Steer-by-Wire Redundancy With Zonal Fault Isolation
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Solution Overview
Problem
Traditional steering systems are prone to faults and failures due to their mechanical nature and high-pressure systems, and while steer by wire systems offer improvements, they can still experience failures from electrical or other faults, necessitating a solution that reduces faults and provides redundancy without adding cost or weight.
Innovation Solution
A steer by wire steering system with zonal isolation and redundancy, featuring dual road wheel actuators, power supply assemblies, and communication networks, which are designed to operate independently to ensure continuous control of the vehicle's lateral motion even if one component fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional mechanical steering system is used, then the system provides mechanical linkage and power assist, but the system is complicated and susceptible to faults and failures due to mechanical nature and high pressure
Solution Approach 1:
The patent replaces the traditional mechanical steering system with an electrical steer-by-wire system. The mechanical linkage between steering wheel and road wheels is substituted with electrical actuators and control systems. This eliminates high-pressure hydraulic components and mechanical linkages, reducing the complexity and fault susceptibility while maintaining steering functionality through electrical actuation of the road wheels.
2Reliability
If a mechanical backup system is added to the steer by wire system, then redundancy is provided, but extra weight and cost are added to the vehicle
Solution Approach 1:
The patent divides the steer-by-wire system into two independently controlled actuators: a primary road wheel actuator and a secondary road wheel actuator. Each actuator can independently control the road wheels, allowing the secondary actuator to serve as a backup without requiring a complete duplicate mechanical steering system. This segmentation provides redundancy while minimizing additional weight and cost.
3Reliability
If zonal isolation is implemented between actuators and power supplies, then fault propagation is reduced, but system complexity increases
Solution Approach 1:
The patent implements zonal isolation by separating the primary and secondary actuators into distinct functional zones with independent power supplies and control systems. The primary actuator has its own power supply and control circuitry, while the secondary actuator has separate power supply and control circuitry. This segmentation prevents fault propagation between zones while maintaining manageable system architecture through modular design.
Data Source
AI summary
A vehicle steering system by wire to control the lateral motion of the vehicle is provided. The system includes a steering wheel torque feedback actuator assembly with two controllers, a front road wheel steering actuator assembly with two zonally isolated motors and controllers, two separate power assemblies, two separate vehicle communication networks in separate wiring bundle assemblies, and three private system communication networks between each node in the steering system. The redundant components are zonally isolated such that common cause of faults do not endanger the system when one or more of the components fails. The system can include differential gearbox road wheel actuator to allow absolute position of the road wheels. The system can further include a set of position sensor assemblies including two magnetic and one inductive sensor assemblies.