Road Wheel Actuator PID Control for Fast Steering and Low NVH

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Solution Overview

Problem

Conventional motor driven power steering (MDPS) steering angle control logic struggles to achieve fast steering responsiveness and noise vibration harshness (NVH) performance simultaneously, as increasing responsiveness through conventional P-PI controllers degrades NVH performance.

Innovation Solution

A PID control logic is applied to the road wheel actuator (RWA) system, incorporating gains Dcmd and Dfed for target and feedback position information, filtered with low pass filters, to enhance steering responsiveness and NVH performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the position control P gain is increased to improve steering responsiveness, then steering response is improved, but NVH performance deteriorates (operation noise and tongue noise increase during sharp reversals)

Engineering Contradiction:

Improvesteering responsivenessVSAvoidNVH performance (operation noise and tongue noise)

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The control system dynamically adjusts control parameters based on operating conditions. The patent implements a variable gain scheduler that modifies P, I, and D gains according to steering state (angle, velocity, acceleration), allowing optimal performance across different operating conditions rather than using fixed high gains that cause NVH issues

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes control parameters (P, I, D gains) based on steering conditions. By monitoring steering angle, angular velocity, and angular acceleration, the system selects appropriate gain sets to maintain responsiveness while suppressing noise and vibrations during different maneuver types

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional P-PI control logic is used to simplify control structure, then device complexity is reduced, but steering responsiveness and NVH performance cannot be simultaneously satisfied

Engineering Contradiction:

Improvecontrol logic complexityVSAvoidperformance criteria satisfaction (responsiveness and NVH)

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements comprehensive feedback control using steering angle, angular velocity, and angular acceleration sensors. The feedback mechanism continuously monitors system state and adjusts control outputs to maintain both responsiveness and NVH performance, enabling the complex control strategy needed to satisfy multiple performance criteria simultaneously

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system is segmented into multiple operational modes or regions based on steering conditions. By dividing the operating space into distinct zones (e.g., normal steering, sharp reversal, parking assist), the system can apply optimized control strategies for each zone, managing complexity through structured organization rather than monolithic control logic

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12612098B2RWA system control apparatus and method

Publication Date: 2026.04.28 HYUNDAI MOBIS CO LTD

AI summary

Provided is an apparatus for controlling a road wheel actuator (RWA) system, the apparatus including a sensor module configured to detect sensing data of at least one of a steering angle, rack position information, angular velocity of a steering wheel, and column torque, and a processor configured to perform a Proportional Integral Differential (PID) control logic based on the sensing data detected by the sensor module and the RWA position information fed back from the RWA system.