Kinematics Simulation And Landing Collision Analysis Of Bio-Frog Jumping Robot

In the last 20 years,the research of bionic robot has become a very active field.The bionic quadruped robot,which has the advantages of biological features and mechanical structure,is significantly more compact and simpler than the multiple footed robots,and has better bearing capacity,higher locomotion stability and wider moving range than the one-legged robot and the biped robot.Because of these excellent properties,it is well suitable to finish tasks instead of human in unknown and unstructured environment,such as harsh environment,complicated environment and so on.Therefore,the bionic quadruped robot is a hot spot in the field of biological robots.In this paper,the frog is selected as the bionic objects because of powerful force,strong leaping performance and good flexibility.Based on the working principle of bionic bouncing mechanism and present status of development as well as the mechanism of frog hopping movement,the virtual prototype model of bio-frog jumping robot is established and simulated,which provides a theoretical basis for subsequent research of robots.The main contents are summarized as follows:The leap mechanism of frogs is comprehensively analyzed from the skeletal,muscle and jumping postures.Based on the jumping mechanism of frogs,the hamstring models of hind legs are established from linear and nonlinear bionic and executed.The kinematic sketch of the frog jumping robot is established and the degree of freedom is analyzed.What's more,the kinematic models of forelimb and hind leg in the take-off stage are established by using D-H theory,and the pose analysis of forward and inverse kinematics are carried out.The three-dimensional model of the robot is established with Pro/E software and the virtual prototype model of robot,which is necessary to add kinematic pairs and driving functions,is built by using ADAMS software.Kinematics simulation is carried out to get the curves of the jumping position,the centroid motion,the driving joint angle and the contact force between the robot limbs and the ground in ADAMS simulation environment.These results are compared with the jumping characteristics of frogs,and the reasonableness of the virtual prototype model are verified.Based on the Hertz's elastic collision theory,the normal contact force model of the robot landing is established,and also the kinematics simulation by ADAMS is carried out to get the regularity of the normal collision force between the shank and the ground during the landing.Furthermore,the influence of the parameters with the material properties of the shank and the contact force between the shank and the ground on the jumping performance and collision process characteristics of the robot is analyzed.Aiming at the large impact force to the shank rigid model,the spring leg model of the shank is established and searching the influence of its parameters about the jumping performance and collision process characteristics of the robot is studied.The elastic leg model with the stiffness coefficient of 9 N/mm and the damping coefficient of 1N ×s/mm is chosen to be compared with the rigid model,and the relevant conclusions are obtained.