Encoder Abnormality Detection Controller Noise Immunity
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Solution Overview
Problem
Existing shift position switch mechanisms in vehicles face false determinations of encoder abnormality due to noise handling issues, leading to incorrect diagnosis and potential system failures.
Innovation Solution
A controller is designed with improved noise-proof characteristics by determining encoder abnormality based on specific criteria, including the duration of abnormal pulse states and the behavior of noise-induced states, to differentiate between actual encoder faults and noise-overlapped signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system detects abnormal pulse states to identify encoder abnormality, then the reliability of abnormality detection is improved, but false determinations occur when noise overlaps the output signal
Solution Approach 1:
The system dynamically adjusts the determination threshold based on the pulse cycle period. By making the threshold adaptive rather than fixed, the system can distinguish between transient noise (short duration) and actual encoder abnormalities (long duration), resolving the contradiction between detecting real abnormalities and avoiding false positives from noise
Solution Approach 2:
The patent changes the parameter of determination time threshold based on the pulse cycle characteristics. When the pulse cycle is short, the threshold is set accordingly, allowing the system to filter noise effectively while maintaining sensitivity to real faults. This parameter adjustment resolves the contradiction by adapting the detection criteria to operating conditions
2Device complexity
If the system uses a fixed determination threshold for abnormality detection, then the detection process is simple, but it cannot differentiate between noise-induced states and actual encoder faults
Solution Approach 1:
The determination threshold is made dynamic by linking it to the pulse cycle period. This allows the system to maintain relatively simple logic while achieving high precision, as the threshold automatically adapts to different operating speeds and conditions without requiring complex algorithms
Data Source
AI summary
A controller has an encoder that outputs four-phase pulse signals according to a rotation of a rotor of a motor by a rule. During a rotational drive of the motor, when (i) an abnormal pulse state is observed in which the pulse signal is output in a non-compliant manner with the rule and (ii) a lapse time from a last normal output timing, which is a last timing of an output of the pulse signal by the rule, is longer than a threshold determination time, it is conclusively determined that the encoder has abnormality. Thus, the encoder is provided with an improved noise-proof character, and is prevented from being falsely determined as abnormal due to the abnormal pulse state, even when an output of the pulse signal from the encoder is temporarily ridden by a noise.