Trailer Brake Pressure Peak Control for Tractor-Trailer Stability
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Solution Overview
Problem
Agricultural vehicles, particularly tractors with trailers, lack effective trailer brake control systems due to the absence of on-board assistant systems like electronic trailer suspension, ABS, and ESP, making it difficult to determine the coupling force and control trailer brakes independently of trailer parameters, leading to issues like jack-knifing and skidding during deceleration.
Innovation Solution
A control system that determines driver deceleration demand and generates a trailer brake signal based on preliminary pressure peaks, using existing tractor components like a vehicle control unit, transmission, gyroscope, and HMI components to control the trailer brake system without requiring additional sensors on the trailer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trailer brakes are activated to reduce coupling force during deceleration, then jack-knifing and skidding are prevented, but excessive braking causes the vehicle combination to be stretched excessively which also applies a yaw moment to the towing vehicle
Solution Approach 1:
The control system continuously monitors the coupling force between tractor and trailer using sensors, and adjusts the trailer brake force in real-time based on this feedback. The control unit compares the measured coupling force with target values and modulates the brake actuation accordingly, preventing both insufficient braking (jack-knifing) and excessive braking (vehicle stretching).
Solution Approach 2:
The system dynamically changes the brake force parameter based on operating conditions. By adjusting the magnitude of brake application according to the actual coupling force, vehicle speed, and deceleration rate, the system optimizes stability while avoiding harmful effects of excessive braking.
2Measurement precision
If electronic braking systems with on-board assistant systems like electronic trailer suspension, ABS, ESP, ASR are used to determine coupling force, then trailer brake control precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The control system utilizes existing multi-functional components already present on modern tractors (engine control unit, transmission control, existing sensors for vehicle speed and engine parameters) to determine coupling force. By making these existing components serve the additional function of trailer brake control, the system avoids adding dedicated specialized sensors while achieving sufficient measurement precision.
Solution Approach 2:
The tractor's existing control systems and sensors serve dual purposes: their primary functions for tractor operation and their secondary function for determining coupling force and controlling trailer brakes. This self-service approach eliminates the need for separate dedicated systems on the trailer.
3Device complexity
If trailer brakes are controlled independently of trailer parameters like weight, then system complexity is reduced and cost is lowered, but braking precision may be compromised
Solution Approach 1:
The system uses the coupling force measurement as an intermediary parameter that indirectly reflects trailer weight and braking requirements. Instead of directly measuring trailer weight, the system measures the force transmitted through the drawbar, which naturally incorporates the effect of trailer mass and momentum, enabling precise brake control without direct weight sensing.
Data Source
AI summary
Systems and methods are provided for controlling operation of a trailer brake system associated with an agricultural vehicle-trailer combination. Using a driver deceleration demand a pressure level and/or duration for a preliminary pressure peak to be provided in one or more fluid lines of the trailer brake system is determined. A trailer brake signal is generated for controlling the trailer brake system in accordance with the preliminary pressure peak.