Development of Genbu : Active wheel passive joint articulated mobile robot

Snake-like robots have good properties to move on rough terrain. Their low-height bodies and articulated structures are proper to go into narrow space and to climb over obstacles. Thus, many applications of articulated mobile robots are expected (e.g. rescue robots). One of the types of snake-like robots named 'Genbu' consists of active wheels and passive jointed multi bodies. We classified this type of snake-like robots as active wheel passive joint articulated mobile robot. Although Genbu cannot go over wide gaps, they have high durability because their joints are not activated with gear-head motors. So, Genbu has high mobility on rough terrain at high-speed. Moreover the long articulated structure is proper to climb over obstacles because of size effect. For example, Genbu 2 equipped with 220mm diameter wheels can climb 300mm vertical wall. These characteristics are proper to use as rescue robots or planetary rovers. However these applications require semi-autonomous robots because the operator cannot approach the robots. The control method of this type of snake-like robots has not been established yet. In order to establish the control method, detecting the posture of the robot is very important. Nevertheless, Genbu 2 was difficult to detect the posture because of the elastic body join is. In addition, Genbu 2 had some problems for practical use (e.g. motor drivers are not inside). In this study, Genbu 3 was newly developed to solve these problems. In order to accomplish these purposes, the passive rigid joints for detecting the posture, and torque sensor with float differential mechanism are newly developed for Genbu 3. In this paper the mechanism of Genbu 3 and basic running experiments of Genbu 3 are described.