Electric Brake Angle Sensor Redundancy Without Extra Signal Lines
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Solution Overview
Problem
Existing motor control systems face reliability issues due to increased parts and signal lines required for sensor diagnosis, and they fail to maintain functionality when sub- MPU failures occur.
Innovation Solution
A motor control device with dual angle sensors, control circuits, and a communication unit that detects sensor failures by comparing detected values and motor control angles, allowing for redundant operation without increasing the number of parts or signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor position sensor of another type is prepared for diagnosis of the two output shaft sensors and connected to the MPU, then the sensor failure diagnosis capability is improved, but the number of parts and the number of connection signal lines increase which deteriorates the reliability
Solution Approach 1:
The motor control device performs multiple functions using the same components: it controls the motor based on sensor inputs and simultaneously diagnoses sensor failures by comparing detected values with expected values calculated from motor control parameters. This eliminates the need for separate dedicated diagnosis hardware.
Solution Approach 2:
The system uses its own operational parameters (motor control angles, command values) to generate expected sensor values and perform self-diagnosis. The motor control device monitors itself by comparing actual sensor readings against theoretically expected readings derived from its own control commands.
2Reliability
If two temperature sensors are connected to separate MPUs and a sub MPU diagnoses a main MPU and a temperature sensor connected thereto, then the diagnosis coverage is improved, but when a failure happens on the sub MPU side, the diagnosis of the main MPU side cannot be performed and the processing is stopped
Solution Approach 1:
The diagnosis function and motor control function are merged into a single MPU. The same processor that controls the motor also performs the sensor failure diagnosis, eliminating the need for separate MPUs and their inter-communication infrastructure.
Solution Approach 2:
The system continuously compares actual sensor detected values with expected values calculated from motor control parameters, creating a feedback mechanism that enables ongoing self-diagnosis during normal operation without requiring separate diagnostic processors.
Data Source
AI summary
A motor control device is provided which achieves redundancy while suppressing an increase in the number of parts and connection signal lines. The device includes angle sensors for detecting a rotation angle of a motor, a first microcomputer unit for controlling the motor based on a stroke sensor and receiving the detected value of the angle sensor, a second microcomputer unit for controlling the motor based on the stroke sensor and receiving the detected value of the angle sensor, and communication units for transmitting and receiving signals between the microcomputer units. The first microcomputer unit includes an angle sensor failure detecting unit for detecting a failure of the angle sensors, according to the detected value of the angle sensors, and a control angle of the motor created in response to the stroke sensor.