A one linear actuator hopping robot: modeling and control

Abstract

This paper addresses the modeling and control design of a one linear actuator hopping robot. The robot consists of a body and a leg, which are in contact with a sufficiently wide horizontal ground surface; both are fixed rigidly. Force actuation affects the angle of the body by a force couple that arises due to the mass of the body, as well as the length of the leg; hence both the angular velocity of the body and height of a jump can be controlled by only one actuator. Since the aim of this study is to achieve continuous hopping motion while keeping the system as simple as possible, an ON-OFF actuator is employed. Hence, we consider utilizing the thrust timing of the actuator—when robot is in the stance phase—to control the gait. For better stability of the hopping motion, optimization of mechanical parameters was made possible by evaluating the numerically obtained transition map, which contains a transition from one standard position to the next. The system is considered as a discrete system, in which one cycle of motion is regarded as one sampling interval. Finally, a control system was designed in which, by simulation, the continuous hopping gait was realized.