Steering Signal Filtering With Time-Variant Noise Suppression
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Solution Overview
Problem
Existing electro-mechanically assisted steering systems amplify both useful and undesired measurement noise, leading to impaired steering feeling and reduced control loop robustness and stability due to overlapping frequency ranges.
Innovation Solution
A method using a filter with time-variant parameters, based on a mathematical model of measurement noise, minimizes the deviation between estimated and actual physical variables, effectively filtering out noise without affecting the useful signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low-pass filter or bandpass filter with chronologically constant transmission behavior is used to reduce measurement noise, then the measurement noise is reduced, but the steering feeling is impaired and the robustness and stability of the control loop are worsened
Solution Approach 1:
The patent applies dynamics by transitioning from static filter parameters to dynamic, time-variant filter parameters. The filter parameters are continuously adapted based on the current operating state and measured variables, allowing the filter to respond to changing conditions in real-time. This dynamic adaptation enables the filter to maintain optimal performance across different operating conditions without compromising control loop stability.
Solution Approach 2:
The patent implements parameter changes by modifying the filter parameters as a function of time and measured variables. Instead of using fixed transmission characteristics, the filter parameters are continuously adjusted based on the current operating state, enabling the filter to adapt to varying signal characteristics and noise conditions while preserving the useful signal components.
2Power
If frequency components in the measurement signal are amplified to generate assistance torque, then the useful signal is enhanced, but measurement noise is simultaneously amplified resulting in undesired noise formation
Solution Approach 1:
The patent applies local quality by implementing frequency-selective filtering with time-variant parameters. The filter is designed to selectively attenuate noise components in specific frequency ranges while preserving the useful signal components in other frequency ranges. The filter parameters are adapted to locally optimize the signal-to-noise ratio at different frequencies based on the current operating conditions.
Solution Approach 2:
The patent implements feedback by continuously monitoring the measured variables and using this information to adapt the filter parameters in real-time. The filter parameters are adjusted based on feedback from the measured signal characteristics, enabling the system to distinguish between useful signal components and noise and apply appropriate filtering accordingly.
Data Source
AI summary
A method is proposed for processing a measurement signal, in particular for a steering system. The method comprises the following steps: A measured variable is acquired based on the measurement signal, wherein the measured variable comprises items of information about a physical variable, and wherein the measured variable is a superposition of the actual value of the physical variable and the measurement noise. Filter parameters of a filter are ascertained based on the measured variable and a mathematical model of the measurement noise. The measurement signal is filtered by means of the filter, whereby an estimated value of the physical variable is obtained, wherein the filter has the ascertained filter parameters. The filter parameters are ascertained in such a way that a deviation between the estimated value of the physical variable and the actual value of the physical variable is approximated and minimized. Furthermore, a control unit for a steering system, a steering system, a computer program, and a computer-readable data carrier are disclosed.