MDPS Steering Feel Stabilization via Signal Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor-driven power steering (MDPS) systems face limitations in stabilizing steering feel due to noise filtering processes, which can lead to decreased motor response speed and phase margin offset, resulting in a limited ability to reduce the sense of difference felt by drivers from vibrations and noises.
Innovation Solution
An apparatus and method that includes an input unit for receiving column torque, a calculation unit to remove noise using a high-pass filter and discretize signals with the trapezoid rule, and a compensation unit to calculate an assist torque for stabilizing steering feel by generating a compensation signal, thereby reducing noise and improving response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If noise filtering is applied to stabilize steering feel, then steering stability is improved, but motor response speed decreases
Solution Approach 1:
The patent segments the steering torque signal processing into multiple independent stages: raw torque acquisition, noise filtering, differentiation for damping calculation, and compensation torque generation. Each stage processes specific aspects of the signal independently, allowing optimization of response speed at earlier stages while maintaining stability through subsequent processing stages.
Solution Approach 2:
The patent applies preliminary noise filtering to the column torque signal before differentiation and damping calculation. By removing noise components in advance, the system prevents noise amplification during subsequent differentiation operations, thereby maintaining both steering stability and acceptable response speed without requiring aggressive noise suppression that would slow down the overall system.
2Object-affected harmful factors
If differentiation process is used in damping logic, then vibration control is improved, but phase margin is significantly offset
Solution Approach 1:
The patent applies preliminary noise filtering to counteract the harmful effect of noise amplification that would occur during differentiation. By removing noise components before the differentiation process, the system prevents the phase margin degradation that would otherwise result from differentiating noisy signals, thereby maintaining both vibration control effectiveness and system stability.
Solution Approach 2:
The patent introduces an intermediate noise filtering stage between torque acquisition and differentiation. This intermediary processing step acts as a buffer that reduces noise content before it reaches the differentiation operator, thereby preventing the phase margin offset that would occur if differentiation were applied directly to noisy torque signals.
3Object-affected harmful factors
If low pass filter is applied to remove noise, then noise reduction is improved, but phase margin and response capability are limited
Solution Approach 1:
Instead of applying a low pass filter that would attenuate high-frequency noise but also limit response capability and phase margin, the patent inverts the approach by using high-pass filtering to remove low-frequency noise components and employing differentiation to enhance high-frequency vibration control. This inverted strategy maintains phase margin while achieving effective noise and vibration reduction.
Data Source
AI summary
An apparatus for stabilizing a steering feel in a motor-driven power steering (MDPS) includes: an input unit configured to receive a column torque of a steering wheel; a calculation unit configured to convert the column torque signal inputted from the input unit into a target signal for generating a compensation signal of the steering wheel; and a compensation unit configured to calculate an assist torque for compensating for a main assist torque based on the target signal from the calculation unit.