Pre-specifiable fixed-time control for quadrotor aircraft with output constraints

For the controller design of quadrotor aircraft with six-DOF, a pre-specifiable fixed-time method combined with state constraints is researched in this paper. The 6-DOF aircraft model is divided into position loop and attitude loop through time scale decomposition method for the convenience of decoupling. Adaptive pre-specifiable fixed-time controllers for the position subsystem and attitude subsystem are proposed to ensure the desired trajectory and the desired attitude angle can be reached within a fixed-time which is independent of initial conditions. Meanwhile, the convergence time can be user-assignable in advance. Time-varying state constraints are considered in the controller design process in order to guarantee the safety of the system and prolong the life of actuator. The Barrier Lyapunov function is applied to ensure quadrotor aircraft's output constraints are not violated. Finally, the effectiveness of the proposed controller is verified by the simulation experiment.