Attraction Domain Estimation for Vehicle Steering Stability
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Solution Overview
Problem
Automated steering of wheeled vehicles, such as those used in road construction and agriculture, faces challenges in maintaining stability and accuracy due to the lack of global stability in control laws, especially when starting from initial states outside the attraction domain, leading to unpredictable behavior and potential loss of stability.
Innovation Solution
The development of an efficient method for estimating the attraction domain using ellipsoidal approximations and dynamic control signals, which allows for switching between control laws to ensure stability and convergence to the target trajectory, accompanied by a visual indicator for operators to safely engage or disengage automatic steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automatic control law is used for steering, then productivity is improved, but stability is worsened when initial state is outside attraction domain
Solution Approach 1:
The control system is segmented into multiple attraction domains, each with its own stable control law. The overall control space is divided into regions, and the system switches between segments based on current state location, ensuring stability regardless of initial conditions.
Solution Approach 2:
The control system dynamically switches between different control laws based on the current state. Instead of using a single static control law, the system adapts by selecting appropriate control laws from a set, with switching triggered when the state enters or exits attraction domains.
2Device complexity
If single control law is used, then device complexity is reduced, but reliability is worsened due to lack of global stability
Solution Approach 1:
The control system uses multiple control laws that can handle different operational scenarios. Each control law is designed to be stable within its specific attraction domain, and together they provide universal coverage for the entire state space, ensuring reliability across all conditions.
Solution Approach 2:
The system continuously monitors the current state and uses feedback to determine which attraction domain the state belongs to. This feedback mechanism triggers appropriate switching between control laws, ensuring the system remains within stable operating regions and maintains reliable tracking.
3Reliability
If attraction domain estimation is added, then reliability is improved, but device complexity is worsened
Solution Approach 1:
The attraction domains are pre-calculated and stored in the system before operation. This preliminary action eliminates the need for complex real-time calculations during operation, as the system only needs to compare the current state against pre-defined domain boundaries to determine the appropriate control law.
Data Source
AI summary
A method and apparatus for operating a vehicle under manual or automatic steering mode is disclosed herein. An estimation of an attraction domain of stability is calculated for the vehicle using the vehicle's current position and orientation information relative to a target trajectory. If an unstable estimation of the attraction domain is determined, then the vehicle is operated in manual mode under control of an operator.