Prescribed performance observer-controller design for MIMO nonlinear systems with unknown control directions | JoVE Visualize

Area of Science:

Control Systems Engineering
Nonlinear System Analysis
Robotics and Autonomous Systems

Background:

Multi-input multi-output (MIMO) nonlinear systems present significant control challenges, particularly with unknown input directions.
Accurate state estimation and precise trajectory tracking are critical for the effective operation of autonomous systems.
Existing control methods often struggle to guarantee performance constraints under uncertainties.

Purpose of the Study:

To develop an observer-controller capable of handling multi-input multi-output (MIMO) nonlinear systems with unknown input directions.
To ensure constrained tracking errors by integrating prescribed performance control techniques.
To validate the proposed methodology in a practical application, such as unmanned surface vehicle (USV) trajectory tracking.

Main Methods:

A novel observer design incorporating equivalent output injection and prescribed performance to limit estimation error.
A controller design utilizing the Nussbaum function and prescribed performance control (PPC) to manage unknown control directions.
Simulation and experimental validation on an unmanned surface vehicle (USV) for trajectory tracking control.

Main Results:

The proposed observer effectively limits estimation errors, even in the presence of system nonlinearities and unknown dynamics.
The integrated observer-controller successfully achieves constrained tracking performance, demonstrating robustness against unknown control directions.
The methodology shows significant effectiveness in the trajectory tracking control task for the unmanned surface vehicle (USV).

Conclusions:

The developed observer-controller provides a robust solution for controlling MIMO nonlinear systems with unknown input directions.
The integration of prescribed performance control and Nussbaum functions offers a powerful approach for achieving constrained control objectives.
The successful application to USV trajectory tracking highlights the practical viability and effectiveness of the proposed control strategy.