Active Chassis Ride Height Control Using Filtered Spring Travel Signals
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Solution Overview
Problem
Existing ride height control systems for motor vehicles struggle to accurately assess roadway conditions and respond appropriately to uneven road surfaces, which can lead to reduced travel safety and comfort.
Innovation Solution
The method employs an actively adjustable chassis with spring-damper units and associated sensors, using frequency filtering, absolute value conversion, and low-pass filtering to process spring travel signals and assess roadway conditions, allowing for timely ride height adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If simple filtering of spring travel signals is used to assess roadway conditions, then the system response is fast, but the measurement precision of roadway condition assessment deteriorates
Solution Approach 1:
The spring travel signal is segmented into multiple frequency components through bandpass filtering. Different frequency ranges correspond to different roadway condition characteristics, allowing the system to analyze specific frequency bands separately and combine them for comprehensive assessment, thus improving precision without sacrificing response speed
Solution Approach 2:
The assessment is extended from a single-dimensional time-domain signal to a multi-dimensional frequency-domain analysis. By transforming the signal into frequency components and analyzing them across different bands, the system gains additional dimensional information about roadway conditions, enhancing measurement precision while maintaining computational efficiency
2Measurement precision
If comprehensive signal processing with multiple filtering stages is used, then the measurement precision of roadway conditions improves, but the device complexity increases
Solution Approach 1:
The patent extracts only the essential frequency components from the spring travel signal that are most indicative of roadway conditions. By selectively filtering and analyzing specific frequency bands rather than processing the entire signal spectrum, the system achieves high measurement precision with reduced computational complexity and simpler processing architecture
Solution Approach 2:
The system dynamically adjusts filtering parameters such as frequency band ranges and cutoff frequencies based on vehicle speed and roadway type. This adaptive parameter adjustment allows the complex multi-stage filtering system to simplify its operation under certain conditions while maintaining high precision when needed, effectively managing the complexity-precision trade-off
3Measurement precision
If ride height adjustment is delayed to ensure accurate roadway assessment, then the measurement precision improves, but the loss of time in responding to uneven road surfaces increases
Solution Approach 1:
The system continuously pre-processes spring travel signals through frequency filtering and analysis, maintaining a ready state for rapid roadway condition assessment. By constantly analyzing frequency components and maintaining processed signal data in memory, the system can immediately determine roadway conditions when needed, achieving both high precision and fast response without delay
Solution Approach 2:
The system implements continuous feedback loops where spring travel signals are constantly monitored, filtered, and analyzed. The processed information feeds back to the ride height control system in real-time, enabling continuous adjustment based on current roadway conditions. This closed-loop feedback mechanism ensures both accurate assessment and timely response by maintaining an ongoing dialogue between detection and actuation
Data Source
AI summary
A method for changing a ride height position of a motor vehicle comprises measuring a respective relative distance of a vehicle superstructure from corresponding wheels, with spring travel sensors and transmitting a respective spring travel signal to an electronic open-loop and closed-loop control device of the motor vehicle. The spring travel signals pass through a frequency filtering in the electronic open-loop and closed-loop control device The frequency filtering initially comprising a bandpass filtering which splits the spring travel signal into a signal component excited by the wheel and a signal component excited by the vehicle superstructure. The signal component excited by the vehicle superstructure is filtered out, the frequency filtering then comprising an absolute value conversion of the bandpass-filtered spring travel signal and subsequently a low-pass filtering.