Servomotor Encoder Fault Detection via Dual Counter Comparison
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Solution Overview
Problem
Conventional fault detection techniques in servo systems have low reliability, which is a concern for ensuring safety and reliability in motor control systems.
Innovation Solution
A servomotor and encoder system that includes multiple rotation counters and cumulative-number calculation units to generate and compare multiple rotation data and accumulated data, using both rotation signals and angle signals to diagnose faults by determining if multiple data sets are identical, thereby enhancing fault detection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fault detection techniques comparing a plurality of signals are used, then the system can detect abnormalities, but the reliability of fault detection remains low
Solution Approach 1:
The encoder is divided into multiple independent counter units (first counter, second counter, third counter, fourth counter) that independently count rotation signals. This segmentation allows parallel comparison of multiple counting results, improving fault detection reliability by identifying inconsistencies between independent counting paths.
Solution Approach 2:
The system continuously compares the counting results from multiple counters and provides feedback to determine encoder normality. When inconsistencies are detected between the first and second counters or between accumulated and non-accumulated counts, the system generates fault signals, creating a closed-loop feedback mechanism for reliable fault detection.
2Reliability
If multiple counters and calculation units are used to generate and compare multiple data sets, then fault detection reliability is improved, but the device complexity increases
Solution Approach 1:
The multiple counters serve dual functions: they simultaneously perform normal rotation counting for motor control and fault detection by comparing their results. The accumulated counter and non-accumulated counter both contribute to operational data while providing redundancy for fault diagnosis, maximizing the utility of each component.
Solution Approach 2:
The fault detection function is merged with the normal operation function by using the same counter units for both purposes. The comparison logic is integrated into the encoder's existing structure, allowing fault detection without adding completely separate detection hardware, thus reducing overall system complexity.
Data Source
AI summary
An encoder includes a first multiple rotation counter that generates first multiple rotation data using a rotation signal indicating one rotation of a rotational shaft of a motor, a second multiple rotation counter that generates second multiple rotation data using the rotation signal, a first cumulative-number calculation unit that calculates first accumulated multiple rotation data using an angle signal indicating a rotational angle of the rotational shaft, a second cumulative-number calculation unit that calculates second accumulated multiple rotation data using the angle signal, and a first comparative diagnosis unit that diagnoses whether the encoder has a fault by performing a comparison to determine whether the first multiple rotation data, the second multiple rotation data, the first accumulated multiple rotation data, and the second accumulated multiple rotation data are a same value.