Electric Power Steering Torque Compensation via Universal Joint Kinematics

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Solution Overview

Problem

Existing electric power steering systems fail to provide an improved steering feel due to kinetic disturbance torques caused by mechanical components in the steering train, affecting the driver's experience.

Innovation Solution

Determining and applying compensation components to counteract these disturbance torques by calculating and applying a total compensation component based on the kinematic behavior of universal joints in the steering train, using steering angle and torque sensor data to adjust the assist torque applied by the electric motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If universal joints are used in the steering train to compensate installation angular offset, then adaptability is improved, but kinetic disturbance torques are generated affecting steering feel

Engineering Contradiction:

Improveinstallation angular offset compensationVSAvoidkinetic disturbance torques

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent calculates the disturbance torques generated by universal joints and applies compensating torques through the electric motor to counteract these harmful effects. The harmful kinetic disturbance torques are converted into a beneficial compensation signal that improves steering feel while maintaining the adaptability benefits of universal joints.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The control unit acts as an intermediary between the universal joints and the steering wheel. It calculates the disturbance torques produced by universal joints and introduces compensating torques through the electric motor, mediating the harmful effects before they reach the driver.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If disturbance torques are compensated to improve steering feel, then steering quality is improved, but control complexity increases

Engineering Contradiction:

Improvesteering feelVSAvoidcontrol complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent employs feedback by continuously monitoring steering angle and torque, calculating the resulting disturbance torques from universal joints, and applying compensating torques through the electric motor. This closed-loop feedback system improves steering feel while managing control complexity through systematic calculation and compensation.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP1935754A1Method and control unit for operating electric power steering

Publication Date: 2008.06.25 ZF LENKSYSTEME GMBH

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AI summary

The method involves initiating steering movement of an electric motor (4) for assisting a unit of steering system into steering line. A compensation portion is determined for compensation of kinetic disturbing torque in the steering line of an electrical power steering (1). The kinetic disturbing torque is retroactive on the steering system. The kinetic disturbing torque is determined from mechanical joint present in steering line. An independent claim is also included for a controller of an electrical power steering with a computer program with program code.