Steering Control System Torque Limit Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Steer-by-wire vehicles experience sudden changes in reaction torque when the steering angle reaches the limit, causing discomfort for the driver due to unexpected steering feelings, as existing technologies fail to smoothly adjust the steering angle ratio characteristic with changes in vehicle state.
Innovation Solution
A steering control system with a controller that adjusts the turning angle and reaction torque characteristics based on the vehicle's state, maintaining the second characteristic at the first state when the steering angle reaches the limit, and gradually changing characteristics to minimize sudden torque variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the steering angle ratio characteristic is adjusted according to vehicle state changes, then the steering optimization is improved, but the reaction torque suddenly changes at the steering limit causing driver discomfort
Solution Approach 1:
The controller predicts future vehicle states and preemptively adjusts the reaction torque characteristic before the steering limit is reached. This preliminary action prevents sudden torque changes by preparing the appropriate characteristic in advance, thereby maintaining driver comfort while enabling adaptive steering optimization.
Solution Approach 2:
The system dynamically switches between multiple reaction torque characteristics based on predicted vehicle states and steering angle trajectories. By making the characteristic selection dynamic rather than static, the system adapts to changing conditions while maintaining smooth torque transitions that preserve driver comfort.
2Manufacturing precision
If the reaction torque is rapidly increased at the steering limit, then the steering angle control precision is improved, but the sudden torque change causes unexpected steering feeling
Solution Approach 1:
The controller calculates predicted steering angles and reaction torque in advance based on current vehicle state and driver input. This preliminary calculation allows the system to prepare appropriate torque limits before reaching the steering boundary, ensuring precise angle control without sudden torque changes that would affect steering feel.
Solution Approach 2:
The predicted reaction torque acts as an intermediary between the driver's steering input and the actual torque applied at the steering limit. By introducing this predictive intermediary, the system smooths the transition at the steering boundary, maintaining both control precision and steering feel consistency.
Data Source
AI summary
A steering control system includes a steering-motor for turning wheels, a reaction-force-motor for applying a reaction torque to a steering of the vehicle, and a controller. The controller calculates a turning angle based on a first-characteristic representing a relationship of the turning angle to a steering angle, and calculates a reaction torque based on a second-characteristic representing a relationship of a reaction torque to the steering angle. The controller changes the first-characteristic from a characteristic corresponding to a first-state to a characteristic corresponding to a second-state in response to a change in the state of the vehicle from the first-state to the second-state. The controller maintains the second-characteristic at the characteristic corresponding to the first-state when the state of the vehicle changes from the first-state to the second-state in the case where the steering angle is steered to a steering limit corresponding to an upper limit of the turning angle.