Trailer Antilock Braking System Wheel Stability Control
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Solution Overview
Problem
Modern vehicle trailer braking systems can cause wheel lock when applied on low μ surfaces, leading to undesirable trailer yaw and potential jack-knifing, as they do not independently monitor and control each wheel effectively.
Innovation Solution
A trailer braking system that includes wheel speed sensors and a controller to monitor each wheel's stability by comparing its velocity to the trailer's velocity, generating a braking signal to reduce braking force on unstable wheels, thereby preventing wheel lock and mitigating jack-knifing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the trailer braking system is applied when a trailer wheel is in contact with a low μ surface, then the braking power is increased, but the wheel rotation stops before the towing vehicle and the trailer have come to a stop (wheel lock)
Solution Approach 1:
The braking system is divided into independent wheel-level control units, with each wheel monitored and controlled separately by individual wheel speed sensors and controlled brakes. This segmentation allows the system to detect and respond to wheel lock conditions on specific wheels independently, preventing complete wheel lock while maintaining overall braking effectiveness.
Solution Approach 2:
The system continuously monitors wheel speed via wheel speed sensors and compares it to the trailer's velocity to detect instability. When wheel lock is detected (wheel speed significantly lower than trailer velocity), the system provides feedback to the brake controller to modulate or release brake pressure on the affected wheel, preventing sustained wheel lock while maintaining braking control.
2Force
If the wheel is locked when the towing vehicle and the trailer are still moving, then the braking force is maximized, but the trailer may experience undesirable trailer yaw and jack-knifing
Solution Approach 1:
The system applies different braking control strategies to different wheels based on their individual conditions. When one wheel shows signs of locking or instability, only that specific wheel's brake pressure is modulated while other wheels maintain normal braking force. This localized control prevents trailer yaw and jack-knifing caused by asymmetric wheel lock while preserving overall braking effectiveness.
3Reliability
If the trailer braking system uses independent wheel monitoring and control, then wheel lock is reduced or prevented, but the system complexity increases
Solution Approach 1:
The brake controller performs multiple functions: it receives brake requests from the towing vehicle, monitors wheel speed signals from all wheels, determines trailer velocity, compares wheel speed to trailer velocity to detect instability, and generates appropriate braking signals. This multi-functionality reduces the need for separate dedicated components for each function, managing system complexity while achieving independent wheel control.
Data Source
AI summary
Techniques of braking a trailer with a trailer braking system. In one example, a controller receives a brake request from a vehicle to apply the trailer braking system, receives a plurality of wheel speed signals from a plurality of wheel speed sensors, and determines a velocity of the trailer based on the plurality of wheel speed signals. The controller determines a wheel speed of one of a plurality of wheels based on one of the plurality of wheel speed signals, compares the velocity of the trailer to the wheel speed to obtain a difference value, and determines that one of the plurality of wheels is unstable when the difference value exceeds a threshold. A braking signal to reduce a braking force on one of the plurality of wheels is generated when one of the plurality of wheels is unstable and when the brake request is received.