JPH0947056A - Speed and position controller for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time to be elapsed before settling at a target speed by making a switching from speed feedback control to position feedback control after the fluctuation of motor speed in constant speed region is settled within a predetermined level. SOLUTION: For example, a motor 6 is started based on a command being set at a start PWM set circuit 18 and speed feedback control is executed for a predetermined time in a constant speed region exceeding an acceleration region. Speed of the motor 6 is then operated over a predetermined continuous period of encoder pulse from an encoder 7 and compared with a reference speed to operate a speed error and a drive signal corresponding to the speed error is outputted from a drive means 5. Upon elapse of a predetermined time, position feedback control is executed in constant speed region. In other words, position of the motor 6 is operated by counting the encoder pulses and compared with a reference position to operate a positional error and a drive signal is outputted from the drive means 5 based on the positional error.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed and position control device for a motor, and more particularly, it can reduce the time required to converge to a target speed and can start the motor smoothly and surely while suppressing unnecessary power consumption. The present invention relates to a motor speed and position control device.

[0002]

2. Description of the Related Art As a conventional motor speed control device, for example, JP-A-57-203579 and JP-A-62.
There is one disclosed in Japanese Patent Publication No. 16088.

The former motor speed control device separates control from the servo motor control system in the acceleration region from the stop of the carriage driving motor to the constant speed motion, while rotating the motor at a constant voltage, When the number of rotations of the motor reaches a predetermined number of rotations, a smooth acceleration of the motor is realized by connecting to a servo motor control system and performing feedback control at a constant speed.

On the other hand, the latter motor speed control device has a means for outputting a drive signal during the period from the start of activation of the DC motor until the DC motor reaches a predetermined speed, and a pulse width while the activation signal is output. It is equipped with a means to keep the modulation signal always on.When the motor is started, the pulse width modulation is not performed, so that the current continues to flow to the DC motor without interruption, and when the motor speed reaches the target speed, the pulse width The modulation control is performed to shorten the motor startup time.

FIG. 9 shows a speed profile when the motor is driven by the speed control device for these motors. As can be seen from this figure, during the acceleration region from time t ₁₀ to time t ₁₁ , the motor is rotated by a constant voltage to reach the target speed. When the motor speed reaches the target speed, the time t to start the deceleration operation
Feedback control is performed during the constant speed range up to ₁₂ . Normally, in the feedback control in the constant speed region of the motor, position control or PLL (Phase Locked Loop) control is performed to improve the constant speed control performance. Next, speed feedback control is performed during the deceleration region from time t ₁₃ to time t ₁₄ .

[0006]

However, according to the conventional motor speed control device, a constant voltage is applied from the time of stop to the target value. Friction, system inertia,
Variations in the motor induced voltage constant, environmental changes such as temperature and humidity, and changes over time cause variations in the time and distance to reach the target speed in the acceleration region, which causes variations in the cumulative speed error value, that is, position error. Occurs. Therefore, when shifting to constant velocity motion, a large overshoot may occur due to the effect of position error.
There is an inconvenience that it takes a long time to converge to the target speed. As a result, in the system design of the carriage of the copying machine, the automatic document feeder, etc., it takes a long time to converge, and there is a problem that the device becomes large and the productivity is lowered. In addition, during startup and during acceleration, a larger voltage is generally required during startup due to the static friction, but a constant voltage is applied based on the voltage required during startup, so unnecessary voltage is required during acceleration. Will be applied,
In addition to wasteful power consumption, a large overshoot occurs depending on the applied voltage, causing the above-mentioned problems. On the other hand, if the voltage at the time of starting is matched with the voltage required during acceleration, the vehicle may not start.

It is also conceivable that the engine is started by feedback control, but such control may not be able to operate initially. This is because the motor voltage (current) command value required to operate due to the influence of the dead zone of the motor, the mechanical time constant, etc. cannot be obtained in the initial stage. It is also possible to operate it through a compensator, but in this case, in order to improve the convergence, the PWM set value is maximized at a slow speed, and the PWM set value is minimized at a fast speed. System, even if it works,
There is a disadvantage that a smooth start cannot be performed because the M setting repeats the maximum and the minimum alternately.

Further, since the conventional motor speed performs position or PLL control in the constant speed region, it has a speed loop and an integral loop inside, so that the convergence to the target speed is worse than the speed control. , It takes longer to converge to the target speed. Therefore, the above-mentioned problems occur.

Therefore, an object of the present invention is to provide a motor speed and position control device which can shorten the time required to converge to a target speed and can be reliably started while suppressing unnecessary power consumption. Is.

[0010]

In view of the above problems, the present invention can shorten the time until the target speed is converged, and
In order to reliably start while suppressing wasteful power consumption, the clock is counted over a continuous predetermined cycle of the encoder pulse at a predetermined timing of each cycle of the encoder pulse, and the speed of the motor is calculated. And a speed error calculating means for calculating a speed error by comparing with a reference speed, and counting the encoder pulse and performing a predetermined calculation to calculate the position of the motor,
Position error calculating means for calculating a position error by comparing this with a reference position, driving means for driving a motor by outputting a drive signal having a pulse width modulation degree according to the speed error or the position error, The control means is provided with a speed feedback control or a position feedback control by controlling the means to output a drive signal, and the control means, after starting the start of the motor, has a predetermined constant speed region exceeding the acceleration region of the motor. (EN) A speed and position control device for a motor having a configuration in which speed feedback control is executed up to time and then position feedback control is executed in the remaining constant speed region.

It is preferable that the predetermined time in the constant speed region is a time when the speed fluctuation of the motor reaches a predetermined value.
Further, the control means inhibits the speed feedback control and the position feedback control from the time when the motor is stopped until a predetermined time within the acceleration region, and starts the motor based on the speed command value set for starting the motor. Is desirable.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION For example, the control means starts a motor based on a preset speed command value, and performs speed feedback control from a start of the motor to a predetermined time in a constant speed region exceeding an acceleration region of the motor. Run. That is, the clock is counted over a continuous predetermined cycle of the encoder pulse at a predetermined timing of each cycle of the encoder pulse to calculate the speed of the motor, and this is compared with a reference speed to calculate a speed error. The drive means outputs a drive signal based on the speed error to drive the motor. Further, the position feedback control is executed in the constant speed region after a predetermined time. That is, the position of the motor is calculated by counting the encoder pulses and performing a predetermined calculation, the calculation result is compared with the reference position, the position error is calculated, and the drive signal based on the position error is output from the drive means. And drive the motor.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The motor speed and position control device of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the structure of a motor speed and position control device according to an embodiment of the present invention. This motor speed and position control device includes a control unit 1 including a microcomputer configured by one chip, an AND circuit 2 that controls passage of an output of the control unit 1, and a drive circuit 5 that drives a motor 6. A short circuit prevention circuit 3 for preventing a longitudinal short circuit of the drive circuit 5, a current limit circuit 4 for limiting the drive current supplied from the drive circuit 5 to the motor 6 by turning off the AND circuit 2, and a rotation of the motor 6. An encoder 7 that generates a pulse according to the speed, an interface circuit 8 that inputs the output of the encoder 7 to the control unit 1, a ROM 9 that stores a predetermined program, and a calculation result of the control unit 1 and the like are temporarily stored. It is configured to include a RAM 10.

The control unit 1 has an edge detection circuit 11 for detecting the rising edge of the encoder pulse of the encoder 7.
And a clock generation circuit 12 that generates a clock signal having a frequency sufficiently higher than that of the encoder pulse, for example, 0.5 MHz, and the edge detection signal of the edge detection circuit 11 is used as a trigger to clock the encoder pulse over a predetermined number of cycles. A counter circuit 13 that counts the clock signal of the generation circuit 12 and outputs a count value (capture number); a memory 14 that stores the count value of the counter circuit 13 and other data such as the number of detected edges;
A predetermined operation is performed based on the sampler 16 that performs sampling based on the time measured by the timer circuit 15, the edge detection signal output from the edge detection circuit 11, and the count value of the counter circuit 13 stored in the memory 14, A calculator 17 for calculating a speed compensation value for compensating the speed error and the position error of the motor 6, and a starting PW when the motor 6 is started.
The start PWM setting circuit 18 in which the M set value is set, the speed compensation value based on the calculation result of the calculation unit 17, and the start PWM
P that outputs a PWM signal according to the set value of the setting circuit 18
It has a WM output circuit 19 and an enable signal output circuit 20 for outputting an enable signal to the AND circuit 2.

The calculation unit 17 performs a predetermined calculation based on the count value of the counter circuit 13 stored in the memory 14 to calculate motor speed data.
And a reference speed setting circuit 22 for outputting a reference speed signal,
A subtractor 23 that calculates the speed error of the motor 6 by comparing the motor speed signal output from the speed data calculation circuit 21 and the reference speed signal output from the reference speed setting circuit 22.
And a speed compensation calculation circuit 24 for calculating a speed compensation value for compensating a speed error based on the calculation result of the subtractor 23 and a speed compensation value according to a position compensation value described later, and an edge output from the edge detection circuit 11. It is output from the position data calculation circuit 25 that counts the number of signal edges and calculates the motor position data by calculating the distance therefrom, the reference position setting circuit 26 that outputs the reference position signal, and the position data calculation circuit 25. The motor position signal and the reference position signal output from the reference position setting circuit 26 are compared to calculate a subtracter 27 that calculates the position error of the motor 6, and a compensation value that compensates the position error based on the calculation result of the subtracter 27. Position compensation calculation circuit 2 for calculation
8.

The ROM 9 is used for the motor 6 as shown in FIG.
At the time of starting, that is, from time t ₂₀ to time t _{21 at} which a predetermined number of samplings are completed, the servo motor control system is set to an open loop, and the PWM signal is output from the PWM output circuit 19 based on the set value of the start PWM setting circuit 20. by output to execute the start-up control to start the motor 9, to perform a speed feedback control from the time t ₂₁ to time t ₂₃ to the speed variation in the constant speed region (time t ₂₂ ~t ₂₄₎ reaches a substantially predetermined value, to execute the position feedback control to the time t ₂₄ to transition from the time t ₂₃ to the deceleration operation, the time t
A control program for executing speed feedback control from ₂₄ to time t ₂₅ when the motor 6 stops is stored.

FIG. 3 shows an encoder pulse output from the encoder 7, a clock output from the clock generation circuit 12, and a motor 6 obtained by counting the clock over a predetermined number of cycles of the encoder pulse, for example, three cycles. Velocity data is shown.

The operation of the above structure will be described with reference to FIGS. First, in the initial operation of S ₁ in FIG. 4, the control unit 1 executes the startup control of the motor 6 (time t _{20 in} FIG. 2). In this control, the servo motor control system is set to an open loop and the PWM output circuit 1
PWM according to the set value of the start PWM setting circuit 18 from 9
For example, 1 sampling period = 2 msec
As 3 times during 3 sampling periods (Fig. 4
S ₂ ). This transmission signal may be a constant value or a variable value, but normally a constant value is sufficient. The number of times of sending is not required to be three if it is surely raised, but if it is too large, it does not match the target speed profile, so it is made small. In addition, the set value of the start PWM setting circuit 18 is a value such that the start profile does not flutter with reference to the speed profile of the device to be applied, that is, the speed within a range in which the speed information can be captured within the sampling interval is experimentally determined. Obtained and determined in advance.

At the same time, the control section 1 outputs an enable signal from the enable signal output circuit 20 to the AND circuit 2 and performs an AND operation based on the high signal output from the current limiting circuit 4.
The PWM signal input to the circuit 2 is passed and supplied to the drive circuit 5. As a result, the motor 6 starts based on the start set value of the PWM signal. At this time, for example, if the encoder pulse is not input to the control unit 1 at the time of 10 sampling, it is highly possible that a system abnormality such as the motor 6 is not operating. The output of the enable signal is turned off and the system abnormality signal is output.

On the other hand, when an encoder pulse is input to the control unit 1, the control unit 1 shifts to the acceleration operation in S ₃ of FIG. 4 (time _{21 in} FIG. 2) and executes speed feedback control (FIG. 4). S ₄ ). In this control, an encoder pulse having a cycle corresponding to the speed of the operating motor 6 is input through the interface circuit 8, and the edge detection circuit 11 causes the rising edge m, m + 1 of each cycle of the encoder pulse,
m + 2 (FIG. 3) is detected and an edge detection signal is output to the counter circuit 13. The counter circuit 13 is, for example,
It has N counters and N consecutive encoder pulses.
The number of clocks input from the clock generation circuit 12 is counted by using the edge detection signal as a trigger over a period (n = 3), and 3 (m) data, 3 (m + 1) data, 3 (m +)
2) Output as data to the memory 14. Naturally, in the counter circuit 13, the first counter is reset after outputting 3 (m) data to the memory 13 and 3 (m + 4).
The data is counted, and the third counter is reset after outputting 3 (m + 2) data to the memory 13 and 3 (m + 5).
Count the data. Hereinafter, the same process is repeated.

The count values sequentially output from the counter circuit 13 in this manner are input to the speed data calculation circuit 16 at a predetermined timing by the sampler 16 which performs sampling operation by the timer circuit 15. The speed data calculation circuit 21 calculates motor speed data based on the input count value (S _{41 in} FIG. 5) and outputs this to the subtractor 23 as a motor speed signal. The subtractor 23 compares the reference speed signal output from the reference speed setting circuit 22 with the motor speed signal to calculate the speed error of the motor 6 (S _{42 in} FIG. 5) and outputs this to the speed compensation calculation circuit 24. To do. The speed compensation calculation circuit 24 calculates a speed compensation value for compensating for the speed error and outputs it to the PWM circuit 19, and causes the PWM circuit 19 to output a PWM signal having a pulse width modulation degree according to the error (see FIG. 5). _S44 ). This PWM signal is the AND circuit 2
To the drive circuit 5, and the drive circuit 5 drives the motor 6 at a speed that reduces the speed error.

The acceleration operation is executed by such speed feedback control, and when the target speed is reached at the time t ₂₂ in FIG. 2, the constant speed operation is started (S _{5 in} FIG. 4). Even in this constant speed operation, the speed feedback control is continuously performed (S _{6 in} FIG. 4), and the speed of the motor 6 is controlled so as to reach the target speed. If speed feedback control is performed even after shifting to constant speed operation in this way, the convergence time T _{2 at} which the speed fluctuation of the motor 6 decreases to a predetermined value becomes shorter than the convergence time T ₁ by position feedback control or phase feedback control. .

[0024] If the speed variation of the motor 6 is converged (time t ₂₃ in FIG. 2), the control unit 1 in S ₈ of FIG. 4 is performed based on the position feedback control in the flowchart of FIG. That is, when the control unit 1 inputs an encoder pulse having a cycle corresponding to the speed of the motor 6 in operation via the interface circuit 8, the edge detection circuit 11 detects a rising edge of each cycle of the encoder pulse and outputs an edge detection signal. Is output to the position data calculation circuit 25. The position data calculation circuit 25 counts the number of edges of the edge detection signal, and calculates the position data of the motor 6 from this (S _{81 in} FIG. 6). That is, since the distance traveled by the system per encoder is mechanically determined, the distance is calculated from the number of edges and the calculation result is used as position data. The position data is output to the subtractor 27 as a motor position signal, and is compared with the reference position signal output from the reference position setting circuit 26 in the subtractor 27 to calculate the position error of the motor 6. The calculation result is output to the position compensation calculation circuit 28 as an error signal. The position compensation calculation circuit 28 calculates a compensation value for compensating the position error of the motor 6 (S _{82 in} FIG. 6) and outputs the calculation result to the speed compensation calculation circuit 24. The speed compensation calculation circuit 24 calculates the speed compensation value of the motor 6 corresponding to the position error compensation ( _{S83 in} FIG. 6) and outputs it to the PWM circuit 19 to cause the PWM circuit 19 to output the pulse width modulation degree according to the error. Then, the PWM signal having is output (S _{84 in} FIG. 6). This PWM signal is AN
Input to the drive circuit 5 via the D circuit 2, and the drive circuit 5 drives the motor 6 at a speed that reduces the position error.

At time t ₂₄ at which the constant speed operation of the motor 6 ends, the deceleration operation starts (S _{9 in} FIG. 4). In this deceleration operation, the control unit 1 executes the speed feedback control according to the above-mentioned flowchart of FIG.

[0026] In the above embodiments, after the speed change is converged in the constant speed region (time t ₂₄ from the time t ₂₂ in FIG. 2), but controls the motor 6 by the position feedback control,
You may replace with the phase feedback control based on PLL.

According to the above-described embodiment, when the motor 6 is started, the servo motor control system is set to the open loop and the start PW is performed.
Since the motor 9 is started based on the set value of the M setting circuit 20 and then accelerated to the target speed by speed feedback control, it is possible to perform a reliable start while suppressing unnecessary power consumption. In addition, the speed feedback control is performed until the time when the speed variation from the acceleration region to the constant speed region reaches a substantially predetermined value, and then the position feedback control is performed until the time when the speed shifts to the deceleration operation. The time can be shortened.

FIG. 7 shows various motors used in the copying machine. In this copying machine, when applied to the control of the platen belt motor 31 for automatically feeding the original onto the platen 29 via the platen belt 30,
When applied to the control of the carriage motor 33 that drives the exposure lamp 32 that exposes the original on the platen 30, the speed profile shown in FIG. In the case of applying to the control of the main drive motor 37 that drives the photosensitive belt 35 that receives the exposure of the reflected light of the original through the optical system 34 and receives the toner development by the developing devices 36a and 36b with the speed profile as the target. , Targeting the speed profile shown in (c) of Fig. 8, the start-up control is executed at the start of each motor, and the speed feedback control is executed until the speed fluctuation from the acceleration range to the constant speed range converges after that. It suffices to execute the position feedback control. This can contribute to downsizing of the copying machine and improvement of productivity.

[0029]

As described above, according to the motor speed and position control device of the present invention, the speed feedback control is switched to the position feedback control after the speed fluctuation of the motor in the constant speed region becomes a predetermined value or less. Therefore, it is possible to shorten the time required to converge to the target speed. Further, at the start of the motor start, the feedback control is prohibited until a predetermined time within the acceleration region, the motor is driven based on the preset speed command value, and then the speed feedback control is performed. The motor can be started smoothly and surely while suppressing wasteful power consumption.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between control timing and speed in a motor operating process according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a counting method of a counter circuit according to an embodiment of the present invention.

FIG. 4 is a flowchart showing speed control according to an embodiment of the present invention.

FIG. 5 is a flowchart showing speed feedback control according to an embodiment of the present invention.

FIG. 6 is a flowchart showing position feedback control according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing various motors of a copying machine to which the present invention is applicable.

8 is a graph showing a speed profile of each motor shown in FIG.

FIG. 9 is an explanatory diagram showing a relationship between control timing and speed in a motor operation process of a conventional motor speed and position control device.

[Explanation of symbols]

 1 Control Section 2 AND Circuit 3 Short Circuit Prevention Circuit 4 Current Limiting Circuit 5 Driving Circuit 6 Motor 7 Encoder 8 Interface Circuit 9 ROM 10 RAM 11 Edge Detection Circuit 12 Clock Generation Circuit 13 Counter Circuit 14 Memory 15 Timer Circuit 16 Sampler 17 Computing Section 18 Start PWM setting circuit 19 PWM output circuit 20 Enable signal output circuit 21 Speed data calculation circuit 22 Reference speed setting circuit 23 Subtractor 24 Speed compensation calculation circuit 25 Position data calculation circuit 26 Reference position setting circuit 27 Subtractor 28 Position compensation calculation circuit 29 Platen 30 Platen Belt 31 Platen Belt Motor 32 Exposure Lamp 33 Carriage Motor 34 Optical System 35 Photosensitive Belt 36 Developer 37 Main Drive Motor

Claims (3)

[Claims] 1. A motor speed and position control device for controlling the speed and position of the motor based on an encoder pulse having a cycle corresponding to the speed output from an encoder provided in the motor, wherein each cycle of the encoder pulse A speed error calculating means for counting clocks over a continuous predetermined cycle of the encoder pulse at a predetermined timing to calculate a speed of the motor, and comparing the speed with a reference speed to calculate a speed error; Position error calculating means for calculating the position of the motor by counting encoder pulses and performing a predetermined calculation, and comparing this with a reference position to calculate a position error, the speed error or the position error Driving means for driving the motor by outputting a driving signal having a pulse width modulation degree according to The control means includes a control means for executing a speed feedback control or a position feedback control by controlling the drive means to output the drive signal, and the control means, after the start of the start of the motor, exceeds the acceleration region of the motor. A speed and position control device for a motor, characterized in that the speed feedback control is executed until a predetermined time in a speed range, and then the position feedback control is executed in the remaining constant speed range. 2. The motor speed and position control device according to claim 1, wherein the predetermined time in the constant speed region is a time when the speed fluctuation of the motor reaches a predetermined value. 3. The control means prohibits the speed feedback control and the position feedback control from a time when the motor is stopped to a predetermined time within the acceleration region,
2. The motor speed and position control device according to claim 1, wherein the motor is started based on a speed command value set for starting the motor.