Material stiffness control of compliant tools by using electromagnetic suction

Abstract

Variable rigidity materials that are safe, controllable, reversible, and repeatable have potentially widespread implications in robotic technologies. This paper presents a method for controlling the stiffness of materials for compliant tools, such as grippers, soft robots, and endoscopes. The force of electromagnetic suction transforms two structures from their relaxed-state into a more rigid state. The system presented here has the ability of quickly increasing the stiffness with increased current in the coils that create electromagnetic suction, wherein the stiffness can be controlled by the variation of supply current. The process of controlling stiffness variation is reversible and repeatable under the safe voltage of human body. The system can lead to the production of tools that are small, flexible, dexterous, and safe. Suction force, friction force, and rotational stiffness were calculated to evaluate the performance of the system. Experiments were carried out to verify the proposed concept and the calculations.