Nonlinear disturbance observer based sliding mode control for a benchmark system with uncertain disturbances

Area of Science:

• Robotics and Control Systems
• Nonlinear Control Theory
• Mechatronics

Background:

• The translational oscillator with rotational actuator (TORA) system presents complex control challenges due to underactuation.
• External disturbances and system uncertainties significantly impact the performance and stability of the TORA system.
• Existing control methods may not adequately address the robustness requirements in the presence of unknown dynamics.

Purpose of the Study:

• To develop a robust control strategy for the TORA system that accounts for uncertain disturbances.
• To ensure asymptotic stability of the underactuated TORA system at the origin.
• To validate the effectiveness and resilience of the proposed control approach through numerical simulations.

Main Methods:

• A coordinate transformation yields a cascade system model for the TORA.
• A disturbance-observer-based methodology estimates unknown system disturbances.
• Backstepping control and sliding mode control techniques are integrated for robust stabilization.

Main Results:

• A novel control law is designed using a combination of backstepping and sliding mode control.
• The proposed method effectively estimates and compensates for unknown disturbances.
• Numerical simulations confirm the asymptotic stability and robustness of the TORA system under the developed control strategy.

Conclusions:

• The disturbance-observer-based sliding mode control approach provides a viable solution for stabilizing the underactuated TORA system.
• The method demonstrates significant robustness against uncertain external disturbances.
• The findings are applicable to other underactuated systems facing similar control challenges.