Design principle based on maximum output force profile for a musculoskeletal robot

Purpose – This paper focuses on an engineering application of the vertebrate musculoskeletal system. The musculoskeletal system has unique mechanisms such as bi-articular muscle, antagonistic muscle pairs and muscle-tendon elasticity. The “Artificial Musculoskeletal System” is achieved through the use of the pneumatic artificial muscles. The study provides a novel method to describe the force property of the articulated mechanism driven by muscle actuator and a transmission. Design/methodology/approach – A musculoskeletal system consists of multiple bodies connected together with rotational joints and driven by monoand bi-articular actuators. We analyze properties of the musculoskeletal system with statically calculated omni-directional output forces. A set of experiments has been performed to demonstrate the physical ability of the musculoskeletal robot. Findings – We propose a method to design a musculoskeletal system based on an analysis of the profile of convex polygon of maximum output forces. The result shows that the well-designed musculoskeletal system enables the legged robot to jump 0.6m high and land softly from 1.0m drop off. Originality/value – The paper provides a design principle for a musculoskeletal robot. The musculoskeletal system is the bio-inspired mechanism for all multi-degrees-of-freedom articulated devices, and has the advantages of optimized actuator configuration and force control.