JPH06343298A - Stepping motor controller - Google Patents

Abstract

PURPOSE:To provide a stepping motor controller which allows a stepping motor to follow a target value rapidly and accurately when the stepping motor starts up. CONSTITUTION:A stepping motor controller 17 is provided with a stepping motor accelerating and reducing program 25 which calculates a difference between a set target value TSTEP and a current position of a stepping motor 15 and then accelerates or reduces the stepping motor according to the difference and stops the stepping motor at the set target value and a start-up command discrimination program 27 which discriminates that a command has been issued to start up the stepping motor 15 from a shutdown state when there is a change in the set target value which has been kept at a constant value. This controller also has a start up delay program 28 which allows the stepping motor 15 to be started up by the stepping motor accelerating and reducing program 25 after the passage of a specified delay time TD.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor control device for rapidly accelerating and decelerating a step motor to a target stop position that changes when the target stop position of the step motor changes momentarily. Relates to a step motor control device for promptly starting a step motor.

[0002]

2. Description of the Related Art In recent years, a method of electronically controlling a throttle valve of an automobile engine by a step motor has been implemented, and a step motor control device for controlling driving and stopping of the step motor is widely used in automobiles. . Here, since it is necessary to control the opening / closing amount of the throttle valve by following the depression amount of the accelerator,
The step motor control device measures the amount of depression of the accelerator as analog data with a potentiometer or the like, samples the measured value of the potentiometer at a constant interval, A / D-converts the target value, and sets the step motor according to the target value. By controlling the stop position, the opening / closing amount of the throttle valve is controlled.

Controlling the stop position of the step motor in order to control the opening / closing amount of the throttle valve differs from a normal step motor control device in the following points. That is, the amount of depression of the accelerator changes from moment to moment depending on the operating state of the vehicle, and control of the opening / closing amount of the throttle valve with respect to the amount of depression of the accelerator also requires prompt responsiveness. However, a normal step motor control device does not change the target stop position within a short time, so the step motor is driven according to a preset speed pattern to the target stop position of the step motor, and the accuracy is improved. The focus was on stopping often.

With a growing demand for electronically controlling the amount of depression of the accelerator by using a step motor, a method of controlling the step motor used for opening and closing the throttle valve is disclosed in, for example, Japanese Patent Laid-Open No. 61-1388.
Japanese Patent No. 55 discloses a method of comparing the target value instructed by the accelerator with the current value of the step motor and controlling the rotation speed of the step motor according to the table stored in the storage means when the values differ. There is.

[0005]

However, the conventional step motor control device has the following problems. The step motor control device samples a potentiometer that measures the amount of depression of the accelerator at regular sampling times to bring the step motor closer to the sampled target value, and to stop the step motor when the target value becomes constant. It is carried out. And
In order to quickly rotate the step motor to the target value,
Control is usually performed in which an acceleration / deceleration cycle is performed in which acceleration is rapidly performed at the start of rotation and deceleration is performed when the target value is approached. Here, in general, the accelerator is first depressed gradually, and then the depression amount is rapidly increased in many cases. This is in order to confirm that the driver's psychology does not mistake the brake and the accelerator.

A specific control method at the start of accelerator depression in the conventional step motor control device will be described with reference to FIG. In the figure, A indicates a value obtained by measuring the accelerator depression amount as analog data with a potentiometer. Further, TSTEP indicates a change in the target value obtained by sampling the accelerator data A at a constant sampling time S and performing A / D conversion. Here, the sampling time S is generally about 6 msec (hereinafter referred to as ms) because the CPU in charge of the main control of the vehicle controls various devices at the same time. Therefore, the accelerator depression start timing and the sampling timing are not always synchronized. Therefore, in the first sampling after the accelerator change, the change amount may be smaller than the actual change amount per time. STEP indicates the current step of the step motor. Also MS
PD indicates the condition of the drive pulse given to the step motor, and is specifically given as the drive frequency and the excitation time. Here, the drive frequency given to the step motor and its excitation time are given from the difference between the current position of the step motor and the target value, for example, using a table as shown in FIG.

That is, since the sampling program always samples the accelerator data A at the sampling interval S = 6 ms, TSTEP = 2 is read at the time t1. When TSTEP changes, the step motor is accelerated to MSPD = 1 and started in a direction to eliminate the difference DSTEP between the current position of the step motor and the target value. Since TSTEP is close, the step motor is stopped when STEP = TSTEP. Then, once the step motor is stopped, it is necessary to wait for a certain stop time B before it is restarted. Therefore, although the accelerator data A is rapidly increasing, the follow-up of STEP is greatly delayed and the throttle valve There was a problem that the car could not be controlled quickly according to the driver's intention, and the speed of the car could not be increased quickly. Once the step motor is stopped, it is necessary to wait a certain stop time B before restarting. The reason for this is that when the step motor is stopped, vibration occurs due to inertia of the drive system such as the throttle valve. This is because the step motor may step out if restarted. With the step motor shown in FIG. 6, about 20 m
There is a s stoppage time.

The present invention has been made to solve the above problems, and when the step motor is started,
An object of the present invention is to provide a step motor control device that can quickly and accurately follow a target value.

[0009]

In order to achieve this object, a step motor control device of the present invention calculates a difference between a set target value and the current position of the step motor, and accelerates the step motor according to the difference. And a step motor acceleration / deceleration means for decelerating the step motor when approaching the set target value and stopping the step motor at the set target value, the set target being held at a constant value. When there is a change in the value, a start command determination means for determining that there is a command to start the step motor from a stopped state, and a predetermined delay when the start command determination means determines that there is a start command for the step motor After a lapse of time, the stepping motor accelerating / decelerating means starts up the stepping motor. Further, in the above step motor control device, there is a sampling means for sampling a set target value that changes with the passage of time at a constant sampling time, and the activation delay means has the sampled set target value and the constant value. The difference from the position is calculated, and the activation delay time is changed according to the difference.

[0010]

The step motor of the present invention having such a structure drives the throttle valve of the engine through the drive system. Further, the sampling means of the step motor control device samples a set target value from the potentiometer, which measures the amount of depression of the accelerator, which changes with the passage of time, at a constant sampling time. Further, the step motor acceleration / deceleration means calculates the difference between the sampled set target value and the current position of the step motor, accelerates the step motor according to the difference, and sets the current position of the step motor to the set target value. When approaching, the step motor is decelerated and stopped at the set target value.

The start command determination means determines that there is a command to start the step motor from the stopped state when the set target value at the fixed position changes. Further, the start delay means causes the step motor acceleration / deceleration means to start the step motor after a predetermined delay time has elapsed when the start instruction determination means determines that the step motor start instruction has been issued. Here, the activation delay means calculates a difference between the sampled set target value and the fixed position, and changes the activation delay time according to the difference.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the step motor control device 17 according to the first embodiment. An intake pipe 13 for inhaling a mixed gas of gasoline and air is connected to an automobile gasoline engine 11. A throttle valve 12 for adjusting the amount of mixed gas supplied to the gasoline engine 11 is held in the intake pipe 13 so as to be rotatable about a throttle shaft 14 with respect to the intake pipe 13. The throttle shaft 14 is connected to the output shaft of the step motor 15 via a reduction mechanism. The step motor 15 is connected to the step motor drive circuit 18 of the step motor controller 17. Drive circuit 18
Is connected to the CPU 19, which is an arithmetic unit. CPU
A RAM 2 for temporarily storing data etc. in 19
3. A ROM 22 storing a control program and the like is connected.

The ROM 22 has a sampling program 24 for sampling the accelerator data measured by the potentiometer 16 at a constant sampling time T.
Is remembered. In addition, the ROM 22 calculates the difference between the sampled value and the current position of the step motor, accelerates the step motor 15 via the drive circuit 18 according to the difference, and the step motor 15 approaches the sampled value. A step motor acceleration / deceleration program 25 for decelerating the step motor 15 and stopping the step motor 15 at a sampling value is stored.

Further, the ROM 22 stores a start instruction determination program 27 for determining that a start instruction has been issued to the step motor 15 for driving the throttle valve 12 due to a change in the amount of depression of the accelerator 26 from zero. The start instruction determination program 27, even when the accelerator 26 changes after being held constant for a certain time or more,
It is determined that the stepping command is issued to the step motor 15. The ROM 22 also stores an activation delay program 28 that delays execution of the step motor acceleration / deceleration program 25 for a predetermined time when the step motor 15 that drives the throttle valve 12 is activated. Also, CPU
Reference numeral 19 indicates A for A / D conversion of accelerator data A which is analog data measured by the potentiometer 16.
The / D converter 20 is connected. The A / D converter 20 is connected to the accelerator 2 via the input interface 21.
Potentiometer 16 for measuring the depression amount of 6
Connected to.

Next, the operation of the step motor control device 17 having the above configuration will be described. When the accelerator 26 is operated by the driver, the potentiometer 16 measures the amount of movement of the accelerator 26 as linear analog data A. The CPU 19 fetches the analog data of the potentiometer 16 from the input interface 21 at every constant sampling time S by the sampling program 24, A / D converts it by the A / D converter 20, and RAM 23 as the sampled target value.
Remember. Here, in this embodiment, the sampling time is S = 6 ms, as in the conventional case.

FIG. 2 shows a diagram for explaining the control state of the step motor. In FIG. 2, TSTEP indicates the measurement value of the potentiometer 16 at the sampling time S = 6 m.
A value obtained by A / D conversion for each s, that is, a target step position at which the step motor 15 that drives the throttle valve 12 should be stopped is shown. STEP indicates the current step position of the step motor 15. Also MSP
D indicates the condition of the drive pulse given to the step motor, and specifically, as shown in FIG. 5, it is given as the drive frequency and the excitation time.

A method of accelerating and decelerating the step motor 15 will be described. FIG. 3 shows a step motor acceleration / deceleration program 25 of the step motor control device 17 and a start command determination program 2
7 and the operation of the activation delay program 28 are shown in a flowchart. This flowchart is activated by the main program or by a timer interrupt when the step motor 15 completes one step operation. First, it is determined whether or not an output request flag that is set when the activation delay program 28 described later is executed is set. When the output request flag is not 1, (S1, N
O), proceed to S2. When the output request flag is 1 (S
1, YES), the output request flag is set to 0 (S11),
Proceed to S7.

The current step STEP of the step motor 15 is updated by one step toward the target step TSTEP (S2). Next, the difference D between the target step TSTEP and the step STEP at which the step motor 15 is present is
STEP is calculated, DSTEP is compared with the current speed MSPD of the step motor 15, and DSTEP> MSP
If D, increase MSPD by 1 to accelerate the step motor 15 (S3). If DSTEP <MSPD, MSPD.
Is decremented by 1 to decelerate the step motor 15 (S
3). If DSTEP = MSPD, constant speed is maintained without changing MSPD (S3). Next, step motor 1
It is determined whether or not No. 5 has been stopped for a certain period of time. That is, after MSPD = 0 is held for a certain period of time, it is determined to be activated when MSPD = 1 is changed this time (S4.
(YES), the process proceeds to S5.

Next, the delay time TD for delaying the activation of the step motor 15 is calculated (S5). When the amount of depression of the accelerator 26 is slow at the beginning, the first target value TSTEP is small, and if the step motor 15 reaches and stops immediately, it takes time to restart next, which is a problem. When the deviation between TSTEP and the current step is small, the long delay time TD is adopted, and when the deviation between the first target value TSTEP and the current step is large, it is not necessary to adopt the delay time TD.

More specifically, the delay time TD is set to TD = 6 ms in the same manner as the sampling time S = 6 ms when the deviation from the target set value TSTEP is one step. When the deviation is 2 steps, the excitation time when MSPD = 1 is 2 ms, so TD = 6-2 = 4 m
s. When the deviation is 3 steps, MSPD =
When 1 is set, the excitation time is 2 ms, and MSPD = 1 is repeated at a constant speed, so TD = 6-2 * 2 = 2 ms. When the deviation is 4, the excitation time is 2 ms when MSPD = 1, and the excitation time is 1.429 ms when MSPD = 2. The speed is reduced and MSPD = 1 is excited again, so TD = 6-2 * 2-1.429 = 0.
571 ms. If the deviation is 5 or more,
TD = 0 is set.

Next, when TD = 0, (S6, YE
S) and S7. When TD = 0 is not satisfied (S
6, NO), the output request flag is set to 1 (S9), TD
After delaying for a time, interrupt and return to S1 (S1
0). Next, in this embodiment, a 4-phase step motor is
Since the control is performed by the -2 phase excitation, the step motor 15 is driven at the drive frequency shown in FIG. 5 according to the pattern shown in FIG.
Is excited (S7). Here, by setting the excitation time shown in FIG. 5 as the interrupt time (S8),
Since the process proceeds to S1 again after the interruption time has elapsed, the step motor 15 is excited for the excitation time shown in FIG.

Next, the above flow chart will be described with reference to a concrete example. At the position of step ST1A in FIG. 2,
Since the output request flag is not set (S1, NO), S
Go to 2. Based on that step, ST
Since EP = 0, ST is updated by step updating.
EP = 1 (S2). Next, TSTEP = 2, ST
Since EP = 1, DSTEP = 1. And
Since MSPD = 0 and DSTEP = 2, DSTEP>
It becomes MSPD and the speed is increased with MSPD = 1 (S3).
Next, since MPSD has changed from 0 to 1, it is determined that a start command has been issued (S4, YES), and the delay time TD is calculated. That is, since the deviation between ST1A and TSTEP is 2, TD = 4 ms (S5). Next, TD =
Since it is not 0 (S6, NO), the output request flag is set to 1 (S9).

Next, the excitation of MSPD = 1 is delayed for TD = 4 ms (S10). That is, TD = 4 ms
After the lapse of time, the process proceeds to S1. Next, in ST1B, since the output request flag is set (S1, YES), the output request flag is set to 0 (S11), and the process proceeds to S7.

Next, the driving frequency shown in FIG. 5 is 500 pps.
Drive pulse is applied to the step motor 15 from the lower 3 bits of the step through the drive circuit 18 in a predetermined excitation pattern shown in FIG. 4 (S7). Next, after a lapse of time shown by the excitation time in FIG. 5, an interrupt is made and the process proceeds to S1. As a result, the drive pulse is applied for a time of 2.000 ms. Then, the current position step ST of the step motor
EP becomes ST2.

In the case of ST2, TSTEP = 7, DST
Since EP = 7-2 = 5, the speed is increased to MSPD = 2 (S3). Next, because it is not starting (S4, NO),
Proceed to S8. Next, since MSPD = 2, a drive pulse having a drive frequency of 700 pps is given according to FIG. 5 (S
7). Next, after a lapse of time shown by the excitation time in FIG. 5, an interrupt is made and the process proceeds to S1. As a result, the drive pulse is applied for 1.429 ms. Then, the current position step STEP of the step motor becomes ST3.

In the case of ST3, TSTEP = 7, DST
Since EP = 7-3 = 4, the speed is increased to MSPD = 3 (S3). Next, because it is not starting (S4, NO),
Proceed to S8. Next, since MSPD = 3, a drive pulse having a drive frequency of 843 pps is given according to FIG. 5 (S
7). Next, after a lapse of time shown by the excitation time in FIG. 5, an interrupt is made and the process proceeds to S1. As a result, the drive pulse is applied for 1.186 ms. Then, the current position step STEP of the step motor becomes ST4. In this way, 6m by the sampling program 24
At the target step TSTEP sampled every s,
At present, control is performed to sequentially bring the step STEP closer.

As described in detail above, according to the step motor controller of this embodiment, the first excitation is performed when the step motor 15 is started according to the target value obtained by sampling the depression amount of the accelerator 26. Since the application timing is delayed by the predetermined delay time TD, even if the depression amount of the accelerator 26 is small at the beginning, the step motor does not stop midway. Therefore, the throttle valve 12 is set according to the depression amount of the accelerator 26. It can be followed quickly and accurately.

Although the present invention has been described with reference to some embodiments, the present invention is not limited to the above embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. This can be easily guessed.
In the present embodiment, the control device for the step motor that drives the throttle valve has been described, but the present invention can be applied to other applications as long as the step motor quickly follows a target value that changes momentarily.

[0029]

As is apparent from the above description, according to the step motor control device of the present invention, when the set target value at the fixed position is changed, the step motor is started from the stopped state. Start command determining means for determining that there is a command to start the step motor, and when the start command determining means determines that there is a step motor starting command, the step motor acceleration / deceleration means starts the step motor after a predetermined delay time has elapsed. Since it has a starting delay means for starting, when the step motor is started, the timing for applying the first excitation is delayed by a predetermined delay time according to the sampled set target value. Even if the initial change in the value is small at the beginning, the step motor does not stop midway, so the step It can be quickly and accurately follow the data.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a step motor control device that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a control state of a step motor controlled by the step motor control device.

FIG. 3 is a flowchart showing an operation of the step motor control device.

FIG. 4 is a data diagram showing an excitation pattern of a step motor.

FIG. 5 is a data diagram showing drive pulses for acceleration / deceleration of a step motor.

FIG. 6 is an explanatory diagram showing a control state of a step motor controlled by a conventional step motor control device.

[Explanation of symbols]

 12 Throttle Valve 15 Step Motor 16 Potentiometer 17 Step Motor Controller 18 Drive Circuit 19 CPU 20 A / D Converter 24 Sampling Program 25 Step Motor Acceleration / Deceleration Program 27 Start Command Discrimination Program 28 Start Delay Program TD Delay Time

Claims (2)

[Claims] 1. A difference between a set target value and the current position of the step motor is calculated, the step motor is accelerated according to the difference, and the step motor is decelerated when the set target value is approached. In a step motor control device having a step motor acceleration / deceleration means for stopping the step motor, if there is a command to start the step motor from a stopped state when the set target value held at a constant value changes. A start command determining means for determining, and a start delay means for starting the step motor by the step motor accelerating / decelerating means after a predetermined delay time has elapsed when the start command determining means determines that there is a start command for the step motor. A stepping motor control device comprising: 2. The apparatus according to claim 1, further comprising sampling means for sampling a set target value that changes with time, at a constant sampling time, and the activation delay means includes the sampled setting. Step motor control means for calculating a difference between a target value and the fixed position, and changing the starting delay time according to the difference.