Hysteresis Loop Steering Control for Friction Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric power steering systems experience undesirable torque feedback due to friction, resulting in varying assist levels when steering into and returning from a corner, which affects driver input.
Innovation Solution
A control system that includes a direction determination module, a position determination module, and a final command module to compensate for friction by determining changes in handwheel torque and positioning on a hysteresis loop, generating an assist command to adjust assist values accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction compensation is not applied, then the system structure remains simple, but undesirable torque feedback occurs when steering direction is reversed
Solution Approach 1:
The control system determines the position on the hysteresis loop in advance based on handwheel torque change, and pre-calculates the appropriate assist value from a map or table before actual steering reversal occurs. This preliminary preparation eliminates torque feedback issues during direction changes without requiring complex real-time calculations.
Solution Approach 2:
A hysteresis loop model is introduced as an intermediary element between the driver's steering input and the power assist output. This model includes parameters such as handwheel torque change and position on the hysteresis loop that mediate the control relationship, allowing friction compensation without directly modifying the mechanical steering components.
2Force
If assist value is increased when steering into a corner, then steering effort is reduced, but torque feedback becomes more undesirable when returning from the corner
Solution Approach 1:
The assist value is made dynamic by determining the position on the hysteresis loop based on the change in handwheel torque. The control system continuously adjusts the assist level according to the current phase of steering (entering or returning from corner) by evaluating torque change magnitude and direction, ensuring optimal assist without excessive torque feedback.
Solution Approach 2:
The system changes the parameter of assist value based on the determined position on the hysteresis loop. By using a map or table that maps hysteresis loop positions to appropriate assist values, the system dynamically adjusts the assist parameter to compensate for friction effects while minimizing undesirable torque feedback during direction reversal.
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
The system provides consistent assist levels by compensating for friction, reducing undesirable torque feedback and improving steering ease by adjusting assist based on torque changes and vehicle speed.
Implementation Method 1
The position determination module determines a position on a hysteresis loop. The position on the hysteresis loop depends on the change in the handwheel torque.
Data Source
AI summary
A control system for a steering system is provided. The control system includes a direction determination module, a position determination module, and a final command module. The direction determination module determines a change in a handwheel torque. The position determination module determines a position on a hysteresis loop. The position on the hysteresis loop depends on the change in the handwheel torque. The final command module determines a final assist value based on the position. The final command module generates an assist command.