Active Rear Toe Control for Vehicle Agility and Stability
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Solution Overview
Problem
Current vehicle systems lack direct and efficient control over rear toe angle, relying on indirect front wheel steering, which limits agility and stability, especially in varying driving conditions and friction levels.
Innovation Solution
An active toe control system with sensors and actuators that adjust the rear toe angle based on vehicle state data, including speed, steering angle, and friction conditions, using a controller to optimize toe settings for improved agility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If front wheel steering is used to control rear toe angle, then the system structure is simple, but the control precision and response speed are insufficient
Solution Approach 1:
The patent divides the rear wheel assembly into independently controllable units, with each rear wheel equipped with its own actuator. This segmentation allows individual control of each wheel's toe angle, transforming the indirect collective control through front steering into direct independent control, thereby significantly improving control precision and response speed.
Solution Approach 2:
The patent introduces actuators as intermediary devices between the control system and the rear wheels. These actuators directly adjust the toe angle of each rear wheel based on control signals, serving as a mediator that translates electronic commands into precise mechanical adjustments, eliminating the need for indirect control through front wheel steering.
2Ease of operation
If front wheel steering is used to control rear toe angle, then the system is simple to implement, but the agility and stability optimization is limited
Solution Approach 1:
The patent implements a dynamic control system that continuously adjusts the rear toe angle based on real-time vehicle operating conditions such as steering angle, vehicle speed, and lateral acceleration. The controller dynamically selects from multiple predefined toe settings (e.g., toe-in for stability, toe-out for agility) or applies continuous variable adjustments, enabling the system to adapt to varying driving maneuvers and optimize both agility and stability as needed.
Solution Approach 2:
The patent changes the toe angle parameter of the rear wheels based on different vehicle states. The system includes multiple predefined toe settings (such as toe-in and toe-out configurations) and selects appropriate settings based on steering angle, vehicle speed, and lateral acceleration. This parameter change approach allows the vehicle to optimize its handling characteristics for different driving conditions.
3Stability of the object's composition
If active toe control is implemented, then agility and stability are improved, but the device complexity increases
Solution Approach 1:
The patent employs a multi-functional control system that integrates multiple functions into a single controller. The controller not only manages the actuators for toe angle adjustment but also processes data from multiple sensors (steering angle sensor, speed sensor, lateral acceleration sensor) and implements various control strategies. This universal controller reduces overall system complexity by consolidating control functions rather than requiring separate dedicated systems for each function.
Solution Approach 2:
The control system is designed to autonomously determine and adjust the optimal toe angle based on sensor inputs without requiring manual intervention. The controller automatically selects from predefined toe settings or applies continuous variable adjustments based on vehicle state, making the system self-sufficient in optimizing vehicle handling characteristics.
4Manufacturing precision
If multiple sensors and actuators are added for active toe control, then control precision is improved, but the cost and complexity increase
Solution Approach 1:
The patent introduces actuators as intermediary devices between the control system and the rear wheels. These actuators directly adjust the toe angle of each rear wheel based on control signals, serving as a mediator that translates electronic commands into precise mechanical adjustments, eliminating the need for indirect control through front wheel steering.
Data Source
AI summary
A toe optimization system for a vehicle with first and second rear wheels defining a rear toe angle. The vehicle includes a plurality of sensors and first and second actuators operatively connected to the first and second rear wheels, respectively, for varying the rear toe angle. A controller has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for controlling the rear toe angle. Execution of the instructions by the processor causes the controller to select one of a plurality of vehicle states. Each of the plurality of vehicle states has a respective toe setting. The controller is configured to actuate the first and second actuators to vary the rear toe angle to the respective toe setting. By actively controlling the rear toe angle, the agility and stability of the vehicle can be optimized according to the specific vehicle state.