Constructive design of disturbance observer-based safe control for strict-feedback nonlinear systems with...

Area of Science:

• Robotics
• Control Systems Engineering
• Nonlinear System Analysis

Background:

• Existing safe backstepping control methods require precise models, limiting robustness against real-world disturbances.
• Strict-feedback nonlinear systems are susceptible to unknown external disturbances, posing challenges for safe operation.

Purpose of the Study:

• To develop a novel constructive control framework for safe control of strict-feedback nonlinear systems under unknown disturbances.
• To enhance robustness and mitigate limitations of existing safe control techniques.

Main Methods:

• Integration of a disturbance observer to estimate and compensate for unknown disturbances.
• Application of filtered backstepping combined with control barrier functions (CBFs) for controller design.
• Recursive design framework to construct smooth virtual and actual controllers.

Main Results:

• The proposed framework effectively estimates and compensates for unknown disturbances, offering a less conservative approach than traditional robust methods.
• The unified approach successfully mitigates the 'explosion of complexity' and avoids nonsmoothness issues.
• Validation through numerical simulations and real-time experiments on a robotic arm.

Conclusions:

• The novel framework provides an effective solution for safe control of nonlinear systems with unknown disturbances.
• The method enhances robustness and computational efficiency compared to existing approaches.
• Demonstrated practical applicability on a robotic manipulator.