Steer-by-Wire Haptic Feedback via Position and Torque Control
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Solution Overview
Problem
Steer-by-wire steering systems lack direct mechanical connection, making it difficult to provide equivalent haptic feedback to the user and implement driver requests effectively.
Innovation Solution
An operating method that uses a control unit to detect actual positions and steering torques in both the steering gear and wheel modules, with communication via a bus to adjust positions and transmit control signals, enabling haptic feedback and precise driver request implementation through assignment rules and torque sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a steer-by-wire steering system is used to eliminate mechanical connection, then system flexibility and adaptability are improved, but haptic feedback quality and direct coupling equivalent to mechanical systems deteriorate
Solution Approach 1:
The patent implements bidirectional feedback loops: (1) Position feedback where the actual position of the steering gear is detected and used to adjust the target position of the steering wheel, and (2) Force feedback where steering torque and steering force are determined from position deviation and torque sensor measurements, then used to control the steering gear positioning. This feedback mechanism restores the haptic coupling sensation absent in pure steer-by-wire systems.
Solution Approach 2:
The control unit acts as an intermediary between the steering wheel module and steering gear module, translating driver inputs into appropriate steering gear commands while synthesizing haptic feedback forces. The assignment rule serves as a mathematical intermediary that maps between steering wheel position and steering gear position, enabling virtual mechanical coupling through software.
2Ease of operation
If steer-by-wire system with signal path coupling is used, then ease of operation and adaptability are improved, but direct mechanical coupling sensation and driver request implementation equivalence deteriorate
Solution Approach 1:
The system dynamically adjusts the assignment rule parameters based on driving conditions, vehicle speed, and steering state. The steering ratio and haptic feedback characteristics are modified in real-time to maintain natural steering feel while adapting to different operational requirements, thereby preserving both ease of operation and precision of driver intent transmission.
3Reliability
If conventional mechanical connection is used, then haptic feedback and direct coupling are improved, but system complexity and adaptability worsen
Solution Approach 1:
The patent replaces the continuous mechanical connection with an electrical signal path consisting of sensors, communication buses, and control units. The mechanical steering gear position and force measurements are converted to electrical signals, processed digitally, and used to control electric actuators, thereby substituting mechanical coupling with electromechanical coupling that offers comparable haptic feedback without mechanical complexity.
Data Source
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AI summary
The invention relates to an operating method for a steer-by-wire steering system (1), which is designed having a steering gear module (10), a steering wheel module (20), and a bus (30) connecting the steering gear module and the steering wheel module, wherein an actual position in the steering gear module (10) is sensed and a setpoint position in the steering wheel module (20) is adjusted in relation to the actual position in the steering gear module (10) by using an association specification. The invention further relates to a control unit (12, 22, 40) for a steer-by-wire steering system (1), to a steer-by-wire steering system (1) as such, and to a vehicle (100) designed having a steer-by-wire steering system (1).