A Continuous Robust Attitude Control Approach for Quadrotors Subject to Disturbance In this paper, a continuous robust attitude control approach is proposed, which can achieve exponential stability even in the presence of external disturbance. In particular, on the basis of configuration space SO(3), the augmented dynamics of the system are transformed into a quasichained form. Subsequently, a continuous sliding mode approach is put forward, which is composed of a sliding mode differentiator and a sliding mode controller. Different from most reported approaches, the proposed control law is essentially continuous and the equilibrium point is exponentially stable even in the presence of complex unknowns. Finally, the simulation result illustrates the high tracking accuracy and strong robustness of the proposed method.

An ApproximationFree Simple Control Scheme for Uncertain Quadrotor Systems: Theory and Validations In this paper, a simple tracking control scheme is proposed for quadrotor systems with uncertain dynamics. It precludes the necessity for prohibitive analytic computation of the derivatives of the desired (virtual) attitude that is typically employed in controlling quadrotor systems. Moreover, this control scheme is approximationfree in the sense that it does not incorporate any adaptive laws, observers, or command filters to compensate for unknown parameters in the dynamics and the absence of the analytic differentiation, thus exhibiting remarkably low complexity levels and making its implementation straightforward. The thrust saturation is approached in the position control design which also enables the singularity in desired attitude extraction to be avoided entirely. It is demonstrated that based on the proposed scheme, the tracking errors can be made arbitrarily small by appropriately selecting design parameters. Extensive simulations and experiments are performed to verify the effectiveness of our scheme.