ISBN 9783843945981

978-3-8439-4598-1, Reihe Informatik

Atabak Nezhadfard
Integration and Design of Actuation Redundancy in Robotic Leg CARL Based on the Physiology of Biarticular Muscles

183 Seiten, Dissertation Technische Universität Kaiserslautern (2020), Softcover, A5

Zusammenfassung / Abstract

The main objective of this thesis is to improve the actuation network of CARL. This planar robotic leg has three degrees of freedom actuated by five actuators. The two extra actuators are biarticular that originally integrated to improve the efficiency of the motion. In this study, the action of biarticulars is analyzed and the modifications are applied to improve their performance. A holistic approach is taken to design the moment arms of the actuators based on the physiology of human musculature.

The coordination of the actuators is the first step to exploit the advantages of bi-articulation. For this purpose, a jump experiment is implemented and the mechanical efficiency of the movement is documented for two coordination algorithms. It is demonstrated that the method based on the minimization of the instant power is capable of improving the efficiency of the jump by 5.1 percent compared to the conventional minimum fatigue method.

The moment arm of the human muscles is exhaustively analyzed to construct a mathematical model that maps the function of each muscle to its moment arm profile. The contribution of the muscles on the ground reaction force is used to define the action of each muscle. This analysis enables the redesign of the actuation network in CARL to replicate the biological behavior of the muscles while satisfying the technical restriction of the mechanical system.

The result is a robotic leg with an increased range of joint angles and larger moment arm of the actuators.The new leg design is expected to perform the jump experiment with eight percent higher efficiency than the older version. The comparison between the energetics of the human muscles and actuators in the vertical jump experiment demonstrates the successful synthesis of the muscle function in the robotic leg.