Double-loop tracking control for a wheeled mobile robot with unmodeled dynamics along right angle roads

Area of Science:

• Robotics
• Control Systems Engineering
• Nonlinear Control Theory

Background:

• Wheeled mobile robots (WMRs) often exhibit unmodeled dynamics and are subject to external disturbances, complicating precise trajectory tracking.
• Existing control strategies may struggle to achieve high accuracy in WMRs due to these uncertainties.
• Accurate path following is crucial for WMR applications, including logistics, exploration, and surveillance.

Purpose of the Study:

• To develop and validate a robust double-loop tracking control strategy for WMRs.
• To address trajectory tracking challenges posed by unmodeled dynamics and external disturbances.
• To improve the tracking accuracy of WMRs navigating complex paths, such as right-angle roads.

Main Methods:

• Design of two nonlinear Extended State Observers (ESOs) to estimate unknown disturbances and unmodeled dynamics.
• Integration of nonlinear ESOs with integral sliding mode control and backstepping control techniques.
• Application of Lyapunov stability theory for rigorous convergence analysis of the proposed control system.
• Experimental validation of the control strategy on a physical WMR platform.

Main Results:

• The nonlinear ESOs effectively estimated external disturbances and unmodeled dynamics.
• The proposed double-loop tracking controller significantly enhanced trajectory tracking accuracy for the WMR.
• Convergence of the ESOs and the overall tracking controller was mathematically proven using Lyapunov methods.
• Experimental results confirmed the practical effectiveness and robustness of the control strategy.

Conclusions:

• The double-loop tracking control strategy offers a viable solution for precise trajectory control of WMRs with unmodeled dynamics.
• The integration of nonlinear ESOs with sliding mode and backstepping control provides superior disturbance rejection and tracking performance.
• The study demonstrates the potential for improved WMR navigation in real-world applications through advanced control techniques.