Autonomous Emergency Braking Control for Articulated Vehicle Stability
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Solution Overview
Problem
Current autonomous emergency braking systems (AEBS) for articulated vehicles, such as trucks and buses, cause jack-knifing or swing-out due to a fixed brake-force strategy, which does not account for varying road conditions, leading to instability during braking.
Innovation Solution
A control system that estimates friction and normal forces for each wheel axle, adapting the brake strategy to adjust brake force dynamically, preventing over or under usage of brakes by considering road friction and axle loads, and includes friction-estimating braking to enhance stability and prevent jack-knifing or swing-out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed brake-force strategy is used in autonomous emergency braking systems, then the system is simple to operate and easy to control, but the articulated vehicle experiences jack-knifing or swing-out instability during braking
Solution Approach 1:
The brake control system transitions from a fixed brake-force strategy to a dynamic brake-force strategy that adapts in real-time based on road friction conditions and axle load estimates. The system continuously adjusts brake forces for different axles (front, rear, trailer) according to current operating conditions, preventing jack-knifing and swing-out while maintaining vehicle stability during emergency braking.
Solution Approach 2:
The system changes the brake force parameter dynamically based on estimated road friction coefficients and axle load conditions. By calculating appropriate brake force limits for each axle based on current parameters (friction estimates, normal forces), the system optimizes braking performance and prevents instability without requiring overly complex hardware modifications.
2Productivity
If the brake force is increased to improve stopping performance, then the braking efficiency is improved, but the articulated vehicle is more prone to jack-knifing and swing-out
Solution Approach 1:
The system applies different brake force strategies to different axles based on their specific conditions. By estimating axle-specific normal forces and applying localized brake force adjustments (increasing front axle brake force while managing rear and trailer axle forces), the system achieves high braking efficiency without inducing jack-knifing or swing-out instability.
Solution Approach 2:
The system dynamically adjusts brake force parameters for each axle based on real-time estimates of road friction and axle loads. By calculating optimal brake force limits that account for current operating conditions, the system maximizes braking efficiency while maintaining vehicle stability, preventing both over-braking (jack-knifing) and under-braking (swing-out).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents jack-knifing and swing-out by dynamically adjusting brake forces based on real-time road conditions and axle loads, ensuring stable braking without fuel consumption increase or brake-disc wear, and can reduce the impact on vehicle stability.
Implementation Method 1
brake control means adapted to apply a friction-estimating braking; brake force capacity estimation means adapted to estimate the brake force capacity of the vehicle as a function of longitudinal wheel slip based on the applied friction-estimating braking; friction estimation means adapted to estimate a friction coefficient based on the estimated brake force capacity
Implementation Method 2
axle load estimation means adapted to estimate the normal force on each wheel axle of the vehicle
Data Source
AI summary
A control system is provided for an articulated vehicle including a towing vehicle, a trailer and an autonomous emergency braking system, wherein the control system includes: a brake control arrangement adapted to apply a friction-estimating braking; a brake force capacity estimation arrangement adapted to estimate the brake force capacity of the vehicle as a function of longitudinal wheel slip based on the applied friction-estimating braking; an axle load estimation arrangement adapted to estimate the normal force on each wheel axle of the vehicle; a friction estimation arrangement adapted to estimate a friction coefficient based on the estimated brake force capacity and at least one of the estimated normal forces; and a brake strategy adaptation arrangement configured to adapt the brake strategy of the autonomous emergency braking system by adjusting the brake force for at least one wheel axle of the Vehicle based on the estimated friction coefficient and the at least one wheel axle's estimated normal force.