Steer-By-Wire Torque Feedback Using Dual Angle Sensor Modeling
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Solution Overview
Problem
Existing steer-by-wire steering systems face challenges in providing low-cost feedback to drivers regarding the driving situation, with incomplete consideration of system influences and increased costs due to additional sensors.
Innovation Solution
A steer-by-wire steering system with a control unit that receives signals from first and second angle sensors on the steering and rotor shafts, determines the difference in rotation based on a stored transmission model, and adjusts the control signal to compensate for transmission influences like friction, using a model to predict and adjust torque without external sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are added to improve feedback accuracy, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses existing internal sensors (first angle sensor on steering shaft, second angle sensor on rotor shaft) to measure transmission influences rather than adding external sensors. The control unit processes signals from these existing sensors to determine friction and stiffness effects, making the system self-sufficient without additional measurement devices.
Solution Approach 2:
The patent introduces a mathematical model of the transmission as an intermediary that translates angle sensor data into compensation values. This model acts as a virtual sensor that derives transmission state information without requiring physical additional sensors, bridging the gap between available measurements and required feedback accuracy.
2Ease of operation
If transmission influences are compensated to improve steering feel, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The control unit continuously monitors angle sensor signals, determines transmission influences (friction, stiffness), and adjusts the control signal to the electric motor in real-time. This closed-loop feedback mechanism compensates for transmission effects dynamically, improving steering feel without requiring complex mechanical modifications.
Solution Approach 2:
The system compensates for transmission influences by dynamically adjusting control parameters (motor torque, steering force) based on calculated friction and stiffness values. Rather than modifying the physical transmission, the control unit changes operational parameters to counteract unwanted effects, simplifying the overall system architecture.
3Ease of manufacture
If internal sensors and models are used to reduce cost, then manufacturing cost is reduced, but measurement precision may worsen
Solution Approach 1:
The patent replaces physical additional sensors with a mathematical model that processes signals from existing angle sensors. This virtual measurement system achieves equivalent or superior precision by calculating transmission state from steering angle and motor position data, eliminating the need for expensive external sensors while maintaining high feedback accuracy.
Solution Approach 2:
The existing angle sensors serve multiple functions: they measure both steering input and transmission output, enabling the system to derive both control information and transmission state information from the same sensors. This multi-functionality eliminates the need for dedicated additional sensors, reducing cost while maintaining precision through sophisticated signal processing.
Data Source
AI summary
The present disclosure relates to a steer-by-wire steering system for a motor vehicle containing a steering shaft that can be torsionally connected to a steering handling device, a feedback actuator having an electric motor acting on a rotor shaft, a transmission by means of which the rotor shaft is connected to the steering shaft, and a first angle sensor and a second angle sensor. A control unit assigned to the steering system is designed to receive a first sensor signal S provided by the first angle sensor, to receive a second sensor signal S provided by the second angle sensor, and to provide a control signal ST for controlling the electric motor.