Motor Driven Power Steering Catch-Up Reduction Control
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Solution Overview
Problem
Motor-driven power steering systems experience 'catch-up' at high steering speeds, leading to increased steering resistance and manufacturing costs due to the inverse proportionality of motor torque and speed, which results in a heavy steering wheel sensation and potential locking feelings when turning rapidly with a vehicle stopped.
Innovation Solution
A control apparatus and method that includes sensors to detect driver and vehicle state information, a catch-up reduction logic unit to determine target steering speed and current compensation values, and a compensation unit to adjust motor current, preventing catch-up by artificially adjusting steering force based on steering speed and reducing motor current to avoid rapid locking feelings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If motor current is increased to provide sufficient assist torque at high steering speeds, then steering assistance is improved, but motor overheating and system complexity increase
Solution Approach 1:
The patent implements dynamic adjustment of motor current based on real-time steering speed detection. The controller monitors steering speed and dynamically modulates motor current to match actual steering demands, preventing excessive current application that would cause overheating while ensuring sufficient torque when needed
Solution Approach 2:
The system changes motor operating parameters (current, torque output) based on steering speed conditions. At high steering speeds, the controller reduces motor current to prevent overheating, while at normal speeds it maintains adequate current for proper steering assistance
2Reliability
If expensive high-performance motors are used to prevent catch-up at high steering speeds, then steering performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the need for mechanically superior (and expensive) motors with a control-based solution. The controller uses sensor data and algorithms to compensate for motor limitations, achieving smooth high-speed steering performance through electronic control rather than mechanical design
Solution Approach 2:
The system uses standard, cost-effective motors combined with intelligent control software to achieve performance that would otherwise require expensive specialized motors. The control algorithm acts as a software-based enhancement to economical hardware
3Force
If motor torque is increased to maintain steering assistance at high steering speeds, then steering force is improved, but steering smoothness deteriorates due to catch-up phenomenon
Solution Approach 1:
The patent employs feedback control by continuously detecting steering speed and using this information to adjust motor current. The steering speed sensor provides real-time feedback to the controller, which then modulates motor output to maintain smooth steering operation and prevent catch-up phenomena
Solution Approach 2:
The controller proactively adjusts motor current based on detected steering speed trends before catch-up occurs. By monitoring steering speed and anticipating high-speed conditions, the system pre-adjusts current levels to prevent the locking sensation rather than reacting after the problem occurs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces or prevents catch-up at high steering speeds, improving vehicle commercial value and reducing manufacturing costs by using an inexpensive DC motor, allowing smoother steering and preventing overheating, while maintaining steering performance without the need for expensive motors.
Implementation Method 1
a torque sensor that detects steering torque that is applied to the steering wheel by a driver
Implementation Method 2
a steering motor (MDPS motor)... an electric motor that assists the steering force applied by a driver, using output torque of an electric motor
Data Source
AI summary
A control apparatus and method of a motor-driven power steering system are provided. The apparatus and method are capable of suppressing catch-up that occurs at a high steering speed even without using an expensive motor, thereby contributing to improving commercial value and reducing the manufacturing cost of a vehicle. The method includes determining a target steering speed using driver-steering input information and vehicle state information and determining the target steering speed corresponds to a condition for avoiding catch-up using the determined target steering speed. A current compensation value is then determined for reducing catch-up using the target steering speed in response to determining that is the target steering speed corresponds a condition for avoiding catch-up and motor current is compensated with the current compensation value.