JP5200648B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device that enables stable gain adjustment with simple operation.

  In recent servo systems, an automatic parameter adjustment function called auto gain tuning is almost standard equipment. This auto-tuning function requires a function for estimating the inertia of the load. This is because the response frequency of the speed control system, which determines the response of the entire control system and is the basis for stable gain adjustment, is proportional to the reciprocal of the total inertia including the motor and load inertia. .

  On the other hand, when compared with a stepping motor or the like, a problem is how to stably perform complicated gain adjustment, which is a weakness of the servo amplifier.

  As a conventional technique for solving the above-described problem, an electric motor control device has been proposed in which two to three control parameters are set at a ratio determined from a control configuration in consideration of a vibration level (see, for example, Patent Document 1). ).

Moreover, what determines a control parameter based on the control object parameter calculated | required with the least squares method is proposed (for example, refer patent document 2).
JP 2003-189653 A JP-A-6-28006

  In Patent Document 1 described above, a value that is used as an inertia compensation gain at the time of torque command calculation is multiplied to compensate for the total inertia, but it is not specified what happens to the compensation gain when the inertia changes. First, when the response frequency of the speed control system changes, there is a possibility of destabilization with respect to the speed integration time constant and position proportional gain set with a fixed ratio.

  On the other hand, Patent Document 2 can estimate the inertia of the load by the least square method and make the response frequency of the speed control system constant. However, for robots whose load inertia changes depending on their posture, and robots intended for pick and place, the speed at which the load inertia changes with respect to the estimated speed that is generally determined by the stable convergence condition of the aforementioned least squares method Since this is often faster, the possibility of the control system becoming unstable in a transient state cannot be eliminated.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a motor drive device that enables a gain adjustment that is robust against fluctuations in load inertia with a simple operation.

In order to solve the above problem, the motor drive device according to claim 1 generates a speed command by multiplying a position deviation which is a difference between the position command and the current motor position by a position proportional gain set by a parameter. A proportional term torque command obtained by multiplying the position controller and the speed deviation, which is the difference between the speed command and the current motor speed, by the speed proportional gain set by the parameter and the estimated total inertia of the motor and load. Calculate the integral term torque command obtained by dividing the proportional term torque command through the integrator and then dividing by the speed integral time constant set by the parameter, and add the proportional term torque command and the integral term torque command. A speed controller that generates a torque command at a time, a torque filter that cuts off a high frequency component with a time constant set by a parameter for the torque command, and the torque filter A current controller that controls the motor by converting the output of the motor into a current command, and stores the maximum and minimum values of the total inertia, and sets the speed proportional gain, position proportional gain, and speed integral time constant parameters. A response frequency of the torque filter is constant with respect to a maximum response frequency of speed control obtained by dividing a result of multiplying the speed proportional gain by a total inertia estimated value by a total inertia minimum value. Set the speed proportional gain parameter so that the ratio is equal to or greater than the ratio, and multiply the speed proportional gain after the change by the estimated value of the total inertia divided by the maximum value of the total inertia. response frequency of the position control, which is calculated from the gain and frequency of the reciprocal of the velocity integration time constant is, the position proportional gain to be a less fixed ratio and speed To set the parameters of the minute time constant.

  In addition to claim 1, the motor drive apparatus according to claim 2 further includes an inertia estimator that outputs an estimated value of the total inertia in real time, and the output value is a maximum value (or a minimum value) of the total inertia. ), The maximum value (or minimum value) is automatically updated.

  Furthermore, in addition to claim 1, the motor drive device according to claim 3 sets a speed response maximum value that defines an upper limit of a response frequency of speed control in the gain setting device, and is proportional to the speed instead of the torque filter. The gain is determined, and the response frequency of the torque filter is determined from the maximum response frequency of the speed control when the total inertia is minimum.

  According to the motor drive device of the first aspect of the present invention, the control parameter associated with the response frequency of the speed control can be always ensured at a certain ratio that satisfies the stability condition. This makes it possible to determine a robust control parameter as long as the actual total inertia is between the maximum value and the minimum value set by the parameter.

  Further, according to the motor drive device of the second aspect, when the output value of the inertia estimator exceeds the maximum value (or the minimum value) of the total inertia, it can be corrected with the actual output value, so that it is more stable. Gain setting is possible.

  Further, according to the motor drive device of the third aspect, the response of the speed control such as the resonance frequency of the device, the response frequency of the current control system, the limit frequency derived from the gain margin and the phase margin including other calculation delays, etc. By using the speed response maximum value for the frequency, the speed proportional gain can be determined first, and the associated control parameters can be automatically determined.

  A position controller that generates a speed command by multiplying the position deviation that is the difference between the position command and the current motor position by the position proportional gain set by the parameter, and a speed deviation that is the difference between the speed command and the current motor speed. On the other hand, the proportional term torque command is calculated by multiplying the speed proportional gain set by the parameter and the estimated value of the total inertia of the motor and load, and after passing the proportional term torque command through the integrator, it is set by the parameter. The integral term torque command divided by the speed integral time constant is calculated, the speed controller that generates the torque command by adding the proportional term torque command and the integral term torque command, and the parameter for the torque command is set A torque filter that cuts off high-frequency components with a time constant generated, a current controller that controls the motor by converting the output of the torque filter into a current command, and a total It further includes a gain setter that stores the maximum and minimum values of inertia, sets the parameters of the speed proportional gain, position proportional gain, and speed integral time constant, and an inertia estimator that outputs the estimated value of total inertia in real time. When the output value exceeds the maximum value (or minimum value) of the total inertia, the maximum value (or minimum value) is automatically updated.

Due to the gain setting device, the response frequency of the torque filter becomes equal to or greater than a certain ratio with respect to the maximum response frequency of speed control obtained by dividing the result obtained by multiplying the speed proportional gain by the total inertia estimated value by the total inertia minimum value. This parameter is calculated from the position proportional gain with respect to the minimum response frequency of speed control, which is obtained by dividing the speed proportional gain parameter by the estimated value of total inertia and dividing the result by the maximum value of total inertia. Position proportional gain and velocity integration time constant parameters are set so that the response frequency of position control and the frequency of the reciprocal of the velocity integration time constant are below a certain ratio. Hereinafter, embodiments will be described.
(Embodiment 1)
FIG. 1 is a principal block diagram of a motor driving apparatus according to the present invention. The first embodiment will be specifically described below with reference to the drawings.

  In FIG. 1, 1 is a position controller, 2 is a speed controller, 3 is a torque filter, 4 is a current controller, 5 is a motor driving device, 6 is a servo motor, 7 is a position detector, and 8 is a gain setting device. is there.

  The position controller 1 receives the position command and the current motor position, and calculates a position deviation that is the difference between them. Thereafter, the result obtained by multiplying the built-in position proportional gain parameter 1a is output to the speed controller 2 as a speed command.

  The speed controller 2 receives the speed command and the current motor speed, calculates the speed deviation that is the difference between them, and then multiplies the speed proportional gain parameter 2a by the estimated value 2b of the total inertia of the motor and the load. Calculate the torque command. Further, after passing the proportional term torque command through an integrator, the integral term torque command is calculated by dividing the proportional term torque command by the speed integral time constant parameter 2c, and by adding the proportional term torque command and the integral term torque command, Output to filter 3.

  The torque filter 3 inputs this torque command, and outputs the result of blocking the high frequency component with a low-pass filter or the like to the current controller 4 as a torque command.

  The current controller 4 converts the torque command into a current command to the motor 6 and actually controls the motor. On the other hand, the position detector 7 connected to the motor 6 outputs the current motor position to the position controller 1, and outputs the current motor speed, which is a derivative thereof, to the speed controller 2.

  Here, the position control system will be described with reference to a control block diagram. FIG. 2A is a control block diagram of the position control system. The position proportional gain is Kp, the speed proportional gain is Kvp, the total inertia estimated value is J ′, the speed integral time constant is Ti, the torque filter time constant is τ, and the total inertia is J.

  If the speed response frequency Gv = Kvp × J ′ / J is set, the control block diagram can be modified as shown in FIG.

  Further, when considering the response of the secondary system individually between the speed response frequency Gv and the remaining three parameters, FIG. 2 (c) to FIG. 2 (e) can be obtained, and each transfer function is expressed by the following equation. It becomes.

FIG. 2C: Kp · Gv / (s ^ 2 + Gv · s + Kp · Gv)
FIG. 2D: (Gv · s + Gv / Ti) / (s ^ 2 + Gv · s + Gv / Ti)
FIG. 2 (e): (Gv / τ) / (s ^ 2 + s / τ + Gv / τ)
The characteristic equation of each denominator is the damping ratio ζ and the natural frequency ω,
s ^ 2 + 2 ・ ζ ・ ω ・ s + ω ^ 2
Therefore, from the condition that the damping ratio ζ at which these secondary systems have non-oscillating responses is 1 or more,
Gv ≧ 4 · Kp
Gv ≧ 4 / Ti
1 / τ ≧ 4 · Gv
Is obtained.

  That is, with respect to the speed response frequency Gv, the position proportional gain Kp and the reciprocal (frequency) 1 / Ti of the speed integration time constant are 1/4 times the reciprocal (frequency) 1 / τ of the torque filter time constant is 4. By setting the value twice, a non-vibrating and smooth response can be obtained.

  However, looking at the calculation formula of the speed response frequency Gv, the inverse of the total inertia J that varies with the load connected to the motor is multiplied, and if this varies, the above-mentioned stable parameter ratio may not be maintained. There is. For this reason, in the first embodiment, the maximum value of the total inertia is stored in the gain setting unit 8 as the parameter 8a, and the minimum value of the total inertia is stored as the parameter 8b.

  The operation of the gain setting device 8 will be described with reference to the flowchart of FIG. In FIG. 3, the maximum value of total inertia is indicated as Jmax, and the minimum value of total inertia is indicated as Jmin. The remaining symbols are the same as in FIG.

  First, in step 1, the speed proportional gain Kvp is obtained by setting the total inertia J = Jmin in the condition that the equation of the torque filter time constant τ and the speed response frequency Gv is established and the calculation formula of the speed response frequency Gv itself. .

  In the next step 2, the speed response minimum value Gvmin is obtained from the calculation formula of the speed response frequency Gv when the total inertia J = Jmax.

  Finally, in step 3, a position proportional gain Kp and a speed integration time constant Ti for obtaining the non-oscillating response with respect to the speed response minimum value Gvmin are obtained.

By setting each parameter with the gain setting unit 8, a non-vibration response can be maintained as long as the actual fluctuation of the total inertia J is between the maximum value and the minimum value. (Embodiment 2)
The second embodiment is different from the first embodiment in that an inertia estimator for estimating the total inertia is added.

  Differences from FIG. 1 will be mainly described with reference to the principal block diagram of FIG. In FIG. 4, the current command to the motor and the current motor speed are input to the inertia estimator 9, and the total inertia is estimated in real time using, for example, the least square method.

The output value of the inertia estimator 9 is input to the gain setting unit 8 and compared with the parameter 8a of the total inertia maximum value and the parameter 8b of the total inertia minimum value before performing the gain setting described in FIG. If it exceeds the value of, the output value of the inertia estimator 9 is updated. As a result of this operation, inertia fluctuations that cannot be recognized only by prior information can be updated using actual output values, so that more stable gain adjustment is possible.
(Embodiment 3)
The third embodiment will be described with reference to the main part block diagram of FIG. The difference from the first embodiment is that a speed response maximum value 10 that defines the upper limit of the response frequency of speed control is added to the gain setting device 8 as a parameter, and the torque filter from the torque filter 3 to the gain setting device 8 is used. This is the point where the time constant input changes to output.

  As an example of the maximum value of the speed response, the ratio of the speed response upper limit is derived from the anti-resonance frequency, the resonance frequency and the peak of the device, or is set to about 1/10 with respect to the response frequency of the current controller 4 Various methods are conceivable, such as setting a limit frequency derived from gain margin and phase margin including.

  The operation of the gain setting device 8 at this time is shown in the flowchart of FIG. Here, the speed response maximum value 10 is Gvmax.

  First, in step 1, Kvp is calculated from the case where the total inertia J = Jmin in the above-described speed response calculation formula. In step 2, the torque filter time constant is set from the relational expression with the maximum speed response value. Steps 3 and 4 can be realized by exactly the same processing as steps 2 and 3 in FIG.

  By this process, not only inertia variation but also speed response restrictions determined by external factors and control factors not shown can be taken in, and more stable gain adjustment can be realized.

  Note that some of the parameters described in Embodiment 1-3 do not necessarily require a high update speed, for example, the maximum and minimum values of total inertia, a gain setting unit, an inertia estimator, and other parameters. It is not necessary to provide all the display means, change means, and the like in the motor drive device. For example, it is needless to say that this can be realized by using a console connected to the servo amplifier through a serial communication bus, or using software operating on a personal computer connected to the servo amplifier by USB communication.

  According to the motor drive device of the present invention, it is possible to easily obtain a gain setting that is robust against inertia fluctuations, and it is also useful for a device in which rapid inertia fluctuations occur.

FIG. 2 is a block diagram of the main part of the motor drive device according to the first embodiment of the present invention. (A) Control block diagram of position control system in Embodiment 1, (b) Control block diagram in which part of (a) is modified, (c) Control block diagram in which part of (b) is omitted, (d) ) (B) control block diagram in which other part is omitted, (e) (b) control block diagram in which another part is omitted Flowchart of operation in gain setting device of embodiment 1 Main part block diagram in motor drive apparatus of Embodiment 2 Main part block diagram in motor drive apparatus of Embodiment 3 Flowchart of operation in gain setting device of embodiment 3

Explanation of symbols

1 Position controller 1a Position proportional gain (parameter)
2 Speed controller 2a Speed proportional gain (parameter)
2b Total inertia estimated value (parameter)
2c Speed integration time constant (parameter)
3 Torque filter 4 Current controller 5 Motor drive device 6 Motor 7 Position detector 8 Gain setting unit 8a Total inertia maximum value (parameter)
8b Total inertia minimum value (parameter)
9 Inertia estimator 10 Speed response maximum value (parameter)

Claims (3)

A position controller that generates a speed command by multiplying a position deviation, which is a difference between the position command and the current motor position, by a position proportional gain set by a parameter;
Calculate the proportional term torque command by multiplying the speed deviation which is the difference between the speed command and the current motor speed by the speed proportional gain set by the parameter and the estimated value of the total inertia of the motor and load. After passing the term torque command through an integrator, the integral term torque command divided by the speed integral time constant set by the parameter is calculated, and the torque command is generated by adding the proportional term torque command and the integral term torque command. A speed controller to
A torque filter that cuts off a high frequency component with a time constant set by a parameter for the torque command;
A current controller for controlling the motor by converting the output of the torque filter into a current command;
A maximum value and a minimum value of total inertia are memorized, and a gain setting device for setting parameters of the speed proportional gain, position proportional gain and speed integral time constant is provided.
Due to the gain setting device, the response frequency of the torque filter becomes equal to or greater than a certain ratio with respect to the maximum response frequency of speed control obtained by dividing the result obtained by multiplying the speed proportional gain by the total inertia estimated value by the total inertia minimum value. This parameter is calculated from the position proportional gain with respect to the minimum response frequency of speed control, which is obtained by dividing the speed proportional gain parameter by the estimated value of total inertia and dividing the result by the maximum value of total inertia. A motor drive device, wherein the position proportional gain and the speed integration time constant parameters are set so that the response frequency of the position control and the reciprocal frequency of the speed integration time constant are less than a certain ratio.   The system further includes an inertia estimator that outputs the estimated value of the total inertia in real time, and automatically updates the maximum value (or minimum value) when the output value exceeds the maximum value (or minimum value) of the total inertia. Item 2. The motor drive device according to Item 1. Set the speed response maximum value that defines the upper limit of the response frequency of speed control in the gain setting unit, determine the speed proportional gain instead of the torque filter, and set the response frequency of the torque filter to the speed control when the total inertia is minimum The motor drive device according to claim 1, wherein the motor drive device is determined from a maximum response frequency of the motor.

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