Musculoskeletal system for bio-inspired robotic systems based on ball and socket joints

Musculoskeletal system is the fundamental structure that allows complex mobility of biological systems. A lot of efforts have been made in the past to mimic this structure using synthetic materials for use in robotic systems. Development challenges for this technology include design and manufacturing, system integration, control methods and energy usage. One of the key elements of musculoskeletal system is artificial muscles or actuators used in this system. Actuators presented in the literature do not match the performance of natural muscles in most of the metrics such as force generation, strain output, frequency, power density, ease of control and repeatability. This paper briefly describes the recently introduced Twisted and Coiled Polymer (TCP) muscles integrated into a ball and socket joint made of ABS plus® material. The proposed structure consists of a class of ball-and-socket joint that incorporates TCP muscles and silicone to generate multidimensional actuation. Most traditional joint-and-actuator assemblies include passive rotary joints actuated by servomotors via gears transmission. Our proposed ABS based 3D printed joint is actuated by artificial muscles without any complex mechanical transmission system. In comparison with other such assemblies, the proposed joint system is a promising solution to the diverse applications in robotics, especially where soft actuators and cost effective solutions are needed.