Neural Oscillator Based CPG for Various Rhythmic Motions of Modular Snake Robot with Active Joints

Abstract

In this paper, construction of a newly designed snake robot is suggested along with the algorithm for generation of different rhythmic motions. The proposed robot system has modular structures with extendable length. It is subdivided into body, neck, head and tail modules. Each body module has two rotary motors to generate pitch and yaw motions of the snake robot. A linear actuator is also installed inside each body module in order to change the length of robot. The neck module in the robot is provided with two rotary motors to make the spherical motion of head module. Neural oscillator based central pattern generators (CPG) are used to produce rhythmic patterns for various snake robot movements, for example, serpentine, side-winding, two-step-concertina and four-step-concertina motions are generated in the snake robot using the proposed CPG algorithm. For serpentine motion, the body of robot is bent to form the planar sinusoidal waveform using whole body modules on the ground. To generate side-winding motion, the robot body is bent in such a way that it makes two dimensional sinusoidal waveform and only a few points of its body make contacts with the ground. By using the CPG algorithm, these contact points are propagated from tail to head, and the robot is ultimately moved along one side. In concertina motion, the body is sequentially pushed forward in steps from tail to head using the proposed algorithm. Finally several experiments are conducted on a laboratory floor in order to confirm the authenticity of robot design and CPG algorithm so that the comparison between different motions can be achieved.