Motor-Efficiency Estimation and Control of Multirotors Comprising a Cooperative Transportation System

A cooperative transportation system (CTS) composed of two multirotors has been developed to facilitate the cooperative transportation of a payload, even in the presence of defective motors. The reduced thrust generated by the faulty motors may cause greater tracking errors, making it challenging to control and estimate the system. Moreover, the reduced thrust can also act as a disturbance to the other UAV, further exacerbating the problem. To address these issues, the motor thrust is reconfigured using an efficiency estimator based on an unscented Kalman filter (UKF). This estimator increases the thrust of the defective motors, thus improving the system's performance. The CTS achieves trajectory tracking despite the defective motors by using a geometric controller that incorporates the motor-efficiency estimator. A stability analysis has been conducted to prove the stability of the tracking errors. The estimation and control performances have been verified through simulations.