JP2002345279A - Motor position controller provided with deviation ripple monitoring function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome a drawback in prior arts that there are cases where location deviation signals cannot be observed. SOLUTION: A position controller for controlling the position of a motor is provided with a subtracting means 13 which subtracts a detected position signal from a position command and outputs the deviation 1d; an integrating means 22 which outputs a model position signal; a subtracting means 23 which subtracts the model position signal from the position command and outputs the deviation 2d; a proportional gain means 20 which is fed with the deviation 2d as input; a speed control system model 21 which is fed with the output of the proportional gain means 20 as the input; and a subtracting means 33 which determines the difference between the deviation 1a and the deviation 2d. The output of the speed control system model 21 is inputted to the integrating means 22, and the proportional gain of the proportional gain means 20 is equalized to the position loop gain 10 of the position controller. The output of the subtracting means 33 is used as a monitor signal for the deviation ripple of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor position control device having a deviation ripple monitor function for calculating and outputting a ripple signal and a ripple amount of a position deviation in a position control system.

[0002]

2. Description of the Related Art One of the performance evaluation indexes of a position control system of a motor is smoothness of rotation or movement (linear motor). In applications where the XY table is driven by two axes of the position control system of the motor to control the trajectory on the XY plane, smoothness of the shape is required, and if there is a ripple in the position deviation,
It becomes a shape error as it is. For applications that rotate or move at a constant speed, the speed ripple must be small,
Evaluate the ripple component of the detection speed. In this case, a ripple also appears in the position deviation, and the speed command is obtained by multiplying the position deviation by the position loop gain (see FIG. 1 described later). Therefore, the ripple of the motor is evaluated by the ripple of the position deviation. be able to. Normally, the position deviation signal can be observed from the monitor of the position control device. However, when the ripple is small, the quantization error of the position deviation signal is less than or equal to that, and there is a problem that the position deviation signal cannot be observed. For example, when driving a one-axis slider mechanism composed of a ball screw with an electric motor, if the accuracy of the position detector of the electric motor is 16 bits / 1 rotation and the ball screw lead is 10 mm, the position resolution is 10 mm / 16.
Bit = 0.15 μm. Assuming a feed speed of 10 m / min, the command pulse speed is 10,000 / 0.00015 /
60 = 1111 Kpps. Position loop gain of 4
If 0 [1 / s], the position deviation is 1111000 /
Since 40 = 2775 pulses, a 16-bit or more DA converter (digital-to-analog converter) is required in order to accurately observe one bit of the deviation in consideration of the sign. In the position control device, there is a strong demand to configure a monitor with a DA converter of about 8 bits for cost reduction. It can be seen that in a DA converter of about 8 bits, a minute ripple of 2775/128 = 21 pulses (3 μm) or less becomes a quantization error or less and cannot be observed. Even in such a case, in order to observe a minute ripple, if only the deviation ripple is extracted from the position deviation signal using a high-pass filter and the gain is enlarged by applying a gain, it can be observed even with an 8-bit DA converter. Conceivable. However, where the speed is changing, such as at the time of acceleration / deceleration, there is a problem that the ripple is outside the display range and cannot be observed because the deviation from the high-pass filter remains as it is. For example, at 1000 revolutions / minute, one cycle of the motor has one cycle of a ripple of 1000/6.
Since 0 = 16 Hz, to observe this accurately,
The cutoff frequency of the high-pass filter needs to be about 1 Hz. If the acceleration time is about 0.2 seconds, the change is 5H
Since it is about z, the signal passes through a high-pass filter of 1 Hz, and it is impossible to detect only the ripple.

[0003]

As described above, the prior art has the following problems. (1) When the ripple of the position deviation signal is small, it becomes smaller than the quantization deviation of the position deviation signal, and the position deviation signal cannot be observed. (2) Where the speed is changing, such as during acceleration / deceleration, the position deviation signal is left as it is from the high-pass filter, so that the ripple is outside the display range and cannot be observed. SUMMARY OF THE INVENTION An object of the present invention is to provide a motor position control device for detecting a minute deviation ripple in order to solve the above-mentioned problems.

[0004]

According to the present invention, there is provided an electric motor position control apparatus having a deviation ripple monitor function, comprising: a subtraction means for subtracting a detected position signal from a position command to output a deviation 1d; Integrating means for outputting a position signal, subtracting means 23 for subtracting the model position signal from the position command to output a deviation 2d, proportional gain means for inputting the deviation 2d, and inputting the output of the proportional gain means A speed control system model; and a subtraction unit 33 for calculating a difference between the deviation 1d and the deviation 2d. An output of the speed control system model is input to the integration unit, and a proportional gain of the proportional gain unit is set to the position control device. And the output of the subtraction means 33 is used as a monitor signal of the deviation ripple of the electric motor. The motor position control device having the deviation ripple monitor function according to the second aspect of the present invention further includes a ripple amount calculation unit that inputs a deviation ripple signal of the subtraction unit 33 and outputs a deviation ripple amount, The output of the means is a ripple amount monitor signal.

[0005]

FIG. 1 shows a first embodiment of the present invention. The speed control means 11 includes a power converter (not shown) for driving the electric motor 1. The position signal of the electric motor 1 detected by the position detecting means 2 is input to the speed calculating means 12.
The motor speed signal output from the speed calculation means 12 is fed back to the speed control means 11. A deviation 1d between the position command and the position signal is multiplied by a position loop gain 10 and input to the speed control means 11 as a speed command. The position command and the deviation 2d of the integration means 22 are multiplied by the position loop gain 20 of the model, and the result is input to the speed control system model 21, and the output of the model 21 is input to the integration means 22. In the subtraction means 33,
The difference between the deviation 1d and the deviation 2d is calculated and used as a deviation ripple monitor signal. The speed control system model 21 may be configured according to the configuration of the control system of the speed control unit 11. For example, assuming that the response of the speed loop is sufficiently faster than that of the position loop, the control block 41 having a gain of 1 shown in FIG.
Approximation. When the acceleration / deceleration is large, FIG.
In the approximation, the error of the model becomes large. Therefore, depending on the control system configuration of the speed control means 11, the proportional control system of FIG. 2B, the proportional integral control system of FIG. 2C, or the integral proportional control of FIG. What is necessary is just to approximate. In FIG. 2, Kv is the gain of the velocity loop model, Ti is the integration constant, and 1 / s is the integration means. In FIG. 1, when the position loop gain 20 of the model is set to be the same as the position loop gain 10 and the various gains (Kv, Ti) of the speed control system are set equal to the corresponding gains of the speed control means 11 according to the model, the position The waveform of the deviation 1d of the control system and the deviation 2d of the position control system of the model are
Since it becomes equal except for the ripple of the deviation 1d, the deviation 1d
And the difference 2d becomes the difference ripple monitor signal. If a quantitative index of the deviation ripple monitor signal is required, the output of the subtraction means 33 is input to the ripple amount calculation means 30 to calculate the deviation ripple monitor signal. When an average value is required as the deviation ripple amount, the ripple amount calculation means 30 is configured as shown in FIG. FIG.
In (a), the average value of the deviation ripple monitor signal is calculated by the whole value calculating means 51, and the average value is calculated by the mean value calculating means 52 using, for example, moving average processing or a low-pass filter. When the rms value (effective value) of the ripple is required, as shown in FIG. 3B, the square of the ripple signal is calculated by the square calculating means 54 and averaged by a moving average or a low-pass filter. The route (square root) of the processed value may be taken by the average value calculating means 53.

[0006]

As described above, according to the present invention,
Since the signal of the deviation 2d without the ripple is subtracted from the signal of the deviation 1d with the ripple, only a minute ripple can be detected even if the positional deviation is large, and the position loop gain of the model and the model of the speed control system are constructed. Because
The signals of the deviation 1d and the deviation 2d are similar, and there is an effect that a minute deviation ripple signal can be detected even during acceleration / deceleration.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is an embodiment of a speed control system model.

FIG. 3 shows an embodiment of a ripple amount calculating means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Position detection means 10 Position loop gain 11 Speed control means 12 Speed calculation means 13 Subtraction means 20 Model position loop gain (proportional gain means) 21 Speed control system model 22 Integration means 23 Subtraction means 30 Ripple amount calculation means 33 Subtracting means 41 proportional element of gain 1 42, 43, 44 proportional calculating means of gain Kv 45, 46, 47 integrating means 48 integrating means of gain Kv / Ti 49 integrating means of time constant Ti 51 absolute value calculating means 52, 53 Mean calculation means 54 Square calculation means 1d, 2d Deviation

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Claims (2)

[Claims] 1. A position control device for controlling a position of an electric motor, wherein a subtraction means 13 for subtracting a detected position signal from a position command and outputting a deviation 1d; an integrating means for outputting a model position signal; Subtraction means 23 for subtracting the model position signal and outputting a deviation 2d; proportional gain means for inputting the deviation 2d; a speed control system model for inputting the output of the proportional gain means;
a subtraction means 33 for taking the difference of d, inputting the output of the speed control system model to the integration means, making the proportional gain of the proportional gain means equal to the position loop gain of the position control device, 33. A motor position control device having a deviation ripple monitoring function, wherein an output of the motor 33 is used as a monitor signal of a deviation ripple of the electric motor. 2. The apparatus according to claim 1, further comprising a ripple calculating means for inputting a deviation ripple signal of the subtracting means and outputting a deviation ripple, wherein an output of the ripple calculating means is a ripple monitoring signal. 2. A motor position control device having the deviation ripple monitor function according to 1.