JP2007004287A - Position control method for belt-driven servo device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein a conventional belt-driven servo device produces drive force ripples with a frequency proportional to motor force transfer speed due to engagement between a pulley and belt, and vibrations of movable portions are generated. <P>SOLUTION: In a position control method for a belt-driven servo device having a motor 6, the pulley combined with a shaft of the motor, the belt driven by the pulley, and the movable portion combined with the belt, the position control method estimates the disturbance force with a disturbance estimation observer 9, on the basis of the speed of the motor 6, and compensates for the disturbance force, by subtracting (5) the value of the disturbance force estimated from a motor torque command. Furthermore, the position control method measures the acceleration of the movable portion with an acceleration sensor 10 so as to damp the vibration of the movable portion by constituting a proportional acceleration control loop through a filter 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a position control method for a belt drive servo device, and more particularly to a vibration suppression control method for a belt drive servo device that positions a movable part.

A conventional belt drive servo apparatus estimates a disturbance force using a disturbance observer, and adds the estimated disturbance force to a motor torque command to attenuate the vibration (see, for example, Non-Patent Document 1).
Further, in conventional vibration suppression control of a servo system, acceleration is measured by an acceleration sensor, negatively fed back to a speed controller, and vibration is attenuated (for example, see Non-Patent Document 2).
In FIG. 7, 101 is a position controller, 102 is a dynamic characteristic of the belt drive system, 103 is a disturbance force observer, 104 is a disturbance force, 105 is an estimated disturbance force, 106 is a subtractor, 107 is a motor torque, Is controlled by a disturbance force observer, and the estimated disturbance force is subtracted from the motor torque to perform vibration suppression control of the belt drive servo device.
As described above, in the conventional belt drive servo apparatus, a procedure is adopted in which the disturbance force is estimated by the disturbance force observer and subtracted from the motor torque to suppress the vibration.
Furthermore, vibration suppression control for industrial robots that are not belt-driven involves measuring acceleration and subtracting it from the motor speed command.
JP-A-9-212203 Japanese Patent Laid-Open No. 10-6261 Lee Yong, Naoyuki Takei, Junji Furuso, “Study on Reduction of Periodic Speed Fluctuation in Toothed Belt Drive Servo System by Disturbance Observer”, Transactions of the Japan Society of Mechanical Engineers (C) Vol.68, No.676, 3673-3680 ( 2002), FIG. S. Futami, N. Kyura and S. Hara: Vibration absorption control of industrial robots by acceleration feedback, IEEE Transaction on Industrial Electronics, 299-305, Vol. IE-30, No. 3 (1983)

The invention described in Patent Document 1 is a servo motor in which a control unit that calculates a command torque to be applied to an amplifier drives a second arm in order to suppress vibration of a robot arm and to increase the speed of arm positioning. And a robot including an amplifier unit that generates torque in the servo motor and an angle detector that detects the angle of the servo motor, based on the command torque and the angle of the servo motor, the arm angle and angular velocity, the servo motor A torsion angle / disturbance estimation observer for estimating the angular velocity and disturbance torque of the servo motor, a feedforward unit for calculating the target angular velocity of the servo motor based on the target angle of the servo motor, the target angle, angle and target angular velocity of the servo motor, Command based on estimated angle and estimated angular velocity of 2 arms 3, servo motor estimated angular velocity and estimated disturbance torque Calculating a torque, and controls the robot based on the command torque control section is calculated.
The invention described in Patent Document 2 simply calculates a constant necessary for estimation calculation from the measured frequency characteristics. For this purpose, a servo motor that drives the second arm, an amplifier unit that generates torque in the servo motor, and a servo A torsion angle / disturbance estimation observer that estimates at least the angle or angular velocity of the second arm based on the command torque and the angle of the servo motor, and a torsion, which is targeted for a robot equipped with an angle detector that detects the angle of the motor Based on the estimated angle or estimated angular velocity of the second arm estimated by the angle / disturbance estimation observer, a control unit for calculating a command torque and various constants for estimating the angle or angular velocity of the second arm 3 are given to the amplifier unit. Estimate constant determination from transfer function from command torque to servo motor angle detected by angle detector It has the door, and controls the robot based on the command torque control section is calculated.

In the conventional vibration suppression control method of the belt drive servo system, the disturbance force is estimated by a disturbance force observer, and the estimated disturbance force is subtracted from the motor torque. Furthermore, the disturbance force ripple is proportional to the motor speed. Since the vibration frequency changes greatly, there is a problem in that it is impossible to estimate the disturbance force quickly in the high speed range and a large vibration suppression effect cannot be obtained.
In the case of an industrial robot, the acceleration is measured by an acceleration sensor and negatively fed back to the speed controller. However, in the belt drive servo device, even if negative feedback is made to the speed control system. There was also a problem that there was no vibration suppression effect.
The inventions described in Patent Document 1 and Patent Document 2 are common in that vibration suppression is measured using a disturbance observer as in the present invention, but there is no acceleration sensor for performing acceleration feedback control. There was a weak point when performing acceleration feedback in the frequency domain.
The present invention has been made in view of such problems. The disturbance force is estimated by a disturbance force observer and the estimated disturbance force value is subtracted from the motor torque, and the acceleration of the movable part is measured by an acceleration sensor. An object of the present invention is to make it possible to perform vibration suppression control of the belt drive servo device by configuring a control loop.
The influence of the acceleration feedback control provided by the present invention on the estimation of the disturbance force by the disturbance observer is considered as follows.
1. Since the vibration frequency of the belt drive system is generally proportional to the speed, acceleration feedback having a vibration suppressing action in a wide frequency band is required.
2. The disturbance observer is effective for correcting a relatively low frequency operation such as friction force.
3. From these, acceleration feedback is effective in a high frequency region, and a disturbance observer is effective in a low frequency region.

In order to solve the above problem, an invention according to claim 1 relates to a position control method for a belt drive servo device, a motor, a motor controller for controlling the motor, a pulley coupled to a shaft of the motor, In a position control method of a belt drive servo device comprising a belt driven by the pulley, a movable part coupled to the belt, and an acceleration sensor provided in the movable part, a disturbance estimation observer from the speed of the motor The disturbance force is estimated by subtracting the estimated disturbance force value from the motor torque command to correct the disturbance force, and at the same time, the acceleration sensor measures the acceleration of the movable part and forms a proportional acceleration control loop through the filter. As a result, the driving force ripple is proportional to the rotational speed of the motor due to the variation in meshing between the pulley and the belt. It is characterized by employing a vibration suppression control method of damping the vibration of the movable portion.
According to a second aspect of the present invention, in the position control method for the belt drive servo apparatus according to the first aspect, an output from the proportional integral speed controller is input to the proportional acceleration controller to obtain a motor torque command from the proportional acceleration controller. In the position control method of the belt drive servo device, the acceleration signal from the acceleration sensor is passed through a band-pass filter and negatively fed back to the output from the proportional integral speed controller.
According to a third aspect of the present invention, in the position control method for the belt drive servo apparatus according to the first aspect, an output from the proportional integral speed controller is input to the proportional acceleration controller to obtain a motor torque command from the proportional acceleration controller. In the position control method of the belt drive servo device, the acceleration signal from the acceleration sensor is negatively fed back to the output from the proportional integral speed controller through a band pass filter and an integrator.
According to a fourth aspect of the present invention, there is provided a position control device for a belt drive servo device, a motor, a motor controller for controlling the motor, a pulley coupled to a shaft of the motor, and a belt driven by the pulley. And a movable part coupled to the belt, and an acceleration sensor provided in the movable part, wherein the disturbance force is estimated by estimating the disturbance force from the speed of the motor. A disturbance estimation observer that subtracts and corrects an estimated value from a motor torque command, and a filter that is inserted in a proportional acceleration control loop that handles acceleration of the movable part measured by the acceleration sensor. .

According to the first and fourth aspects of the invention, by configuring the proportional acceleration control loop, vibrations whose frequency is proportional to the speed can be suppressed in a wide range, and the remaining low-frequency vibrations are corrected by the observer. Can do.
Further, according to the second aspect of the present invention, it is possible to limit the vibration frequency region to be suppressed and prevent oscillation in a higher-order vibration mode.
Further, according to the invention described in claim 3, in addition to the effect described in claim 1, it can be applied to a servo system having a structure in which speed feedback is effective.

Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an entire system of a belt drive servo apparatus for carrying out the method of the present invention. In the figure, M is a servo motor, R is a motor controller for controlling the servo motor, C is a coupling, P1 and P1 are pulleys, B is a belt, T is a movable part formed of a table, and A is provided in the movable part. Acceleration sensor. As can be seen from the figure, a pulley P1 meshing with the belt B is coupled to the servo motor M via a coupling C. The movable portion (table) T is coupled to the belt B, and the movable portion T moves to the left and right according to the forward / reverse rotation of the servo motor M. The acceleration sensor A detects the movement of the movable part T.

  FIG. 2 is a block diagram illustrating a configuration of a belt drive servo apparatus that performs the method according to the first embodiment of the present invention. In the figure, 1 is a proportional controller for position, 2 is a proportional integral controller for velocity, 3 is a subtractor, 4 is a proportional controller for acceleration, 5 is a subtractor, 6 is a motor, 61 is an encoder, 7 is an encoder 61 A physical integrator from the detected motor speed to the motor position, 8 is a belt drive mechanism, 9 is a disturbance force observer, 10 is an acceleration sensor, and 11 is a filter. The proportional controller 1 to the subtractor 5, the integrator 7, the disturbance force observer 9, and the filter 11 are housed in the motor controller R of FIG.

FIG. 3 shows the configuration of the disturbance force observer 9. In the figure, the upper part from the broken line is a block diagram to be controlled, and the lower part is a disturbance force observer.
here,

で、1/s は積分を表し、Jはサーボモータとベルトを合わせた慣性モーメントである。破線から下が外乱力オブザーバで、Lはオブザーバのバンド幅を決定するパラメータである。

Where 1 / s represents the integral and J is the moment of inertia of the servo motor and belt. Below the broken line is a disturbance force observer, and L is a parameter that determines the bandwidth of the observer.

FIG. 4 shows the time response of the rotation speed of the servo motor when the disturbance force observer and acceleration control are performed, and FIG. 5 shows the time response of the rotation speed of the servo motor without the disturbance force observer and acceleration control.
In both figures, the vertical axis represents angular velocity (rad / s), and the horizontal axis represents time (s).
In FIG. 5, since there is no disturbance force observer and acceleration control, the time response of the rotation speed of the servo motor generates a remarkable vibration of about 55 Hz as shown in the figure. This frequency is equal to a value obtained by multiplying the rotation speed of the servo motor and the number of teeth of the pulley, and is a vibration generated by a change in meshing between the pulley and the belt.
In contrast, since the disturbance force observer and acceleration control according to the present invention are performed in FIG. 4, the speed of the movable part is multiplied by the equivalent radius of the rotational speed pulley. It can be seen that the vibration shown in FIG. 5 is suppressed.

  As described above, according to the present invention, the disturbance force is estimated by the disturbance force observer, the estimated disturbance force value is subtracted from the motor torque, and the acceleration of the movable part is measured by the acceleration sensor, thereby forming a proportional acceleration control loop. The vibration whose frequency is proportional to the speed can be suppressed in a wide range by the proportional acceleration control loop, and the remaining low-frequency vibration can be corrected by the observer. It becomes possible to perform suppression control.

FIG. 6 is a block diagram showing a configuration of a belt drive servo apparatus that performs the method according to the second embodiment of the present invention. The reference numerals in the figure that are the same as those in FIG.
The belt drive servo apparatus according to the second embodiment is different from that shown in FIG. 2 in that an integrator 12 is inserted between the filter 11 and the subtractor 3 to convert acceleration information into speed information. The integrator 12 is also housed in the motor controller R (FIG. 1).
As a result, when the output from the proportional integral speed controller 2 is input to the proportional acceleration controller 4, the acceleration signal from the acceleration sensor 10 is passed through the bandpass filter 11 and the integrator 12 as a speed instead of an acceleration. Since the feedback from the controller 2 is negatively fed, it can be applied to a servo system having a structure in which velocity feedback is effective instead of acceleration.
Also according to the second embodiment, the disturbance force is similarly estimated by the disturbance force observer and the estimated disturbance force value is subtracted from the motor torque, and the acceleration of the movable part is measured by the acceleration sensor to constitute a proportional acceleration control loop. Since the proportional acceleration control loop can suppress the vibration proportional to the vibration in a wide range and the remaining low-frequency vibration can be corrected by the observer, the vibration of the belt drive servo device can be controlled in a wide range. Will be able to.

It is a block diagram which shows the structure of the belt drive servo apparatus to which the method of this invention is applied. 1 is an outline view of a belt drive servo device to which a method according to Embodiment 1 of the present invention is applied. It is a block diagram of the disturbance force observer applied by this invention. It is a time response of the motor rotational speed when the method of the present invention is applied. It is a time response of the motor rotational speed when the present invention is not applied. It is an external view of the belt drive servo apparatus to which the method which concerns on Example 2 of this invention is applied. It is a block diagram which shows the structure of the belt drive servo apparatus to which the conventional method is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Proportional position controller 2 Proportional integral speed controller 3 Subtractor 4 Proportional acceleration controller 5 Adder 6 Motor 61 Encoder 7 Integrator 8 Belt drive mechanism 9 Disturbance force observer 10 Acceleration sensor 101 Controller 102 Dynamic characteristic of belt drive system 103 Disturbance force observer 104 Disturbance force 105 Estimated disturbance force 106 Subtractor 107 Motor torque M Servo motor R Motor controller C Coupling P1, P1 Pulley B Belt T Table (movable part)
A Accelerometer

Claims (4)

A motor, a motor controller for controlling the motor, a pulley coupled to the shaft of the motor, a belt driven by the pulley, a movable part coupled to the belt, and a movable part provided in the movable part In a position control method of a belt drive servo device including an acceleration sensor,
At the same time as estimating the disturbance force by the disturbance estimation observer from the speed of the motor, subtracting the estimated disturbance force estimated value to the motor torque command,
A driving force proportional to the rotational speed of the motor due to the change in meshing between the pulley and the belt by measuring the acceleration of the movable part with the acceleration sensor and forming a proportional acceleration control loop through a filter. A position control method for a belt drive servo device, wherein a vibration suppression control method for attenuating vibration of the movable part generated by a ripple is adopted. In the position control method of the belt drive servo device that inputs the output from the proportional integral speed controller to the proportional acceleration controller and obtains the motor torque command from the proportional acceleration controller,
2. The position control method for a belt drive servo apparatus according to claim 1, wherein an acceleration signal from the acceleration sensor is negatively fed back to an output from the proportional integral speed controller through a band pass filter. In the position control method of the belt drive servo device that inputs the output from the proportional integral speed controller to the proportional acceleration controller and obtains the motor torque command from the proportional acceleration controller,
2. The position control method for a belt drive servo apparatus according to claim 1, wherein an acceleration signal from the acceleration sensor is negatively fed back to an output from the proportional integral speed controller through a band pass filter and an integrator. A motor, a motor controller for controlling the motor, a pulley coupled to the shaft of the motor, a belt driven by the pulley, a movable part coupled to the belt, and a movable part provided in the movable part In a position control device of a belt drive servo device provided with an acceleration sensor,
A disturbance estimation observer that estimates disturbance force from the speed of the motor and corrects the estimated disturbance force estimated value by subtracting it from the motor torque command;
And a filter inserted in a proportional acceleration control loop for handling the acceleration of the movable part measured by the acceleration sensor.

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