H∞ Model Based Control via Mixed Sensitivity for 2DOF Control of Twin Rotor MIMO System With Experimental Validation

Abstract

This article provides a comprehensive study about optimization and real-time implementation of H∞ model-based controller for uncertain systems (having external perturbations) using robust control methods. The complicated air vehicle modeling is quite difficult because of highly nonlinear behavior, un-modeled states, and cross-coupling effect. The helicopter flight control also depends on two rotors generating continuous thrust simultaneously in two different directions. Simple linear feedback controllers cannot ensure the stability of highly nonlinear systems like a helicopter. The controllability and observability full rank matrix output ensure the credibility of the system before a controller design. The design of a robust controller for the desired flight control, demands the availability of all its states and varying parameters for real-time robust feedback control. However, its prototype, Twin-rotor MIMO System (TRMS) facilitates the researchers and control engineers in terms of the real-time environment of a helicopter flight control. Various control strategies are presented to elaborate the behavior of the MIMO system and the limitations of robust control methods. Each control strategy has been comprehensively discussed with the stability analysis and the design requirements. The considered control techniques, such as the loop-shaping control and H∞ model-based control augmented with mixed sensitivity control function, make use of control in such a way that robust stability and robust performance are ensured for highly nonlinear systems. Model-based H∞ optimization technique elaborates the robustness and stability of the system by reducing tracking error of all its states towards origin and thereafter system becomes stable for an infinite period. The loop-shaping control performance as compared to H∞ model-based control has some limitations to ensure closed-loop robustness and real-time implementation under perturbations. The performance evaluation is done at the end which shows that the H∞ model-based control gives optimal robust performance including perturbations and coupling effect. The real-time implementation on MATLAB/Simulation via personal computer validates the worth of the optimization method in the presence of uncertainties (matched, unmatched, coupling effect) of a linearized state-space model of the TRMS system.

A flexible mixed-optimization with H∞ control for coupled twin rotor MIMO system based on the method of inequality (MOI)- An experimental study

“…This singularity can alter the rank of the system matrix, leading to discontinuous behavior and potentially causing unbounded elements in the matrix. To mitigate these drawbacks, a solution is proposed in [37], which involves augmenting a scaling factor, as elaborated below:…”

“…In essence, the weights represented by W p and W u are treated as design parameters. This approach implies that the design challenge can be reconfigured so that the parameters of the weighting functions serve as design variables aimed at satisfying a set of closed-loop performance constraints, as elaborated in [37]. The designer's responsibility is not to determine the controller's order but rather to determine the order of the weighting functions.…”

A Robust Controller Design for an Inlet Throttling Speed Control System for a Rotary Actuator

“…The non-dimensional pressure rise equation can finally be written as follows, (13) Where the dimensionless groups and are defined in Eqs. ( 14) and ( 15) respectively.…”

“…The results were compared to the H-∞ controller design method. An investigation on the optimization and real-time design of the H∞ controller for systems with uncertainties was proposed in [13]. Ring modulation control with mixed sensitivity control functionality is implemented such way that ensures system robustness of the system with nonlinearities.…”