Steer-by-Wire Fallback Control Using Another Vehicle's SFA
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Solution Overview
Problem
In steer-by-wire systems, a breakdown of the steering feedback actuator (SFA) leads to an unsafe condition where steering is impossible, as the road wheel actuator (RWA) cannot operate without mechanical feedback.
Innovation Solution
A steer-by-wire system that includes a steering controller capable of receiving and outputting control signals to the road wheel actuator (RWA) using information from a functioning steering feedback actuator of another vehicle, allowing temporary control of the vehicle even when the SFA is malfunctioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a steer-by-wire system uses electrical connection between SFA and RWA without mechanical connection, then the system achieves higher integration and reduced mechanical complexity, but steering control becomes impossible when SFA breaks down
Solution Approach 1:
The patent introduces another vehicle's SFA information as an intermediary resource to bridge the control gap when the primary SFA fails. The steering controller receives and processes external SFA data through a receiver, using it as a substitute signal source to maintain RWA control capability despite the breakdown of the onboard SFA.
Solution Approach 2:
The system dynamically changes the source of steering control parameters based on system state. When SFA is functional, it uses direct SFA output signals; when SFA breaks down, it switches to using received SFA information from another vehicle as the control parameter source, thereby maintaining continuous operational capability.
2Device complexity
If the system relies solely on onboard SFA for steering control, then the control system remains simple and direct, but steering becomes impossible when SFA experiences breakdown
Solution Approach 1:
The system performs preliminary actions by establishing a receiver and communication protocol in advance to acquire SFA information from other vehicles. This preparatory infrastructure is built before any failure occurs, enabling the system to immediately switch to alternative data sources when SFA breakdown happens, thus maintaining steering operability without complex real-time decision-making under failure conditions.
Solution Approach 2:
The patent implements beforehand cushioning by having the receiver continuously acquire and buffer SFA information from neighboring vehicles before any failure occurs. This creates a ready pool of alternative control data that cushions the system against the impact of SFA breakdown, ensuring seamless transition and continuous steering operability.
3Reliability
If the steering controller uses information from another vehicle's SFA, then steering control can be maintained during SFA breakdown, but the system requires additional receiver and communication components
Solution Approach 1:
The receiver component serves multiple functions: it continuously receives SFA information from other vehicles for potential future use, validates incoming data packets, and interfaces with the steering controller for seamless integration. This multi-functionality justifies the added component by maximizing its utility across normal and failure operating conditions.
Solution Approach 2:
The patent uses communication protocols and data processing routines as intermediaries to efficiently bridge the gap between external SFA information and the steering control system. These software-based intermediaries minimize the need for additional hardware while enabling reliable information transfer and integration, thus reducing the overall complexity increase from adding receiver functionality.
Data Source
AI summary
A steer-by-wire system according to the present disclosure includes a steering feedback actuator, a road wheel actuator, and a steering controller configured to receive a signal from the steering feedback actuator and output a control signal to the road wheel actuator, in which the steering controller controls the road wheel actuator by using information of a steering feedback actuator of another vehicle when the steering feedback actuator is broken down.