Locomotion Principles of 1D Topology Pitch and Pitch-Yaw-Connecting Modular Robots

Abstract

The last few years have witnessed an increasing interest in modular reconfigurable robotics. The applications include industrial inspection (Granosik, 2005), urban search and rescue (Zhang, 2006a), space applications (Yim, 2003) and military reconnaissance (Zong, 2006). They are also very interesting for research purposes. Modular robots are composed of some identical or similar units which can attach to and detach from each other and are capable of changing the configurations. Some modular prototypes are quite famous, such as Polybot from Mark Yim (Yim, 2000), CONRO (Castano, 2000), SuperBot (Chen, 2006) from the Information Sciences Institute and Computer Science and M-TRAN robot from Japan (Kurokawa, 2003). These prototypes have two things in common. Normally this kind of robots consists of many modules which are able to change the way they are connected. In addition the modular approach enables robots the reconfiguration capability which is very essential in such tasks which are difficult for a fixed-shape robot. It also endows the mobile robotic system the characteristics of versatility, robustness, low-cost and fast-prototyping so that new configurations of different robots can be built fast and easily, for the exploration, testing and analysis of new ideas. The more exciting advantage is that the robots have the capability of adopting different kinds of locomotion to match various tasks and suit complex environments. Modular robots can be classified according to both the connection between the modules and the topology of their structure. One important group are the Snake robots, whose configurations consist of one chain of modules (1D Topology). Locomotion is performed by means of body motions. Depending on the type of connection between the modules, there are pitch, yaw and pitch-yaw connecting snake robots. The locomotion capabilities of the yaw family have been thoroughly studied (Hirose, 1993). There is also research work on the locomotion capabilities of some specific pitch-yaw modular robots. In (Chen, 2004) the rolling gaits are comprehensively studied and (Mori, 2002) implemented different gaits in the ACM robot. However, the locomotion principles for the whole pitch-yaw family have not been fully studied. In this chapter we propose a model for the locomotion of pitch-yaw snake robots that allows them to perform five different gaits: forward and backward, side-winding, rotating, rolling and turning. The rotating gait is a new one that, to the best of our knowledge has not been previously achieved by other researchers. Each joint is controlled by means of a sinusoidal O pe n A cc es s D at ab as e w w w .ite ch on lin e. co m