Vehicle Steering Control Using Axle Drift Dynamics
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Solution Overview
Problem
Existing vehicle control systems rely on static parameters in the bicycle model, which do not directly link to the dynamic behavior of the vehicle, leading to inefficiencies in controlling lateral dynamics and stability.
Innovation Solution
A control device that utilizes a lateral dynamic behavior model incorporating specific drifts of each wheel set, including drift stiffness, steering angles, and vertical load, to provide dynamic control of actuators for steering and decoupled braking, optimizing vehicle response and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a static bicycle model with conventional parameters (front mass, rear mass, equivalent drift rigidities, yaw inertia) is used to control vehicle chassis, then the control system is simple to implement, but the model does not directly link to the dynamic behavior of the vehicle, resulting in poor control precision for lateral dynamics
Solution Approach 1:
The patent transforms the static bicycle model parameters into dynamic parameters by introducing specific drift angles for front and rear axles that vary with vertical load. This allows the model to adapt to changing vehicle conditions while maintaining the fundamental bicycle model structure, thus improving control precision without excessive complexity
Solution Approach 2:
The patent introduces dynamic elements to the traditionally static bicycle model by making the drift rigidities variable based on vertical load conditions. The specific drift angles are calculated dynamically during vehicle operation, allowing the model to reflect real-time dynamic behavior while keeping the control system manageable
2Reliability
If the vehicle model is adjusted by trial and error during development tests to represent desired behavior, then the model can be tuned to match target performance, but the process is time-consuming and does not provide a direct link between parameters and dynamic behavior
Solution Approach 1:
The patent replaces the trial-and-error mechanical adjustment process with a analytical calculation system. The specific drift angles are computed directly from vertical load measurements and predefined relationships, eliminating the need for iterative testing and adjustment while achieving accurate dynamic behavior representation
Solution Approach 2:
The model automatically adjusts its parameters based on real-time vertical load measurements from sensors. The system self-calibrates by calculating specific drift angles from measured loads, eliminating the need for external trial-and-error tuning during development and operation
3Stability of the object's composition
If controlled actuators are used for power steering and decoupled braking to adapt vehicle behavior to driving conditions, then vehicle stability and guidance performance are improved, but the control system complexity increases
Solution Approach 1:
The patent divides the vehicle into distinct front and rear axle segments, each with its own specific drift angle calculation. This segmentation allows independent control of front and rear wheel drift characteristics, enabling precise stability control while maintaining modular control logic that manages system complexity
Solution Approach 2:
The system uses vertical load measurements from sensors as feedback to continuously calculate and adjust the specific drift angles. This feedback loop enables automatic adaptation to changing driving conditions, improving stability while using simple proportional control based on measured parameters rather than complex control algorithms
Data Source
Figure 1
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AI summary
A device for controlling the steering (10) of a motor vehicle comprises at least one piloted actuator associated with a system for steering (4) a wheel of the vehicle and/or a piloted actuator associated with a decoupled braking system (6) at a wheel of the vehicle, the control device comprising at least one control unit (12) configured to recover at least one value characteristic of the travel of the vehicle and to issue, according to said recovered value(s), a control instruction (13) to the at least one piloted actuator (4, 6). According to the invention, the control unit (12) comprises a calculation module (14) in which a model of the lateral dynamic behaviour of the vehicle frame (16) is implemented, at least one specific physical quantity of the lateral dynamic behaviour being expressed according to the specific drifts (δs1, δs2) of each set of front and rear wheels of the vehicle.