Analysis and design of a tilted rotor hexacopter for fault tolerance

GIRIBET J. I.; SÁNCHEZ PEÑA R.; A. GHERSIN

IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2016 vol. 52

0018-9251

A proof is presented, of how an hexagon shaped hexacopter can be designed in order to keep the ability to reject disturbance torques in all directions while counteracting the effect of a failure in any of its motors. The method proposed is simpler than previous solutions since it does not require to change the motor rotation direction or any in-flight mechanical reconfiguration of the vehicle. It consists in tilting the rotor a small fixed angle with respect to the vertical axis. Design guidelines are presented to calculate the tilt angle in order to achieve fault tolerant attitude control without loosing any significant vertical thrust.It is also formally proved that the minimum number of unidirectional rotating motors needed to have fault tolerance is six, and that this can be achieved by tilting their rotors. This proof is essentially a control allocation analysis which recovers in a very simple way a result already known: the standard configuration (without tilting the motors) is not fault tolerant. A simulation example illustrates the theory.