Trailer Brake Pressure Control via Speed-Threshold Logic
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Solution Overview
Problem
Conventional systems for controlling wheel brakes in tractor-trailers often modulate fluid pressure to maintain trailer stability during emergency braking, which reduces braking force and increases stopping distance due to uncertainty about the presence of anti-lock braking systems on trailers.
Innovation Solution
A system and method that uses a vehicle speed sensor and controller to determine trailer stability based on friction levels and apply appropriate fluid pressure to the trailer wheel brakes, allowing increased braking force during stable conditions without modulating pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the AEB system modulates fluid pressure delivery to the trailer wheel brakes to maintain trailer stability, then the stability of the trailer is improved, but the braking force is reduced and stopping distance increases
Solution Approach 1:
The system changes the control parameter from modulated fluid pressure to speed-based control logic. The controller monitors vehicle speed and compares it against a threshold speed to determine whether to apply high or reduced braking pressure, eliminating the need for pressure modulation while maintaining stability
Solution Approach 2:
The system performs preliminary assessment of trailer stability conditions by monitoring vehicle speed before applying brakes. By determining whether the vehicle speed is below the threshold speed (indicating stable conditions), the system pre-determines the appropriate braking strategy, allowing full braking force to be applied without risking instability
2Loss of time
If the AEB system applies high fluid pressure to the trailer wheel brakes to reduce stopping distance, then the braking force is improved, but the risk of trailer instability increases
Solution Approach 1:
The system changes the control parameter from modulated fluid pressure to speed-based control logic. The controller monitors vehicle speed and compares it against a threshold speed to determine whether to apply high or reduced braking pressure, eliminating the need for pressure modulation while maintaining stability
Solution Approach 2:
The system uses vehicle speed as a feedback parameter to continuously assess trailer stability conditions. The controller compares the current speed against the threshold speed and adjusts braking pressure accordingly, creating a closed-loop control system that maintains stability while maximizing braking force when conditions permit
Data Source
AI summary
A system and method for controlling wheel brakes on a trailer in a tractor-trailer are provided. Upon receiving a command to apply a trailer wheel brake, the system determines a speed of the tractor-trailer responsive to a speed signal generated by a vehicle speed sensor. The system also estimates a threshold speed based on a level of friction between the tractor-trailer and a road surface on which the tractor-trailer is travelling. The system then generates a control signal to control delivery of fluid pressure to the trailer wheel brake. The control signal causes delivery of a first fluid pressure to the trailer wheel brake when the speed meets a predetermined condition relative to the threshold speed and a second fluid pressure, less than the first fluid pressure, when the speed does not meet the predetermined condition.