Soft Finger Model with Adaptive Contact Geometry for Grasping and Manipulation Tasks

This paper presents a method for building analytical contact models for soft fingers. Friction constraints are derived based on general expressions for non-planar contacts of elastic bodies, taking into account the local geometry and structure of the objects in contact. These constraints are then formulated as a linear complementarity problem, the solution of which provides the normal and frictional forces applied at each contact, as well as the relative velocity of the bodies involved. This approach captures frictional effects such as coupling between tangential force and frictional torque. We illustrate this method by analyzing manipulation tasks performed by an anthropomorphic robotic hand equipped with soft fingerpads

Motion planning for cooperative manipulators folding flexible planar objects

Abstract — Research on robotic manipulation has mostly avoided the grasping of highly deformable objects, although they account for a significant portion of everyday grasping tasks. In this paper we address the problem of using cooperative manipulators for folding tasks of cloth-like deformable objects, from a motion planning perspective. We demonstrate that complex deformable object models are unnecessary for robotic applications. Consequently, a simple object model is exploited to create a new algorithm capable of generating collision-free folding motions for two cooperating manipulators. The algorithm encompasses the essential properties of manipulator-independence, parameterized fold quality, and speed. Numerous experiments executed on a real and simulated dual-manipulator robotic torso demonstrates the method’s effectiveness. I

Sensory Communication

Contains table of contents for Section 2 and reports on five research projects.National Institutes of Health Contract 2 R01 DC00117National Institutes of Health Contract 1 R01 DC02032National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Contract N01 DC22402National Institutes of Health Grant R01-DC001001National Institutes of Health Grant R01-DC00270National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Air Warfare Center Training Systems Division Contract N61339-94-C-0087U.S. Navy - Naval Air Warfare Center Training System Division Contract N61339-93-C-0055U.S. Navy - Office of Naval Research Grant N00014-93-1-1198National Aeronautics and Space Administration/Ames Research Center Grant NCC 2-77

Theoretical Model Construction of Deformation-Force for Soft Grippers Part II: Displacement Control Based Intrinsic Force Sensing

Force-aware grasping is an essential capability for most robots in practical applications. Especially for compliant grippers, such as Fin-Ray grippers, it still remains challenging to build a bidirectional mathematical model that mutually maps the shape deformation and contact force. Part I of this article has constructed the force-displacement relationship for design optimization through the co-rotational theory. In Part II, we further devise a displacement-force mathematical model, enabling the compliant gripper to precisely estimate contact force from deformations sensor-free. The presented displacement-force model elaborately investigates contact forces and provides force feedback for a force control system of a gripper, where deformation appears as displacements in contact points. Afterward, simulation experiments are conducted to evaluate the performance of the proposed model through comparisons with the finite-element analysis (FEA) in Ansys. Simulation results reveal that the proposed model accurately estimates contact force, with an average error of around 3% and 4% for single or multiple node cases, respectively, regardless of various design parameters (Part I of this article is released in Arxiv1

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on fifteen research projects.National Institutes of Health Grant RO1 DC00117National Institutes of Health Grant RO1 DC02032National Institutes of Health Contract P01-DC00361National Institutes of Health Contract N01-DC22402National Institutes of Health/National Institute on Deafness and Other Communication Disorders Grant 2 R01 DC00126National Institutes of Health Grant 2 R01 DC00270National Institutes of Health Contract N01 DC-5-2107National Institutes of Health Grant 2 R01 DC00100U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-94-C-0087U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-95-K-0014U.S. Navy - Office of Naval Research/Naval Air Warfare Center Grant N00014-93-1-1399U.S. Navy - Office of Naval Research/Naval Air Warfare Center Grant N00014-94-1-1079U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research Grant N00014-92-J-1814National Institutes of Health Grant R01-NS33778U.S. Navy - Office of Naval Research Grant N00014-88-K-0604National Aeronautics and Space Administration Grant NCC 2-771U.S. Air Force - Office of Scientific Research Grant F49620-94-1-0236U.S. Air Force - Office of Scientific Research Agreement with Brandeis Universit

Stable Object Grasping With Dextrous Hand In Three-Dimension

This paper considers a grasp planning scheme for dextrous hands. The grasp is assumed to be a precise one, which means that only the fingertips of the hand are in contact. The most important algorithm of the grasp planner is the placement of contact points in the presence of friction. Based on a heuristic search, a number of grasp configurations are generated. A proposed method for evaluation of the configurations and determination whether a grasp is a force closure, is introduced. These algorithms are used in the experimental control system of an industrial robot, which the dextrous hand is attached to. A two-level robot programming language, which was written for the robot-hand system, is briefly introduced

Mechanical design of a biologically inspired prosthetic hand, the touch hand 3.

Masters Degrees. University of KwaZulu-Natal. Durban.The Touch hand 3 was developed to improve on the mechanical and mechatronic design of the Touch hand 2. A basic prototype hand was rapidly developed using 3D CAD software and 3D printing and tested on an amputee. The improvements in the final design included an improved finger actuation system utilizing mechanical linkages, an improved Electromyography (EMG) operated control system, four micro-linear servo-motors, modular fingers, hinges and chassis. The final design was designed such that the hand can be easily interchanged between a fully mechatronic system and full mechanically operated system using the same generic parts including the chassis, finger and wrist components. The hands were both tested with the Yale Open Hand test, a test used to assess robotic grippers. The Southampton Hand Assessment Procedure (SHAP), a test usually used to assess the effectiveness of upper limb prostheses, was also carried out on both versions of the hand. The hands were also tested with a hand dynamometer to assess their grip strength. The hand were compared to current hands on the market and their strength and weaknesses analysed

Theoretical Model Construction of Deformation-Force for Soft Grippers Part I: Co-rotational Modeling and Force Control for Design Optimization

Compliant grippers, owing to adaptivity and safety, have attracted considerable attention for unstructured grasping in real applications, such as industrial or logistic scenarios. However, accurately modeling the bidirectional relationship between shape deformation and contact force for such grippers, the Fin-Ray grippers as an example, remains stagnant to date. To address this research gap, this article devises, presents, and experimentally validates a universal bidirectional force-displacement mathematical model for compliant grippers based on the co-rotational concept, which endows such grippers with an intrinsic force sensing capability and offers a better insight into the design optimization. In Part I of the article, we introduce the fundamental theory of the co-rotational approach, where arbitrary large deformation of beam elements can be modeled. Its intrinsic principle allows taking materials with varying stiffness, various connection types, and key design parameters into consideration with few assumptions. Further, the force-displacement relationship is numerically derived, providing accurate displacement estimations of the gripper under external forces with minor computational loads. The performance of the proposed method is experimentally verified through comparison with Finite Element Analysis (FEA) in simulation, obtaining a fair degree of accuracy (6%), and design optimization of Fin-Ray grippers is systematically investigated. Part II of this article demonstrating the force sensing capabilities and the effects of representative co-rotational modeling parameters on model accuracy is released in Arxiv