Steer-by-Wire Steering System Redundancy
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Solution Overview
Problem
Existing steer-by-wire steering systems lack sufficient redundancy to ensure fail-safe operation in case of electrical failures, which can lead to loss of steering control.
Innovation Solution
A steer-by-wire steering system with three redundant operation information obtaining systems and three redundant wheel-steering systems, utilizing dedicated communication lines and a communication bus to ensure continued vehicle direction control even if two systems fail, with an auxiliary steering device like a brake system acting as a backup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy is increased to ensure fail-safe operation, then reliability is improved, but device complexity increases
Solution Approach 1:
The communication system is segmented into multiple independent communication paths: a first communication path connecting the operation information obtaining device to the steering device, and a second communication path connecting the reaction force applying device to the steering device. This segmentation allows the system to maintain functionality even when one path fails, thereby improving reliability without requiring a completely redundant complex configuration.
Solution Approach 2:
The steering device acts as an intermediary that receives operation information from the operation information obtaining device through the first communication path and reaction force information from the reaction force applying device through the second communication path. This intermediary structure enables the system to process information from multiple sources independently, improving failsafe capability while maintaining manageable system complexity.
2Reliability
If three redundant systems are implemented, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The communication bus serves multiple functions: it carries operation information from the operation information obtaining device to the steering device, and also carries reaction force information from the reaction force applying device to the steering device. This multi-functionality reduces the need for completely separate dedicated communication lines for each function, thereby reducing manufacturing cost while maintaining the three-redundant-system reliability.
Solution Approach 2:
The first and second communication paths are merged into a shared communication bus infrastructure, where multiple devices (operation information obtaining device, reaction force applying device, steering device) communicate through common communication lines. This merging reduces the total number of communication components needed compared to having completely separate dedicated lines for each communication function, thereby reducing manufacturing cost while preserving redundancy.
Data Source
AI summary
A steer-by-wire steering system, including: a two-system reaction force applying device including two reaction force controllers and configured to obtain operation information and apply an operation reaction force; a two-system steering device including two steering controllers and configured to steer a wheel; an operation information obtaining device; an auxiliary steering device capable of changing a direction of a vehicle; two dedicated communication lines one of which information-transmittably and information-receivably connects one of the two reaction force controllers and one of the two steering controllers to each other, and the other of which information-transmittably and information-receivably connects the other of the two reaction force controllers and the other of the two steering controllers to each other; and a first communication bus to which the operation information obtaining device is at least information-transmittably connected and to which the two steering controllers and the auxiliary steering device are at least information-receivably connected.