SIMBA: Tendon-Driven Modular Continuum Arm with Soft Reconfigurable Gripper

Abstract

In this paper, we describe the conceptual design and implementation of the Soft Compliant Manipulator for Broad Applications (SIMBA) manipulator, which is designed and developed for participating in the RoboSoft Grand Challenge 2016. In our novel design, we have proposed (1) a modular continuum arm with independent actuation units for each module, to increase maintainability; (2) a soft reconfigurable hand, for a better adaptation of the fingers to objects of different shapes and size; (3) a moving base for increasing the workspace. We used a hybrid approach in designing and manufacturing by integrating soft and hard components, in both materials and actuation, providing high lateral stiffness in the arm through flat springs, soft joints in fingers for more compliancy and tendon-motor actuation mechanism providing flexibility but at the same time precision and speed. The SIMBA manipulator has demonstrated excellent grasping and manipulation capabilities by being able to grasp objects with different fragility, geometry, and size; and by lifting objects with up to 2 kg of weight it demonstrate also to be robust and reliable. The experimental results pointed out that our design and approach can lead to the realization of robots able to act in unknown and unstructured environments in synergy with humans, for a variety of applications where compliancy is fundamental, preserving robustness and safety.

Soft Robotic Grippers

“…One approach is to use hinges made of elastic materials, leading to simpler systems compared to rigid joints with mechanical springs . Elastic hinges allow exploiting stored bending energy to return the actuated fingers to their initial position.…”

A 3D-Printed Omni-Purpose Soft Gripper

“…It is higher than the grip force reported in [38] and lower than the one reported in [37] for grippers based on PneuNets. It is higher than the grip forces reported in [11,12] for grippers and hands based on hybrid fingers made of soft and rigid materials. It is higher than the blocked force reported in [9] for a gripper based on compliant mechanisms and higher than the blocked forces reported in [49,50] for FDM 3D printed soft actuators.…”

“…Electric motors are the most widely used external actuators in the first class of soft grippers. Tendon-driven soft grippers coupled with electric motors have been developed based on multiple techniques including fused deposition modeling (FDM) 3D printing [8,9], silicone molding [10] and assembled hybrid structures made of soft and rigid materials [11][12][13]. Other soft grippers and robotic hands use electric motors to drive compliant and adaptive bioinspired soft structures [14][15].…”

Bendy ARM 2.0: Continuum Arm Manipulator Refinement and Control for Assistive Technology

“…There has been a history of soft or flexible robotics which often share similar features as continuum manipulators, in that they're made of soft material, able to bend, and have at least a semi continuous backbone (Ansari et al, 2017). As continuity lies on a spectrum, many current research goals aim to push robotics further towards being fully continuous, while some research also goes into making hybrid type robots, that exhibit a mix of rigid joints and fluid segments (Mishra et al, 2017). Though research in continuum robotics has been limited, multiple papers have defined continuum manipulators as having infinite-DOF, elastic structure, continuously bending, and lacking rigid links and rotational joints (Chamberlain, Kordell, & WallEpstein, 2015;Renda, Cianchetti, Giorelli, Arienti, & Laschi, 2012;Togashi, Matsuda, & Mitobe, 2014;Walker, 2013).…”

“…Continuum robots utilize elastic material that allows it to exhibit infinite degrees of freedom (Mishra, Del Dottore, Sadeghi, Mondini, & Mazzolai, 2017). There has been a history of soft or flexible robotics which often share similar features as continuum manipulators, in that they're made of soft material, able to bend, and have at least a semi continuous backbone (Ansari et al, 2017).…”