JP2827893B2 - Step motor drive controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a step motor used for driving an actuator for driving a control target in various control devices and the like.

[0002]

2. Description of the Related Art A step motor is widely used as a drive source for driving an actuator in various control devices, and is used for driving an actuator to a target position determined by a microprocessor or the like. Specifically, the output data calculated based on the difference between the obtained target position and the current position is stored in an output register or the like,
At a predetermined output timing, the value of this output register is read and a drive command for the step motor is output.

Here, in such a step motor drive circuit, there is no particular problem if the power supply voltage is normally maintained. However, if the power supply voltage falls below the minimum operation voltage of the step motor, In this case, even if a drive command is normally output from the microprocessor, the step motor is not driven, so that the step motor does not operate to the target position. For example, if the stepping motor is sampled by a timer interrupt and the stepping motor is driven between the previous interrupt and the current interrupt, and the power supply voltage falls below the minimum operating voltage of the stepping motor, the stepping motor will It is not known whether one step operation has been performed since output.

In order to cope with such a problem, the power supply voltage of the step motor is constantly monitored. For example, a cycle in which the power supply voltage falls below the minimum operating voltage of the step motor, a sampling cycle in the microprocessor, and the like. Are synchronized with each other, the voltage is normal at the time of the sampling timing, and if there is a drop in the power supply voltage during the sampling timing, this drop in the power supply voltage cannot be detected.

It is conceivable to shorten the sampling period in consideration of such a case. However, if the fluctuation of the power supply voltage is synchronized with the short sampling period, it is impossible to detect the decrease of the power supply voltage. . In addition, a process of monitoring the power supply voltage by an external interrupt may be performed, but frequent occurrence of the external interrupt affects other task processes.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the above circumstances. Even when the power supply voltage drops in a state synchronized with the sampling cycle of a microprocessor for controlling a step motor, It is an object of the present invention to provide a step motor drive control device capable of reliably detecting the step and responding to the control of the step motor and enabling highly reliable position control of the step motor.

[0007]

A step motor drive control device according to the present invention monitors a power supply voltage, detects a voltage drop below the operating voltage of the step motor, and identifies the voltage drop by a power supply voltage drop detection means. For each sampling period, the occurrence of the voltage drop within the sampling period is detected, and the step motor is driven based on the value of the output data memory in a state where the occurrence of the voltage drop is not detected. The rotation data obtained based on the difference between the target position and the current position of the step motor is set in the output data memory. And a re-output control means for re-outputting the value of the output data memory as the step motor control output when the power supply voltage drop detection means detects a voltage drop within the sampling period.

[0008]

In the drive control device for a step motor constructed as described above, when the power supply voltage is in a normal state, the rotation data is determined based on the difference between the obtained target position data and the current position data of the step motor. Is obtained, and the rotation data is stored in the output data memory, and the value of the output data memory is output as a control command for the step motor in the sampling cycle. However, if the power supply voltage falls below the minimum operating voltage of the step motor during this sampling period, it is not clear whether the step motor was actually operated based on the control command, and the step motor is operated one step. Not always. Therefore, if the control operation of the step motor is continued as it is,
If the stepping motor is not operated when the power supply voltage drops, it remains as an error, so that highly accurate and reliable control is not performed. However, a place drop in the power supply voltage is detected by the power supply voltage drop detection means
If, stops the step motor control output at the sampling period, i.e. a total of the previous sampling timing
Write the calculated output data memory value to the output port
Stop output and re-output the previous output data value , that is, output the previous port value as it is
By that, the process returns to the previous state of detecting a drop in power supply voltage, the drive control of high precision step motor is restarted, reliable control results.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration, in which a power supply 11 such as a battery is supplied to a constant voltage power supply circuit 12, and a constant voltage obtained by the constant voltage power supply circuit
13 is driven. Then, based on a command from the microprocessor 13, the step motor 14, which is a load,
The drive is controlled by 11.

The voltage of the power supply 11 is a voltage drop detecting means.
A state in which the voltage of the power supply 11 drops below the minimum operating voltage of the step motor 14, for example, 9.5 V or less, is detected by the power supply voltage monitoring circuit 15, and the rise of the voltage accompanying this voltage drop is detected. The edge counter 101 incorporated in the microprocessor 10 counts up in response to the edge. The edge counter 101 may count the falling edge of the power supply voltage.

That is, in the microprocessor 13, the presence of a drop in the power supply voltage within a predetermined sampling cycle is determined by the count value of the signal accompanying the drop in the power supply voltage which is input to the edge counter 131 which is the power supply voltage drop detection means. When the power supply voltage drop is detected (step 101) , the processing in the microprocessor is changed, and the output from the microprocessor 13 to the step motor 14 at the time when the power supply voltage drop is detected is stopped. To be done. Then, the output pattern in the previous process, that is, the value of the output port register is re-outputted, and control is performed so as to cope with a case where the step motor 14 is not driven one step due to a decrease in the power supply voltage. However, what you force out the last output pattern in such Cimicifuga, limited to the case where the supply voltage is restored, prohibits the output continues until the next interrupt when the power supply voltage is not restored I do.

Here, the factor that the voltage supplied from the power supply 11 such as a battery to the microprocessor 13 and the step motor 14 drops below the minimum operating voltage of the step motor 14 is, for example, the terminal of the battery constituting the power supply 11. In the case of looseness, poor contact of the connector between the battery and the step motor 14, and furthermore, in the case of a step motor mounted on a vehicle equipped with an engine, the start of the engine when starting the starter is mainly considered.

FIG. 2 shows the flow of processing in the microprocessor 13, and a timer interrupt is executed every 3.3 msec. First, the power supply voltage monitoring circuit 15 includes a comparator circuit for comparing the voltage of the power supply 11 with the minimum operating voltage of the step motor 14, and outputs a low level when the voltage from the power supply 11 falls below the minimum operating voltage. The high level is output when the voltage of the power supply 11 is higher than the minimum operating voltage, and the falling edge to the low level or the rising edge to the high level is counted by the edge counter 131 of the microprocessor 13. You.

Accordingly, in this processing flow, first, in step 101, the count value of the edge counter 131 for counting the rise of the detection signal from the power supply voltage monitoring circuit 15, for example, is monitored, and whether or not the count value is "0" is determined. Is determined.
That is, during the period from the sampling timing of the previous process to the sampling timing of the current process, the power supply 11
If the voltage has dropped below the minimum operating voltage, the number of drops has been counted by the edge counter 131, and if the count value is “0”, the voltage of the power supply 11 has been normal. Means

If it is determined in step 101 that the count value of the edge counter 131 is "0" and the power supply voltage is normal, the flow advances to step 102 to determine whether the current voltage of the power supply 11 is normal. Is determined. Steps 101 and 102
If it is determined that the voltage of the power supply 11 has been maintained normally at the present time during the sampling cycle,
The process proceeds to step 103 and thereafter, and the control process of the step motor 14 in the normal state is executed.

In step 103, the value of the output data memory storing the output data value obtained in the previous interrupt processing is written to the output port register, and the output data value calculated by the previous interrupt is output to the port.

In step 104, the value of the target position counter is compared with the value of the current position counter to determine the direction of the difference. If the value of the difference is ">0", the flow proceeds to step 105. The program proceeds to enter the left rotation data into the output data memory. Conversely, if "<0", the routine proceeds to step 106, where the right rotation data is stored in the output data memory. Then, in steps 107 and 108, the value of the current position counter is set to "-1" and "+1", respectively, and a return process is performed. If it is determined in step 104 that the difference value is "0", stop data is stored in the output data memory in step 109, and the routine returns.

If it is determined in step 101 that the count value of the rising edge detection counter is not "0", the flow advances to step 110 to clear this edge counter.
That is, it is detected in step 101 that the power supply voltage has dropped at least once or less to the minimum operating voltage or less of the step motor 14 during the period from the previous interrupt to the current interrupt. Is returned to the initial state, and preparation is made so that monitoring of a drop in the power supply voltage until the next interrupt can be performed.

After the edge counter is cleared in step 110, and when it is determined in step 102 that the current power supply voltage is low and not normal,
Proceed to 111 to stop all output.

That is, as described above, when the power supply voltage drops below the minimum drive voltage of the step motor, the step motor is not driven even if the drive command is normally output from the microprocessor. It is not known whether one step operation has been performed since the previous output. If the step motor is driven by a new command in such a state, the position of the step motor will be shifted from the position recognized by the microprocessor, so that normal position control cannot be continued. For this reason, the step motor is prevented from being operated by a new command in a state where the decrease in the power supply voltage is recognized.

At step 112, the data pattern of the output port register is compared with the lower two bits of the current position counter. If they match, the process returns as it is. If it is determined that the lower two bits are one bit larger, the routine proceeds to step 113, where the current position counter is corrected to "-1". If it is determined that the lower bit is smaller by one bit, the process proceeds to step 114, where the current position counter is corrected to "+1". Then, when the correction processing in steps 113 and 114 is completed, the routine returns and the output pattern in the previous interruption processing is output again.

By performing the processing of steps 112 to 114, even if the power supply voltage decreases and becomes lower than the minimum operating voltage of the step motor, the value of the current position counter of the microprocessor and the actual step motor Of the current position is corrected, and the position accuracy of the drive control of the step motor thereafter is reliably improved.

[0023]

As described above, according to the drive control apparatus for a stepping motor according to the present invention, various control objects are driven, for example, when the power supply voltage is unstable in a vehicle-mounted device. Position control of a step motor used as a drive source of the actuator is executed with high accuracy and reliability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining a step motor drive control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of processing of a microprocessor in the embodiment.

[Explanation of symbols]

11 ... power supply (battery), 12 ... constant voltage power supply, 13 ... microprocessor, 14 ... step motor, 15 ... power supply voltage monitoring circuit.

Claims (2)

(57) [Claims] 1. A step-down voltage detecting means for monitoring a power supply voltage to detect a voltage drop below an operation voltage of a step motor, and for each specified sampling timing, the voltage drop detecting means detects the voltage drop within a sampling cycle immediately before the sampling timing. Power supply voltage drop detection means for detecting the occurrence of a voltage drop; motor drive means for driving the step motor based on a value in an output data memory when the occurrence of the voltage drop is not detected; a target position of the step motor If a data setting means for setting the rotation data obtained based on a difference in the output data memory the current position, when detecting a voltage drop in the sampling period in the power supply voltage drop detection means, said motor drive The means is now
Output data memory value at the time of sampling timing
Regardless of the mode at the previous sampling timing,
The stepper motor control output to drive the over motor, comprising a re-output control means for re-output, further, the sampling at the power supply voltage drop detection means
If a voltage drop within the cycle is detected, the output at that time
The value of the output data memory set in the port register,
Compare the current position data of the step motor and
The value of the current position is corrected based on the comparison result.
Drive controller of the step motor, characterized in that the. 2. The power supply voltage drop detecting means is configured by a counter that detects a rising or falling edge of a voltage corresponding to a voltage drop of the power supply voltage below the operating voltage of the step motor and counts the rising or falling edge. The drive control device for a step motor according to claim 1.