Epi.q-1.2, a hybrid mobile mini robot with a reconfigurable three wheeled locomotion unit

This document presents Epi.q-1.2, a smart mini robot able to move on flat, inclined, undulating or uneven terrain, to climb over obstacles, to go up stairs and to change its kind of locomotion from a rolling (on wheels) to a stepping (on legs) one. The kind of locomotion changes automatically according to ground conditions or thanks to an axial device. Moreover robot locomotion unit can vary its geometry from a closed configuration to an open one: the first configuration is suitable to reach restricted spaces and the second one to get over high obstacles. All these kinds of functioning are obtained thanks to its innovative driving device that consists of a double epicyclic gearing and an axial device, able to lock or free some DOFs along the kinematic chain. Epi.q-1.2 consists of three elements: the forecarriage, the central body and the rear axle, these three elements are linked by two mutually perpendicular cylindrical joints that grant to the robot great mobility and a correct contact between wheels and ground, even in presence of uneven terrain. Epi.q-1.2 overall dimensions are about 160×360×280 mm (height×length×width) and weighs about 2,6 kg. The robot was designed on the basis of the results of some kinematic and dynamic models presented in this paper. It was experimentally tested on flat ground, slopes, uneven terrain, it goes up stairs and climbs over 90 mm obstacles, that are 72% of the locomotion unit height.