Electric Power Steering Travel Stop Simulation
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Solution Overview
Problem
Electric Power Steering Systems (EPS) lack the ability to effectively simulate end stops, which are essential for limiting travel when steering a vehicle, especially in situations where mechanical end stops are not desirable.
Innovation Solution
A control system that determines a position control value based on the handwheel position and generates a torque command to simulate an end of travel stop in the EPS, utilizing a control module with sub-modules for state determination, gain calculation, damping adjustment, and torque command generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical end stops are used in the steering system, then travel limitation is achieved, but noise and vibration increase
Solution Approach 1:
The patent replaces mechanical end stops with an electronic control system that generates torque commands to simulate end stop behavior. The control module monitors handwheel position and applies counteracting torque near end positions, eliminating physical contact and associated noise/vibration while maintaining travel limitation functionality.
Solution Approach 2:
The patent introduces a control module as an intermediary between the driver's steering input and the steering mechanism. This intermediary processes handwheel position data and generates appropriate torque commands to simulate end stops, providing a soft transition that avoids the harsh mechanical impact of traditional end stops.
2Adaptability or versatility
If different rack and pinion configurations are used for various vehicle platforms, then specific travel distance requirements are met, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the control module universal by programming it with vehicle-specific parameters (maximum handwheel angle, end stop position thresholds) rather than requiring different hardware configurations. The same physical steering system can be adapted to different vehicle platforms simply by changing software parameters, enabling one rack and pinion design to serve multiple applications.
Solution Approach 2:
The patent achieves adaptability through parameter changes in the control software. By modifying threshold angles, torque magnitudes, and position limits in the control module, the system can accommodate different vehicle platforms and travel distance requirements without any physical modifications to the steering mechanism.
3Reliability
If mechanical end stops are used, then travel limitation is provided, but chassis forces can cause unwanted handwheel rotation
Solution Approach 1:
The patent replaces mechanical end stops with an electronic torque counteraction system that actively resists unwanted handwheel rotation caused by chassis forces. The control module continuously monitors handwheel position and applies corrective torque to maintain the handwheel at the end stop position, providing stability that mechanical stops cannot achieve.
Solution Approach 2:
The patent implements feedback control where the control module continuously monitors handwheel position and adjusts torque commands accordingly. When chassis forces cause the handwheel to move from the intended end stop position, the system detects this deviation and applies corrective torque to restore the desired position, creating a stable, controlled end stop experience.
Data Source
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AI summary
A control system for controlling a steering system is provided. The control system includes a first module that determines a position control value based on a handwheel position. A second module generates a torque command based on the position control value to simulate an end of travel stop in the steering system.