Motor-Driven Power Steering Pull Compensation Logic

Solution Overview

Problem

Motor-driven power steering systems fail to prevent vehicle pulling due to road surface conditions during deceleration in straight-driving and non-steering states, leading to instability and potential safety issues.

Innovation Solution

An apparatus and method for controlling a motor-driven power steering system that includes an information detection device, an MDPS basic logic device, a state determination device, a compensation logic device, and a motor control logic device, which detect necessary information, determine steering-assist and pull-compensation control values, and control the steering motor to prevent vehicle pulling by generating a control target value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the MDPS system provides steering assistance based on driver input, then steering performance and steering feel are improved, but the system cannot prevent vehicle pulling during deceleration on crowned road surfaces

Engineering Contradiction:

Improvesteering performanceVSAvoidvehicle pulling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control apparatus proactively detects deceleration states and crowned road surface conditions before vehicle pulling occurs, and preemptively adjusts the steering motor torque to counteract the expected pulling force. This preliminary action prevents the harmful effect rather than reacting after it occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The steering motor acts as an intermediary force that compensates for the unbalanced road surface forces. By detecting the crowned road surface condition and deceleration state, the system uses the steering motor to generate a counteracting torque that balances the lateral force difference between left and right wheels, thereby preventing vehicle pulling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the controller increases motor output torque at low speed, then steering assistance is improved, but vehicle stability may be compromised

Engineering Contradiction:

Improvesteering assistanceVSAvoidvehicle stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The control apparatus dynamically adjusts the steering motor torque based on real-time detection of vehicle speed, deceleration state, and steering conditions. The system transitions from a static torque assistance approach to a dynamic one that adapts to changing vehicle states, providing high torque when needed for steering assistance while maintaining stability during deceleration on crowned surfaces.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the torque parameter of the steering motor based on detected vehicle conditions. During deceleration on crowned road surfaces, the controller modifies the motor torque to counteract pulling forces, while at normal operating conditions, it provides appropriate steering assistance torque based on driver input and vehicle speed.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If the MDPS system decreases motor output torque at high speed, then steering wheel stiffness is improved for stability, but the system cannot compensate for road surface-induced pulling

Engineering Contradiction:

Improvedriving stabilityVSAvoidvehicle pulling

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The control apparatus proactively detects deceleration states and crowned road surface conditions before vehicle pulling occurs, and preemptively adjusts the steering motor torque to counteract the expected pulling force. This preliminary action prevents the harmful effect rather than reacting after it occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The steering motor acts as an intermediary force that compensates for the unbalanced road surface forces. By detecting the crowned road surface condition and deceleration state, the system uses the steering motor to generate a counteracting torque that balances the lateral force difference between left and right wheels, thereby preventing vehicle pulling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10689028B2Control apparatus and method of motor-driven power steering system

Publication Date: 2020.06.23 HYUNDAI MOTOR CO LTD

AI summary

An apparatus and method for controlling an MDPS system may include an information detection device configured to detect information for steering assistance and pull-compensation control; an MDPS basic logic device configured to determine a steering-assist control value from the detected information; a state determination device configured wherein whether conditions corresponding to a non-steering state, a straight-driving state, a deceleration state, and a state in which pulling of the vehicle occurs are satisfied is determined based on the detected information; a compensation logic device configured wherein when the conditions are satisfied, a pull-compensation control value is determined from the detected information using stored configuration information and a control target value is determined using the steering-assist control value and the pull-compensation control value; and a motor control logic device configured to control an operation of a steering motor depending on the control target value.