Raptor 2: Design of fast biped robot for 3D environments us- ing active tail stabilization

1. Motivation Legged robots will need to be fast, robust and efficient for real world applications. In this research, we aim to design a high speed bipedal running robot on 3D environments based on active tail stabilization method, Raptor 2 robot. 2. State of the Art Many legged robots have been studied and developed so far, but only a few robots have achieved stable fast legged locomotion. In Legged locomotion, usually leg actuators should satisfy highly coupled two control objectives (leg configuration and body balance simultaneously)[1][2], It aggravate legged robot performance (computation load, complicated structure, etc.). The FastRunner is a biped robot consist of under actuated linkage legs and tendon networks passively. It achieved a running speed of 35.4 km/h in simulation [3]. However the FastRunner robot is not proper for 3D uneven dynamic situations. Animals use their tails as dynamic stabilizers to improve locomotive performance [3]. Thus, active tail stabilizer in animal can be an effective solution for maintaining legged robot balance. The MIT Cheetah robot has a tail to reject disturbances [4]. However, this long tail design is limited in stroke such that balance controllability is restrained.