Steering Feedback Torque Control for Rack Friction Changes
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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 sensations for drivers.
Innovation Solution
A steering apparatus with sensors and processors to detect changes in frictional forces by analyzing angle and position signals, providing feedback torque adjustments, and outputting warnings for friction, temperature, foreign substances, or mechanical defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a steering-by-wire system is used to eliminate mechanical connection between steering wheel and rack bar, then steering control flexibility is improved, but frictional force changes between internal members occur leading to inconsistent steering sensation
Solution Approach 1:
The system continuously monitors the frictional force between the rack bar and guide hole using a sensor, and feeds this information back to the controller. The controller then adjusts the motor torque in real-time to compensate for frictional force changes, ensuring consistent steering sensation for the driver throughout the vehicle's operational life.
Solution Approach 2:
The system dynamically changes the motor torque parameter based on detected frictional force variations. By adjusting the torque parameter in response to measured friction changes, the system maintains consistent steering characteristics despite wear, loosening, or rust in the mechanical components.
2Stability of the object's composition
If mechanical components are used in the steering system, then structural stability is improved, but frictional forces increase over time due to wear, loosening, or rust
Solution Approach 1:
A sensor detects the frictional force between the rack bar and guide hole, providing continuous feedback to the controller. This enables real-time monitoring and compensation of frictional force changes caused by wear, loosening, or rust in the mechanical components.
Solution Approach 2:
The system replaces pure mechanical force transmission with an electromechanical system that uses motor torque to compensate for mechanical friction. The motor acts as an intermediary that can dynamically adjust the force applied to overcome varying frictional forces in the mechanical components.
3Device complexity
If frictional force changes are not detected and compensated, then device complexity is reduced, but steering sensation inconsistency increases affecting driver experience
Solution Approach 1:
The system incorporates a sensor to detect frictional force changes and a controller to process this information and adjust motor torque accordingly. This feedback mechanism maintains consistent steering sensation without requiring complex mechanical adjustments or maintenance.
Solution Approach 2:
The steering system performs self-adjustment by automatically compensating for frictional force changes through motor torque control. This eliminates the need for manual mechanical adjustments or maintenance interventions, allowing the system to maintain optimal performance autonomously throughout its service life.
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.