Landing Impact Simulation of a One-Legged Robot with a Series Elastic Actuator

Currently, natural disasters occur frequently. Therefore, disaster response robots are expected to reach disaster areas and operate at dangerous sites as quickly as possible. Humanoid robots are considered promising disaster response robots for performing various tasks instead of humans at disaster sites. To deploy robots at these sites, parachute descent is considered because the roads to reach the destination are generally destroyed. However, during parachute descent, the impact on the robot is quite significant compared to falling when standing or walking. To achieve parachute descent, it is necessary to generate an impact-absorbing landing motion. This paper develops a landing impact simulator to demonstrate the landing motion of a one-legged robot equipped with a series elastic actuator (SEA). The SEA features necessary characteristics to reduce impact while executing appropriate motion. First, the impact on a one-legged robot during landing was analyzed using a drop test. Second, based on the assumption of the linear spring-damper model of the SEA, the model parameters, such as the spring and damping coefficients, were identified through an optimization method using the results of the impact experiment. Subsequently, a landing impact simulation of the robot was performed to evaluate the validity of the developed SEA model. Compared with the drop test of a one-legged robot, it is confirmed that the developed SEA model has sufficient performance to reproduce the behavior of the flexible joint during landing.