JPH03198684A - Motor controller - Google Patents

Abstract

PURPOSE:To obtain an accurate speed even if a speed detection signal is temporarily largely varied due to noise or the like by deciding whether the data calculated previously is erroneous or not, and outputting data corresponding in response to the fact that the data falls within or out of a predetermined range as motor control speed data. CONSTITUTION:When data regarding the rotating speed of a motor 10 calculated previously is not erroneous, data stored in a first storage means of a controller 14 is sequentially fed to discard oldest data, and the data calculated this time is stored in a latest data storage area. If the data calculated previously is erroneous, the data calculated this time is stored in the latest data storage area, and the data of the previous time is stored in a second storage means of the controller 14. When the data of this time falls within a predetermined range of the data of the previous time, the data of this time is output as motor 10 control speed data. If the data of this time falls out of a predetermined range of the data of the previous time, the data corresponding to a center of large and small values stored in the first storage means is output as motor 10 control speed data.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a motor control device.

<Background of the Invention> For example, in a DC servo motor control device for driving an optical system in a document reading device such as a copying machine, even if the motor load fluctuates due to changes in frictional resistance etc. as the optical system moves, it is difficult to follow the It is necessary to maintain the servo motor at a constant speed and move the optical system at a constant speed.

In order to keep the servo motor at a constant speed, it is necessary to accurately detect the actual rotational speed of the servo motor.

In conventional devices, the rotational speed of the servo motor is detected at predetermined timings based on the output (speed detection signal) of a speed detector such as an encoder connected to the servo motor.

However, the method of speed detection in conventional devices is
If the detected rotational speed is affected by noise or the like, there is a drawback that the motor rotational speed cannot be detected accurately.

Therefore, in order to eliminate errors caused by noise etc.
Some methods have been adopted, such as finding the average of the previously detected speed and the currently detected speed, and taking that as the current speed.

<Problem to be solved by the invention> However, in the method of calculating the average detection speed,
Since we are trying to reduce the error by averaging the detected speeds, even if an accurate rotational speed is detected, the speed will be averaged and will remain constant relative to the original speed (actual speed). This will result in a deviation of

Furthermore, if temporally large noise occurs, the noise error cannot be removed even if it is averaged, and a relatively large error remains in the speed after averaging.

For this reason, for example, if such thick noise occurs in a steady state, speed unevenness will occur.

This invention was made in view of the above circumstances, and
It is an object of the present invention to provide a motor control device that can obtain an accurate speed without being affected by the fluctuation even if a speed detection signal fluctuates greatly over time due to noise or the like.

Means for Solving the Problems> The present invention is a motor control device that performs feedback control of a motor so that the motor rotation speed becomes equal to a command speed, and which calculates data regarding the motor rotation speed at every predetermined timing. a first storage means having a plurality of storage areas capable of storing data related to the motor rotation speed for a predetermined plurality of times in chronological order; and a second storage means capable of storing data related to the motor rotation speed for at least one time.
storage means, means for checking whether or not the previously calculated data was determined to be incorrect data each time data related to the motor rotation speed is calculated; and when the previously calculated data was not determined to be incorrect data; , a first storage control means for sequentially shifting the data already stored in the first storage means one by one and discarding the oldest data, and storing the data calculated this time in the latest data storage area; When the data is determined to be incorrect,
Second storage control for moving the previously calculated data stored in the latest data storage area of the first storage means to the second storage means and storing the currently calculated data in the latest data storage area of the first storage means means, the data calculated this time stored in the latest data storage area corresponds to the data corresponding to the center of magnitude among the data stored in the first storage means, or the data corresponding to the center of magnitude. The first determining means determines whether or not the data is within a predetermined range. When it is determined that the data is within a predetermined range, the currently calculated data is taken out as speed data to be used for motor control, and the first determining means determines that the currently calculated data is data corresponding to the center of magnitude. When it is determined that the data is outside the predetermined range, the currently calculated data is further compared with the previously calculated data stored in the second storage means, and the currently calculated data is compared to the previously calculated data. When the second determining means determines whether the data is within a predetermined range, the data calculated this time is taken out as speed data to be used for motor control. ,
Among the data stored in the first storage means, data other than the currently calculated data stored in the latest data storage area is shifted one by one and the oldest data is discarded;
The third storage control means stores the previously calculated data stored in the second storage means in the storage area next to the latest data storage area of the first storage means, and the second determination means determines whether the data is outside the predetermined range. When it is determined that the data calculated this time is incorrect data, the first
This motor device is characterized in that it includes means for extracting data corresponding to the center of magnitude among data for a plurality of times stored in a storage means as speed data to be used for motor control.

Function> Data regarding the motor rotation speed is calculated at each predetermined timing.

Furthermore, each time data related to the motor rotation speed is calculated, it is checked whether the previously calculated data was determined to be incorrect data.

Then, when the previously calculated data is not determined to be incorrect data, the data for a predetermined plurality of times already stored in the first storage means are sequentially shifted one by one, the oldest data is discarded, and the data is replaced. The data calculated this time is stored in the latest data storage area.

When the previously calculated data was determined to be incorrect data, the data already stored in the first storage means is not shifted, and the currently calculated data replaces the previous data as the latest data. The data is stored in the storage area, and the previous data is stored in the second storage means.

Next, check whether the current data corresponds to the data corresponding to the center of the size among the multiple data stored in the storage means (these data include the current data), or It is determined whether the data corresponding to the center is within a predetermined range.

Then, when it is determined that the current data corresponds to the data corresponding to the center of magnitude or is within a predetermined range with respect to the data corresponding to the center of magnitude, the current data is the current data to be used for motor control. Extracted as speed data.

On the other hand, when it is determined that the current data is outside the predetermined range with respect to the data corresponding to the center of magnitude, further
The current data is compared with the previous data stored in the second storage means, and it is determined whether the current data is within a predetermined range of the previous data.

0 When it is determined that the current data is within a predetermined range of the previous data, the current data is extracted as the current speed data to be used for motor control, and the first
Among the data stored in the storage means, data other than the current data are shifted one by one, the oldest data is discarded, and the previous data is stored in the storage area next to the current data instead. Ru.

Further, when it is determined that the current data is not within the predetermined range of the previous data, the current data is determined to be incorrect data, and the data corresponding to the middle of the size among the data stored in the first storage means is determined. Data is retrieved as current speed data to be used for motor control.

<Embodiment> An embodiment of the present invention will be described below, taking as an example a case where the present invention is applied to a control circuit of a DC servo motor for driving an optical system (illumination unit and reflection mirror) of a copying machine.

FIG. 1 is a block diagram showing an example of the configuration of a control circuit for a D1C servo motor for driving the optical system of a copying machine. This control circuit uses PWM (pulse width 1Tlod) as the voltage applied to the DC servo motor.
ulatjon) signal is used.

This DC servo motor 10 is of a permanent magnet field type, and is rotationally driven by a driver section 11.
Move 7.

A rotary encoder 12 is installed on the rotating shaft of the servo motor 10.
are connected. As is already well known, the low rotation encoder 12 outputs a speed detection pulse every time the servo motor 10 rotates by a predetermined minute angle. The rotary encoder 12 of this embodiment outputs A-phase and B-phase speed detection pulses (speed detection signals) that have the same period and are out of phase by 90 degrees, and the servo motor 10
When the motor rotates once, each phase, for example, 200 speed detection pulses are output.

The speed detection pulse output from the low-resolution encoder 12 is given to the encoder signal input section 13. The encoder signal input section 13 is a circuit for detecting the rotational speed of the servo motor 10 based on the speed detection pulse given from the low-return encoder 12, as will be described in detail later. Encoder signal input section 13
The output is given to the control section 14.

The control unit 14 includes a CPU, an RO that stores programs, etc.
M, is equipped with RAM etc. to store necessary data,
Calculation process of difference between command speed and detected speed, calculation process of phase difference between speed detection signal and speed command signal, servo motor 10
Performs processing such as calculation of PWM data for controlling.

The control section 14 is given an operation command signal and a speed command signal (speed command clock) from a control section (not shown) of the main body of the copying machine.

The control section 14 executes arithmetic processing based on each input signal, calculates PWM data, and provides it to the PWM unit 16, and also provides a driver section drive signal to the driver section 11 described above.

The PWM unit 16 receives PW from the control unit 14.
This is a unit I for generating a PWM signal with a pulse width (output duty) corresponding to M data. The rotational speed of the servo motor 10 is controlled by a PWM signal output from the PWM unit 16. Further, the driver unit drive signal determines the rotation direction of the servo motor 10 and performs braking.

By the way, in order to rotate the servo motor 10 at a desired command speed, it is necessary to accurately detect the rotation speed of the servo motor 10 as a premise.

Therefore, in this control circuit, the encoder signal input section 13
The configuration is as shown in FIG. 2, and the signal reading by the control section 14 is devised so that accurate speed detection can be performed.

To explain with reference to FIG. 2, encoder signal input section 1
3 is a rise detection circuit 13 that detects the rise of the A-phase speed detection pulse sent from the rotary encoder 12;
1. For example, a 16-bit free running counter 133 that counts up the reference clock and a rising edge detection output of the rising edge detection circuit 131 are used as capture signals; A register 134 is provided.

The reference clock is a reference clock that serves as a reference for the operation timing of the entire circuit shown in FIG. 1, and when the circuit is composed of a microcomputer, a machine clock is used. Also, if there is no such reference clock,
A reference clock generation circuit may also be provided.

The encoder signal human input section 13 further includes an up/down detection section 135 and an up/down counter 136. The up/down detection section 135 includes a rise detection circuit 1
When the rising detection output of the A-phase speed detection pulse is given from 31, the level of the B-phase rotation pulse is determined, and depending on whether the B-phase rotation pulse is high level or low level, the servo motor 10 (Fig. 1) This is to determine whether the motor is rotating forward or backward. Up/down counter 136
is based on the discrimination output of the up-down detection section 135,
The detection output of the rising edge detection circuit 131 is counted up or down by 5.

Next, the operation of the circuit shown in FIG. 2 will be explained.

The contents of the capture register 134 include the capture signal,
That is, it is updated every time the rising edge of the A-phase speed detection pulse is detected. In addition, up/down counter 13
6 counts the number of times the rising edge of the speed detection pulse is detected, in other words, the number of speed detection pulses.

Therefore, if the up-down counter 136 counts n rotation pulses within a predetermined sampling time ΔT, and the number of reference pulses counted by the free-running counter 133 during that period is measured, the number of rotations is calculated based on that. N can be calculated.

In other words, the rotation speed N [rpm] of the servo motor 10 is determined by the frequency of the reference clock being f [Hz], and the number of A-phase rotation pulses output from the row encoder 12 when the servo motor 10 rotates once being C [ ppr], the current content of the capture register 1316 is CPT, and the previous content of the capture register 131 is CP T ++-1, it can be calculated as follows (1).

Here, in equation (1), since the reference clock frequency f and the number of rotational pulses C are constants, N-n A = Dan (2) CPT, -C
PTll, X However, A: LX60 X: CPT, CPTll-+.

FIG. 3 shows the motor rotational speed detection processing procedure performed by the control unit 4, and FIG. 4 shows three types of memories M1, M2, and M3 used in this processing.

In FIG. 4, the memory M1 is for storing five rotation speed data in order from the newest to the oldest rotation speed data storage area. Five storage areas E1 to E5 are provided in order. That is, the latest rotation speed data N is stored in El.

However, E2 contains the previous rotation speed data N. -1, but 2 to E3
Previous rotation speed data N. -2, is the rotation speed data N, three times before E4. -1 is stored in E5, and the rotational speed data N(,4,) of the previous four times is stored respectively.

The memory M2 is for sorting the five rotational speed data N0 to N (TI-41) stored in the memory M1, that is, arranging them in order of size, and has five storage areas E.
It has 11 to E15. 5 stored in memory M1
rotation speed data N. -N(n-41 is sorted and stored in memory M2, for example, area El
The largest of the five rotational speed data N, ... Ntn-41 is in area E12, the third largest is in area E1B, and the largest one is in area E14.
The largest one is stored in area Ell, and the smallest one is stored in area Ell. Therefore, the rotation speed data corresponding to the center of the five rotation speed data stored in the memory M1 is stored in the area E1B.

Note that the memories M1 and M2 do not need to be used to store rotation speed data for five rotations, but may be used to store any number of rotation speed data of three or more, preferably an odd number.

Memory M3 is the latest data storage area E1 of memory M1
This is for temporarily storing the data in the storage area E1 when it is determined that the data stored in the storage area E1 is incorrect data.

Returning to FIG. 3, the motor rotation speed detection process is performed every sample time Δt.

The sample time Δt is set to an appropriate time that satisfies Δt≧X=CPT, −CPT, −+ −(3).

Next, explanation will be given with reference to FIGS. 1 to 4.

In the control unit 14, an internal timer keeps a constant sampling time Δt.
Each time the timer reaches (step S1), the timer is reset (step S2), and the contents of the capture 9 register 134 and up/down counter 136 are read (step S3).

Then, from the count number CPT of the capture register 134 read this time, the count number CPT of the capture register 134 that was already stored and read last time is calculated.
After the reference clock number X within one sample time Δ is obtained by subtracting n-1, CPT is stored (step S4).

Also, from the count number UDCn of the up-down counter 136 read this time, the count number UDC of the up-down counter 136 read last time that has already been stored.
, , -+, the number n of rotational pulses within one sample time Δ is determined, and then the UDC, , is stored (step S5).

Thereafter, the rotation speed N of the servo motor is determined based on the above-mentioned formula (2). (Current rotational speed data N.) is calculated (
Step S6).

When the rotation speed data N0 is calculated, the previous rotation speed data N is calculated. -117> (It is confirmed whether or not the data has been determined to be incorrect. This confirmation is performed by checking whether or not the flag F is set to 0 (F=1) (step S7 ).

As will become clear later, the flag F is set (F-1) when the previous rotational speed data N (.-1) is determined to be incorrect data, and the previous rotational speed data N is set. −
1, is not determined to be incorrect data, it is set to a reset state (F-0).

In the case of F-0, that is, the previous rotation speed data N
. , -1, is not determined to be incorrect data, the five rotation speed data N from the previous time to the previous five times are already stored in the memory M1. -1) to N(*-6) are shifted (step S8). As a result, the previous rotation speed data N (n-1+) is stored in area E2, the rotation speed data N (.-2) is stored in area E3, and the rotation speed data N (three times before) is stored in area E3.
(++-3+ is in area E4, rotation speed data N from 4 times ago)
. -4, is stored in area E5 and is the oldest data 5
The previous rotation speed data N(.-5) is no longer stored.

Then, the rotation speed data N calculated this time. is memory M1
(Step S1 10).

On the other hand, in step S7, in the case of F-1, that is, when the previous rotation speed data N(.-1) is determined to be incorrect data, the five rotation speed data N already stored in the memory M1 (fi-,,~N,.

5) is not shifted and the process proceeds to step S9.

In step S9, the previously calculated rotation speed data NL stored in area E1 of memory M1.

3. is moved to memory M3. The area E1 of the memory M1 contains the rotation speed data N calculated this time. is memorized. Note that the data in areas E2 to E5 of memory M1 are not shifted and remain as N<n-2) to N<*-51. In other words, the previous calculated incorrect data N. -1,
Instead of , the currently calculated rotational speed data N, , is stored in area E1 of memory M1.

By performing this processing, there are the following advantages. In other words, if the calculated data is erroneous data that differs significantly from the actual motor rotation speed due to the influence of noise, etc., this erroneous data is stored in memory M1.
Shifting within the memory M1 will substantially reduce the number of reliable data present in the memory Ml, reducing the reliability of the data. More specifically, as described below,
When sorting the five pieces of data stored in memory M1, the incorrect data will always come to the end (because the incorrect data is extremely large or small), so in the end, the center of the data excluding the incorrect data will be sorted. Having to extract the data reduces the reliability of the data. In particular, if incorrect data is calculated continuously, the incorrect data may be taken out as the current rotational speed data to be used for motor control, and in such a case, severe drive unevenness will occur.

According to the above-described control, if erroneous data is calculated, the erroneous data is replaced with the currently calculated rotational speed data N, so the above-mentioned problem does not occur. Therefore, according to the control according to this embodiment, the reliability of the central data N, which will be described later, becomes high, and even if incorrect rotation speed data is calculated continuously, the incorrect rotation speed data is It is possible to prevent the data from being determined as the central data Nm.

Next, five rotation speed data N stored in the memory M1. -N (II-4+ or N. + N(n-21~
N(II-51) are sorted and stored in the memory M2 (step 511). As a result, five rotation speed data N11 are stored in areas Ell to E15 of the memory M2.
-N(.-4) or N11. N(II-21~N(
n-5) are stored in descending order. In this case, the area E13 contains five rotational speed data N, , ~N(,.

4, or Nn + N+n-2+ ~N(II-5+
Rotation speed data corresponding to the center of the size (center data N
□) is memorized.

The central data Ni stored in the area E13 of the memory M2 is the rotation speed data corresponding to the middle of the five rotation speed data for the current time and the past four times. Therefore, if this rotational speed data N1 is used for control as the current rotational speed N, the speed detection signal will fluctuate due to noise etc., and even if incorrect rotational speed data Nfi is calculated in step S6, the incorrect Rotation speed data Nゎ can be removed.

However, this method alone can prevent false detections due to sudden fluctuations due to noise, etc. However, if the motor rotation speed is changing in one direction over a long period of time (for example, if the rotation speed is increasing) ) etc., there are the following problems.

For example, the motor rotation speed is a command speed N as shown in FIG. In the case where the rotation speed is rising toward the current direction, at the current time t7, the rotation speed data N* to N (II-4+) for five times from time t to time t(n-4) are stored in the memory M1.

Then, since the data N (II-21) corresponding to the middle of these data is always smaller than the latest data N, even if the actual motor rotation speed almost reaches the command speed N, the current The rotational speed of the motor is determined to be lower than the commanded speed N, and the motor rotational speed is controlled to further increase.

As a result, the motor rotation speed is the command speed N. It becomes bigger. Then, the speed is controlled to decrease, but in this case as well, the actual motor rotation speed is approximately the command speed N. Even if the current rotational speed reaches the commanded speed N. It is determined that the motor rotation speed is higher than that, and the motor rotation speed is controlled to further decrease.

Therefore, the motor rotation speed is the command speed N, as shown in FIG. This results in undulations (hunting) centered around .

Therefore, in this embodiment, the following control is performed in order to prevent such hunting phenomenon.

The current rotational speed data Nゎ stored in area E1 of memory M1 corresponds to central data N□ stored in area E13 of memory M2, or does not correspond to central data N□
It is determined whether or not it is within a certain range (step 51
2). In other words, it is determined whether the latest rotational speed data N7 is within the range expressed by the following equation.

Nff1 (1-p)≦Nfi≦N, (1+q)...
(4) However, p and q are values determined in consideration of the follow-up characteristics of the motor when changing the motor rotation speed.

If the current rotational speed data N is within the range shown by equation (4) (YES in step S12), the current rotational speed data N. is determined not to have been affected by noise or the like, and the current rotational speed data N, , stored in area E1 of memory M1, is taken out as the current motor rotational speed N and stored in a buffer, for example. , used for control. Also, flag F is reset (F=O)
(step 813). Therefore, as shown in FIG. 10, even when the motor rotational speed changes in one direction over a long period of time, accurate speed data can be obtained and the hunting phenomenon can be prevented from occurring.

On the other hand, if the current rotational speed data Nゎ is not within the range shown by formula (4) (NO in step S12)
, rotation speed data N calculated this time. The rotation speed data N(.-1, calculated last time) stored in the memory M3 are compared, and the current rotation speed data N. is within a certain range with respect to the previous rotation speed data N.-8. It is determined whether or not (step S714).

In other words, the current rotation speed data N. It is determined whether or not is within the range shown by the following formula.

N(II-1) (1r)≦Nn<N(It-11
(1+S)...(5) However, r and S are values determined in consideration of changes in motor rotational speed, etc.

Rotation speed data N calculated this time. is not within the range shown by the above formula (5) (in step S14, N
O), the current rotational speed data N, is determined to be incorrect data, and the central data N, stored in area E13 of memory M2, is retrieved as the current motor rotational speed,
For example, it is stored in a buffer and used for control. Additionally, flag F is set (F-1) (step 515
).

Therefore, even if the speed detection signal suddenly fluctuates greatly due to noise or the like, it is not used for control, so that erroneous control operations due to noise or the like can be prevented.

On the other hand, this rotation speed data N. is within the range shown by the above formula (5) (YES in step 8 S14), the rotation speed data Nn calculated this time
is taken out as the current motor rotation speed N, stored in a buffer, for example, and used for control.

Additionally, flag F is reset (F=0) (step 516).

Furthermore, data in areas E2 to E5 of memory M1 are shifted one by one, rotation speed data N (II-s+) previously stored in area E5 is discarded, and area E
Rotation speed data N(.-2) is stored in area E4, data N(.-9, is stored in area E5, pig N.-4, is stored in area E5, and memory M3 is stored in area E2. The previously calculated rotational speed data N (n-11) is stored (step 517).As a result, it is possible to eliminate incorrect data due to noise, etc., and when the motor rotational speed actually changes, the corresponding Rotational speed data based on changes in the motor rotational speed can be accurately grasped, and motor control can be performed that quickly responds to fluctuations in the actual motor rotational speed without being delayed.

9. Each time a speed detection pulse is output, the count number CPT, , of the capture register 134 is read out, the previous count number CPT, , is subtracted to calculate the cycle of the latest speed detection pulse, and this cycle is calculated by subtracting the previous count number CPT, . The rotation speed data N may be obtained based on the following.

Next, the speed command signal input section 15 will be explained in detail.

FIG. 5 is a block diagram showing a specific example of the configuration of the speed command signal input section 15. As shown in FIG. In the speed command signal input section 15,
A rise detection circuit 151 for detecting the rise of the speed command clock, a free running counter 152 for up-counting the reference clock, and a rise detection output of the rise detection circuit 151 are used as a capture signal, and the capture signal is used as a trigger to control the free running counter 152. It includes a capture register 153 that reads and holds a count number, and an up counter 154 that counts up the output pulse of the rising edge detection circuit 151.

0 Free running counter 152 is, for example, a 16-bit counter. This free running counter 152 may also be used in common with the free running counter 133 of the encoder signal input section 13 described above.

The operation of this circuit is as follows.

A speed command clock outputted from a control side microcomputer on the apparatus main body side, for example, a copying machine main body, is applied to a rising edge detection circuit 151, and a rising edge is detected. Since the output of the rising edge detection circuit 151 is given to the free running counter 152 as a capture signal, the contents of the capture register 153 are updated in response to the rising edge of the speed command clock. Therefore, the contents of the capture register 153 are read based on a certain rising detection signal, and the contents of the capture register 153 are read based on the next rising detection signal.
By reading out the contents of and finding the difference between them, it is possible to measure the count number of the free running counter 152 in one cycle of the speed command clock. In other words, the rotation speed N is the command speed.

1 can be obtained.

Note that in this embodiment, each time the contents of the capture register 153 are updated, the difference between the count number after the update and the count number before the update is calculated. , the same reading method as the count number reading of the capture register 153 in the encoder signal input section 13 is used.

That is, the control unit 14 reads the contents of the capture register 153 and the contents of the up counter 154 at every predetermined sampling time Δt, calculates the difference between the count number read this time and the count number read last time in the capture register 153, and calculates the difference between the count number read this time and the count number read last time in the capture register 153. By dividing the difference by the difference between the count number read this time and the count number read last time in the up counter, a more accurate reference clock number within one cycle of the speed command clock is obtained.

FIG. 6 shows a procedure for calculating the phase difference between the speed command clock and the speed detection pulse by the control unit 14.

First, the rising edge detection circuit 13 of the encoder signal input section 13
1, when the rising edge of the speed detection pulse is detected (step 521), the count value of the free running counter 133 is read and the value is stored as the phase comparison value PDT (step 522). Since the free running counter 133 starts counting the reference clock from the start of motor control, the value of the phase comparison value PDT is a value corresponding to the time from the start of motor control to the current pulse rise detection point. Become.

Next, the phase reference value PPIn is calculated and stored according to the following equation (step 823).

P P I -=P P I (--11+S P D
...' (6) Here, PPI(.-1,: Previously stored phase reference value SPD
: Number of reference clocks per cycle of speed command clock (
SPD is a fixed value. ).

3 However, since the initial value of P P I <fi-1, is zero, in step S21, the first
The value of the phase reference value PPI corresponding to the time when the rising edge of the speed detection pulse is detected becomes SPD.

Thereafter, the phase difference PHDT is calculated by the following equation and stored (step $24).

PHDT=PP''-PD'', (7) SPD Then, the above process is repeated. That is, every time the rising edge of the speed detection pulse is detected (step 521)
, reading the count value of the free running counter 133 and the phase comparison value PDT. update (step 522)
, phase reference value PPI. calculation and update (step 82
3) and calculation of phase difference PHDT (step 524)
is repeated.

After the start of motor control, when the second rise of the speed detection pulse is detected in step S21, step 8
The value of the phase reference value PP41 calculated in step 23 becomes 2SPD, and becomes 3SPD when the third rising edge of the speed detection pulse is detected. In other words, the value of the phase reference value PPI calculated in step 323 is the total number of speed detection pulses output from the start of motor control to the rising time of the current speed detection pulse and SPD.
It becomes the product value of

Since SPD is a fixed value depending on the period of the speed command clock, the phase reference value PPI calculated in step 523
, is a value corresponding to the time from the start of motor control to the time of the rise of the speed command clock corresponding to the speed detection pulse whose rise was detected this time.

Then, a value (phase comparison value PD
T, ) and the value (phase reference value PPI,) corresponding to the time from the start of motor control to the time of the rise of the speed command clock corresponding to the speed detection pulse whose rise was detected this time is calculated as the speed command clock. Value according to the period of (SPD)
By dividing by 5, the phase difference PHDT is obtained. Therefore, even if the phase difference between the speed command clock and the speed detection pulse is one cycle or more of the speed command clock, the phase difference PHDT can be accurately detected.

Next, a method for calculating PWM data output from the control unit 14 will be explained.

The rotation speed N of the servo motor 10 is the command speed N.

The voltage vO that should be output to the servo motor 10 in order to make it follow
It is expressed by the following formula.

VO-V1+V2 (8) That is, in this embodiment, the speed difference ΔN(-N.

-N) is corrected by the control voltage v2 based on the phase difference PHDT. The reason for this is that with only proportional control based on the speed difference ΔN, the acceleration when increasing the motor speed from the actual detected speed to the target speed changes depending on the size of the target speed. This is because it takes a long time to reach the target and the followability is not good6.

Therefore, in order to improve followability, in this embodiment, the control voltage V1 based on the speed difference ΔN (-N.-N) is corrected by the control voltage v2 based on the phase difference PHDT.

The control voltage v2 due to the phase difference PHDT is obtained, for example, as follows, assuming that the predetermined maximum value of the control voltage v2 is α.

(a) When the phase difference is smaller than one cycle (-1<PHDT<+1) V2-a ・PHDT -(9)(b
) When the phase difference is one cycle or more and the phase of the speed detection signal is ahead of the phase of the speed command signal (PHDT≦-1) V2--α ... (10) (e
) When the phase difference is one cycle or more and the phase of the speed detection signal lags the phase of the speed command signal (PHDT≧+1) V2-+α... (
11) Therefore, the relationship between the phase difference PHDT and the control voltage v2 is as shown in FIG. 7.

The control voltage v1 due to the speed difference ΔN is calculated using the following formula (%) (12) Ra: amateur resistance [Ω] KT: torque constant [kgm/A] Ke: induced voltage constant [V/rpm] Io: no load Current [A] GD2: Moment of inertia due to load and motor [kg
m2] TBL: sliding load [kgm].

7 8 The control unit 14 detects the rotation speed N of the servo motor 10 (step S6 in FIG. 3), and calculates the speed difference Δ from the command speed N0.
Each time N is calculated or the phase difference PHDT is calculated (step 524 in FIG. 6), the above equations (8) to (
12), calculate vO and set PW accordingly.
Output M data. This PWM data is sent to the PWM unit 16, and the servo motor 10 is controlled via the driver section 11.

FIG. 8 is a block diagram showing a specific example of the configuration of the PWM unit 16, and FIG. 9 is a timing chart for explaining the operation of the PWM unit 16.

The PWM unit 16 includes a set signal generation section 161,
PWM data register 162 and down counter 163
and an RS flip-flop 164.

The set signal generator 161 generates a set signal at regular intervals. This set signal generating section 161
The counter 9 is composed of a ring counter, for example, and is configured to generate a set signal every time a certain number of reference clocks are counted.

The PWM data register 162 is for holding PWM data given from the control unit 14. The PWM data given from the control unit 14 is expressed by the above-mentioned formula (8
) is the voltage data determined by That is, it is the voltage vO obtained by correcting the voltage v1 of equation (12) with the control voltage 2 based on the phase difference data PHDT. This PWM data is used to determine the duty of the PWM output signal output from the PWM unit 16.

The down counter 163 counts down every time a PWM reference clock (in this embodiment, the PWM reference clock is a reference clock used in the encoder signal input section 13 and the speed command signal input section 15) is provided. When the set number is counted, a reset signal is output.

The operation of the PWM unit 16 is as follows.

When the set signal generation section 161 outputs a set signal of 0, the contents of the PWM data register 162, that is, the PWM data given from the control section 14, are set in the down counter 163, and the flip-flop 164 is also set by the set signal. Set. Therefore, the output of the flip-flop 164, that is, the PWM signal becomes high level.

Next, the down counter 163 counts down based on the PWM reference clock, and when the set count value reaches "0", a heliset signal is given to the flip-flop 164. Therefore, the output of flip-flop 164 is inverted to low level.

As a result, the duty is determined by the value held in the PWM data register 162, that is, the voltage data calculated by equation (8), and a PWM signal is derived from the PWM unit 16.

The present invention is applicable not only to the optical system control of a copying machine, but also to a motor for controlling a reading device of a facsimile machine, a motor for controlling the operation of a robot, and other general motor control circuits.

1 The present invention can also be applied to the case where applied voltage is calculated using other than PWM signals.

<Effects of the Invention> Since the present invention is configured as described above, even if the speed detection signal fluctuates over time due to noise etc., accurate speed can be obtained without being affected by the fluctuation. and good motor control is possible.

Further, according to the present invention, good motor control can be performed even when the motor rotational speed changes in one direction over a long period of time.

Further, according to the present invention, when the motor rotational speed is changing, highly responsive and highly accurate control that can quickly follow the change is possible. Furthermore, since high response and highly accurate control is possible even at low sampling speeds, the circuit can be configured using a general-purpose microprocessor or the like, making it possible to create a low-cost motor control device.

[Brief explanation of drawings]

2 FIG. 1 is a block diagram showing the electrical configuration of a drive control circuit for an optical system drive DC servo motor to which an embodiment of the present invention is applied. FIG. 2 is a circuit block diagram showing the electrical configuration of the encoder input section according to the embodiment of the invention. FIG. 3 is a flowchart showing the rotational speed detection processing procedure in the embodiment of the present invention. FIG. 4 is a diagram showing two memories M1 and M2 used for rotational speed detection processing in the embodiment of the present invention. FIG. 5 is a block diagram showing the electrical configuration of the speed command signal manual section. FIG. 6 is a flowchart showing a phase difference detection processing procedure in an embodiment of the present invention. FIG. 7 shows the phase difference PHDT and the control voltage v based on the phase difference.
2 is a graph showing the relationship with 2. FIG. 8 is a block diagram showing a specific electrical configuration of the PWM unit. FIG. 9 is a timing chart showing the operation of the PWM unit. 3 FIG. 10 is a diagram for explaining one of the problems solved by this embodiment, and shows the content of the motor detection signal when the motor rotation speed changes in one direction over a long period of time. FIG. FIG. 11 is a diagram for explaining the hunting phenomenon. In the figure, 10...DC servo motor, 11...
Driver section, 12... Rotary encoder, 13...
・Encoder signal human power section, 14...control section, 15...
・Speed command signal input section, 16...PWM unit, M
1, M2...indicates memory. 4 Low

Claims (1)

[Claims] 1. A motor control device that performs feedback control of a motor so that the motor rotation speed becomes equal to a command speed, comprising: a calculation means for calculating data regarding the motor rotation speed at each predetermined timing; a first storage means having a plurality of storage areas capable of storing a predetermined number of times of data regarding the rotational speed in chronological order; a second storage means capable of storing at least one time of data regarding the motor rotational speed; means for checking whether the data calculated last time was determined to be incorrect data each time the data calculated last time is determined to be incorrect data; A first storage control means that sequentially shifts the data one by one, discards the oldest data, and stores the currently calculated data in the latest data storage area, when the previously calculated data is determined to be incorrect data; Second storage control for moving the previously calculated data stored in the latest data storage area of the first storage means to the second storage means and storing the currently calculated data in the latest data storage area of the first storage means means, the currently calculated data stored in the latest data storage area corresponds to the data corresponding to the center of magnitude among the plural data stored in the first storage means, or the data corresponding to the center of magnitude The first determining means determines whether the data calculated this time corresponds to the data corresponding to the center of magnitude or the data corresponding to the center of magnitude. means for extracting the data calculated this time as speed data to be used for motor control when it is determined that the data calculated this time is within a predetermined range; further compares the currently calculated data with the previously calculated data stored in the second storage means,
A second determination means for determining whether or not the data calculated this time is within a predetermined range of the data calculated last time. When the second determination means determines that the data is within the predetermined range, the data calculated this time is In addition to extracting the speed data to be used for motor control, among the data stored in the first storage means, data other than the currently calculated data stored in the latest data storage area are sequentially shifted one by one to obtain the most recent data. a third storage control means for discarding old data and storing the previously calculated data stored in the second storage means in a storage area next to the latest data storage area of the first storage means; and a second determination means When it is determined that the data is outside the predetermined range, the data calculated this time is determined to be incorrect data, and the data corresponding to the center of the size among the data stored in the first storage means for multiple times is calculated. A motor control device comprising: means for extracting the speed data as speed data to be used for motor control.