Adaptive/multi-model height control system of a quadrotor constant unknown load transportation

This paper presents a methodology for height control of a quadrotor that transports a constant unknown load, given the estimates on both weight and state variables, based on measurements from motion sensors installed on-board. The proposed controller is an adaptive controller, scheduling LQR gains and gravitational force compensation. The in flight estimation problem is tackled resorting to a multiple-model adaptive estimator, providing also vertical velocity estimates. The control system obtained is validated both in simulation and resorting to an off-the-shelf commercially available quadrotor equipped with an IMU, an ultrasound height sensor, and a barometer, among other sensors.