JPH04281396A - Control device for stepping motor - Google Patents

Abstract

PURPOSE:To prevent a step-out condition from being generated by applying timer interruption at each fixed time, and performing motor control based on an encoder pulse counting value at the point of time of the interruption. CONSTITUTION:In the case of performing speed control and position control of a stepping motor 6 by a computer comprising microprocessors (MPU)1, ROM2 and RAM3, a pulse signal from an encoder 8, output in accordance with rotation of the stepping motor 6, is added or subtracted by an up/down counter 9 to apply interruption to the MPU1 with a fixed time interval by a timer circuit 5, and speed setting is performed relating to the stepping motor 6 based on a counting value of the up/down counter 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling the speed and position of a stepping motor used in various drive sources such as office automation equipment.

0002

2. Description of the Related Art Stepping motors, in which the rotation angle of the motor is proportional to the number of input pulses and whose rotation can be accurately controlled, are used in various office automation equipment such as copying machines and facsimile machines. As a method of controlling this type of motor, the rotation speed is controlled by varying the pulse interval of a pulse signal applied to the stepping motor. The configuration of the control device is, for example, in JP-A No. 63-56199, a memory that stores count value data corresponding to the pulse interval and bit data indicating another acceleration/deceleration mode or constant speed mode for each count value data. means for outputting a signal depending on whether the data in the storage means indicates acceleration/deceleration mode or constant speed mode; means for outputting pulses to the stepping motor by the counting means; Bit data is used to permit or prohibit setting of count value data in the counting means.

0003

[Problems to be Solved by the Invention] However, conventional stepping motor control is usually an open loop;
It rotated according to the set number of pulses. For this reason, when sudden load fluctuations or rapid speed changes are made, the drive control cannot be followed, resulting in a step-out state. SUMMARY OF THE INVENTION An object of the present invention, which has been made in view of the above-mentioned actual state of the prior art, is to provide a control device for a stepping motor that prevents step-out conditions from occurring.

0004

Means for Solving the Problems In order to achieve the above object, the present invention provides a stepping motor control device that uses a common microprocessor to control the speed and position of a stepping motor. an encoder that outputs a pulse signal according to the
an up/down counter that adds or subtracts the output pulses of the encoder; a timer circuit that interrupts the microprocessor; and a number of pulses to ensure the set speed at the current position based on the count of the up/down counter. and control means for applying control to the stepping motor. In order to perform speed control and position control with high precision, the control means activates the timer circuit at regular intervals when the stepping motor starts rotating, and generates an interrupt corresponding to the count value of the up/down counter. Set the speed of the stepping motor using the table value, do not change the speed setting value after reaching a constant rotation speed, set the speed according to the incremented table value at the deceleration position, and when the timer interrupt reaches the predetermined number of times. It is desirable to give instructions for reverse rotation.

[0005]

[Operation] According to the above-mentioned means, an interrupt by the timer circuit is applied to the microprocessor at regular intervals,
A table value corresponding to the count value of the up/down counter at that time is given to the stepping motor as a speed setting value. Therefore, speed control and position control corresponding to acceleration, constant speed, and deceleration are performed at regular time intervals, making it possible to prevent synchronization caused by start-up, rapid load fluctuations, and the like. Furthermore, the microprocessor only needs to perform control operations during timer interrupts, and there is no need to use a high-speed microprocessor.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a stepping motor control device according to the present invention. The control device is MPU (micro processor unit) 1
A ROM (read only memory) 2 and a RAM (random access memory) 3 are connected via a bus. ROM2 stores a program for executing motor control, and RAM3 stores a program for executing motor control.
In addition to the stack and temporary numerical values necessary for the operation of the MPU 1, data accompanying control execution is stored. The MPU 1 has multiple input/output terminals (I/O) and interrupt input terminals (I/O).
NT), and an AND gate 4 connected to an interrupt timer circuit 5 is connected to an interrupt input terminal (INT). A driver 7 for driving the stepping motor 6 and an up/down counter 9 for counting output pulses of an encoder 8 for detecting the number of rotations of the stepping motor 6 are connected to the input/output terminal (I/O) of the MPU 1. has been done. The timer circuit 5 generates an output signal at regular time intervals, and when the AND gate 4 is logically ANDed with the control signal output from the MPU 1, it outputs an interrupt signal to the interrupt input terminal (INT) of the MPU 1. Apply.

Next, the operation of the embodiment with the above configuration will be explained with reference to the speed diagram shown in FIG. In addition to a program for operating the MPU 1, a numerical value table corresponding to the speed diagram shown in FIG. 2 is written in the ROM 2. When the power is turned on and in a reset state, an interrupt time interval is set in the timer circuit 5. Before startup, the stepping motor 6 is at time A in FIG. 2, and no pulse train is applied to the stepping motor 6 (that is, no interrupts are permitted). When a start signal is given, M
The PU 1 resets the up/down counter 9, reads data from the speed setting table, writes pulse train data to the driver 7, and permits timer interrupts. As a result, the stepping motor 6 is activated. When the stepping motor 6 starts rotating, an output pulse from an encoder 8 connected to the rotating shaft of the stepping motor 6 is input to an up/down counter 9. Next, at time point B in FIG. 2, a timer interrupt is performed at regular intervals, and the value of the up/down counter 9 is read. A value in a table (provided in the ROM 2) corresponding to this read value is set in the driver 7. The values in this table are
This is a value for setting the next speed after the current speed. Further, the time point C is the time point when the rotation starts at a constant speed, and the table corresponding to the speed diagram is not incremented. Further, the up/down counter 9 continues counting, and the timer circuit 5 also continues to operate. At time D in Figure 2,
When the value of the up/down counter 9 reaches the deceleration position, the table corresponding to the speed diagram in the ROM 2 is incremented, and the next data is read and set in the driver 7. This starts the deceleration operation.

[0008] At time E in FIG. 2, the speed becomes 0, and the MPU 1 is counting the number of timer interrupts. At time F, the timer interrupt has been performed a predetermined number of times (that is, a predetermined time has elapsed), and the MPU 1 instructs the driver 7 to rotate in the opposite direction. moreover,
At time G, the rotation direction is reversed, timer interrupts are performed at regular intervals, and the value of the up/down counter 9 is read. A table value corresponding to this read value is set in the driver 7. At this time, the up/down counter 9 is performing subtraction counting. At time H, like time C, the rotation starts at a constant speed, and the table corresponding to the speed diagram is not incremented. At this time, the up/down counter 9 continues counting, and the timer circuit 5 also continues to operate. At time I, when the value of the up/down counter 9 reaches the deceleration position, the same operation as at time D is performed. Further, at time J, the value of the up/down counter 9 becomes 0, indicating that the vehicle has returned to its starting position. In the manner described above, speed control and position control of the stepping motor are reliably executed.

[0009]

[Effects of the Invention] Since the present invention is constructed as described above, it achieves the following effects. In the stepping motor control device according to claim 1, the stepping motor control device performs speed control and position control of the stepping motor using a common microprocessor, and an encoder that outputs a pulse signal according to the rotation of the stepping motor. an up/down counter for adding or subtracting output pulses from the encoder; a timer circuit for interrupting the microprocessor; and a pulse for ensuring a set speed at the current position based on the count value of the up/down counter. Since the stepper motor is provided with a control means for applying a number to the stepping motor,
It is possible to prevent synchronization caused by sudden load fluctuations. In the stepping motor control device according to claim 2, the control means activates the timer circuit at regular intervals upon the start of rotation of the stepping motor to generate an interrupt, and calculates a table value corresponding to the count value of the up/down counter. Set the speed to the stepping motor, do not change the speed setting value after reaching constant speed rotation, set the speed according to the incremented table value at the deceleration position, and reverse rotation when the timer interrupt reaches the predetermined number of times. Since the microprocessor only needs to operate at timer interrupts, there is no need to use a high-speed microprocessor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a stepping motor control device according to the present invention.

FIG. 2 will be described with reference to a speed diagram showing the operation of the embodiment of the present invention.

[Explanation of symbols]

1 Micro Processor Unit (MPU) 2
Read-only memory (ROM) 3 Random access memory (RAM) 4 AND gate 5 Timer circuit 6 Stepping motor 7 Driver 8 Encoder 9 Up/down counter

Claims (2)

[Claims] 1. A stepping motor control device that performs speed control and position control of the stepping motor using a common microprocessor, comprising: an encoder that outputs a pulse signal according to the rotation of the stepping motor; and an output pulse of the encoder. an up/down counter that adds or subtracts , a timer circuit that interrupts the microprocessor, and a number of pulses given to the stepping motor to ensure a set speed at the current position based on the counted value of the up/down counter. 1. A stepping motor control device comprising: a control means for controlling a stepping motor; 2. The control means activates the timer circuit at regular intervals upon the start of rotation of the stepping motor to generate an interrupt, and transmits a table value to the stepping motor at a speed corresponding to the count value of the up/down counter. Control content that does not change the speed setting value after reaching constant speed rotation, sets the speed according to the incremented table value at the deceleration position, and instructs reverse rotation when the timer interrupt reaches a predetermined number of times. 2. The stepping motor control device according to claim 1, further comprising: