Order-supplementary finite-time trajectory tracking control of quadrotor unmanned aerial vehicles

This paper investigates the finite-time position trajectory tracking control problem of quadrotor unmanned aerial vehicles (UAVs). Different from the standard inner–outer-loop control scheme, the proposed finite-time controller is constructed with an order-supplementary mechanism. Concretely, some virtual extended states with second-order dynamics are utilized in the controller design of the UAV’s position-loop subsystem, to replace the original feedback part of tracking errors. Then, the adding a power integrator technique is used in the establishment of the virtual state dynamics, such that the position loop of quadrotor UAVs achieves the trajectory tracking tasks in finite time. Meanwhile, the attitude command references are directly formulated from the virtual extended states. Moreover, to deal with disturbances or unknown velocities, some finite-time observers are further combined in the proposed approach to obtain the corresponding estimates of disturbances and velocities. Compared with the existing results, the proposed order-supplementary finite-time trajectory tracking approach can remove the use of filters in the attitude command resolution and realize strict finite-time convergence. The thrust control input for the position-loop subsystem can be adjusted more flexibly by setting the initial values of the introduced virtual states. In addition, the finite-time velocity observer provided in this paper takes aerodynamic damping into account and has more accurate estimation in practice. Some simulations are given to validate the effectiveness of the proposed approach.