Design Of Pneumatic Stiffness Adjustable Foot And Gait Planning For Biped Robot

Relying on the flexible mobile mechanis m,the humanoid bipedal robots have a strong ability to move,and the mobility of bipedal robots have a distinct advantage over wheel and crawler robots,especially on uneven ground.However,most of the bipedal robots use flat feet and point-contact feet which can not provide a reliable support in the process of walking.The shape of the supporting area can be changed and the contact points can be shifted while the foot is stepping on the bumps on the ground,which is harmful to the stability of the bipedal walking.Therefore,the purpose of this paper is to design a foot mechanism and the corresponding gait which can improve the stability of the bipedal walking.Firstly,This paper discussed the disadvantages of the rigid and flat foot and point-contact foot.Then,refers to some adaptable foot mechanism,the method of stiffness transformation rely on passive exhaust gas is put forward,which allows the variable stiffness units can switch the satus between stiff and soft passively,Thus,the pneumatic variable stiffness foot can adapts to the bumps on the ground and provides effective support for the bipedal walking in the meantime.Then,the foot structure is designed and checked,and the FSR sensors are integrated,and the foot is completed.Secondly,the kinematics of the robot is disgussed by considering the structure of the pneumatic-electric hybrid driven bipedal robot especially its knee joint which has two coupled DOFs.The dynamics of the robot is proposed by considering the elastic potential energy and the flexibility of the foot.Thirdly,considering the contact condition of the pneumatic variable stiffness foot and the ground,the bipedal walking gait,which is suitable for the pneumatic variable stiffness foot,is planned according to the kinematic s of the bipedal robot.And the trajectories of the joints were calculated.Considering the performance characteristics of the artificial muscle,the trajectories of the pneumatic pressure of the muscle were calculated.Finally,the stiffness experiment platform is built,and the stiffness characteristics of the pneumatic variable stiffness unit s are analyzed.The FSR sensors were calibrated.The circuit of the control system and the walking experiment platform are designed and built.The joint controllers of the robot are designed by considering the actuation method.Both of the rigid and flat foot and the pneumatic variable stiffness foot are using by the b iped robot,and the walking experiments on even and uneven ground are carried out.The applicability of the gait is verified,and the function that the pneumatic variable stiffness foot can improve the walking stability of the biped robot is also verified.