A highly-underactuated robotic hand with force and joint angle sensors

This paper describes a novel underactuated robotic hand design. The hand is highly underactuated as it contains three fingers with three joints each controlled by a single motor. One of the fingers ("thumb") can also be rotated about the base of the hand, yielding a total of two controllable degrees-of-freedom. A key component of the design is the addition of position and tactile sensors which provide precise angle feedback and binary force feedback. Our mechanical design can be analyzed theoretically to predict contact forces as well as hand position given a particular object shape

Grasping With Mechanical Intelligence

Many robotic hands have been designed and a number have been built. Because of the difficulty of controlling and using complex hands, which usually have nine or more degrees of freedom, the simple one- or two-degree-of-freedom gripper is still the most common robotic end effector. This thesis presents a new category of device: a medium-complexity end effector. With three to five degrees of freedom, such a tool is much easier to control and use, as well as more economical, compact and lightweight than complex hands. In order to increase the versatility, it was necessary to identify grasping primitives and to implement them in the mechanism. In addition, power and enveloping grasps are stressed over fingertip and precision grasps. The design is based upon analysis of object apprehension types, requisite characteristics for active sensing, and a determination of necessary environmental interactions. Contained in this thesis are the general concepts necessary to the design of a medium-complexity end effector, an analysis of typica.1 performance, and a computer simulation of a grasp planning algorithm specific to this type of mechanism. Finally, some details concerning the UPenn Hand - a tool designed for the research laboratory - are presented

Dynamic grasping of objects with a high-speed parallel robot

Underactuated grippers aim to simplify the control strategies for performing stable grasps due to their inherent shape adaptability. While at the beginning, the main research area was focused on developing human-like robotic hands for disabled people, in the last years, a new eld of application appeared with the constant evolution of the industry: the implementation of a single underactuated gripper as a replacement of diverse dedicated fully-actuated grippers. However, two main issues are restraining its use: the stability of the grasp and the speed of performance. The rst is an active topic as all underactuated grippers need to ensure the stability of the grasped object through an adequate kinematic design, while, the latter is not widely treated as there weren't many application elds where high-speed was required and, at the end, the quasi-static analysis must be also ensured. For this reason, the present research work has been focused on the speed of the grasping. In the rst place, an introduction to underactuated hands is made, and is followed by two main stability criteria. Then, the development of a model for an underactuated nger that allows analyzing the complete grasping sequence at high-speed along with a collision model are presented. Following, a design-based analysis to simplify the model is performed, and the graspstate volume tool is introduced in order to inspect the impact of the design variables on the proposed criteria. In the last chapter, an optimization over the design space is performed and a design is chosen, crosschecked with ADAMS software and prototyped. Finally, an overview remarking the strengths and gaps in the research is presented in the form of conclusions, and closing them, future works that could be interesting to develop

Anthropomorphic transradial myoelectric hand using tendon-spring mechanism

In the developing countries, the need for prosthetic hands is increasing. In general, transradial amputee patients use prosthetic hands that are passive like a body-powered prosthesis. This research proposes a low-cost myoelectric prosthetic hand based on 3D printing technology. Hand and finger size were designed based on the average size of human hands in Indonesia. The proposed myoelectric hand employs linear actuator combined with the tendon-spring mechanism. Myoelectric hand was developed with five modes of grip pattern to perform various object grasping in activity of daily living. Control strategy had been developed for controlling the motion of flexion and extension on the hand and saving the energy consumed by the actuators. The control strategy was developed under MATLAB/Simulink environment and embedded to Arduino Nano V3 using Simulink Support Package for Arduino Hardware. Surface electromyography (EMG) sensor was used in this research for reading the muscle activity of the user/wearer. The proposed myoelectric hand had been tested in object grasping test and was implemented on a study participant with transradial amputee

Single degree-of-freedom exoskeleton mechanism design for finger rehabilitation

This paper presents the kinematic design of a single degree-of-freedom exoskeleton mechanism: a planar eight-bar mechanism for finger curling. The mechanism is part of a fingerthumb robotic device for hand therapy that will allow users to practice key pinch grip and finger-thumb opposition, allowing discrete control inputs for playing notes on a musical gaming interface. This approach uses the mechanism to generate the desired grasping trajectory rather than actuating the joints of the fingers and thumb independently. In addition, the mechanism is confined to the back of the hand, so as to allow sensory input into the palm of the hand, minimal size and apparent inertia, and the possibility of placing multiple mechanisms side-by-side to allow control of individual fingersPeer ReviewedPostprint (author’s final draft

Review of Development Stages in the Conceptual Design of an Electro Hydrostatic Actuator for Robotics

The design of modern robotic devices faces numerous requirements and limitations which are related to optimization and robustness. Consequently, these stringent requirements have caused improvements in many engineering areas and lead to development of new optimization methods which better handle new complex products designed for application in industrial robots. One of the newly developed methods used in industrial robotics is the concept of a self-contained power device, an Electro-Hydrostatic Actuator (EHA). EHA devices were designed with a central idea, to avoid the possible drawbacks which were present in other types of actuators that are currently used in robotic systems. This paper is a review of the development phases of an EHA device for robotic applications. An overview of the advantages and disadvantages related to current EHA designs are presented, and finally possible ideas for future developments are suggested