Hopping by a Monopedal Robot with a Biarticular Muscle by Compliance Control – An Application of an Electromagnetic Linear Actuator –

The compliance of muscles with external force and the structural stability given by biarticular muscles are important features of animals for realizing dynamic whole-body motion such as running and hopping in various environments. For this reason, we have been studying an electromagnetic linear actuator. This actuator emulates the behavior of a human muscle, such as spring-damper properties, through the quick control of output force, i.e., impedance control. It is expected to be used as an artificial muscle. In this paper, we design a monopedal robot possessing bi- and mono-articular muscles implemented by linear actuators. Thanks to the biarticular muscle, the direction of bouncing by a robot can be controlled by changing the stiffness ellipse at the endpoint, i.e., foot, of the robot. We make a simulator of the robot to evaluate dynamic characteristics and show that the robot hops stably by adjusting the stiffness ellipse. We also confirm that the behavior of the real robot is consistent with that of our simulator.