Nonsingular recursive-structure sliding mode control for high-order nonlinear systems and an application in a wheeled...

Area of Science:

• Control Systems Engineering
• Robotics
• Nonlinear Dynamics

Background:

• High-order nonlinear systems often face challenges with matched disturbances affecting tracking control.
• Existing finite-time control methods may not offer practical solutions for complex systems.

Purpose of the Study:

• To develop a novel finite-time tracking control strategy for high-order nonlinear systems with matched disturbances.
• To design a practical fixed-time disturbance observer and a new nonsingular sliding mode surface.
• To ensure fast and accurate trajectory tracking in the presence of uncertainties.

Main Methods:

• A practical fixed-time disturbance observer using a smooth hyperbolic tangent function.
• A nonsingular recursive-structure sliding mode surface based on terminal sliding mode concepts.
• A finite-time tracking control approach with a new adaptive law, utilizing Lyapunov stability theory.
• Application to a mobile robotic experimental platform for trajectory tracking on uneven ground.

Main Results:

• The proposed control scheme ensures tracking errors converge to a small region in finite time.
• Finite-time stability of the closed-loop system is rigorously proven.
• Effective trajectory tracking on an uneven ground surface was achieved using a mobile robot.

Conclusions:

• The developed control approach offers an effective and superior solution for fast tracking control of high-order nonlinear systems with matched disturbances.
• The practical fixed-time disturbance observer and nonsingular sliding mode control enhance system performance and robustness.
• Experimental validation on a mobile robot confirms the practical applicability and effectiveness of the proposed method.