Steer-by-Wire Torque Adaptation for Realistic Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current steer-by-wire steering systems struggle to accurately reproduce realistic steering sensations due to neglecting disturbance influences like roadway conditions, resulting in suboptimal feedback and steering characteristics.
Innovation Solution
A method for adapting steering torque by comparing a basic torque with a rack-force-based torque, using an uncertainty band to adjust the feedback actuator, incorporating vehicle and steering models to enhance accuracy and realism, particularly during cornering and varying road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a feedback actuator is provided at the steering wheel to simulate retroactive effects, then steering sensation is provided, but the steering sensation is not accurate enough due to neglecting disturbance influences like roadway conditions
Solution Approach 1:
The patent implements a feedback mechanism where the actual rack force is continuously measured via a torque sensor and used to adjust the feedback actuator's output torque. This closed-loop feedback ensures the steering sensation accurately reflects real-time road conditions and vehicle dynamics, resolving the contradiction between sensation accuracy and system complexity by making the system adaptive rather than statically complex
Solution Approach 2:
The patent replaces direct mechanical force transmission with an electrical control system. Instead of relying on mechanical coupling between the steering wheel and wheels, the system uses electrical signals to control the feedback actuator, enabling precise replication of rack force variations caused by road conditions without adding complex mechanical linkages
2Measurement precision
If the rack force is determined using a model based on transverse acceleration and steering angle, then steering torque can be estimated, but the accuracy is insufficient because the model does not consider disturbance influences such as roadway conditions
Solution Approach 1:
The system uses the torque sensor to directly measure the actual rack force, allowing the system to self-correct and adapt to disturbance influences like roadway conditions without requiring complex external sensing or modeling of these disturbances. The measured rack force automatically incorporates all real-time road conditions, eliminating the need to separately detect and measure individual disturbance factors
3Ease of operation
If an artificially produced steering torque is used for activating the feedback actuator, then the feedback actuator can be controlled, but it is highly complicated to reproduce the road feedback and steering sensation in and over a limit range in terms of driving dynamics
Solution Approach 1:
The patent uses a feedback loop where the actual rack force measured by the torque sensor is continuously compared with the currently applied feedback torque, and the difference is used to adjust the feedback actuator's output. This ensures accurate reproduction of road feedback across the full range of driving dynamics, from normal conditions to limit ranges, while maintaining ease of control through automated adjustment
Data Source
AI summary
A method can be used to adapt a steering torque for controlling a feedback actuator of a steer-by-wire motor vehicle steering system. The method may involve providing a basic steering torque, providing a rack-force-based steering torque, determining a difference between the basic steering torque and the rack-force-based steering torque, and if the difference exceeds a predetermined limit value adapting the basic steering torque to the rack-force-based steering torque and transmitting a resulting steering torque to control the feedback actuator. However, if the difference remains below the predetermined limit value, then the method may involve transmitting the basic steering torque to control the feedback actuator.