Improved Robust Adaptive Control of High-order Nonlinear Systems with Guaranteed Performance

TL;DR

This paper introduces advanced adaptive control methods, including fuzzy-L1 and MRAC with prescribed performance, for high-order nonlinear systems, enhancing robustness, tuning, and guaranteed performance.

Contribution

It proposes a fuzzy-based tuning approach for L1 adaptive controllers and an MRAC method with prescribed performance for uncertain high-order nonlinear systems.

Findings

Fuzzy-L1 adaptive controller effectively decouples robustness and adaptation.

Particle Swarm Optimization optimally tunes the fuzzy controller.

Proposed methods guarantee prescribed performance in complex nonlinear systems.

Abstract

This thesis presents fuzzy-L1 adaptive controller and Model Reference Adaptive Control (MRAC) with Prescribed Performance Function (PPF) as two adaptive approaches for high nonlinear systems as two original contribution to the literature. L1 adaptive controller has a structure that allows decoupling between robustness and adaption owing to the use of a low pass filter with adjustable gain in the feedback loop. A practical new fuzzy based approach for the tuning of the feedback filter of L1 adaptive controller is proposed. The fuzzy controller is optimally tuned using Particle Swarm Optimization (PSO) to minimize the tracking error and the control signal range. An adaptive control of multi-input multi-output uncertain high-order nonlinear system capable of guaranteeing a predetermined prescribed performance is presented as MRAC with PPF. Keywords: Review, L1 adaptive controller, MRAC, twin rotor, UAV, unmanned aerial vehicle, quadrotor, desired, actual, overshoot, neighbourhood, origin, time variant, invariant, simulation, submarine, unmanned underwater vehicle, mobile robot, MARES, stochastic, noise, random, trade off, two degree of freedom planner robot, multi input multi output, single input single output, fuzzy logic controller, fuzzy filter, tuning, optimization, membership function, PSO, MOPSO, multi objective, particle swarm optimization, steady state error, transient performance, asymptotic, assigned, stability, robustness, robust, stable, adaptive control, nonlinear control, uncertain, unknown, prescribed performance function, nonlinear L1 adaptive observer, model.