JP4058524B2 - Servo system residual vibration suppression system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a servo system residual vibration suppression system.
[0002]
[Prior art]
Conventionally, the output of a rotary encoder, which is a means for detecting the rotation state of a servo (control) motor, and the output from the winding of the motor are passed through an observer (state observer), a torque loop (acceleration loop), that is, a speed. There has been a method of suppressing residual vibration of the load of the control system by feeding back to the subsequent stage of the controller and the previous stage of the torque (acceleration or current) controller.
In this conventional method, the load or motor state (speed or speed) is calculated from the motor operation amount (output of the torque controller) and the output of the rotary encoder, which is a detectable motor state amount, and the winding output of the motor. Residual vibration is suppressed by using an observer that estimates (acceleration) and feeding back the output of the observer to a predetermined loop of the servo system.
However, this conventional residual vibration suppression method has a drawback in that residual vibration is likely to occur when the loop gain is increased when the rigidity of the load (machine) to be controlled is low. In general, the higher the loop gain is, the closer the phase difference between the control input and the rotary encoder output is to -180 degrees, so that the so-called phase margin is reduced, and the servo system becomes oscillating. That is, it becomes sensitive to high gain. In the conventional residual vibration suppression method, depending on the rigidity of the machine, when the motor is driven with a loop gain as desired in the operation of the machine, the residual vibration becomes so large that it cannot be ignored. .
[0003]
[Problems to be solved by the invention]
The present invention aims to solve the following problems.
Conventionally, when a motor is driven with a predetermined loop gain, even if the servo system has a load that generates residual vibration that cannot be ignored, residual vibration is reduced while using the conventional observer described above for the servo system. It is an object of the present invention to provide a servo system residual vibration suppression method that can be performed.
[0004]
[Means for Solving the Problems]
The servo system residual vibration suppression system according to the present invention solves the above-mentioned problems, and the invention of claim 1 is as follows. A speed controller in the subsequent stage of the position controller, a torque controller in the subsequent stage of the speed controller, a motor in the subsequent stage of the torque controller, a load in the subsequent stage of the motor, and a motor angle detection means, In the servo system in which the output of the angle detection means is fed back to the position controller and the speed controller via a differentiator, the difference between the output from the motor winding and the output of the angle detection means based on, provided with a first observer to estimate the torque of the motor or the load, the basis of the control input to the servo system (value) to the control deviation is obtained by subtracting the output value of said angle detection means, the motor or provided a second observer to estimate the torque of the load, by multiplying the output of the output of the first observer the second observer, the It is configured to negatively feed back the only calculated value to the torque controller.
[0005]
According to a first aspect of the present invention, in the servo system residual vibration suppression system, the second observer includes an absolute value calculator, a dead band calculator, a multiplier, a saturator, and a low-pass filter.
[0006]
FIG. 1 is a block diagram showing an embodiment of a servo system residual vibration suppression system according to the present invention. The main constituent elements (main constituent elements) of the servo system of the present invention are the position controller 1 and speed controller 2 as so-called transmission elements in the subsequent stage of the control input (or target value or set value input), as in the past. The torque controller 3 and the motor 4 are located. A load 6 is connected to the subsequent stage of the motor 4, and angle detection means (for example, an optical rotary encoder, encoder 5 ) for detecting the rotation state (for example, the rotation speed) of the motor 4 is provided. Yes. The output of the angle detection means is negatively fed back to the position controller 1 and, if necessary, to the speed controller 2 via a differentiator (not shown), thereby forming a position loop 10 and a speed loop 11, respectively. ing. This is also the same as in the prior art. In the figure, control elements represented by circles are so-called addition points, which are parts to be added / subtracted.
[0007]
The present invention is different from the conventional one in that the output of the first observer 7 (the internal configuration is the same as the prior art) and the output of the second observer 9 (integrated output) is negatively fed back to the torque controller 3. It is to let you.
The second observer 9 in this specification is a vibration controller, which is a transmission element that performs the function of adjusting the gain of the first observer.
In order to implement the present invention, it is necessary to return to the torque controller 3, the motor 4, the encoder 5, the first observer 7, the multiplier 8, and the torque controller 3 to form a torque loop 12. On the other hand, the winding output 18 of the motor 4 needs to be output to the first observer 7 as in the prior art, and the winding output is preferably fed back to the torque controller 3.
The first observer 7 takes in the winding output 18 of the motor 4 and the output of the encoder 5 (the angular velocity of the motor 4) as in the prior art, and sets the state of the motor 4 or the load 6 (eg, torque, rotational speed, etc.). Estimate and output to the subsequent stage.
Of course, in order to eliminate or reduce the residual vibration, the output of the first observer 7 must be 0 or almost 0 when the motor is stopped. However, in reality, in the servo system in which residual vibration occurs, the output of the first observer 7 does not become zero even when the motor 4 is stopped.
[0008]
As a countermeasure against this problem, for example, it is conceivable to appropriately adjust the inside of the first observer 7 by resetting the internal parameters of the first observer 7. However, with this measure, there is a possibility that an adverse effect may occur when the motor 4 is moving, that is, during acceleration control, deceleration control, and constant speed control. In the state where the motor 4 is moving, it is not appropriate to change the internal parameters of the first observer 7 even though ideal control is performed by the first observer 7 (in any case). it is conceivable that.
[0009]
Therefore, in the present invention, the first observer 7 is not particularly messed up, and the torque loop 12 is formed by multiplying the output of the second observer 9 with the output of the second observer 9 and negatively feeding back the integrated output. Was taken.
The second observer 9 outputs a numerical value of gain 1 or a value close to gain 1 when the motor 4 is moving, and converges to gain 0 or 0 when the motor 4 is stopped. The gain value is output.
[0010]
For example, the second observer 9 includes an absolute value calculator 13, a dead band calculator 14, an amplifier 15, a saturator 16, and a low-pass filter 17 (primary) after the control deviation (subtracting the encoder output from the control input). By using the one provided with the delay element), the gain of the output value of the first observer 7 can be adjusted according to the driving state of the motor 4.
[0011]
The absolute value calculator 13 is provided to prevent a negative gain from being output from the second observer 9. The dead zone calculator 14 is a transfer element that functions as a proportional controller when the input value (control deviation) is equal to or greater than a predetermined value, and outputs zero gain when the input value is equal to or less than the predetermined value. .
The amplifier 15 is for adjusting the gain of the second observer 9, and simply functions as an amplifier. The saturator 16 is provided so that an output of gain 1 or higher is not output to the subsequent stage. This is because when the motor 4 is being driven, a gain higher than the gain necessary for the original control purpose is not output from the torque controller 3 to the motor 4.
The low-pass filter 17 is a first-order lag element itself, and is provided as a transmission element for the effect of providing the second observer 9 gradually after the motor 4 stops. That is, the output of the multiplier 8 does not suddenly become zero, but decreases toward a gain of 0 at a certain rate after the motor stops.
FIG. 2 is a block diagram showing one embodiment of a servo system residual vibration suppression system according to the present invention.
The servo system according to the present invention causes the control deviation to be taken into the second observer 9 and causes the torque controller 3 to negatively feed back the product of the output of the first observer 7 and the output of the second observer 9. The actual configuration of the position controller 1, the speed controller 2 and the torque controller 3 is a design choice for those skilled in the art.
For example, the position controller 1 and the speed controller 2 are caused to bypass the proportional control element Ka and the proportional control element Kb, respectively, and the output is added or subtracted to the output behind the position controller 1 and the speed controller 2. You may let them. Such a thing is usually performed in the servo system so that the response is quick and the response is not sensitive.
In other words, the present invention can be applied to servo system transmission elements conventionally used, such as the position controller 1, the speed controller 2, the torque controller 3, and the first observer 7, regardless of their configuration. That's what it means.
[0013]
【The invention's effect】
The servo system residual vibration suppression method according to the present invention is configured as described above, and therefore has the following effects.
When the motor 4 is driven with a predetermined loop gain, the conventional first observer 7 can be used as it is even in a servo system having a load 6 that generates residual vibrations that cannot be ignored. The sensitivity to the slight gain due to the small phase margin that is one of the causes of residual vibration has the effect of gradually reducing the remaining gain to zero when the motor 4 is stopped. Since the observer 9 is provided and a product obtained by multiplying the output of the first observer 7 and the output of the second observer 9 is negatively fed back to the torque controller 3 directly related to the torque control of the motor 4, the motor 4 It is possible to provide a servo system residual vibration suppression method that can reduce residual vibration caused by an extra gain when the motor 4 is stopped without adversely affecting driving.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a servo system residual vibration suppression system according to the present invention. FIG. 2 is a block diagram showing an embodiment of a servo system residual vibration suppression system according to the present invention. Explanation】
DESCRIPTION OF SYMBOLS 1 Position controller 2 Speed controller 3 Torque controller 4 Motor 5 Encoder 6 Load 7 1st observer 8 Multiplier 9 2nd observer 10 Position loop 11 Speed loop 12 Torque loop 13 Absolute value calculator 14 Dead zone calculator 15 Amplifier 16 Saturator 17 Low-pass filter 18 Winding output Ka, Kb Proportional control element

Claims (1)

The speed controller in the latter part of the position controller,
Torque controller after the speed controller,
A motor behind the torque controller;
A load is provided at the subsequent stage of the motor,
Comprising an angle detection means of the motor;
In the servo system in which the output of the angle detection means is fed back to the position controller and the speed controller via a differentiator, respectively .
Based on the difference between the output from the winding of the motor and the output of the angle detection means, a first observer for estimating the torque of the motor or the load is provided, and from a control input which is an input command to the servo system Based on a control deviation obtained by subtracting the output value of the angle detection means, a second observer is provided for estimating the torque of the motor or the load,
Multiplying the output of the first observer and the output of the second observer, and configured to negatively feed back the multiplied value to the torque controller ,
The second observer includes an absolute value calculator, a dead band calculator, an amplifier, a saturator, and a low-pass filter.
The absolute value calculator that inputs an input command to the position controller is to prevent a negative gain from being output from the second observer,
The dead band computing unit following the absolute computing unit functions as a proportional controller when the input value is equal to or greater than a predetermined value, and functions to output a gain of 0 when the input value is equal to or smaller than the predetermined value. Element
The amplifier subsequent to the dead zone calculator is an amplifier for gain adjustment of a second observer,
The saturator at the latter stage of the amplifier is provided so that an output with a gain of 1 or more is not output to the latter stage motor.
The low-pass filter in the latter stage of the saturator is a servo system residual vibration suppression system , which is a first-order lag element .

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