Dynamics And Driving Characteristics Study Of Elastic Actuator Of Legged Robots

This paper is based on National Natural Science Fund. Robots are required to work under extremely complicated circumstance, however, the research on drive unit of robots legs can hardly meet this demand. So this paper targeted at designing an elastic actuator needed in walking robots or prosthesis which are of high adaptation to complex terrains, dependable and can move limberly, and did research on mechanical structures, dynamic models and simulations of elastic actuator.This paper designed an elastic actuator which is functional similar to muscles based on the characteristic of animal leg muscles and the theory of traditional zero damping elastic actuator, and then established a model of damped elastic actuator. This paper established dynamic models of zero damping elastic actuator and damped elastic actuator, and also dynamic simulations and analysis of these two kinds of elastic actuators are made in this paper, which prove that driving stiffness and speed of elastic actuator can be regulated according to load-magnitude, so as to simulate the function of muscles better.This paper designed a cylindrical damped elastic actuator based on the structure features of traditional zero damping elastic actuator. According to the index of robot legs, the general rigidity of elastic actuator is 25N/mm through compution. This paper introduced the selecting principle of damped elastic actuator elements. Then this paper made finite element strength analysis of two kinds of elastic actuators, and designed the control circuit of elastic actuators.This paper made analysis of elastic actuators using dSPACE. First, the damping coefficient of elastic actuator which was obtained by experiment is 0.1Ns/mm; secondly, the damping coefficient of elastic actuator which was obtained by simulations and experiments under different bandwidths is between 0 and 0.2Ns/mm; the damping coefficient measuring experiment not only got the damping coefficient of elastic actuator, but also proved that the simulations and experiments under different bandwidths were practical. The damping coefficient measuring experiment provided basis of intensive study of elastic actuator and the selection of damping coefficient. Finally, the experiment that displacement following under different load-magnitude was made, which got the displacement under different load-magnitude of elastic actuator, and the reliability of elastic actuator can be verified by index of robot legs mechanical structure.This paper made a conclusion that the damped elastic actuator is more functional similar to muscles by dynamic analysis and research on drive characteristic of two kinds of elastic actuators, and can solve the problem that impact force of walking robots feet better and reduce the impact of impact force on feet, and then the damping coefficient influence on drive characteristic and the selection of damping coefficient was obtained by experiments.