A Fully Quaternion based Nonlinear Attitude and Position Controller

Abstract

In this paper, a novel fully quaternion based second order stable error dynamics controller is developed to address the attitude tracking problem in general and the position tracking problem of fixed pitch and variable pitch quadrotors in particular. Since the singularity associated with Euler angle representation is avoided using a unit quaternion approach, our algorithm finds its advantage in controlling highly maneuverable systems like variable pitch quadrotor which are capable of generating negative thrust and transition to inverted flight. Our controller is also well suited for rigid systems like satellites which require tracking of large-angle amplitude trajectories. Numerical simulations show good tracking performance using the proposed control methods for satellites and quadrotors. Experimental results on commercially available fixed pitch quadrotor using open-source architecture validate the novel attitude controller.