Steering System Static Friction Monitoring
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Solution Overview
Problem
The existing methods for diagnosing the condition of a vehicle's steering system are inadequate, as they often fail to detect wear or damage, especially in electric power assisted steering systems, which can lead to safety concerns and premature failure, as they rely on visual inspections that may not detect subtle changes in friction levels.
Innovation Solution
A method and apparatus that monitor the steering system by repeatedly measuring the angular position and torque of the steering wheel to calculate static and dynamic friction values, comparing them to target values to indicate the condition of the system, and using these measurements to alert drivers or mechanics to potential wear, which can be implemented using existing sensors in electric power assisted steering systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual inspection methods are used to diagnose steering system condition, then the inspection process is simple and quick, but wear or damage cannot be detected reliably
Solution Approach 1:
The patent replaces visual inspection (mechanical/manual examination) with automated sensor-based measurement systems. Torque sensors and position sensors automatically measure steering parameters, eliminating the need for manual visual assessment and providing reliable detection of wear and damage through quantitative data.
Solution Approach 2:
The steering system performs self-diagnosis by continuously monitoring its own operational parameters. The system uses onboard sensors to measure torque and position, automatically calculating friction levels and comparing them against thresholds to detect wear, enabling the system to monitor its own condition without external intervention.
2Measurement precision
If friction measurements are taken over long elapsed times, then more accurate baseline comparisons can be made, but the load on the steering system changes making measurements unreliable
Solution Approach 1:
The patent implements dynamic measurement windows that adapt to steering conditions. The system calculates friction over varying time periods based on steering wheel movement patterns, adjusting the measurement duration to capture sufficient data while ensuring load conditions remain relatively constant. This dynamic approach optimizes both precision and reliability.
Solution Approach 2:
The system performs preliminary assessments of steering conditions before taking friction measurements. It monitors steering wheel position and torque to determine appropriate measurement windows, ensuring that measurements are taken during stable load conditions while capturing sufficient data for accurate friction calculation.
3Reliability
If static friction measurements are used to monitor steering condition, then early detection of wear is possible, but the system requires repeated measurements during use
Solution Approach 1:
The patent implements continuous monitoring of steering parameters during normal operation. Torque and position sensors continuously measure steering wheel conditions, and the system continuously calculates friction levels, providing ongoing surveillance of steering system health without requiring the vehicle to be taken out of service for separate diagnostic procedures.
Solution Approach 2:
The system performs periodic friction calculations at strategically determined intervals based on steering wheel movement patterns. Rather than continuous computation, it calculates friction at key moments when sufficient data is available, reducing processing time while maintaining detection capability.
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 approach provides early detection of excessive wear, increasing safety by alerting drivers or mechanics to potential issues that may not be visible during routine inspections, and allows for adaptive adjustment of assistance torque in electric power assisted steering systems to compensate for changing friction conditions.
Implementation Method 1
measuring the torque applied to the steering system
Implementation Method 2
repeatedly measuring the angular position of a steering wheel
Implementation Method 3
calculating the difference between the measured torques at the first moment of time and second moment of time to provide a static friction value that is dependent upon the static friction Tfriction in the steering system
Data Source
AI summary
A method of monitoring the condition of a steering system comprises the steps of repeatedly measuring the angular position of a steering wheel, identifying from the measurements of steering wheel position a first moment in time at which the steering wheel comes to rest in an off center position following movement in a first direction away from a straight ahead position, measuring the torque applied to the steering system at that first moment in time, identifying from the measurements of steering wheel position a second moment in time at which the steering wheel first starts to moves away from the off center position in the opposite direction to the first direction, measuring the torque applied to the steering system at that second moment in time, calculating the difference between the measured torques at the first moment of time and second moment of time to provide a static friction value and comparing the calculated static friction value with a target static friction value to provide an indication of the condition of the steering system.