Dynamic Modeling and Simulation of Compliant Legged Quadruped Robot

Quadruped robot has many advantages over wheeled mobile robots, but it is a discrete system in which joints of each leg has to operate in particular fashion to get the desired locomotion. So, dynamics plays an important role in the operation and control of quadruped robot. Proper conception of the dynamic formulation is must for the complex system like quadruped robot. Here, an attempt is made to generate three dimensional model of a quadruped using the bond graph technique. Bond graph is an efficient tool for system modeling from the physical model itself and various control strategies can be developed very efficiently. A quadruped robot configuration used for analysis is two links legged robot in which upper link is rigid and lower link is compliant. In a lower link, piston and piston rod is sliding inside the cylinder and movement is restricted by the internal hydraulic pressure of the cylinder which will generate compliance in the leg. Simulation of the various gait performed by the quadruped is carried out, which proves the versatility of the three dimensional model generated. The generated model can be used in research of various aspects pertaining to quadruped, the same thing is demonstrated by doing performance evaluation between compliant and rigid legged robot and also between two different gaits like trot gait and amble gait. Keywords—Quadruped robot, Bond graph, Dynamic model