Vehicle-Trailer Stability Control via Hitch Rate Feedback
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Solution Overview
Problem
Long-wheelbase trailers exhibit reduced yaw stability when towed, leading to instability issues such as jackknifing, lateral oscillation, and rearward amplification, which can worsen at higher velocities, compromising the safety and control of vehicle-trailer systems.
Innovation Solution
A stability control system comprising sensors, predictive components, and control actuators that monitor vehicle and trailer characteristics, detect yaw rate deviations and hitch oscillations, and implement braking or steering control actions to mitigate instability, using feedback mechanisms to adjust hitch rate and lateral forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a trailer is attached to a vehicle to increase load capacity, then the towing capability is improved, but the yaw stability of the vehicle-trailer system deteriorates
Solution Approach 1:
The patent implements a feedback control system that continuously monitors yaw rate and hitch rate of the vehicle-trailer system. When instability is detected (excessive yaw rate deviation or hitch rate oscillation), the system automatically applies braking forces to the trailer wheels to counteract the unstable motion. This closed-loop feedback mechanism directly addresses the stability deterioration caused by trailer attachment while maintaining the load capacity benefit.
2Productivity
If the velocity of the vehicle-trailer system is increased to improve productivity, then the towing efficiency is improved, but the yaw stability and damping ratio deteriorate
Solution Approach 1:
The control system is designed to operate across a wide velocity range, with the feedback controller continuously adjusting braking forces based on real-time yaw rate and hitch rate measurements. This allows the system to maintain stability even at higher velocities where the natural damping ratio would otherwise deteriorate, thereby enabling improved productivity without sacrificing safety.
3Reliability
If active stability control systems are added to mitigate instability, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent employs a feedback control system that utilizes existing sensors (yaw rate sensor, hitch rate sensor) and standard braking components. By leveraging available sensors and straightforward control logic that compares measured values against thresholds, the system achieves improved safety without requiring overly complex additional hardware or sophisticated control algorithms.
Solution Approach 2:
The control system acts as an intermediary between the vehicle's existing braking system and the trailer stability requirements. Rather than requiring a completely new complex system, the patent interfaces with the vehicle's existing braking infrastructure, using a relatively simple control unit to mediate between sensor inputs and actuator outputs, thereby limiting the increase in overall system complexity.
4Ease of operation
If the hitch rate oscillation is allowed to increase for maneuverability, then the ease of operation is improved, but the likelihood of jackknifing and instability increases
Solution Approach 1:
The feedback control system continuously monitors hitch rate and sets appropriate thresholds based on operating conditions. This allows the system to tolerate larger hitch rate oscillations during low-speed maneuvering when jackknifing risk is low, while automatically intervening to prevent instability during high-speed operation when the same oscillations would be dangerous. This conditional threshold approach balances maneuverability and stability requirements.
Data Source
AI summary
A method for stability control may include receiving vehicle characteristics of a vehicle of a vehicle-trailer system, trailer characteristics of a trailer of the vehicle-trailer system, or steering inputs for the vehicle. The method may include determining a prediction based on yaw rate deviation for the vehicle determined from the vehicle characteristics, trailer characteristics, or steering inputs or hitch rate oscillation of a hitch coupling the vehicle to the trailer determined from the vehicle characteristics, trailer characteristics, or steering inputs, where the prediction may be indicative of a likelihood of instability for the vehicle-trailer system. The method may include generating control actions based on the prediction and hitch rate feedback from the hitch of the vehicle-trailer system or lateral hitch force feedback.