Abstract:
Multi-mode mobility is prevalent in biological systems where organisms efficiently switch between different modes of locomotion to conserve energy, traverse long distances, and maneuver through confined spaces. This paper describes the design and experimental validation of an all-terrain cyclocopter MAV capable of efficient aerial, terrestrial, and aquatic locomotion with seamless transition between the modes. The vehicle weighs 1010 grams and solely relies on its four cycloidal rotors (cyclorotors) as source of propulsion for all modes. In aerial mode, cyclorotor rotational speeds and thrust vectors were individually modulated to sustain stable hover. A similar control strategy using aerodynamic forces generated by cyclorotors was also implemented for aquatic locomotion. Because cyclorotors rotate about the horizontal axis, wheels were efficiently integrated into the carbon fiber rotor endplates and terrestrial locomotion was commanded directly by motor torque. A key component that enables mode conversion is the retractable landing gear system. Seamless transition between aerial and terrestrial modes was accomplished within 5 seconds using two linear servos that extend/retract the landing gears to achieve aerial–aquatic or aerial–terrestrial modes. Polystyrene foam pontoons were integrated to the landing gear system for sufficient buoyancy. Structural components required to permit terrestrial and aquatic locomotions weighed 200 grams, which accounted for 20% of total vehicle weight. In aerial mode, cyclorotors operated at 1550 rpm and consumed 232W to sustain hover. In terrestrial mode, forward translation at 2 m/s required 28 W, which was a 88% reduction in power consumption required to hover. In aquatic mode, cyclorotors operated at 348 rpm and consumed 19 W, a further 92% reduction in power consumption. In this manner, with only a modest weight addition, a versatile platform capable of multi-modal operation is achieved. Overall, the all-terrain cyclocopter successfully demonstrated sustained hover, efficient translation and rotational maneuvers on ground, and aquatic locomotion.