Electric Power Steering Motor Torque Control via Segmented Open-Loop and Closed-Loop Components
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Solution Overview
Problem
Existing methods for generating a motor torque preset value for electric power assisted steering systems lack simplicity and precision in influencing steering behavior and driver feedback.
Innovation Solution
A method combining open-loop and closed-loop controlled motor torque components, where the pilot control component is determined based on torsion bar torque and vehicle speed, and the closed-loop controller component is limited by a steering-specific maximum value, using an assistance characteristic curve and a saturated PID controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single closed-loop control method is used to generate motor torque preset value, then the control precision can be maintained, but the ability to comprehensively influence steering behavior and steering sensation is limited
Solution Approach 1:
The motor torque preset value is segmented into multiple independent components: a pilot control component (open-loop) that provides basic steering assistance based on steering angle and vehicle speed, and a closed-loop controller component that refines the torque based on actual steering feedback. This segmentation allows each component to perform its specific function independently, achieving comprehensive steering behavior control while maintaining clear structural organization.
Solution Approach 2:
The patent merges open-loop pilot control and closed-loop feedback control into a unified motor torque control system. The pilot control component provides proactive steering assistance based on predicted steering needs, while the closed-loop component adjusts torque based on actual steering deviation. This combination enables the system to both anticipate and respond to steering requirements, achieving versatile steering behavior control.
2Manufacturing precision
If complex control algorithms are used to achieve precise steering control, then steering precision can be improved, but the ease of implementation and basic setting is reduced
Solution Approach 1:
The pilot control component performs preliminary steering assistance by pre-calculating the required motor torque based on steering angle and vehicle speed before the actual steering action occurs. This proactive control provides a head start in compensating for steering effort, reducing the complexity of real-time control adjustments and simplifying the overall control implementation while maintaining precision.
3Ease of operation
If only open-loop control is used for motor torque, then the control structure is simple, but the precision and responsiveness to actual steering conditions is insufficient
Solution Approach 1:
The closed-loop controller component continuously monitors actual steering conditions and compares them with the desired steering state, generating corrective torque adjustments based on the deviation. This feedback mechanism ensures high steering control precision while the modular structure (separating pilot control from closed-loop control) maintains relative simplicity in control structure implementation.
Data Source
AI summary
A method for determining a desired preset value (YMSM) for a motor torque of an electric servomotor in a power assisted steering system for a motor vehicle, wherein the desired preset value is determined using a motor torque servo control component (MVSK) which forms a controlled section, and using a motor torque regulator component (MRK) which forms a regulated section, wherein the regulating variable is a torsion bar torque (MDS), the two motor torque components being functionally offset against one another in order to determine therefrom the desired preset value (YMSM) for the motor torque (MSM) of the servomotor (SM).