For example, a robot that transports an object often makes a fixed movement such as a CCW direction when an object is mounted and a CW direction when the object is not mounted. In such a case, vibration can be reduced by adopting a configuration in which the vibration suppression filter is automatically switched according to the motor rotation direction.

  In addition, although two damping filters can be set, two or more damping filters may be set. In this case, selection can be made by combining an external switching signal and the motor rotation direction 22b.

  According to the motor control device of the present invention, the rigidity of the robot arm is automatically changed to detect the change of the anti-resonance frequency caused by the expansion / contraction of the robot arm and the loading / unloading of the object by the transfer machine. Vibration can be suppressed even for a low machine, which is useful when it is desired to shorten the settling time.

Motor control system block diagram in Embodiment 1 of the present invention The figure which shows the operation | movement sequence in Example 1 of this invention. Motor control system block diagram in Embodiment 2 of the present invention The figure which shows the operation | movement sequence in Example 2 of this invention. Graph showing frequency characteristics of notch filter in the prior art Graph showing frequency characteristics of two-inertia system in the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Command output device 2 Motor control device 3 Damping filter 3a 1st damping filter 3b 2nd damping filter 4 Command direction detection means 5 Control means 6 Power conversion means 7 Motor 8 Encoder 9 Filter switching means 10 2 Inertia system Load 11 Rotation direction detection means 21 Pulse command 22a Command direction 22b Motor rotation direction 23a First pulse command 23b Second pulse command

Claims (6)

A command output device that outputs a position command, a vibration control filter that creates a command from which a vibration component has been removed from the command from the command output device, a control unit that causes the motor to follow the command from the vibration suppression filter, Command direction detecting means for detecting a direction in which the motor is rotated from a command from the command output device, and a first damping filter and a second damping filter from the command direction. And a filter switching means for switching between the two. A command output device that outputs a position command, a vibration control filter that creates a command from which a vibration component has been removed from the command from the command output device, a control unit that causes the motor to follow the command from the vibration suppression filter, A rotation direction detection means for detecting the rotation direction of the motor, and a filter switching means for switching the first damping filter and the second damping filter from the rotation direction of the motor. A motor control device comprising: A semiconductor manufacturing apparatus using the motor control device according to claim 1. A robot using the motor control device according to claim 1. A machine tool using the motor control device according to claim 1. A transport device using the motor control device according to claim 1.