Motor Encoder Fault Diagnosis Using Disturbance Current Feedback
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Solution Overview
Problem
Existing motor encoder diagnostic systems cannot distinguish between a motor that is not rotating and an encoder failure when the feedback position indicates a fixed motor position, leading to uncontrollable and potentially dangerous situations.
Innovation Solution
A failure diagnostic system and method that includes a safety module to determine the motor's state by analyzing the feedback position and applying a disturbance current to differentiate between motor non-rotation and encoder malfunction, using additional current commands to assess the encoder's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the servo driver only reads the encoder to obtain feedback position, then the system is simple and easy to operate, but the system cannot distinguish between motor non-rotation and encoder failure
Solution Approach 1:
The system applies a disturbance current to the motor before checking the feedback position to proactively test whether the motor can respond. This preliminary action allows the system to distinguish between motor non-rotation and encoder failure by observing whether the motor responds to the disturbance signal, thereby resolving the ambiguity while maintaining system simplicity
Solution Approach 2:
The system uses the encoder's feedback position in conjunction with the motor's response to disturbance current to determine the actual motor state. By comparing the expected position change with the actual feedback, the system can reliably distinguish between motor non-rotation and encoder failure without adding complex hardware
2Device complexity
If the system does not implement failure diagnosis, then the device complexity is low, but the system may fail to discover encoder abnormality causing uncontrollable and dangerous situations
Solution Approach 1:
The diagnostic system performs preliminary testing by applying disturbance current and monitoring feedback position changes before normal operation continues. This allows the system to detect encoder abnormalities early without requiring complex continuous monitoring during all operating conditions
Solution Approach 2:
The system implements periodic failure diagnosis by intermittently applying disturbance current and checking feedback positions at scheduled intervals. This periodic approach maintains system safety and reliability while avoiding the complexity of continuous monitoring, balancing diagnostic thoroughness with system simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively diagnoses encoder malfunctions, ensuring motor control accuracy and safety by distinguishing between motor non-rotation and encoder errors, thereby preventing system failures.
Implementation Method 1
a failure diagnostic system of a motor encoder... applying a disturbance current to differentiate between motor non-rotation and encoder malfunction
Data Source
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AI summary
A failure diagnostic system of a motor encoder is disclosed and includes a motor (1), an encoder (2), a servo driver (3), and a safety module (4). The servo driver (3) controls the motor (1) through a current command (5). The safety module (4) continuously obtains a feedback position of the motor (1) through the encoder (2). When the safety module (4) determines based on the feedback position that the current state of the motor (1) is consistent with a predetermined disturbance condition, the safety module (4) requests the servo driver (3) to output an additional current command (6) to disturb the motor (1). Next, the safety module (4) determines whether the encoder (2) is failure based on a variation of following feedback position.