Rear Toe Control System Speed Limiting for Failure Safety
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Solution Overview
Problem
Existing rear toe control systems fail to effectively manage vehicle speed when encountering poor road surfaces, particularly during system failures, which can lead to loss of control or accidents.
Innovation Solution
A rear toe control system with an electronic control unit that determines system failures and poor road conditions, imposing a low speed limit to ensure safety by integrating sensors and actuators to control rear wheel toe angles and vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rear toe control system allows normal vehicle operation after detecting system failure by actuating at least one toe-angle actuator to make the toe angles of the two wheels agree with one another, then the vehicle can continue operation under faulty conditions, but the vehicle may lose control or experience accidents when encountering poor road surfaces due to insufficient speed management
Solution Approach 1:
The system changes the speed parameter dynamically based on detected failure conditions and road surface quality. When RTC system failure is detected and poor road surface is identified, the system imposes a low speed limit (e.g., reducing maximum speed to 30 km/h or lower) to maintain safe operability. This parameter change resolves the contradiction by adapting the vehicle's operating speed to the degraded control conditions, allowing continued operation while preventing loss of control on slippery surfaces.
2Object-affected harmful factors
If the rear toe control system imposes a low speed limit when RTC system failure and poor road surface are detected, then vehicle safety is improved, but the vehicle's speed capability and operational flexibility are reduced
Solution Approach 1:
The speed limit is not fixed but dynamically adjusted based on the severity of the failure condition and road surface assessment. The system can impose different speed limits (e.g., 30 km/h, 50 km/h, or 70 km/h) depending on the specific failure mode and detected road conditions. This dynamic approach resolves the contradiction by providing the minimum necessary speed restriction for safety while preserving as much operational flexibility as possible under the given constraints.
Solution Approach 2:
The system uses a look-up map (pre-stored data structure) to determine appropriate speed limits based on detected failure conditions and road surface characteristics. This copying approach allows the system to reference pre-calculated safe speed values without requiring complex real-time calculations, efficiently balancing safety requirements with operational capability while reducing computational burden during failure conditions.
Data Source
AI summary
A rear toe control (RTC) system and method for a vehicle includes rear actuators for applying rear steering to rear wheels of the vehicle and rear sensors for measuring individual toe angles of the rear wheels. The system further includes a RTC failure module that determines when the RTC system has failed and a road condition determining module that determines whether the vehicle is encountering a poor road surface condition. An electronic control unit (ECU) is disposed on the vehicle and is configured to impose a speed limit for the vehicle when the RTC failure module determines that the RTC system has failed and the road condition determining module determines that the vehicle encountering a poor road surface condition.