Lecture Notes in Computer Science: An Antagonistic Actuation Technique for Simultaneous Stiffness and Position Control

The application of soft robots can result in significant improvements within a number of areas where traditional robots are currently deployed. However, a challenging task when creating soft robots is to exert effective forces. This paper proposes to combine pneumatic and tendon-driven actuation mechanisms in an entirely soft outer sleeve realising a hybrid actuation principle, to realise a new type of robotic manipulator that can collapse entirely, extend along its main axis, bend along its main axis and vary its stiffness. The created robot arm is inherently flexible manufactured from sections that consist of an internal stretchable, air-tight balloon and an outer, non-stretchable sleeve preventing extension beyond a maximum volume. Tendons connected to the distal ends of the robot sections run along the outer sleeve allowing each section to bend in one direction when pulled. The results from our study show the capabilities of such a robot and the main advantages of the proposed technique compared to traditional, single-actuation type robot manipulators.