Motor Control Device Abnormality Detection via PWM Duty Ratio Feedback
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Solution Overview
Problem
Existing motor control devices for game machines fail to detect abnormalities in motor operation, such as reduced rotation speed or incomplete movement, due to external forces or increased friction, which can lead to motor overload and breakdown.
Innovation Solution
A motor control device that includes a communication interface, sensor interface, and controller to receive control commands, detect signals from a rotation angle sensor, and generate drive signals, calculating differences in target and actual rotation amounts to determine abnormality occurrence based on update frequency and non-update periods, as well as actual rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a DC motor is used to drive a movable body, then the motor can exert high torque and be smaller in size, but the motor may rotate backward or rotate at lower speed due to external forces or increased friction, causing failure to detect abnormalities
Solution Approach 1:
The patent implements feedback by continuously monitoring the duty ratio of the PWM signal and comparing it against threshold values. The controller detects abnormalities when the duty ratio exceeds a predetermined threshold, indicating that the motor is operating under abnormal conditions such as backward rotation or reduced speed due to friction or external forces
Solution Approach 2:
The patent replaces mechanical abnormality detection mechanisms with an electronic control system that uses PWM duty ratio monitoring. Instead of mechanical sensors or switches to detect motor abnormalities, the system uses electronic signal processing to detect changes in motor operation through the duty ratio feedback from the PWM controller
2Measurement precision
If a rotation angle sensor is used to detect motor rotation, then the moving amount can be accurately measured, but the system may fail to detect abnormalities when the motor rotates backward or at reduced speed
Solution Approach 1:
The patent uses feedback from the PWM duty ratio to detect abnormalities that the rotation angle sensor alone cannot detect. By monitoring the duty ratio and comparing it against predetermined thresholds, the system can identify abnormal operating conditions such as backward rotation or reduced speed even when the rotation angle sensor is functioning correctly
Solution Approach 2:
The patent makes the PWM duty ratio monitoring system serve multiple functions: it controls motor speed and position while simultaneously detecting abnormalities. This multi-functional approach allows the same control signal to provide both operational control and diagnostic information, eliminating the need for separate detection mechanisms
3Force
If the motor is forced to move a locked movable body, then the motor can overcome mechanical restrictions, but an overload may be applied to the motor causing heat generation and breakdown
Solution Approach 1:
The patent implements feedback monitoring of the PWM duty ratio to detect when the motor is operating under excessive load conditions. When the duty ratio exceeds a predetermined threshold, it indicates that the motor is applying excessive force to a locked or restricted movable body, allowing for early detection and prevention of motor damage before heat generation and breakdown occur
Data Source
AI summary
In a motor control device, a communication interface receives a control command defining a target rotation amount and a target rotation speed of a motor. A sensor interface receives a detection signal from a rotation angle sensor outputting a detection signal in every rotation of the motor at a predetermined angle. A controller decides a set value of a rotation speed of the motor. A drive signal generator generates and outputs a drive signal for rotating the motor. The controller calculates a difference between the target rotation amount and a total rotation amount of the motor from start of execution of the control command, based on the number of received detection signals, and determines whether an abnormality occurs in operation of the motor based on an update frequency of a minimum value of the difference or a non-update period when the minimum value of the difference is not updated.