Multi-Trailer Axle Force Control for High-Speed Off-Tracking
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Solution Overview
Problem
Multi-trailer vehicles experience significant off-tracking during abrupt turns and evasive maneuvers, which can lead to safety hazards and reduced control efficiency due to excessive wheel slip and non-linear vehicle behavior.
Innovation Solution
A method is developed to reduce off-tracking by determining non-linear optimal control problem (NOCP) solutions for vehicle dynamics, which include force trajectories for axles, accounting for road friction and wheel slip limits, and using these to control vehicle motion during maneuvers, either through real-time processing or pre-computed look-up tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional passive dolly vehicles are used in multi-trailer combinations, then the vehicle structure is simple and easy to manufacture, but the trailer units experience significant off-tracking during abrupt turns and evasive maneuvers
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting axle force distributions and wheel slip trajectories through non-linear optimal control. The system modifies control parameters (longitudinal forces on axles) in real-time during maneuvers to minimize trailer off-tracking, transforming the passive dolly into an actively controlled system that adapts its mechanical parameters to maintain precise tracking.
Solution Approach 2:
The patent replaces traditional mechanical steering mechanisms with a control system that uses longitudinal force application and non-linear optimal control algorithms. Instead of mechanically steering the trailers through articulation points, the system uses force trajectories and wheel slip control to achieve the same tracking objective, substituting mechanical complexity with computational control.
2Reliability
If non-linear optimal control is implemented to minimize off-tracking, then trailer tracking accuracy is improved, but the computational complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-computing non-linear optimal control solutions and storing them in look-up tables before actual maneuvers occur. The system calculates optimal axle force distributions and wheel slip trajectories in advance for various maneuver scenarios, then retrieves pre-computed control commands during real-time operation, avoiding the need for complex real-time non-linear optimization calculations.
Solution Approach 2:
The patent uses copying by creating pre-computed look-up tables that contain copies of optimal control solutions for different maneuver scenarios. Instead of solving the non-linear optimal control problem in real-time, the system copies the appropriate pre-solved solution from the look-up table based on current vehicle state and maneuver type, significantly reducing computational complexity while maintaining tracking accuracy.
3Stability of the object's composition
If axle forces are increased to maintain control during evasive maneuvers, then vehicle stability is improved, but wheel slip increases leading to loss of traction and reduced control
Solution Approach 1:
The patent applies feedback by continuously monitoring wheel slip conditions and adjusting axle force distributions accordingly. The non-linear optimal control system uses feedback from vehicle state measurements (including wheel slip indicators) to modify force trajectories in real-time, ensuring that stability is maintained while wheel slip remains within acceptable limits that preserve traction.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the distribution of longitudinal forces across different axles based on real-time vehicle state. Instead of applying uniform or fixed force increases, the system modifies individual axle force parameters to achieve the desired stability while minimizing total wheel slip through optimal force allocation.
Data Source
AI summary
A method for reducing off-tracking by a multi-trailer heavy duty vehicle during a maneuver is disclosed. The method obtains a model of vehicle dynamics describing dynamics of the multi -trailer heavy duty vehicle, determines respective force trajectories for two or more axles of the vehicle as a solution to a NOCP. The NOCP is formulated with an objective to at least minimize trailer off-tracking, and based on the model of vehicle dynamics. The motion of the heavy duty vehicle is controlled during the maneuver based on the determined force trajectories.