Rear Wheel Steering Control Using Estimated Front Wheel Angle
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Solution Overview
Problem
Existing vehicles with front and rear wheel steering systems require redundant components, increasing cost, weight, and complexity, and there is a need for systems to control rear wheel steering when front wheel steering is compromised without these redundancies.
Innovation Solution
A rear wheel steering system that uses a rear wheel steering ECU and stability control module to estimate a front wheel steering angle based on existing sensors, eliminating the need for redundant components and enabling safe maneuvering to the side of the road.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant components are added to the front and rear wheel steering systems to enable limping function when front wheel steering is compromised, then the reliability of vehicle steering is improved, but the device complexity and cost increase
Solution Approach 1:
The rear wheel steering system is designed to perform multiple functions: normal coordinated steering with front wheels, and independent limping function when front wheel steering fails. The control unit receives inputs from multiple sources (front wheel steering angle sensor, vehicle speed sensor, yaw rate sensor) and automatically switches between normal operation and limping mode, eliminating the need for separate redundant limping components
Solution Approach 2:
The limping function components are merged into the existing rear wheel steering system rather than being separate redundant systems. The control unit integrates multiple sensor inputs and control algorithms into a single system that can operate in both normal and failure modes, reducing overall system complexity while maintaining reliability
2Reliability
If multiple redundant steering actuators and sensors are used to control rear wheel steering when front wheel steering fails, then the safety of vehicle maneuvering is improved, but the weight of the steering system increases
Solution Approach 1:
The existing rear wheel steering actuators and sensors are designed to serve dual purposes: normal steering operation and emergency limping function. The control unit automatically determines when front wheel steering has failed and activates the limping function using the same physical components, eliminating the need for separate redundant weight-bearing components
3Reliability
If a steer-by-wire system with multiple redundant components is implemented to enable rear wheel steering control when front wheel steering is compromised, then the reliability of steering control is improved, but the cost of the steering system increases
Solution Approach 1:
The rear wheel steering system is designed as a multi-functional system that can operate in both normal and failure conditions using the same components. The control unit integrates multiple sensor inputs (front wheel steering angle, vehicle speed, yaw rate) and automatically switches between normal operation and limping mode, eliminating the need for separate redundant limping components and reducing overall system cost
Solution Approach 2:
The system automatically detects front wheel steering failure through sensor inputs and activates the limping function without requiring separate manual override systems or additional failure detection components. The control unit self-manages the transition from normal to emergency operation using existing sensors and actuators
Data Source
AI summary
A rear wheel steering system for a vehicle selectively controls a vehicle after front wheel steering is compromised. The rear wheel steering control system includes a rear wheel steering electronic control unit (ECU) and a stability control module. The rear wheel steering ECU electrically communicates with a front wheel steering ECU used to control the front wheel steering. The front wheel steering ECU is coupled to a front wheel steering angle sensor that detects a measured front wheel steering angle and transmits the measured front wheel steering angle to the rear wheel steering ECU. The stability control module is electrically coupled to the rear wheel steering ECU and receives the vehicle yaw data and vehicle speed data. The rear wheel steering ECU and/or stability control module estimates a front wheel steering angle for the vehicle for use in selectively steering the vehicle.