Implementing Damper and Spring Virtually On A Quasi-Direct Drive Leg Robot

Designing an actuator for robotic leg has been an interesting sector of robotics, especially on how an actuator damp impact on landing while running or jumping. The need of protecting the gear and other mechanical components makes robot designers use series elastic actuators (SEA) as their robotics limbs. While using series elastic actuators have made it possible to damp ground reaction force on jumping or running and also storing the resulting energy from jumping, SEAs was able to do that at the cost of increased control complexity and it was hard to adjust the mechanical components to fit a certain value of spring constant or damping constant. Hence, to have an actuator which can do both damping and have a pretty high adjustability in this paper we introduce virtual damper and spring on a quasi-direct drive actuator using proportional integral and derivative (PID). Based on experiments demonstrated in this paper, by using virtual damper and spring Ground Reaction Force (GRF) of the same falling height was reduced by 2 times actuator's weight compared to when dropped without virtual damper and spring, which is about 5-6 times of actuator's weight.