The utility of miniature ground robots has long been limited by reduced locomotion capabilities compared to larger robots. Many avenues of research have been pursued to improve ground locomotion to alleviate this issue. In this paper, another option is explored in which a small ground robot is equipped with the ability to fly, allowing it to move to previously unreachable areas if necessary. The robot design is presented with an emphasis on mechanical aspects. The design utilizes a minimalistic two-wheeled ground mode to minimize weight, and a rotary-wing flight mode, enabling transformations at will. The transition between modes requires a transformation wherein the robot tips itself on-end and unfolds rotors or vise versa. The design presented herein is an improvement upon previous designs using the same concept; it is more robust in both its transformation process and locomotion capabilities [1], [2]. In addition to a new robot design, two new principles for the design of such robot are proposed: protection of flight mode components and isolation of the two modes' drivetrains.

Small ground robots remain limited in their locomotion capabilities, often prevented from accessing areas restricted by tall obstacles or rough terrain. This paper presents the improved design of a hybrid-locomotion robot made to address this issue. It uses wheels for ground travel and rotary-wing flight for scaling obstacles and flying over rough terrain. The robot's initial design suffered from a number of issues that prevented it from functioning fully, such as overheating motors, inadequate control electronics, and insufficient landing gear. Several improvements have been made to the robot's design to correct these problems. These obstacles, and the solutions implemented in the improved design, have enabled several design principles to be formulated for miniature hybrid-locomotion robots. It is found that hybrid-locomotion vehicles utilizing rotary-wing flight are most useful when the design is optimized for ground mode performance. Collapsibility is necessary in such vehicles to reduce the impact of the helicopter rotor on the size of the ground mode. Finally, since a large number of actions are necessary to propel and transform the robot, integrating multiple functions into each mechanism can reduce the mass of the robot.

Mobility in small ground robots is often improved by novel mechanisms or wheel designs. This can be successful when navigating rough terrain or climbing small obstacles. However, few such robots are capable of scaling obstacles of arbitrary height or traversing all types of terrain. This paper presents a concept for a miniature robot that combines wheeled ground locomotion with rotary-wing flight capabilities, which has the potential to offer the best features of both helicopters and ground vehicles while addressing the aforementioned challenges to mobility.