Active Suspension Frequency Control for Repeating Road Undulations
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Solution Overview
Problem
Vehicles experience excessive pitching and discomfort when driving over undulating roads due to resonance issues caused by mismatched suspension frequencies with road surface undulations, limiting driver speed choices and increasing the risk of body-to-ground contact.
Innovation Solution
An active suspension control system that adjusts the leading and trailing wheel suspension frequencies based on vehicle speed and surface wavelength, using sensors and communication interfaces to determine surface frequency and control actuator forces dynamically, allowing for a range of driving speeds without excessive pitching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the driver chooses a speed that matches the natural passive frequency of the suspension, then vehicle comfort is improved, but the driver loses speed flexibility and may encounter resonance issues at other speeds
Solution Approach 1:
The suspension system dynamically adjusts its frequency characteristics in real-time based on detected road conditions and vehicle speed. The active suspension controller modifies suspension frequencies to match surface frequencies of undulations, enabling comfort across a range of speeds rather than a fixed speed point.
Solution Approach 2:
The system changes the frequency parameter of the suspension system adaptively. By detecting surface wavelength and calculating surface frequency, the controller adjusts suspension frequencies to match the road undulations, allowing the vehicle to maintain comfort across varying speeds by continuously adapting the frequency parameter.
2Stability of the object's composition
If the suspension frequency is fixed to match surface frequency, then pitch changes are reduced, but the system cannot adapt to varying vehicle speeds
Solution Approach 1:
The suspension frequency is made dynamic rather than fixed. The active suspension controller continuously adjusts the suspension frequencies based on real-time detection of surface wavelength and calculation of surface frequency, enabling the system to maintain pitch stability across varying vehicle speeds by adapting the frequency to match the road conditions at each speed.
Solution Approach 2:
The system uses feedback from surface wavelength detection and surface frequency calculation to continuously adjust suspension frequencies. The controller receives information about road undulations and adjusts the suspension system accordingly, creating a closed-loop control that maintains pitch stability while adapting to speed changes.
3Adaptability or versatility
If the driver travels too fast or too slow over undulations, then speed flexibility is maintained, but excessive vehicle body pitching and wheel hop occur due to resonance
Solution Approach 1:
The system changes the suspension frequency parameter to match the surface frequency of road undulations. By detecting surface wavelength and calculating the corresponding surface frequency, the active suspension controller adjusts suspension frequencies to avoid resonance, allowing drivers to maintain speed flexibility without experiencing excessive pitching or wheel hop.
Solution Approach 2:
The system implements feedback control by detecting surface characteristics and adjusting suspension frequencies accordingly. The controller uses surface wavelength detection and frequency calculation to continuously adapt the suspension system, preventing resonance-related harmful effects while maintaining driver speed choice freedom.
4Stability of the object's composition
If active suspension control is applied, then vehicle composure is improved, but system complexity increases
Solution Approach 1:
The active suspension controller performs multiple functions: detecting surface undulations, calculating surface frequency, determining optimal suspension frequencies, and controlling the suspension system. This multi-functionality consolidates what could be separate complex systems into a single integrated control unit, improving vehicle composure while managing overall system complexity.
Data Source
AI summary
A control system (300) configured to control an active suspension system (104) of a vehicle (100), the control system comprising one or more controller (301), wherein the control system is configured to: determine (702) that the vehicle is travelling on or approaching repeating surface undulations; determine (709) vehicle speed; determine (708) an indication of surface wavelength of the repeating surface undulations; and control (722, 728) the active suspension system to control at least one of a leading wheel suspension frequency and a trailing wheel suspension frequency in dependence on the vehicle speed and surface wavelength.