Technology these days is making giant steps, and one of the more prolific field is for sure robotics. In spite of rapid development in robotic technologies, living creatures are still superior to robots existing currently in various aspects. Thus, it is necessary to understand the principles underlying the motions and behaviors of biological subjects for the control of robots. Mimicking living creatures currently becomes one of the worldwide trends for robotic innovations . It is considered as one of the most adequate way of developing a robot since biological systems provide a number of useful ideas concerning the control of robots. Recently, robotic researchers as well as biologists propose innovative ideas for the control of the walking robot system. Among several ideas, mimicking the rhythmic motion of animals is one of the most promising ways to control the walking robot system. By studying on this, the locomotion of the walking robot can be close to that of the real animal. ...