The Highly Adaptive SDM Hand: Design and Performance Evaluation

Abstract

The inherent uncertainty associated with unstructured environments makes establishing a successful grasp difficult. Traditional approaches to this problem involve hands that are complex, fragile, require elaborate sensor suites, and are difficult to control. Alternatively, by carefully designing the mechanical structure of the hand to incorporate features such as compliance and adaptability, the uncertainty inherent in unstructured grasping tasks can be more easily accommodated. In this paper, we demonstrate a novel adaptive and compliant grasper that can grasp objects spanning a wide range of size, shape, mass, and position/orientation using only a single actuator. The hand is constructed using polymer-based Shape Deposition Manufacturing (SDM) and has superior robustness properties, making it able to withstand large impacts without damage. We also present the results of two experiments to demonstrate that the SDM Hand can reliably grasp objects in the presence of large positioning errors, while keeping acquisition contact forces low. In the first, we evaluate the amount of allowable manipulator positioning error that results in a successful grasp. In the second experiment, the hand autonomously grasps a wide range of spherical objects positioned randomly across the workspace, guided by only a single image from an overhead camera, using feed-forward control of the hand.

Exploitation of Environmental Constraints in Human and Robotic Grasping

“…In accordance with these initial findings, RBO Hand 2 was also shown to be able to grasp many differently shaped objects (Deimel and Brock, 2014). Compliant actuation has also been successfully used by the SDM hand (Dollar and Howe, 2010) and the positive pressure gripper (Amend et al, 2012) to automatically adapt to diverse object shapes.…”

“…The SDM hand (Dollar and Howe, 2010), the Velo gripper (Ciocarlie et al, 2013), the i-HY hand (Odhner et al, 2014), and the Pisa/IIT SoftHand (Catalano et al, 2014) couple the actuation of degrees of freedom using tendonpulley systems, adapting the shape of the hand to the object while equalizing contact forces.…”

Stiffness Control With Shape Memory Polymer in Underactuated Robotic Origamis

“…Independent actuation of each DoF in such a system results in a highly dexterous but rather complex robot. The need for lighter and easier to control robots has lead to an alternate approach of using under-actuated mechanisms for activating many DoFs using a single source of actuation [2], [3]. Moreover, the inherent tolerance of the under-actuated hands to impacts and their ability to conform to their environment through distribution of the input actuation between the joints [4] makes them soft and inherently safe for human interaction.…”

Manipulation Capabilities with Simple Hands

“…The robotic hands found in the literature that are closest to our work on simple hands are: Dollar and Howe's SDM hand [9], with four two-jointed fingers all compliantly coupled to a single actuator; Ciocarlie and Allen's [5] two-fingered gripper with three joints per finger all compliantly coupled to a single actuator; Xu, Deyle and Kemp's [20] end-effector designed to robustly capture a large and carefully chosen set of household objects; and Theobald et al's simple gripper Talon [18] with two facing sets of fingers driven by a single actuator, for grasping rocks of varying shape and size.…”