Steering Wheel Reaction Torque Generation in SBW Systems
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Solution Overview
Problem
Existing Steer-by-Wire (SBW) systems face challenges in maintaining constant hysteresis of steering wheel reaction torque across varying steering angles and rack forces, leading to inconsistent driver feedback.
Innovation Solution
An apparatus and method that determine an offset based on input factors like steering angle and rack force, calculate target reaction torque, and generate steering wheel reaction torque to maintain consistent hysteresis through a reaction torque generator, using a corrected reaction torque map to ensure uniform driver feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steering wheel reaction torque is determined based on steering angle or rack force, then the SBW system can generate steering feedback, but the hysteresis value cannot be constantly maintained across different steering sections
Solution Approach 1:
The patent applies dynamics by making the reaction torque map adjustable and variable based on driving conditions. The system dynamically modifies the reaction torque map according to vehicle speed, steering angle, and rack force, allowing the hysteresis characteristics to be maintained consistently across different operating sections. This dynamic adjustment resolves the contradiction by enabling the system to adapt its feedback characteristics in real-time rather than using a fixed torque map.
Solution Approach 2:
The patent changes parameters by introducing multiple input factors (vehicle speed, steering angle, rack force) that modify the reaction torque map characteristics. By varying these parameters, the system can maintain constant hysteresis values across different steering sections while still providing appropriate steering feedback. The offset value is specifically adjusted based on these parameters to ensure consistent hysteresis behavior.
2Device complexity
If a fixed reaction torque map is used, then the system structure remains simple, but the hysteresis varies in sections with different reaction torque variations
Solution Approach 1:
The patent transforms the fixed reaction torque map into a dynamic one that adjusts based on driving conditions. The system uses vehicle speed, steering angle, and rack force as inputs to modify the torque map characteristics, ensuring consistent hysteresis across different sections. This dynamic approach maintains reliability without requiring overly complex hardware, as the adjustments are made through software-based map modification.
Solution Approach 2:
The patent makes the reaction torque map multi-functional by enabling it to serve different purposes across different operating conditions. The same basic torque map structure is used universally, but it is dynamically adjusted to provide appropriate hysteresis characteristics for various driving scenarios. This universal approach avoids the need for completely separate control systems for different sections.
3Reliability
If the reaction torque map is adjusted based on multiple input factors, then constant hysteresis can be maintained, but the calculation complexity increases
Solution Approach 1:
The patent manages calculation complexity by systematically varying parameters (vehicle speed, steering angle, rack force) to adjust the reaction torque map. The offset value is calculated based on these parameters using defined relationships, which maintains constant hysteresis without requiring excessively complex algorithms. The parameter changes are implemented through structured calculations that balance accuracy with computational efficiency.
Solution Approach 2:
The patent applies preliminary action by pre-defining the relationships between input factors and the reaction torque map adjustments. The offset calculations and torque map modifications are prepared in advance based on expected operating conditions, reducing the complexity of real-time calculations. This preliminary structuring allows the system to maintain constant hysteresis through pre-planned parameter adjustments rather than complex on-the-fly computations.
Data Source
AI summary
An apparatus and method for generating steering wheel reaction torque. Steering wheel reaction torque is generated in an SBW system so as to be able to maintain constant hysteresis regardless of a steering angle or rack force. The apparatus for generating steering wheel reaction toque in an SBW system for a vehicle includes: an offset determiner determining an offset on the basis of input factors; a target reaction torque determiner determining target reaction torque on the basis of at least one of the input factors and the offset; and a reaction torque generator generating steering wheel reaction torque on the basis of the determined target reaction torque.