Trailer Brake Pressure Control Using Tractor ABS Friction Estimation
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Solution Overview
Problem
Existing automated emergency braking systems in tractor-trailers often fail to apply maximum braking force due to uncertainty about the operational status of trailer anti-lock braking systems, leading to reduced braking efficiency and increased stopping distance, especially on low-friction surfaces.
Innovation Solution
A system and method that uses real-time data from the tractor to determine the friction level of the surface without relying on trailer ABS information, adjusting brake pressure to trailers based on tractor ABS data, ensuring maximum braking force on high-friction surfaces and mitigating trailer swing on low-friction surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the AEB system modulates (pulses) delivery of fluid pressure to the trailer wheel brakes to ensure trailer stability, then the stability of the trailer is maintained, but the braking force is reduced and the stopping distance increases
Solution Approach 1:
The patent replaces the traditional mechanical/pneumatic pressure modulation system with an electronic control system. The brake controller electronically determines pressure demands and generates control signals based on deceleration demands and friction surface conditions, substituting electronic signaling for direct pneumatic pressure pulsing to achieve both stability and braking efficiency
Solution Approach 2:
The system dynamically changes the fluid pressure parameter delivered to trailer brakes based on detected friction surface conditions. On high-friction surfaces, maximum pressure is applied; on low-friction surfaces, pressure is modulated. This parameter adaptation resolves the contradiction by optimizing pressure delivery according to actual road conditions rather than using a conservative fixed approach
2Productivity
If the AEB system requests maximum possible trailer braking, then the braking efficiency is improved, but the risk of trailer swing increases on low friction surfaces
Solution Approach 1:
The system uses feedback from the friction surface detection mechanism (which monitors tractor ABS pressure reductions) to continuously adjust trailer brake pressure commands. This feedback loop allows the system to request maximum braking when conditions permit while automatically reducing pressure when low-friction surfaces are detected, thus preventing trailer swing while optimizing braking efficiency
Solution Approach 2:
The brake control system transitions from a static, conservative pressure delivery approach to a dynamic system that continuously adapts pressure delivery based on real-time friction surface conditions. The system can rapidly switch between maximum pressure and modulated pressure modes, enabling optimal braking performance that responds to changing road conditions
3Reliability
If the AEB system uses conservative braking pressure to prevent trailer swing, then the risk of trailer instability is reduced, but the braking force and stopping capability are compromised
Solution Approach 1:
The system changes the fluid pressure parameter dynamically based on friction surface conditions detected through tractor ABS data analysis. Rather than maintaining a conservative fixed pressure level, the system adapts pressure delivery to match actual road friction characteristics, achieving both reliability and braking force optimization
Data Source
AI summary
A method and system for providing maximum trailer braking during a high pressure demand, such as during autonomous emergency braking (AEB), for tractor-trailers is provided. The system can include a brake controller of the trailer that uses only tractor anti-lock brake system (ABS) data from the tractor wheels, without using any trailer ABS information, to estimate the surface friction and generate a high or low pressure command to be sent to the trailer based on only the tractor ABS data. The estimation of surface friction may be accomplished using the ABS information from the tractor and the pressure being demanded to determine a percent reduction of pressure requested by the tractor that may be compared to a threshold percentage to differentiate between high and low mu surfaces in real time.