robust performance analysis for a cascade nonlinear h∞ control algorithm in quadrotor position tracking

This paper presents a new hierarchical robust algorithm to solve the position tracking problem, in presence of exogenous disturbances and modeling uncertainties, of a quadrotor helicopter. the suggested controller includes a nonlinear h∞ algorithm to track the reference trajectory in the outer loop and a nonlinear h∞ controller to stabilize the rotational movements in the inner loop. the resultant controller consists of three important parts to regulate tracking errors for translational and rotational motions, maintain robust performance confronting random disturbances and modeling uncertainties and reject the sustained disturbances from the system to vanish the steadystate errors. analytical study on the stability of the cascade system is mentioned to verify the compatibility of two controllers considering coupling terms. numerical performance analysis is accomplished using montecarlo simulation. statistical results obtained from 1000 simulations considering environmental disturbances and modeling uncertainties depict less than 5 cm for position tracking error and less than 2 degrees for attitude tracking error in steady state performance. the closedloop performance of the controller is also compared with two previous algorithms by determining two numerical indexes for state tracking performance and control efforts, respectively. simulation results of the suggested control algorithm depict a significant reduction in both indexes for a similar mission.