Development and experimental investigation of a Quadrotor’s robust generalized dynamic inversion control system

Abstract

The development of a two-loops Quadrotor’s robust generalized dynamic inversion (RGDI)-based control system is presented. The outer (position) loop utilizes PD position control of the Quadrotor’s center of gravity (CG) in the three-dimensional inertial space, and it provides reference pitch and roll tilting angles commands to the inner loop, in addition to the thrust command that is required to track desired altitude trajectories. The inner (attitude) loop applies RGDI control of a prescribed asymptotically stable dynamics of tilting and attitude errors from reference-tilting and desired-attitude trajectories, and it provides the three required control torque values such that desired CG positions in instantaneous horizontal inertial planes and desired-attitude trajectories of the Quadrotor are tracked. The proposed closed loop system is shown to guarantee finite-time semi-global practically stable trajectory tracking. Numerical simulations of the proposed closed loop control system are performed on a six degrees of freedom Quadrotor’s mathematical model for nominal conditions and under parametric uncertainties and exogenous disturbances. Apart from numerical simulations, experimental tests are conducted on a three degrees of freedom Quadrotor test bench to assess performance of the RGDI control loop. Experimental results demonstrate improved tracking performance in comparison with classical Linear-Quadratic optimal control and conventional sliding mode control.