Adaptive quaternion-based quadrotor control system

In this paper we propose the quaternion-based control system for quadrotor. Adaptive scheme for thrust coefficients identification, based on speed-gradient method, is designed. Proofs of stability are provided, as well the results of numerical simulations. In existing theoretical works, Euler angles are often used as coordinates for for describing quadrotor’s coordinates. Equations using those coordinates, however, have a singularity, which prevents their use near certain points. We use quaternions instead, which have no such restrictions. The process of discovering PID-regulator coefficients is known to be tedious, error-prone and specific for each quadcopter. We propose a control scheme in which most of the parameters are physical values, and the rest do not depend on the quadcopter and can be found once for the whole class of the flying machines. An identification algorithm for obtaining physical parameters is also described. MATLAB modelling is used to test and confirm the performance of the proposed scheme.