EPS Motor Torque Control for Steering Wheel Vibration Reduction
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Solution Overview
Problem
Existing Electric Power Steering (EPS) systems face challenges in effectively suppressing periodic steering wheel vibrations (SWVs) without requiring additional hardware or wiring, as current algorithms can interfere with normal driving operations and stability.
Innovation Solution
A method involving a gain-and-phase-compensated motor drive command signal is generated based on the angular velocity and position of the wheel, which is communicated to the EPS system to reduce periodic content in the motor torque signal, thereby counteracting vibrations at the steering wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing EPS control algorithms are used to suppress vibrations, then steering wheel vibrations are reduced, but normal driving operation and system stability are interfered with
Solution Approach 1:
The patent applies vibration cancellation by generating an anti-phase vibration signal through the EPS motor to counteract the detected steering wheel vibrations. The control algorithm creates a compensating torque that oscillates at the same frequency as the detected vibration but with opposite phase, effectively canceling the harmful vibrations while maintaining system stability through precise frequency and phase control.
Solution Approach 2:
The system implements feedback control by continuously monitoring steering wheel position and torque through existing sensors, detecting vibration patterns, and adjusting the EPS motor output in real-time. The control algorithm processes the detected vibration signals and generates appropriate compensating torque commands, creating a closed-loop system that reduces vibrations while maintaining normal steering operation.
2Object-affected harmful factors
If additional hardware or wiring is added to suppress vibrations, then vibration suppression effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent achieves vibration suppression by utilizing the existing EPS motor as a multi-functional component. The same motor that provides power steering assistance is also used to generate anti-vibration torque, eliminating the need for separate vibration suppression hardware. The control algorithm enables the motor to perform both steering assistance and vibration cancellation functions simultaneously.
Solution Approach 2:
The system uses existing sensors (torque sensor, position sensor) and the EPS motor itself to detect and suppress vibrations, making the system self-sufficient. The same components that enable normal power steering operation are leveraged to detect vibration patterns and generate compensating forces, eliminating the need for additional dedicated vibration sensing or actuation hardware.
3Object-affected harmful factors
If vibration suppression algorithms are implemented, then steering wheel vibrations are reduced, but steering performance and driver perception are affected
Solution Approach 1:
The control algorithm applies periodic compensating torque through the EPS motor that matches the frequency and phase of detected steering wheel vibrations. By using periodic action synchronized with the vibration frequency, the system effectively cancels vibrations while maintaining natural steering characteristics, as the compensating torque is applied only during vibration cycles rather than continuously.
Solution Approach 2:
The vibration suppression is applied locally to the specific frequency range where vibrations occur, rather than affecting the entire steering frequency spectrum. The control algorithm identifies vibration frequencies and applies compensating torque specifically at those frequencies, leaving other steering operations unaffected and preserving natural driver feedback and steering performance.
Data Source
AI summary
Methods, system and apparatus are provided for reducing steering wheel vibrations (SWVs). At least one heterodyning operation is performed during the generation of a gain-and-phase-compensated motor drive command signal. The gain-and-phase-compensated motor drive command signal is generated at a particular angular frequency, based on an angular velocity and an angular position of a wheel. The gain-and-phase-compensated motor drive command signal is communicated to an electric power steering system to control motor torque to reduce periodic content in a periodic electrical torque signal at the particular angular frequency.