Power Steering Control System for Wheel Disturbance Mitigation

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Solution Overview

Problem

Current steering systems are inadequate in effectively mitigating road wheel disturbances, such as wheel imbalance, which cause vibrations in the handwheel, and existing solutions have drawbacks.

Innovation Solution

A control system for a power steering system that includes a frequency estimation module, a scaling module, and a command module to calculate a scale factor and determine a wheel disturbance cancel amount based on wheel speed, generating an assist command to reduce handwheel vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If wheel imbalance disturbance occurs, then handwheel vibrations increase, but driver comfort and vehicle stability deteriorate

Engineering Contradiction:

Improvehandwheel vibrationsVSAvoidvehicle stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The control system applies preliminary anti-action by detecting wheel speed variations caused by wheel imbalance and generating compensatory steering torque in advance. The command module calculates a disturbance cancel amount based on the detected wheel speed and applies it through the power steering system before the vibrations significantly affect the driver, thereby preventing handwheel vibrations and maintaining vehicle stability.

Inventive Principle:

Principle #9Preliminary anti-action

2Measurement precision

If wheel speed variations are detected, then disturbance identification improves, but system complexity increases

Engineering Contradiction:

Improvedisturbance detection accuracyVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control system uses self-service by leveraging existing wheel speed sensor data that is already available in the vehicle's power steering system. Instead of adding separate vibration sensors or complex detection devices, the system repurposes the wheel speed information to identify disturbances, thereby improving measurement precision without significantly increasing device complexity.

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If assist command is generated based on wheel disturbance cancel amount, then vibration reduction effectiveness improves, but control system complexity increases

Engineering Contradiction:

Improvehandwheel vibrationsVSAvoidcontrol module complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The control system applies parameter changes by dynamically adjusting the assist command parameters based on the detected wheel speed variations. The command module modifies the steering assist torque in real-time according to the calculated disturbance cancel amount, enabling effective vibration reduction through parameter adaptation rather than adding complex mechanical components.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2604490B1A vehicle power control steering system with a wheel speed velocity variation scaling device

Publication Date: 2020.02.05 STEERING SOLUTIONS IP HOLDING CORP

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AI summary

A control system for a power steering system is provided. The control system includes a scaling module for calculating a scale factor based on a wheel frequency. The control system also includes a command module that evaluates a wheel disturbance based on a wheel speed and that determines a wheel disturbance cancel amount based on the wheel speed. The command module generates an assist command to the power steering system based on the wheel disturbance cancel amount and the scale factor.