An Aerial Robot Passively Transforming Between Hovering and Forward Flight via Aerodynamically Bistable Structure

With the ubiquitous deployment of drones in various fields, aircraft capable of both hovering and forward flight have garnered increasing attention due to their versatility and long-range cruising capability. Currently, these multimodal aerial vehicles are generally achieved by introducing additional actuators, which inevitably results in redundant mass, complex structures, and reduced flight efficiency. In this work, we propose a 39-g bimodal aerial robot equipped with only two propellers as actuators. The robot can cruise like a fixed-wing aircraft or hover in place through self revolving. The transition between its flight modes is achieved through the introduction of several passive morphing mechanisms and aerodynamically bistable structure. With only two rotors, the robot leverages aerodynamic loads on the wings to maintain its flight configuration. Strategic adjustment of propeller thrust enables seamless transition between forward flight and hovering modes. Extensive indoor and outdoor experiments demonstrate the robot’s stable operation in both flight modes, with power loading of 10.24 g/W in forward flight and 7.11 g/W in hovering mode. The robot successfully performs mode transitions in a predictable and repeatable manner. This approach enables a structurally proficient solution for multimodal flight without the need for additional actuators.