Steering Feedback Control for Rack Friction Change Detection
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Solution Overview
Problem
Steering-by-wire systems experience changes in frictional forces between internal members due to wear, loosening, or rust, leading to inconsistent steering feel for the driver.
Innovation Solution
A steering apparatus with sensors and processors to detect and control frictional forces by identifying rack and steering wheel torques, providing electrical signals for warnings or normal operation indications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If steering-by-wire system operates for extended traveling distance, then mechanical members wear and loosen, but frictional forces between internal members decrease leading to inconsistent steering feel
Solution Approach 1:
The system performs preliminary identification of frictional force changes by comparing current rack force and feedback torque values against pre-stored reference values. This early detection mechanism allows the system to identify wear or rust conditions before they significantly degrade steering performance, enabling proactive maintenance or compensation.
Solution Approach 2:
The system continuously monitors rack force via position sensor and feedback torque via angle sensor, then compares these real-time measurements against reference values. This closed-loop feedback mechanism detects frictional force changes and triggers appropriate responses (compensation control or maintenance alerts) to maintain consistent steering feel throughout the vehicle's operational life.
2Reliability
If rust occurs on mechanical unit, then frictional forces between internal members increase, but steering feel becomes inconsistent
Solution Approach 1:
The system establishes reference values for rack force and feedback torque during normal operation. When rust increases frictional forces, the system detects this by comparing current measurements against these pre-established references, enabling early identification of rust conditions before they cause significant steering inconsistency.
Solution Approach 2:
Through continuous monitoring of rack force and feedback torque with real-time comparison against reference values, the system provides feedback on frictional force changes. This allows the control system to identify rust-related friction increases and implement compensation or alert the driver for maintenance.
3Loss of information
If frictional forces change due to wear or loosening, then steering feel changes, but driver awareness of mechanical condition is reduced
Solution Approach 1:
The system provides feedback to the driver through output devices (display, audio, or haptic feedback) when frictional force changes are detected. By comparing real-time rack force and feedback torque against reference values, the system informs the driver of mechanical conditions such as wear or rust, maintaining driver awareness of steering system health.
Solution Approach 2:
The control system acts as an intermediary between the mechanical steering components and the driver. It translates physical measurements (rack force, feedback torque) into meaningful information for the driver through output devices, bridging the gap between mechanical condition and driver perception.
Data Source
AI summary
A steering apparatus includes a steering wheel provided in a vehicle, a feedback motor including a rotation shaft connected to the steering wheel, an angle sensor configured to output an angle signal corresponding to rotation displacement of the steering wheel, a rack bar connected to a rotation shaft of the wheel provided in the vehicle, a steering motor including a rotation shaft connected to the rack bar, a position sensor configured to output a position signal corresponding to linear displacement of the rack bar assembly, and a processor configured to control the steering motor to linearly move the rack bar based on the angle signal, identify a rack force applied to the rack bar based on the position signal, and control the feedback motor to apply a feedback torque corresponding to the rack force applied to the rack bar to the steering wheel.