Steer-by-Wire Haptic Feedback Fault Isolation
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Solution Overview
Problem
In steer-by-wire steering systems, the lack of mechanical connection between the steering wheel and gear complicates ensuring driver awareness of system faults, as haptic feedback types are superimposed, making it difficult for the driver to reliably perceive warning signals in all driving states.
Innovation Solution
An evaluation unit is integrated with the control unit to weaken or deactivate haptic roadway feedback during steering system faults, allowing the driver to more easily perceive warning feedback, with additional modules generating steering counter torque and roadway signals to provide feedback on steering forces and road conditions, and a diagnostic module generating a warning signal for the hand actuator to provide multi-channel warnings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If haptic roadway feedback is provided to the driver during steering system faults, then the driver receives information about road conditions, but the warning feedback becomes difficult to perceive due to superposition with roadway feedback
Solution Approach 1:
The patent extracts and separates the warning feedback from the roadway feedback by selectively deactivating or weakening the roadway feedback when a steering system fault is detected. This allows the warning feedback to be perceived independently without being masked by the roadway feedback, resolving the contradiction between providing road condition information and ensuring fault awareness.
Solution Approach 2:
The system dynamically adjusts the haptic feedback characteristics based on the detected fault state. When a steering system fault is detected, the control unit modifies the roadway feedback in real-time by deactivating or weakening it, while maintaining or emphasizing the warning feedback. This dynamic adaptation ensures that the warning feedback remains perceptible across different driving conditions and fault scenarios.
2Adaptability or versatility
If multiple types of haptic feedback are provided simultaneously on the steering wheel, then comprehensive information is transmitted to the driver, but the driver cannot reliably perceive warning feedback in all driving states
Solution Approach 1:
The patent segments the haptic feedback system into distinct functional components: roadway feedback for normal operation and warning feedback for fault conditions. By separating these feedback types and implementing selective activation/deactivation logic, the system ensures that warning feedback can be reliably perceived when needed without being obscured by other feedback types, while still maintaining comprehensive information provision during normal operation.
3Extent of automation
If the steering wheel and steering gear are mechanically decoupled in a steer-by-wire system, then electronic control flexibility is improved, but driver awareness of system faults becomes more difficult
Solution Approach 1:
The patent implements a comprehensive feedback system that compensates for the mechanical decoupling. Multiple sensors detect steering wheel position, actuator position, and system fault states, and this information is fed back to the control unit. The control unit then generates appropriate haptic feedback through the hand actuator to inform the driver about system status and faults, maintaining driver awareness despite the lack of mechanical connection.
Solution Approach 2:
The hand actuator serves as an intermediary between the electronic steering control system and the driver. It transmits haptic feedback forces to the steering wheel based on commands from the control unit, effectively bridging the mechanical gap created by the steer-by-wire architecture. This intermediary enables the driver to perceive system status and faults through tactile feedback even without a direct mechanical connection to the steering gear.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances driver perception of steering system faults, reducing the risk of accidents by ensuring reliable feedback and increased driving safety through clear and distinct warning signals, even in critical driving situations.
Implementation Method 1
an electromechanical hand actuator is also provided, which acts as a force feedback actuator and generates the different types of haptic feedback on the steering wheel
Implementation Method 2
The steering sensor detects the steering request given by the driver on the basis of a rotary position and/or a rotary actuation of the steering wheel
Data Source
AI summary
A steer-by-wire steering system for a vehicle, having a steering handle, a steering gear actuator mechanically decoupled from the steering handle, a steering sensor which detects a rotational position and/or a rotational movement of the steering handle as a steering command, an electronic control unit which, as a function of the detected steering command, activates the steering gear actuator to set a vehicle wheel steering angle (α), and a hand actuator activatable by the control unit, which generates different types of haptic feedback (R1, R2, R3) for the driver on the steering handle, namely a haptic steering feedback (R1) in which a steering counter torque is applied to the steering handle, a roadway feedback (R2), which correlates with a roadway-side disturbance excitation acting on the vehicle, and a warning feedback (R3), which informs the driver of a fault in the steer-by-wire steering system.