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

Purpose – The purpose of this paper is to focus 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 mono‐ and bi‐articular actuators. The paper analyzes 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 – A method to design a musculoskeletal system is proposed 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 0.6 m high and land softly from 1.0 m 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.