Active Suspension Force Pulsing for Wheel Contact Patch Traction
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Solution Overview
Problem
Existing vehicle systems struggle to maintain optimal wheel-to-surface contact patch forces, leading to inadequate tractive force and wheel slip, particularly in challenging terrains like sand, where partial tire deflation is often required.
Innovation Solution
An active suspension system with actuators controlled by a control system to repetitively pulse vertical force through vehicle wheels in a pattern, varying contact patch forces by pulsing at least one wheel at a first phase and another at a second phase, with phase offsets and frequencies adjusted based on terrain and vehicle conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If drivers partially deflate the vehicle's tyres to increase the area of the wheel contact patches, then the contact area increases and traction improves, but the vehicle's handling and stability deteriorate and tire wear increases
Solution Approach 1:
The active suspension system applies periodic vertical force pulses to the wheels through the actuators. This repetitive pulsing action dynamically varies the contact patch forces without requiring permanent tire deflation, thereby maintaining both traction and vehicle handling characteristics.
Solution Approach 2:
The system changes the temporal parameter of contact force by introducing periodic variations in the vertical force applied to wheels. This allows the contact patch area and force distribution to be dynamically adjusted through control signals rather than static tire pressure changes, resolving the contradiction between traction and handling.
2Reliability
If the vehicle uses a conventional passive suspension system, then the system complexity is low, but the ability to control wheel-to-surface contact forces and prevent wheel slip is insufficient
Solution Approach 1:
The active suspension system performs multiple functions: it maintains vehicle ride comfort, controls wheel-to-surface contact forces, prevents wheel slip, and enhances traction. By integrating these functions into a single system, the patent justifies the increased complexity through substantial performance improvements across multiple parameters.
Solution Approach 2:
The control system receives surface information and wheel performance data, then adjusts the actuator control signals accordingly. This feedback mechanism allows the system to adapt to varying terrain conditions and maintain optimal contact forces, thereby achieving superior traction control despite the added system complexity.
3Reliability
If the active suspension system applies continuous vertical force to all wheels, then the contact patch forces are maximized, but energy consumption increases and the system cannot adapt to varying terrain conditions
Solution Approach 1:
Instead of continuous force application, the system uses periodic pulsing of vertical forces through the actuators. This reduces average energy consumption while maintaining effective traction control through the cumulative effect of repeated force applications at optimized intervals.
Solution Approach 2:
The control system applies different pulsing patterns and force magnitudes to different wheels based on local terrain conditions and wheel-specific requirements. This localized control approach optimizes energy distribution across the vehicle, applying force only where and when needed rather than uniformly to all wheels.
Data Source
AI summary
A control system (300) for controlling an active suspension system (104) of a vehicle (100), the active suspension system comprising suspension actuators (502), the control system comprising one or more controller (301), wherein the control system is configured to: in dependence on an activation signal (904), provide (908) a control signal to the active suspension system to cause the suspension actuators of the active suspension system to repetitively pulse vertical force through wheels (FR, FL, RR, RL) of the vehicle in a controlled pattern determined by the one or more controller, to vary wheel-to-surface contact patch forces, wherein the pattern comprises repetitively pulsing vertical force through at least one of the wheels at a first phase and through at least one other of the wheels at a second phase.