Steering Device Double Failure Redundancy
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Solution Overview
Problem
In existing steer-by-wire steering devices, when both microprocessors connected to steering angle sensors fail, the steering control unit cannot receive signals, leading to a failure in steering control even if one microprocessor operates normally in each control unit.
Innovation Solution
The steering device includes a first and second operation amount sensor that output signals directly to corresponding steering actuator control units, allowing the steering control to continue even when one microprocessor operates normally during a double failure scenario.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If steering angle sensors output signals to microprocessors in a centralized control unit, then system simplicity is maintained, but reliability deteriorates when double failures occur
Solution Approach 1:
The patent divides the centralized control unit into multiple independent microprocessors (first and second microprocessors), each capable of independently receiving signals from steering angle sensors and controlling the steering actuator. This segmentation ensures that a failure in one microprocessor does not compromise the entire steering control system, thereby improving reliability while maintaining manageable complexity through modular architecture.
2Reliability
If redundant microprocessors are implemented in each control unit, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements redundant microprocessors locally within each control unit (steering input control unit and steering control unit), rather than distributing redundancy across the entire system. Each control unit has its own pair of microprocessors that can operate independently, providing localized fault tolerance without requiring complex inter-unit redundancy mechanisms, thus improving reliability with moderate complexity increase.
3Reliability
If steering control signals are routed through multiple microprocessors, then system redundancy is achieved, but signal transmission reliability deteriorates under double failure conditions
Solution Approach 1:
The patent introduces steering angle sensors as intermediary devices that directly output signals to multiple microprocessors. This intermediary architecture allows the sensors to serve as reliable information sources that can independently feed data to either the first or second microprocessor, ensuring that sensor signal availability is not compromised by microprocessor failures. The sensors act as mediators that maintain information flow even when the control processing path is disrupted.
Data Source
AI summary
Provided are steering device and a steering control device that are capable of continuing steering control of steered wheels when one of microprocessors on a steering control unit side operates normally at a time of occurrence of a double failure. A first steering angle sensor outputs a first operation amount signal to a first steering actuator control unit of a steering control unit, and a second steering angle sensor outputs a second operation amount signal to a second steering actuator control unit of the steering control unit.