HYDRAULIC MULTI-ROTOR AERIAL VEHICLE

A multi-rotor aerial vehicle comprises least two rotors, a controller, a power supply having an output shaft, a shaft-driven hydraulic machine coupled to the output shaft and at least two rotor-driving hydraulic machines coupled to respective rotors. At least one of the hydraulic machines is an electronically commutated hydraulic machine in which the displacement of hydraulic fluid through each working chamber is regulated by one or more electronically controllable valves, during each cycle of working chamber volume, in phased relationship to cycles of working chamber volume. The controller controls the one or more electronically controllable valves of each of the electronically commutated hydraulic machines to independently control the rotation of the rotors. It may be that the shaft-driven hydraulic machine is an electronically commutated machine with a plurality of independent outputs, which independently drive the rotor-driving hydraulic machines. It may be that the rotor-driving hydraulic machines are electronically commutated machines the displacement of which is independently controlled to independently drive the rotors.