On the influence of elastic actuation and monoarticular structures in biologically inspired bipedal robots

Implementing the intrinsically compliant and energy-efficient leg behavior found in humans for humanoid robots is a challenging task. Control complexity and energy requirements are two major obstacles for the design of legged robots. Past projects revealed that the control complexity can be drastically reduced by designing mechanically intelligent systems with self-stabilization structures. Breaking through the latter obstacle can be achieved by the development and use of compliant actuators. Mechanical elasticity and its online adaptation in legged systems are generally accepted as the technologies to achieve human-like mobility. However, elastic actuation does not necessarily result in energy-efficient systems. We show that mechanical elasticity, although being worthwhile, can have negative effects on the performance of drives. We present a methodology that introduces both elasticity and energy-efficiency to a bipedal model. To this end, we report on the influence of monoarticular structures and demonstrate that these structures have the potential to both take us a step further toward the goal of realizing human-like locomotion and reduce the energy consumption.