Antagonism in pneumatically-actuated, stiffness-controllable robot fingers
Title: Antagonism in pneumatically-actuated, stiffness-controllable robot fingers
Authors: Agostino Stilli (University College London, Department of Computer Science, Surgical Robot Vision Group); Helge A. Wurdemann (University College London, Department of Mechanical Engineering); Kaspar Althoefer (Queen Mary University of London, Advanced Robotics @ Queen Mary (ARQ));
Citation: Stilli, A., Wurdemann, H. A., Althoefer, K., (2018). Antagonism in pneumatically-actuated, stiffness-controllable robot fingers. UK-RAS Conference: ‘Robots Working For & Among Us’ Proceedings, 155-157.
The capability to vary stiffness in flexible robotic fingers provides increased dexterity and manipulation capabilities – opening up a completely new approach to grasping a wide range of objects. The proposed robot finger concept marries the advantages of soft material robotics with the advantages of robot systems that are stiff and capable of handling high-payload objects. Is it widely accepted that most soft material robots such as those made from silicone rubber suffer from an inability to apply high forces to the environment they are in contact with, limiting their application. On the other hand, traditional non-compliant robot hands made of rigid components often require accurate information about the location of objects to be handled and advanced control strategies to achieve a good grasp – further, the range of objects is often limited, since a particular grasper architecture is often optimized for grasping a small set of objects. The proposed stiffness-controllable finger can approach the object in a low-stiffness state with all its advantages of compliance and can then adjust the stiff- ness adjusting to the shape of the object and requirements of the grasping task – once a grasp is established the stiffness can be ramped up considerably to lift heavy objects whilst not changing the assumed finger configuration. Hence, lifting heavy, but fragile objects becomes a possibility at low control cost. The proposed robot finger concept extends from existing robot fingers proposed elsewhere, because with its 2-DoF motion capability it can bend in different directions further enhancing the grasping capabilities of robot hands with which the pro- posed fingers is intended to be integrated – imagine a robot finger that can bend not only along one axis but in all directions around its longitudinal axis. The proposed concept provides the additional capability of massively extending from a collapsed state to a fully-extended state, even further enhancing the grasping and manipulation capabilities. This paper reports on the proposed robot finger concept highlighting its capability to bend in a multitude of directions, vary its stiffness and apply forces to the environment in a well-controlled fashion.