Fundamental Three-Dimensional Configuration of Wire-Wound Muscle-Tendon Complex Drive

Abstract

For robots to become more versatile and expand their areas of application, their bodies need to be suitable for contact with the environment. When the human body comes into contact with the environment, it is possible for it to continue to move even if the positional relationship between muscles or the shape of the muscles changes. We have already focused on the effect of geometric deformation of muscles and proposed a drive system called wire-wound Muscle-Tendon Complex (ww-MTC), an extension of the wire drive system. Our previous study using a robot with a two-dimensional configuration demonstrated several advantages: reduced wire loosening, interference, and wear; improved robustness during environmental contact; and a muscular appearance. However, this design had some problems, such as excessive muscle expansion that hindered inter-muscle movement, and confinement to planar motion. In this study, we develop the ww-MTC into a three-dimensional shape. We present a fundamental construction method for a muscle exterior that expands gently and can be contacted over its entire surface. We also apply the three-dimensional ww-MTC to a 2-axis 3-muscle robot, and confirm that the robot can continue to move while adapting to its environment.

Figures (18)

• Figure 1: (a) Muscle-tendon complexes adjust their shape and internal spatial relationships when encountering contact, enabling continued movement while adapting to the environment. They return to their original position after contact with the environment ends. (b) 2-axis 3-muscle robot with three-dimensional configuration.
• Figure 2: (a) Conceptual diagram of wire-wound Muscle-Tendon Complex driveMTC-2D:Ribayashi:HUMANOIDS2023. (b) 1-axis 3-muscle robot with two-dimensional configurationMTC-2D:Ribayashi:HUMANOIDS2023.
• Figure 3: Three-dimensional ww-MTC consists of the muscle exterior and the tendon based on Stiffness Adjustable Tendon (SAT)robomech2003:shirai:sat.
• Figure 4: (a) Conceptual diagram of three-dimensional muscle. Muscle exterior is made by frame determining shape change and braided sleeve covering the surface. (b) Assembly of the muscle exterior.
• Figure 5: The PP sheet is processed as shown in (a). The distance from the hole through which the wire passes to the seam corresponds to the length of the beam and is an important parameter that defines the deformation of the muscle exterior. (b) PTFE tube is inserted to prevent wires from getting stuck.