Time-varying Formation Control for Small-scale Unmanned Helicopters With Error Constraints and Disturbances

This work investigates the time-varying formation tracking control (TVFTC) problem of multiple small-scale unmanned helicopters (SUHs) with disturbances. The SUHs are required to achieve a desired time-varying formation flight while guaranteeing the tracking error without violating the prescribed constraint. Based on backstepping technique, a fully distributed formation control scheme is proposed, where a barrier Lyapunov function is adopted to address the error constraint, and disturbance observers are employed to estimate the unknown disturbances. It is mathematically proved that all the closed-loop states of SUH formation are bounded under the proposed scheme while the prescribed error constraints will not be exceeded, which enhances the flight safety and applicability. Simulation results further verify the effectiveness of proposed method.