A new bio-inspired, antagonistically actuated and stiffness controllable manipulator

Robotic manipulators can be divided into different classes, including discrete, serpentine and continuum robots [1]. Most robots in use today have a number of discrete and usually rigid links connected by simple joints. Our work though has been inspired by biology [2], [3] specifically by the octopus, with its soft tentacles and virtually infinite number of degrees of freedom (DoFs). Biological studies show that the octopus is capable of actuating the different types of muscles in such a way that it can control the stiffness of its arms, enabling the animal to catch fish, move stones or even walk across the seabed. Taking inspiration from the antagonistic behaviour of octopus arms, our robot manipulator makes use of two fundamental actuation means, pneumatic actuation and tendon-based actuation, able to oppose each other and thus capable of varying the arms’ stiffness over a wide range. Our robot arm can be said to employ two main actuation mechanisms in a hybrid fashion intrinsic (pneumatics in our case) and extrinsic (tendon actuation in our case) [1], [4].