Trajectory control of multirotor helicopters with thrust vector constraints

The multirotor control system structure that has mostly been adopted is constituted by an inner and an outer control loop. In this scheme, the inner loop carries out attitude control while the outer loop is responsible for trajectory control. The present work addresses the problem of safely controlling the trajectory of a multirotor helicopter by taking into account specified constraints on both the total thrust magnitude and the inclination of the rotor plane. The proposed solution partitions the whole problem into an altitude and an horizontal position control. The control laws of the two parts combine the feedback linearization principle with saturated proportional-derivative controllers. The proposed method is evaluated by computational simulations, which show its effectiveness to control the vehicle along a spiral trajectory as well as respond to abrupt position commands.