JPH06225592A - Controller for stepping motor - Google Patents

Abstract

PURPOSE:To eliminate a low speed initial conduction state by providing initial number-of-steps storage means for storing number of steps at the time of inter ruption in the case of the interruption at the time of stopping the conduction or number of correcting steps in the case of no interruption as number of steps at the time of restarting next conduction. CONSTITUTION:When a slowing-down control is executed based on a reference position reset signal E1, synchronous movement interruption deciding means H is started to decide whether an object C is synchronized with switching of an exciting phase or not, and at the time of interruption, number of steps in the case of interruption is stored in initial number-of-steps storage means M by interruption time number-of-steps counting means I. On the other hand, in the case of no interruption, number of steps at the time of stop of conduction is stored in conduction stop time number-of-steps storage means J, further number of deviated steps thereafter is counted by number of deviated steps count K, number of steps corresponding to that when the object C is reset to a reference position by number-of-corrected steps count means L is counted, and stored in the means M.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is biased by a biasing means such as a spring toward a reference position such as a fully open or fully closed position such as a throttle valve for adjusting an intake air amount of an engine. The present invention relates to a control device for a step motor used to move an object against its urging force.

[0002]

2. Description of the Related Art When an object is moved by a step motor, if the position of the rotor or the object does not change while the energization of the step motor is stopped, the energization is restarted in the excitation phase when the energization is stopped. The rotor and the excitation phase are in synchronization with each other from the start of energization, and the object is moved in synchronization with the switching of the excitation phase. However, for example, in the case where the valve is biased toward the reference position, such as a throttle valve, the rotor and objects move while the energization is stopped, and the energization is restarted in the excitation phase when the energization is stopped. But it doesn't sync right away.

If the positional relationship between the reference position and the step motor is accurately known, the excitation phase synchronized with the object at the reference position can be accurately determined. Therefore, by starting the energization in this excitation phase, immediately after the start of the energization. You should be able to ensure synchronization from. However, in reality, the excitation phase that synchronizes with the reference position is often unknown, and even if the excitation phase is synchronized at one time (for example, even when it is synchronized with the factory), the reference position shifts due to the secular change thereafter. Or, the backlash or the like of the gear train mechanically linking the object and the step motor may change, and the gears may not be synchronized in the planned excitation phase.

Therefore, the techniques disclosed in Japanese Patent Publication No. 57-54613 and Japanese Patent Laid-Open No. 1-259793 are known. In the former case, the excitation phase is switched at relatively long intervals until a predetermined time has elapsed after the start of energization. In the latter case, the excitation phase switching time interval is kept long until the excitation phase completes one cycle. In these technologies, the excitation phase switching time interval is secured long so that sufficient torque is generated to move the rotor, object, etc., and synchronization is secured while switching the excitation phase at long intervals. I am trying to do it.

[0005]

However, in these techniques, the excitation phase is switched at a long time interval for a predetermined time or until the excitation phase completes one cycle, so that the rotation of the step motor is not speeded up during that period. . Therefore, it is difficult to move the object with good responsiveness. Therefore, in the present invention, the synchronization of the excitation phase with the object or the rotor is secured from the start of energization, and the low-speed initial energization state required for synchronizing the excitation phase with the object or the rotor, that is, the excitation phase is set at a long time interval. The present invention proposes a step motor control device that can eliminate the need for switching the energized state.

[0006]

Therefore, according to the present invention,
We created a step motor controller whose concept is schematically shown in Fig. 1 (a). The control device for the step motor controls the step motor D based on the target step number instruction signal E to move the object C urged by the spring B or the like toward the reference position (for example, the position where the stopper A contacts). Object position detecting means G for detecting the existing position of the object C by the number of steps of the step motor D.
When the step-by-step excitation phase switching means F for sequentially switching the excitation phase following the step number change of the step motor D and the target step number instruction signal E is the reference position return signal E1 for returning the object C to the reference position Then, the state in which the object C is moving in synchronism with the switching of the excitation phase is interrupted from the detection value by the object position detecting means G and the excitation phase switching timing by the step-by-step excitation phase switching means F. Whether or not there is a synchronous movement interruption determining means H, when the interruption is determined by the synchronous movement interruption determining means H, an interruption step number counting means I that counts the number of steps at that time, the synchronous movement interruption determining means When the interruption is not determined by H before energization is stopped, the energization stop step number storage means J for storing the number of steps when energization is stopped, energization stop A deviation step number counting means K for counting deviations in time and a step number after a lapse of a predetermined time, the number of steps stored in the energization stop step number storage means J, and the number of steps counted by the deviation step number counting means K. When the interruption is determined by the correction step number counting means L and the synchronous movement interruption determination means H, the step number of the interruption step number counting means I is set to the synchronization step When the movement interruption determination means H does not determine the interruption, it has an initial step number storage means M for storing the number of steps of the correction step number counting means L as the number of steps when the energization is restarted next time.

[0007]

When the target step number of the target step number instruction signal E is the step number when the object C is moved to the reference position (for example, the position where it abuts on the stopper A), that is, the signal for returning the object C to the reference position. If it is E1, FIG.
As shown by Mb in (b) or MC in FIG. 1 (c), the excitation phase is switched while the energization time per excitation phase is lengthened.
When the longest switching time is reached, the energization in that excitation phase is the last and the energization is stopped. The numbers in FIGS. 1 (b) and 1 (c) are values corresponding to the switching time intervals of the excitation phase. The smaller the number, the longer the switching time interval, and the slower the rotation speed of the step motor. The level "0" is the longest switching time interval. This is usually called slowdown control.

In this slowdown control, the level is "0".
Then, the object C located at the position synchronized with the excitation phase when becomes is exactly the reference position. However, this is not always what was intended, and as shown in FIG. 1 (b), the energization is stopped before the object C returns to the reference position,
Alternatively, as shown in FIG. 1C, the object C may return to the reference position during the switching of the excitation phase.

In the former case, the object C moves while the energization is stopped, and when the amount of movement is equal to or more than 1/2 cycle of the excitation phase, the energization is restarted even if the energization is resumed in the excitation phase when the energization is stopped. The first excitation phase and the object position are not synchronized. In the latter case, since the movement of the object is prohibited before reaching the position corresponding to the excitation phase when the energization is stopped, even if the energization is restarted in the excitation phase when the energization is stopped, the first excitation phase and the object The position is not synchronized.

According to the present invention, when the slowdown control is executed on the basis of the reference position return signal E1, the synchronous movement interruption determining means H is activated and the object C is in a state of being synchronized with the switching of the excitation phase, or Determine if the state was interrupted. As shown in FIG. 1 (b), if the object C can move freely until the power supply is stopped, no interruption occurs. On the other hand, if the movement of the object C is restricted before the power supply is stopped as shown in FIG. 1 (c), the interruption occurs. That is, the synchronous movement interruption determining means H is shown in FIG.
Execute the case classification of (c).

As a result, in the case of "interruption occurrence" shown in FIG. 1C, the interruption step number counting means I causes the number of steps at interruption (in the case of FIG. 1C, when the speed level is "1"). Is stored,
This is stored in the initial step number storage means M. On the other hand, in the case of "without interruption" shown in FIG. 1 (b), first, the number of steps when energization is stopped is stored in the energization stop step number storage means J, and the deviation step number after that is stored by the deviation step number counting means K. Is counted. Here, the deviation step number DS is equal to the deviation between the step number when the energization is stopped and the step number when the object C reaches the reference position, as shown in FIG. 1 (b). Therefore, the correction step number counting means L counts the number of steps corresponding to when the object C returns to the reference position. In this case, this step number is stored in the initial step number storage means M.

At the next start of energization, energization is restarted in the excitation phase corresponding to the number of steps stored in the initial step number storage means M. This excitation phase is in a relationship of synchronizing with the object returning to the reference position, as indicated by Nb in FIG. 1 (b) or NC in FIG. 1 (c). Therefore, according to the present invention, the synchronization between the object and the excitation phase is secured from the start of reenergization, and the step motor can be speeded up quickly.

[0013]

As described above, according to the present invention, the stepping motor can be quickly accelerated and the position of the object can be tracked with good time responsiveness. Therefore, when the present invention is applied to the step motor for opening and closing the throttle valve, the response of the engine is improved.

[0014]

FIG. 2 shows a system configuration of an embodiment in which the present invention is applied to an engine traction control system. Reference numeral 2 in the figure denotes an engine, and a main throttle valve 8 is attached to an intake pipe 6 thereof. The main throttle valve 8 is mechanically linked to an accelerator pedal (not shown) and rotates according to the amount of depression of the accelerator pedal. A sub-throttle valve 12 is incorporated in the intake pipe 6 for traction control of the engine 2. The sub-throttle valve 12 is biased to the fully open position by a spring (not shown). When a wheel slips, it is used to reduce the passage area of the intake passage 6 and eliminate the slip. The sub-throttle valve 12 is rotated by the step motor 10. That is, in this embodiment, the sub throttle valve 12 is an object that is moved by the step motor 10. A throttle sensor 4 is attached to the shaft of the sub-throttle valve 12, and the opening degree of the sub-throttle valve 12, that is, the position where an object moved by the step motor 10 exists can be detected.

The detection signal of the throttle sensor 4 can be input to the CPU 26 via the input interface 24. In addition, the detection signal of the sensor 14 for detecting the accelerator opening and the detection signal of the sensor 16 for detecting the wheel speed can be input to the CPU 26 via the input interface 24. The CPU 26 has a ROM 28 and a RAM 3
0 is connected to form a microcomputer system 20. In addition, a drive circuit 22 is connected to the CPU 26, and the step circuit 10 is driven by the drive circuit 22.

In the case of this embodiment, the step motor 10 is of a four-phase type, which is used for 1-2 phase excitation.
That is, for each phase of the step motor 10, the excitation phase is sequentially switched according to the excitation phase pattern shown in FIG. In order to move the sub-throttle valve 12 from the fully opened position to the closed side, the excitation phase pattern is switched in the order of 7 → ... → 0 → 7 →.

In this embodiment, a program for causing the CPU 26 to execute the processes of FIGS. 4 and 5 is stored in the ROM 28. In the processing of FIG. 4, the target opening of the sub-throttle valve 12 calculated by the CPU 26 based on the values of the sensor 14 for detecting the opening of the accelerator and the sensor 16 for detecting the speed of the wheels is different from the current opening. When interrupt is executed,
After that, it is arranged that an interrupt is executed every time the time set in steps S20, S9, etc. elapses.

Prior to describing the process of FIG. 4, the MSPD used in the process will be described. MSPD
Is a value that determines the switching time interval of the excitation phase, and takes any value from level 0 to level 8. When the level is 0, the switching time interval is the longest, and the step motor 10 is driven in the lowest speed and maximum torque state. At level 8, the switching time interval is the shortest, and the step motor 10 is driven in the maximum speed / minimum torque state. As long as the rotor and the object can move to the position corresponding to the excitation phase, that is, unless the stopper that restricts the fully open position prohibits further movement, the level 0 time interval corresponds to the position corresponding to the excitation phase. It is a time interval in which an object can be moved. The time intervals of level 2 and above are not so long as to synchronize non-synchronized objects, although the synchronized state can be maintained if the object and the rotor are synchronized. These levels are the levels used during accelerated energization.

Now, when the target opening of the sub-throttle valve 12 is different from the current opening, the processing of FIG. 4 is first executed. At this time, it is determined in step S1 whether the check request flag is "1". As will be apparent from the description below, the check request flag is normally "0", and is also "0" when the target opening and the current opening do not match and the step motor 10 starts moving. Therefore, in this case, the process proceeds to step S2.

A step S2 decides whether or not the target number of steps is the reference number of steps SINT. Here, the target number of steps is calculated and calculated by the CPU 26 based on the values of the accelerator opening sensor 14 and the wheel speed sensor 16. Although this calculation is executed by the CPU 26, the calculation process itself is irrelevant to the control of the step motor, and as for the step motor control procedure shown in FIG. 4, the target number of steps is instructed by another processing procedure. is there. Target step number instruction signal E shown in FIG. 1 (a)
Indicates the data of the target number of steps used in step S2 or S3 of FIG. 4, and in the case of this embodiment, the target number of steps is also calculated by the same CPU 26 as the CPU that executes the control of the step motor. is there. The reference step number SINT is Pb in FIG. 1 (b) or FIG.
It is the number of steps exemplified in the PC of (c), and is the number of steps that should return the sub-throttle valve 12 to the fully open position (reference position). However, in many cases, the reference step number SINT and the reference position do not correspond accurately due to aging. This reference step number SINT
Learns in steps S13 to S22 as described below.
It has been updated and modified so that the number of steps corresponds well to the reference position.

When the result of step S2 is YES, the target number of steps is the number of steps for returning the sub-throttle valve 12 to the reference position (fully open position), and corresponds to the case where the reference position return signal E1 is input. On the other hand, the case of No corresponds to the case where the sub-throttle valve 12 is set to a predetermined closing angle. In the latter case, step S3 in FIG.
The step motor 12 is driven so that the specified number of steps is achieved. Details of the control procedure at this time are shown in FIG. This will be described later.

When step S2 is YES, that is, while the reference position return signal E1 is being input, step S2
Go to 4. A step S4 decides whether or not the current step number STEP of the step motor 12 is a predetermined value or more. As illustrated in FIGS. 1B and 1C, in this embodiment, the sub-throttle valve 12 increases as the step number STEP increases.
Have a large opening relationship. The predetermined value is the number of steps by which the sub-throttle valve 12 should be very close to the reference position (fully open position). To be more precise, the maximum number of steps that can be taken under the condition that the sub-throttle valve 12 will not be fully opened with the number of steps equal to or less than the predetermined value even if aging and component tolerance are taken into consideration. Has been done.

If the answer in step S4 is NO, that is, if the sub-throttle valve 12 has not yet approached full opening, the operation proceeds to step S5. Step S5 is a step of determining the level value of the speed level MSPD that determines the switching time interval of the excitation phase, and is the step number of the current step number and the target step number (in this case, the step number corresponding to a predetermined value that is very close to the fully open position). While the difference is large, the speed level MSPD is increased by 1 each time step S5 is executed (however, the maximum value of MSPD is 8 as described above, so 8 is maintained when 8 is reached), while the sub-throttle valve 12 When the difference between the current step number and the predetermined value becomes smaller as the value approaches the predetermined value, the speed level MSPD is decreased by 1 each time step S5 is executed, and when the difference between the current step number and the predetermined value is zero, the speed is just increased. Level is “zero”
The value of MSPD is set so that Note that this is a technique known as slow-up / slow-down control, and detailed description thereof will be omitted.

If the current number of steps is less than the predetermined value, the process proceeds to step S6 after the process of step S5 is completed. In step S6, the current opening degree of the sub-throttle valve 12, that is, the opening degree of the sub-throttle valve 12 before the excitation executed in step S8 is stored as TA. Then, step STEP is updated so that the current number of steps is stored in a variable called STEP. Then, in step S8, the excitation in the excitation phase corresponding to the step number STEP is started. The value of STEP changes by one each time step S7 is executed. Since the excitation phase is defined by the lower 3 bits of the STEP value, the excitation phase pattern of FIG. 3 is sequentially switched every time step S8 is executed. That is, steps S7 and S8 and the like constitute a means for sequentially switching the excitation phase for each step.

When energization to one excitation phase is started in step S8, then the speed level MSP at that time is started.
After the time determined by D, the process of FIG. 4 is arranged to be interrupted again (step S9), and the process is temporarily terminated while the energization to the excitation phase is continued.

After the time determined by the MSPD, the processing of FIG. 4 is executed again, but at that time, the processing of steps S5, S7, and S8 is repeated in the case of NO at step S4. That is, the excitation phases are sequentially switched, and the switching time interval is gradually extended as it approaches the fully open position. And while repeating this, step S4 becomes YES.

If the answer in step S4 is YES, that is, if the sub-throttle valve 12 is very close to the fully open position, step S10 is executed. In step S10, the difference between the current throttle opening and the previous throttle opening stored in step S6 when the processing of FIG. 4 is executed last time is compared with a predetermined value. Here, the predetermined value is the excitation phase. Is about 1/2 of the opening change amount when one phase is switched. That is, if the sub-throttle valve 12 is rotating in synchronism with the switching of its excitation phase due to the excitation executed in step S8 when the processing of FIG. 4 was executed last time, step S10 becomes YES and the sub-throttle valve 12 is turned on. If it does not follow the switching of the excitation phase, it will be NO. That is, this step S10 executes a process for judging whether the synchronous movement of the object is maintained or interrupted, and corresponds to the synchronous movement interruption judging means H.

When the step S10 is NO, that is, when the synchronous movement interruption judging means H judges "the interruption is present" (the case of FIG. 1C corresponds to that case), the step S
13, the current number of steps, that is, the number of steps S at the time of interruption
The TEP is called (this step corresponds to the step number counting means I at the time of interruption), and this is input to the reference step number SINT. Here, the value of SINT is the number of steps for determining the first excitation phase at the time of restarting the next energization, and the variable SINT indicates the number of steps at the time of restarting the next energization, as will be understood in step S306 in FIG. 5 described later. It is utilized as the initial step number storage means M to be stored. Next step S1
In step 4, the flag indicating that learning has been completed is set to "1", the energization is stopped in step S15, and the interrupt is disabled in step S16. In this state, until the current step number and the target step number do not match,
Is not executed.

In the case shown in FIG. 1 (b), step S10 does not become negative. So in this case,
Step S11 is executed. In step S11, it is determined whether or not the current number of steps matches the reference number of steps. While the determination is NO, the speed level MSPD is set to zero and the excitation phase switching time interval is maximized in step S12. Then, in this state, steps S7, S8, etc. are executed so that the actual number of steps becomes the target number of steps at the lowest speed. While repeating the process, step S1
1 becomes yes. In this case, as shown in FIG. 1 (b), the reference step number is reached before the sub-throttle valve 12 is fully opened, and it is necessary to calculate the deviation. Therefore, "1" is added to the flag indicating that it is necessary to check the number of deviation steps.
Is set (step S18), the energization is stopped (step S19), and the process of FIG. 4 is executed again after a predetermined time (step S20). Here, this predetermined time is the time required for the sub-throttle valve 12 rotated to the reference step number to be opened to the fully open position by the spring force, as shown in FIG. 1 (b). The current throttle opening is stored in TA prior to the stop of energization (step S17). This corresponds to a concrete example of the step number storage means J when the energization is stopped.

After this time has elapsed, step S1 becomes YES when the process of FIG. 4 is executed next.
In this case, when the process of FIG. 4 was executed last time, step S
The throttle opening stored in 17 (this is detected by the number of steps) and the sub-throttle valve 1
2. Find the difference from the opening after moving 2 to the fully open position and set this to D
S (step S21). The DS calculated in this manner corresponds to a difference in the number of steps between when the energization is stopped and when the sub-throttle valve 12 is in the fully open position after a predetermined time has passed since the energization was stopped.
21 corresponds to the deviation step number counting means K.

Next, D is added to the step number STEP when the energization is stopped.
S is added and stored as a new reference step number SINT (step S22). The addition step on the right side of step S22 corresponds to the corrected step number counting means L, and by storing this in the reference step number SINT, the corrected reference step number is stored in the initial step number storage means M. .

After the above processing is completed, the reference step number SI
"1" is set to the flag indicating that NT has been updated (step S23), and the check request flag is "0".
(Step S24), and the interruption is not permitted (step S25). As a result, the process of FIG. 4 is temporarily suspended until the current number of steps and the target number of steps do not match.

When the wheels begin to slip after the sub-throttle valve 12 returns to the fully open position in this way, the target opening degree of the sub-throttle valve 12 becomes the closed step number. Therefore, the process of FIG. 4 is executed again. At this time, step S1 is NO, step S2 is NO, and step S3 is executed. The details of this step S3 are shown in FIG.

In step S301, it is determined whether energization is resumed while the sub-throttle valve 12 is returned to the fully open position and energization of the step motor is stopped, or energization has already been started. Yes when slip occurs and traction control starts. Next, in step S302, it is determined whether the learned flag is "1". The learned flag is set to "1" in steps S14 and S23 of FIG. That is, the reference number of steps SI is determined by steps S13 and S22.
When NT is updated as a result of learning, "1" is "0" among unlearned. Counter SCN if learned
T is set to zero, and SCNT is set to 7 when unlearned (steps S303 and 304). Next, MSPD is set to zero (step S305) to maximize the energization time per phase. Next, the number of steps is set as the reference number of steps SINT (step S306). Then, the excitation phase corresponding to the number of steps is determined, and energization is started (step S31
2) After the time corresponding to the speed level MSPD (zero in this case), the processing of FIG. 5 is executed again. As a result, if the reference step number SINT has been updated, the sub-throttle valve 12 and the excitation phase are synchronized with each other in the first excitation phase.

When the time corresponding to MSPD = 0 has elapsed, the processing of FIG. 5 is executed again. In this case, step S3
01 is NO, and step S307 is step S307.
No only if 304 is executed. That is, steps S308 and 309 are executed only when the energization is restarted using the unlearned reference step number SINT, and in other cases, step S310 is executed. Step S
308 is to maintain the speed level at "1" in order to execute the low-speed initial energization. And step S30
Excitation at speed level “1” is 7 by 9 and 307
It will be repeated. Here, speed level "1"
Excitation is a state in which a sufficient torque is generated to rotate the sub-throttle valve 12, and even if the reference step number SINT is deviated, synchronization is secured during the excitation of the speed level "1" seven times. I am trying to do it. That is, the unlearned SINT is subjected to the low-speed initial energization similar to the conventional technique.

After step S303 is executed, that is, when SINT has been learned, step S307 becomes YES from the beginning, and step S308 is skipped. Instead, step S310 is executed. Step S310 is similar to step S5 of FIG. 4, and performs slow-up / slow-down control.

As a result of this processing, (1) If the reference step number SINT has been learned, energization is started in the excitation phase determined by the SINT when reenergization is started, and acceleration is started immediately thereafter. (2) On the other hand, if the reference step number SINT is unlearned, energization is started in the excitation phase determined by the predetermined reference step number SINT, then low-speed initial energization is executed until the excitation phase completes one cycle, and then It will accelerate.

FIG. 6 and FIG. 7 show changes in the excitation phase according to this embodiment, both of which are the reference step number SINT.
This is the case when has been learned. FIG. 6 is a case corresponding to FIG. 1 (c). If the reference step number SINT has not been learned and updated, the sub-throttle valve 12 starts to move at the excitation phase of Q during the low speed initial energization period, and the low speed After the timing R at which the initial energization ends, the motor is finally accelerated, whereas when the reference step number SINT is learned, synchronization is secured immediately after that and the motor is immediately accelerated.

On the other hand, FIG. 7 shows a case corresponding to FIG. 1 (b). In this case, in the conventional technique, the sub-throttle valve can be synchronized in the first excitation phase. However, in this case, it is necessary to move the sub-throttle valve relatively large to obtain synchronization, and the energization time of the first excitation phase, that is, the time corresponding to MSPD = 0 is required to be long (this is illustrated as O (old) in the figure. Has been).

On the other hand, according to the present embodiment, since the reference step number SINT is learned and updated, it is guaranteed that the sub-throttle valve will be in the synchronized state even if the sub-throttle valve is slightly moved. The energization time of the phase is also short (this is described as 0). In addition to this, naturally, the presence or absence of low-speed initial energization also differs. In this way, according to the present embodiment, the step motor is accelerated with the synchronous state quickly obtained without unnecessary initial energization, and the responsiveness of the sub-throttle valve is greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the concept of the present invention.

FIG. 2 is a diagram showing a system configuration of an embodiment.

FIG. 3 is a diagram showing an excitation phase pattern.

FIG. 4 is a diagram showing a processing procedure.

FIG. 5 is a diagram showing details of part of a processing procedure.

FIG. 6 is a diagram showing an example of a processing result.

FIG. 7 is a diagram showing another example of the processing result.

[Explanation of symbols]

 D: Step motor E: Target step number instruction signal E1: Reference position return signal F: Step-by-step excitation phase switching means G: Object position detection means H: Synchronous movement interruption determination means I: Interruption step number counting means J: Energization stop Hour step number storage means K: Deviation step number count means L: Corrected step number count means M: Initial step number storage means

Claims (1)

[Claims] 1. A step motor control device for moving an object urged toward a reference position based on a target step number instruction signal, wherein the existing position of the object is detected by the step number of the step motor. Object position detection means, step-by-step excitation phase switching means for sequentially switching the excitation phase following changes in the step number of the step motor, when the target step number instruction signal is a reference position return signal for returning the object to the reference position Whether the state in which the object is moving in synchronism with the switching of the excitation phase is interrupted based on the detection value by the object position detection means and the excitation phase switching timing by the step-by-step excitation phase switching means. And a synchronous movement interruption determining means for determining whether the interruption is determined by the synchronous movement interruption determining means, and counts the number of steps at that time. An interruption step number counting means, an energization step number storage means for storing the number of steps when the energization is stopped when the interruption is not determined by the synchronous movement interruption determination means before the energization is stopped, when the energization is stopped and for a predetermined time Deviation step number counting means for counting deviation of step number after elapse, step after the predetermined time has elapsed from the number of steps stored in the energization stop step number storage means and the number of steps counted by the deviation step number counting means A correction step number counting means for counting the number, when the synchronous movement interruption determining means determines interruption, the step number of the interruption step number counting means is not determined by the synchronous movement interruption determining means. In this case, the step number of the correction step number counting means is set to Initial step number storage means for storing as a flop number, the control device of the stepping motor and having a city.