Electric Power Steering Signal Control Arbitration
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Solution Overview
Problem
Conventional electric power steering systems face challenges in accurately controlling the steering operation due to errors in detection angles between sensor systems, leading to excessive torque output and overheating, especially when inter-computer communication is disrupted.
Innovation Solution
A signal control apparatus with multiple control units that acquire sensor signals, calculate detection angles, and perform angle feedback control by correcting angle differences between systems, using arbitration steering angles to balance errors and prevent excessive torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two sensor units are provided for two microcomputers with independent detection systems, then system redundancy and reliability are improved, but detection angle errors between systems cause excessive torque output and overheating
Solution Approach 1:
The patent implements feedback control by having each microcomputer acquire sensor signals, calculate detection angles, and perform angle feedback control based on the difference between target angle and detection angle. The system uses feedback from the other microcomputer's detection angle to correct its own control output, ensuring that torque commands are adjusted based on actual detection angle errors, thereby preventing excessive torque and motor overheating while maintaining redundant sensor systems
Solution Approach 2:
The patent changes the control parameter from raw sensor signals to corrected detection angles. Each microcomputer calculates its detection angle from sensor signals, then corrects this angle using the detection angle from the other microcomputer. This parameter transformation allows the system to maintain redundant sensing while eliminating the harmful effects of detection angle discrepancies through mathematical correction before applying control commands
2Reliability
If detection angle errors occur between dual sensor systems, then measurement precision deteriorates, but providing two independent systems should improve reliability
Solution Approach 1:
The patent merges the detection angle information from both microcomputers through correction processing. Each microcomputer not only uses its own detection angle but also acquires and utilizes the detection angle from the other microcomputer. By combining both detection results through correction algorithms, the system achieves both reliability (using both sensors) and precision (correcting for systematic errors between the two detection systems)
Data Source
AI summary
An ECU, which is a signal control apparatus, has a plurality of control units, which control one same motor. Steering angle calculation units acquire sensor signals from the angle sensors provided corresponding to the steering angle calculation units, respectively, and calculate the steering angles in correspondence to the sensor signals. The angle FB units perform the angle FB control based on the angle differences, which are between the target angle and the steering angle and between the target angle and the steering angle, respectively. In the angular FB unit of at least one of the control units, the angular feedback control is performed using the angle difference, which is subjected to the correction processing to reduce the error between the detection angle of the own system and the detection angle of the other system calculated by the steering angle calculation unit of the other control unit.