JP3320454B2 - Motor position control device and motor position control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor position control device.
And a motor position control method .

[0002]

2. Description of the Related Art An example of a block diagram of a motor position control system (I-PD control system) is shown in FIG. In FIG. 2, 1
Is a position target value θ ^* (i), 2 is a position deviation e (i), 3 is a control output signal (current command) IC (i), 4 is a position pulse signal θ (i), and 5 is a speed signal ω (i ), 6 are integral terms, 7
Is a proportional term, 8 is a differential term, 9 is a low-pass filter, and 10 is a filter passing speed ωF (i). Here, i indicates the number of samples in the digital control, and the control output signal (current command) IC (i) is calculated by equation (1).

[0003]

(Equation 1)

[0004] However,

The position pulse signal θ (i) used here
And the speed signal ω (i) are generated from the output pulse of the encoder, and the output pulse of this encoder is composed of two pulses AP and B having a phase difference of 90 ° as shown in FIG.
Consists of P. The rotation direction of the motor is as shown in FIG.
It is determined from the phase relationship between these two pulses. A quadruple pulse signal P is generated using the rising and falling edges of these two pulses, and the position pulse signal θ (i) counts up the pulse signal P when rotating forward and counts down when rotating backward. Is obtained by In the following description, the direction (count-up / down) of the quadrupled pulse signal P will be distinguished by the expression shown in FIG.

As one of the methods of detecting the speed from the quadrupled pulse signal P, a method of obtaining the difference of the position pulse signal θ (i) for each sampling time as shown by the equation (2), in other words, The number of quadrupled pulses per unit time ω
There is a method of using P (i) as a detection signal (hereinafter, abbreviated as a pulse difference method ).

ΩP (i) = θ (i) −θ (i−1) (2) where ωP (i): detection speed by pulse difference method θ (i): position pulse signal and pulse difference method Alternatively, as shown in FIG. 4, there is a method of measuring the time interval of the quadrupled pulse signal P and detecting the speed using the reciprocal of this value (hereinafter, abbreviated as the time interval method). In FIG. 4, PT (i) is a pulse time interval. Here, the detected speed ωT (i) is calculated by equation (3).

ΩT (i) = KT / PT (i) (3) where ωT (i): detection speed by time interval method PT (i): pulse time interval KT: speed conversion constant

[0009]

In the pulse difference method, since the position pulse signal is differentiated, the quantization noise of the speed signal is large in a low speed region as compared with the time interval method, and when this signal is used for position control, the stop accuracy is deteriorated. Or the gain cannot be increased. Therefore, the time interval method with high speed accuracy is used in the low speed range. FIG. 5 is a graph showing speed and detection accuracy. In the time interval method, it is assumed that the measurement of the pulse time interval is counted by a single clock. In FIG. 5, ω0 is a speed at which the speed accuracy of the time interval method matches the speed accuracy of the pulse difference method, and the time interval method and the pulse difference method are switched at this speed.

In the case where the time interval method is used in the low-speed region as described above, when a high-level noise is added to the pulse signal of the encoder from, for example, a motor driver (inverter), as shown in FIG. When the speed is measured at t0, the pulse time interval is correctly detected as PT0, but when the speed is measured at time t1, the interval generated by noise is measured, and the pulse time interval is erroneously detected as PT1 instead of PT0. I do. Also, when measured at time t2, TP0 is erroneously detected as PT2.

Of course, this problem also occurs when the pulse difference method is used in the high-speed region. However, when the measurement is performed at time t2, the counter also goes up and down due to the up and down of the noise signal. Does not occur. Even if measured at time t1, the error is within the range of ± 1 pulse,
In the high-speed range, the error is negligibly small.

[0012] The present invention is intended to solve the above problems, the position control device and a motor having a speed detecting function capable of preventing the speed erroneous detection due to noise which is added to the pulse signal of the encoder at time interval method Said speed misdetection
It is an object of the present invention to provide a motor position control method capable of preventing the motor from coming out .

[0013]

In order to achieve this object, a motor position control device according to the present invention is a motor position control device using an output pulse of an encoder as a position detection signal, wherein The motor speed is detected by the reciprocal of the time interval, and the detected speed value is
Speed due to noise added to the output pulse signal
Whether the detection is erroneous is determined by reversing the time interval of the output pulse.
Simultaneous detection using output pulses in speed detection by number
Number of output pulses per unit time of the encoder
The determination is made based on the speed detection value of In order to achieve this object, the position control method of the motor of the present invention is a position control method of the motor using the output pulses of the encoder as a position detection signal, the motor of the reciprocal of the time interval of the output pulse Detecting the speed and the reciprocal of the time interval of the output pulse
The speed detection value by the output pulse signal of the encoder
Whether the speed is incorrectly detected due to the added noise
For speed detection by the reciprocal of the time interval of the output pulse.
Said encoders detected simultaneously using output pulses in
Speed detected by the number of output pulses per unit time
And a step of making a determination based on this .

[0014]

According to this configuration, the output pulse of the encoder is
When detecting the motor speed detection value by the reciprocal of the time interval
In this case, the encoder
Based on the motor speed detection value based on the number of output pulses,
Due to noise added to the coder output pulse signal
It is now possible to judge erroneous speed detection.
An adverse effect on the control performance of the motor can be prevented.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart for preventing erroneous speed detection in a motor position control device according to one embodiment of the present invention. In the following embodiment, as a speed conversion constant KT used in equation (3), ωT (i) × 2 ^{− m} = ωP (i) (4) where m is a positive integer and a pulse time interval PT () when the motor rotation speed is exactly 1 [pulse / sample] so as to satisfy the relationship expressed by the expression (4). The value calculated from the following equation (5) using i) is used.

KT = PT (i) × 2 ^{m In} FIG. 1, in step 1, the detected speed ωP (i) is calculated by the pulse difference method shown in equation (2). In Step 2, ωP (i) calculated in Step 1 is compared with the speed ω0 at which the speed accuracy of the time interval method and the speed accuracy of the pulse difference method match, and ωP
If (i) is equal to or greater than ω0, as shown in step 2-1, this ωP (i) is changed to ωT
The result of the calculation for the accuracy of (i) is adopted as the speed signal ω (i), and the filter processing is performed in step 6. If ωP (i) is smaller than ω0 in step 2, the process proceeds to step 3 to calculate the detected speed ωT (i) by the time interval method represented by the equation (3).

Next, in step 4, it is determined whether ωT (i) is erroneously detected due to noise. Assuming now that the true speed is ωS (i), the detection value ωP (i) by the pulse difference method is due to the finite resolution of the encoder with respect to this true value ωS (i). It has a quantization error within ± 1 [pulse / sample]. That is, when this relationship is expressed by an equation, the equation (6) is obtained.

ΩP (i) −1 <ωS (i) <ωP (i) +1 (6) The speed ωT (i) obtained by the time interval method naturally corresponds to a speed within ± 1 pulse of ωP (i). Must be in range. Therefore, the relational expression expressed by the expression (7) is established from the expressions (4) and (6).

(ΩP (i) −1) × 2 ^m <ωT (i) <(ωP (i) +1) × 2 ^m (7) Therefore, the speed ωT (i) by the time interval method is (7)
If the relational expression is not satisfied, it can be determined that speed detection is erroneous due to high frequency noise or the like. If it is determined that the detection is erroneous, the speed value ω (i-1) at the previous sampling time is adopted as the speed ω (i) at the current sample in step 4-1 and the value is filtered in step 6. If no erroneous detection is determined in step 4, as shown in step 5, ωT (i) obtained in step 3 is used as it is as ω (i), and filtering is similarly performed in step 6.

As described above, according to the present embodiment, erroneous speed detection due to noise added to the encoder output pulse signal in the time interval method is determined. By determining the speed detection value in the current sample based on the information of the detection value, it is possible to prevent deterioration in control performance due to erroneous speed detection in a low speed range.

In this embodiment, the simplest example of using the previous sample value ω (i-1) as it is in step 4-1 when it is determined that the speed is erroneously detected has been described. ), A filter passing speed ωF (i) of the previous sample, a speed ωP (i) of the current sample by the pulse difference method, or the like can be used.

In step 4, the speed ωP (i) based on the pulse difference method, which is used as a criterion for erroneous detection, has an extremely low probability, but may have an error of ± 1 pulse as described above. Therefore, it is needless to say that the judgment criterion in step 4 is also set to a range corresponding to within ± 2 pulses of ωP (i), thereby making it possible to reduce the erroneous judgment of erroneous speed detection.

[0023]

As described above, according to the present invention, in the digital position control of the motor using the output pulse of the encoder as the position detection signal, the reciprocal of the time interval of the encoder output pulse in the low-speed range is determined. When using the number of encoder output pulses per unit time as the motor speed, based on the speed detection value based on the number of encoder output pulses per unit time, based on the speed detection value based on the reciprocal of the output pulse time interval, Judgment of speed erroneous detection caused by noise added to the output pulse signal, and in the case of erroneous detection, by determining the speed value in the current sample based on the information of the speed detection value up to the current sample, An excellent motor position control device capable of preventing deterioration of control performance due to erroneous speed detection in a low speed range can be realized. Than it is.

[Brief description of the drawings]

FIG. 1 is a flowchart for preventing erroneous speed detection in a motor position control device according to one embodiment of the present invention.

FIG. 2 is a block diagram of a motor position control system.

FIG. 3 is an output pulse waveform diagram of an encoder in the motor position control device.

FIG. 4 is an explanatory diagram of a time interval method in the motor position control device.

FIG. 5 is a diagram showing the relationship between speed and resolution in a motor position control device.

FIG. 6 is an explanatory diagram of speed error detection caused by noise added to an encoder pulse waveform.

[Explanation of symbols]

 θ (i) Position pulse signal ω (i) Speed signal ωP (i) Detection speed by pulse difference method ωT (i) Detection speed by time interval method ω0 Switching speed of pulse difference method / time interval method PT (i) Pulse time interval KT speed conversion constant

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-132967 (JP, A) JP-A-63-190583 (JP, A) JP-A-49-34371 (JP, A) 4009 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05D 3/00-3/20 H02P 5/00

Claims (6)

(57) [Claims] 1. A motor position control device using an output pulse of an encoder as a position detection signal, wherein the output pulse
The speed of the motor detected by the reciprocal of the time interval of the pulse, added to the speed detection value output pulse signal of the encoder
Whether or not the speed was incorrectly detected due to the detected noise.
In speed detection by the reciprocal of the time interval of the output pulse
Unit of the encoder detected simultaneously using output pulses
Based on speed detection value based on the number of output pulses per unit time
A motor position control device characterized in that the determination is made by the following. 2. The method according to claim 1, wherein an output pulse of the encoder is used as a position detection signal.
A position control device for a motor used as
The motor speed is detected by the reciprocal of the
For speed detection value by the reciprocal of the time interval of the serial output pulses determines whether the speed detection error due to the added noise in the output pulse signal of the encoder, the output
Judgment is made based on whether or not the speed detection value based on the reciprocal of the pulse time interval is within an error range due to the resolution of the encoder in the speed detection value based on the number of output pulses per unit time of the encoder. Motor position control device. Wherein when it is determined that the speed detection value by the reciprocal of the time interval of the output pulse is a speed detection error due to the added noise in the output pulse signal of the encoder, to the current sample of the output pulse 3. The motor position control device according to claim 1, wherein the speed detection value in the current sample is determined based on the information on the speed detection value. 4. A method according to claim 1, wherein when a speed detection value based on a reciprocal of a time interval of the output pulse is determined to be a speed error detection caused by noise added to an output pulse signal of the encoder, the speed detection value in a current sample of the output pulse is determined. 4. The motor position control device according to claim 3, wherein a speed detection value based on the number of output pulses per unit time of the encoder is set as a speed detection value in the current sample. 5. The motor speed is detected by a reciprocal of a time interval of the output pulse in a low speed region of the motor, and the motor speed is detected by a number of output pulses per unit time of the encoder in a high speed region of the motor. The motor position control device according to any one of claims 1 to 4, wherein the position is switched. 6. A method of controlling the position of a motor using an output pulse of an encoder as a position detection signal, the method comprising: detecting a motor speed by a reciprocal of a time interval of the output pulse; Speed detection value before
The noise added to the encoder output pulse signal.
The speed of the output pulse.
Using output pulse in speed detection by reciprocal of interval
Output per unit time of the encoder
Determining based on a speed detection value based on the number of force pulses .