JPH109894A - Method for detecting abnormality of encoder signal in motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the abnormal detection function of an encoder signal by an inexpensive microcomputer, in an encoder signal abnormality detection method of a motor control unit, by using general-purpose port input usually built in a microcomputer of every kind. SOLUTION: The A-phase 1 of an encoder signal and the B-phase 2 thereof are only shifted by π/2 in phase but same in cycle and duty ratio and, when the signal levels of the A-phase 1 and B-phase 2 of the encoder signal within a range of a certain definite time T are High, both of the A-phase and the B-phase become t1+t2+t3. Therefore, a time when the signal levels of the A-phase 1 and B-phase 2 inputted to general-purpose port input by using the timer interruption processing of the microcomputer of a motor control unit are High is counted to compare two data and, if the ratio is 2:1 or less, normality is judged and, if the ratio is 2:1 or more, abnormality is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of an encoder signal in a motor control device by using a general-purpose port input of a microcomputer.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a signal form of an encoder signal.
In FIG. 5, 1 indicates the A phase of the encoder signal, 2 indicates the B phase of the encoder signal, 1a and 2a indicate the high signal levels, and 1b and 2b indicate the low signal levels.

The A-phase and B-phase of the encoder signal are pulse signals indicating the number of rotations and the direction of rotation of the motor. The duty ratio is 50%, and the A-phase and the B-phase having the same period are input with a π / 2 phase shift. Is done.

[0004] The duty ratio is the ratio of the time during which the pulse signal level is high in one cycle of the pulse signal, and the duty ratio of 50% is the time when the pulse signal level is high and the time when the pulse signal level is low. Means the same.

Conventional encoder signal abnormality detection methods include the following: (1) An encoder signal is input to an external interrupt terminal of a microcomputer of a motor control device, and the signal level is changed from high to low.
It is checked whether a changing edge from ow and Low to High alternates between A-phase 1 and B-phase 2. (2) The above signal is input to a pulse width measuring terminal of the microcomputer of the motor control device, and the pulse width of this signal is measured by the microcomputer to check whether the duty ratio is 50%. There was a method.

[0006]

However, in the above method, the abnormality can be detected only by a microcomputer having two built-in terminals, an external interrupt terminal and a pulse width measurement terminal, and an expensive microcomputer must be used. There was a problem that it did not become.

The present invention solves the above-mentioned conventional problems, and realizes an encoder signal abnormality detection function with an inexpensive microcomputer by using a general-purpose port input normally incorporated in any type of microcomputer. The purpose is to:

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention is to input an A-phase signal and a B-phase signal of an encoder to a general-purpose port of a microcomputer, and to obtain a Hi-level signal of the A-phase and B-phase signals.
The time of gh and Low is measured using a timer built in the microcomputer, and the A-phase signal level for a certain period of time is High.
When the ratio between the time h and the time when the B-phase signal level is High is 2: 1 or more, it is regarded as abnormal.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a motor control device for controlling the number of rotations of the motor and the forward / reverse rotation of the motor by a pulse signal from the encoder. Then, the High / Low time of the A-phase and B-phase signal levels is measured using a timer built in the microcomputer, and the time when the A-phase signal level is High and the B-phase signal level for a certain time are measured H
This is a method for detecting an encoder signal abnormality of a motor control device which determines that an abnormality has occurred when the ratio of time to high is 2: 1 or more. Since the abnormality detection is performed by using the processing, it is possible to realize an encoder signal abnormality detection function with an inexpensive microcomputer without using an expensive microcomputer having a built-in external interrupt terminal or pulse width measurement terminal.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining an abnormality judgment of an encoder signal according to the present invention, and shows a case where the encoder signal is normal. In FIG. 1, 1 is an A phase of the encoder signal, 2 is a B phase of the encoder signal and the phase is The cycle and the duty ratio are the same only by shifting by π / 2.

Therefore, A within a certain time period T
During the time when the signal levels of Phase 1 and Phase 2 are High, Phase A and Phase B
Both phases are t1 + t2 + t3.

That is, A is input to the general-purpose port input using the timer interrupt processing of the microcomputer of the motor control device.
The time during which the signal levels of phase 1 and phase B 2 are high is counted. If the time is the same, the encoder signal is regarded as normal, and if not the same, it is regarded as abnormal.

FIG. 2 is a device connection diagram of an embodiment of the present invention.
Is a motor, 4 is an encoder mounted on the rotating shaft of the motor 3, 5 is an A-phase signal input as a signal from the encoder 4, 6 is a B-phase signal input as a signal from the encoder 4, 7 is a motor control device, and 8 is a motor. A microcomputer built into the control device 7
A phase signal input and a B phase signal input are input.

FIG. 3 is a flowchart of the timer interrupt process of the present invention. The software is set so that the timer interrupt process of the microcomputer is performed at a period of 100 μs by connecting the devices described in FIG.

During the timer interruption process of 100 μs, a 25 ms time counting process, an A-phase high time counting process, and a B-phase high time counting process are performed.

FIG. 4 is a flowchart of a main routine according to the present invention. The processing of the main routine is executed once every 25 ms using the time of 25 ms counted in the timer interrupt processing.

In the main routine, A-phase High time data counted in the timer interrupt processing;
Reference the High time data of the phase.

That is, it refers to how long the A-phase and B-phase signals have been at the High level within 25 ms.

If the encoder signal is normal, this A phase,
Since the ratio of the two data of the B-phase signal should not exceed 2: 1, the two data are compared, and if the ratio is 2: 1 or less, it is determined to be normal, and if the ratio is 2: 1 or more, it is determined to be abnormal.

[0021]

As described above, according to the present invention, the A-phase and B-phase signals of the encoder are input to the general-purpose port input of the microcomputer to detect the abnormality of the encoder signal. Even if an expensive microcomputer with a built-in terminal is not used, an inexpensive microcomputer can realize the abnormality detection function of the encoder signal.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an abnormality determination of an encoder signal according to the present invention.

FIG. 2 is a device connection diagram according to an embodiment of the present invention.

FIG. 3 is a flowchart of a timer interrupt process according to the present invention;

FIG. 4 is a flowchart of a main routine of the present invention.

FIG. 5 is a diagram showing a signal form of an encoder signal.

[Explanation of symbols]

 Reference Signs List 1 A phase of encoder signal 2 B phase of encoder signal 1a, 2a Signal level High 1b, 2b Signal level Low 3 Motor 4 Encoder 7 Motor controller 8 Microcomputer

Claims (1)

[Claims] In a motor control device for controlling the number of rotations of a motor and the forward / reverse rotation by a pulse signal from an encoder, an A-phase signal and a B-phase signal of an encoder are inputted to a general-purpose port of a microcomputer, and the A-phase and B-phase signals are inputted. High / phase B signal level
The Low time is measured using a timer built in the microcomputer, and the A-phase signal level for a certain period of time is Hig.
An encoder signal abnormality detection method for a motor control device that determines that an abnormality has occurred when the ratio of the time h and the time when the B-phase signal level is High is 2: 1 or more.