Modeling and Motion Analysis for Flexible Legs of a Bio-Falling Cat Robot

A bio-falling cat robot is designed to have possible motion abilities of flipping, walking, bounce, landing and buffering in the unstructured environment. The kinematics using standard Denavit-Hartenberg method and the dynamics using Lagrange method are analyzed for the flexible legs driven by pneumatic muscles. The mathematical model of the pneumatic muscle is established and combined with the dynamics of the flexible legs to obtain the relationship between air pressure and joint angles. Then, the three-dimensional model of the robot is imported into Adams and the co-simulation technology of MATLAB and Adams is developed to analyze behavior of the virtual prototype. Moreover, the gait planning and foot trajectory planning with compound cycloid is proposed. The simulation results of the trot gait for the bio-falling cat robot verify its motion capability.