Design Of Cheetah Robot’s Hindlimb Based On Pneumatic Muscle

It is challenging to design kinetic robot with high-speed in the field of robotdesigning as high-speed movement put forwards higher requirements for the design ofmechanical structure, related theory for research and controlling method which arouseskeen interest of researchers to the run-type robot in high-speed nowadays. Because onlyunder the condition that having ultimate velocity and force in short time can a robotachieve vacated state required in high-speed running, and thus it is a must to provide thiskind of explosive force and velocity in mechanical design. As joint driven of the leg, thepneumatic muscle not only provides explosive force and velocity required in high-speedrunning for legged robot, but also enhanced flexibility of robot’s joint that improves sportperformance and environment. Based on the musculoskeletal and movement characterist-ics of cheetah, this paper designs the cheetahc hindlimb with three active-degree offreedom and one passive-degree of freedom, and the joint is driven by pneumatic muscle.This paper gives a new attempt for pneumatic muscle to be used in the robot design withhigh-speed and high-flexibility.Firstly, having analyzed the skeleton structure and muscle organization of cheetahdeeply, this paper utilizes pneumatic muscle whose characteristics are similar tobiological muscle as joint driver and designs one cheetahc robot hindlimb with threeactive-degree of freedom and one passive-degree of freedom. That utilizing thepneumatic muscle driving method not only improve the joint flexibility which enablesthe design structure to be compact, but also perform well in the energy efficiency, designcost and other aspects. With the lighter but high-strength aluminum alloy as designmaterials, the kinetic properties of robot hindlimb has been improved as much as possible.Secondly, this paper designs the hardware and software of cheetahc robot hindimbon the basis of hierarchical control method. This paper uses the controller of hip joint,knee-joint and ankle joint as the executive level and the monopod kinetic controller asthe organization level, and they use the same hardware structure. We use CAN bus tocommunicate between the executive level and organization level. The organization levelcoordinates the movement of the three joints while the executive level controls thecontraction and stretch of pneumatic muscle to complete the rotation of joint. Thishierarchical control system enjoys great controlling properties for those robots whichneed to get joint angles frequently.Finally, the paper tests the kinetic performance of cheetahc robot hindimb. We buildthe experimental platform and carry out experiments for the dynamic responsecharacteristics of robot hindlimb’s joint, coordinated kinetic properties of each joint and the ground reaction force. The experiment results show that the robot hindlimb canachieve the given joint movement well and possess high-speed running ability.