Prosthetic finger phalanges with lifelike skin compliance for low-force social touching interactions

10.1186/1743-0003-8-16Journal of NeuroEngineering and Rehabilitation81

Patient-Specific Prosthetic Fingers by Remote Collaboration - A Case Study

The concealment of amputation through prosthesis usage can shield an amputee from social stigma and help improve the emotional healing process especially at the early stages of hand or finger loss. However, the traditional techniques in prosthesis fabrication defy this as the patients need numerous visits to the clinics for measurements, fitting and follow-ups. This paper presents a method for constructing a prosthetic finger through online collaboration with the designer. The main input from the amputee comes from the Computer Tomography (CT) data in the region of the affected and the non-affected fingers. These data are sent over the internet and the prosthesis is constructed using visualization, computer-aided design and manufacturing tools. The finished product is then shipped to the patient. A case study with a single patient having an amputated ring finger at the proximal interphalangeal joint shows that the proposed method has a potential to address the patient's psychosocial concerns and minimize the exposure of the finger loss to the public.Comment: Open Access articl

Data for benchmarking low-cost, 3D printed prosthetic hands

In this article, three different data sets are presented to evaluate a representative of openly accessible 3D printed prosthetic hand. The first data set includes grasping force measurements of human hand and low-cost 3D printed hand. Three grasping functions were evaluated, spherical, cylindrical, and precision grasps. The experimental test was performed using a wearable tactile sensor. The second data set includes the numerical analysis of prosthetic fingers made from Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) materials under different carrying loads. The numerical analyses were carried out by LS-DYNA software. The files can be used for the prosthetic fingers’ evaluation and for the selection of suitable material. The third data set includes the experimental tensile test of ABS and PLA materials. The mechanical properties were calculated from the results, which can be used in the design and fabrication of products from these materials. All the datasets are available from Harvard Dataverse: https://doi.org/10.7910/DVN/GCPAIL.The work is supported by an internal QUCG grant from Qatar University under the grant No. QUCG-CENG-2018/2019-3 . The statements made herein are solely the responsibility of the authors

Reflex: A Closed-Loop Tactile Feedback System for Use in Upper Limb Prosthesis Grip Control

Tactile sensing provides valuable insight to the environment in which we interact with. Upper limb amputees lack the sensations that generates the necessary information to stably grasp the wide variety of objects we interact with on a daily basis. Utilizing tactile sensing to provide feedback to a prosthetic hand provides a mechanism for replacing the grip control functionality of the mechanoreceptors found in human skin. Novel customizable, low cost tactile sensors for monitoring the dynamics of an object grasped by a prosthetic hand are developed and presented as part of this thesis. The response of sensors placed on a prosthetic hand provides information regarding the state of a grasped object, particularly contact and slip. The sensors are made up of various textile materials, including stretchable interfacing layers and conductive traces. Essentially a force sensitive resistor, each sensor is shaped into stretchable cu ff that can be placed around the finger of a prosthetic hand. An outer rubber layer on the sensor provides compliance, which is found to enhance grasping performance with a prosthesis. Two control algorithms were developed as part of the closed-loop tactile feedback system, called Reflex, to enhance grasping functionality with a prosthesis. A Contact Detection strategy uses force information to effectively reduce the user's electromyography (EMG) signals, which are used to control the prosthesis. Essentially, the goal of this strategy is to help a user grab fragile objects without breaking them. A second strategy, Slip Prevention, uses the derivative of a force signal to detect slip of a grasped object. Instances of slip trigger electrical pulses sent from the prosthesis control unit to close the hand in an effort to prevent additional slip. The Reflex system, comprised of two control strategies along with flexible textile based force sensors on the fingers of a prosthesis, was shown to improve the grasping functionality of a prosthesis under normal use conditions. Able body participants were used to test the system. Results show the sensors' ability to greatly enhance grasping fragile objects while also helping prevent object slip. The compliant nature of the sensors enables users to more confidently pick up and move small,fragile objects, such as foam peanuts and crackers. Without sensors and tactile feedback, users had a higher likelihood of breaking objects while grabbing them. The addition of sensors reduced this failure rate, and the failure rate was reduced even further with the implementation of control algorithms running in real-time. The slip prevention strategy was also shown to help reduce the amount of object movement after a grasp is initiated, although the most benefit comes from the compliant nature of the sensors. Reflex is the first closed-loop tactile feedback system with multiple control strategies that can be used on a prosthetic hand to enhance grasping functionality. The system allows one to switch between Contact Detection or Slip Prevention control strategies, giving the user the ability to use each control as needed. Feedback from the textile sensors directly to the prosthesis control unit provides valuable information regarding grasping forces. This research aims to help improve prosthetic technology so that one day amputees will feel as if their device is a natural extension of their body

Faces and hands : modeling and animating anatomical and photorealistic models with regard to the communicative competence of virtual humans

In order to be believable, virtual human characters must be able to communicate in a human-like fashion realistically. This dissertation contributes to improving and automating several aspects of virtual conversations. We have proposed techniques to add non-verbal speech-related facial expressions to audiovisual speech, such as head nods for of emphasis. During conversation, humans experience shades of emotions much more frequently than the strong Ekmanian basic emotions. This prompted us to develop a method that interpolates between facial expressions of emotions to create new ones based on an emotion model. In the area of facial modeling, we have presented a system to generate plausible 3D face models from vague mental images. It makes use of a morphable model of faces and exploits correlations among facial features. The hands also play a major role in human communication. Since the basis for every realistic animation of gestures must be a convincing model of the hand, we devised a physics-based anatomical hand model, where a hybrid muscle model drives the animations. The model was used to visualize complex hand movement captured using multi-exposure photography.Um überzeugend zu wirken, müssen virtuelle Figuren auf dieselbe Art wie lebende Menschen kommunizieren können. Diese Dissertation hat das Ziel, verschiedene Aspekte virtueller Unterhaltungen zu verbessern und zu automatisieren. Wir führten eine Technik ein, die es erlaubt, audiovisuelle Sprache durch nichtverbale sprachbezogene Gesichtsausdrücke zu bereichern, wie z.B. Kopfnicken zur Betonung. Während einer Unterhaltung empfinden Menschen weitaus öfter Emotionsnuancen als die ausgeprägten Ekmanschen Basisemotionen. Dies bewog uns, eine Methode zu entwickeln, die Gesichtsausdrücke für neue Emotionen erzeugt, indem sie, ausgehend von einem Emotionsmodell, zwischen bereits bekannten Gesichtsausdrücken interpoliert. Auf dem Gebiet der Gesichtsmodellierung stellten wir ein System vor, um plausible 3D-Gesichtsmodelle aus vagen geistigen Bildern zu erzeugen. Dieses System basiert auf einem Morphable Model von Gesichtern und nutzt Korrelationen zwischen Gesichtszügen aus. Auch die Hände spielen ein große Rolle in der menschlichen Kommunikation. Da der Ausgangspunkt für jede realistische Animation von Gestik ein überzeugendes Handmodell sein muß, entwikkelten wir ein physikbasiertes anatomisches Handmodell, bei dem ein hybrides Muskelmodell die Animationen antreibt. Das Modell wurde verwendet, um komplexe Handbewegungen zu visualisieren, die aus mehrfach belichteten Photographien extrahiert worden waren

Enhancing Upper Limb Prostheses Through Neuromorphic Sensory Feedback

Upper limb prostheses are rapidly improving in terms of both control and sensory feedback, giving rise to lifelike robotic devices that aim to restore function to amputees. Recent progress in forward control has enabled prosthesis users to make complicated grip patterns with a prosthetic hand and nerve stimulation has enabled sensations of touch in the missing hand of an amputee. A brief overview of the motivation behind the work in this thesis is given in Chapter 1, which is followed by a general overview of the field and state of the art research (Chapter 2). Chapters 3 and 4 look at the use of closed loop tactile feedback for improving prosthesis grasping functionality. This entails development of two algorithms for improving object manipulation (Chapter 3) and the first real-time implementation of neuromorphic tactile signals being used as feedback to a prosthesis controller for improved grasping (Chapter 4). The second half of the thesis (Chatpers 5 - 7) details how sensory information can be conveyed back to an amputee and how the tactile sensations can be utilized for creating a more lifelike prosthesis. Noninvasive electrical nerve stimulation was shown to provide sensations in multiple regions of the phantom hand of amputees both with and without targeted sensory reinnervation surgery (Chapter 5). A multilayered electronic dermis (e-dermis) was developed to mimic the behavior of receptors in the skin to provide, for the first time, sensations of both touch and pain back to an amputee and the prosthesis (Chapter 6). Finally, the first demonstration of sensory feedback as a key component of phantom hand movement for myoelectric pattern recognition shows that enhanced perceptions of the phantom hand can lead to improved prosthesis control (Chapter 7). This work provides the first demonstration of how amputees can perceive multiple tactile sensations through a neuromorphic stimulation paradigm. Furthermore, it describes the unique role that nerve stimulation and phantom hand activation play in the sensorimotor loop of upper limb amputees

Kinematic Analysis of Multi-Fingered, Anthropomorphic Robotic Hands

The ability of stable grasping and fine manipulation with the multi-fingered robot hand with required precision and dexterity is playing an increasingly important role in the applications like service robots, rehabilitation, humanoid robots, entertainment robots, industries etc.. A number of multi-fingered robotic hands have been developed by various researchers in the past. The distinct advantages of a multi-fingered robot hand having structural similarity with human hand motivate the need for an anthropomorphic robot hand. Such a hand provides a promising base for supplanting human hand in execution of tedious, complicated and dangerous tasks, especially in situations such as manufacturing, space, undersea etc. These can also be used in orthopaedic rehabilitation of humans for improving the quality of the life of people having orthopedically and neurological disabilities. The developments so far are mostly driven by the application requirements. There are a number of bottlenecks with industrial grippers as regards to the stability of grasping objects of irregular geometries or complex manipulation operations. A multi-fingered robot hand can be made to mimic the movements of a human hand. The present piece of research work attempts to conceptualize and design a multi-fingered, anthropomorphic robot hand by structurally imitating the human hand. In the beginning, a brief idea about the history, types of robotic hands and application of multi-fingered hands in various fields are presented. A review of literature based on different aspects of the multi-fingered hand like structure, control, optimization, gasping etc. is made. Some of the important and more relevant literatures are elaborately discussed and a brief analysis is made on the outcomes and shortfalls with respect to multi-fingered hands. Based on the analysis of the review of literature, the research work aims at developing an improved anthropomorphic robot hand model in which apart from the four fingers and a thumb, the palm arch effect of human hand is also considered to increase its dexterity. A robotic hand with five anthropomorphic fingers including the thumb and palm arch effect having 25 degrees-of-freedom in all is investigated in the present work. Each individual finger is considered as an open loop kinematic chain and each finger segment is considered as a link of the manipulator. The wrist of the hand is considered as a fixed point. The kinematic analyses of the model for both forward kinematics and inverse kinematic are carried out. The trajectories of the tip positions of the thumb and the fingers with respect to local coordinate system are determined and plotted. This gives the extreme position of the fingertips which is obtained from the forward kinematic solution with the help of MATLAB. Similarly, varying all the joint iv angles of the thumb and fingers in their respective ranges, the reachable workspace of the hand model is obtained. Adaptive Neuro-Fuzzy Inference System (ANFIS) is used for solving the inverse kinematic problem of the fingers. Since the multi-fingered hand grasps the object mainly through its fingertips and the manipulation of the object is facilitated by the fingers due to their dexterity, the grasp is considered to be force-closure grasp. The grasping theory and different types of contacts between the fingertip and object are presented and the conditions for stable and equilibrium grasp are elaborately discussed. The proposed hand model is simulated to grasp five different shaped objects with equal base dimension and height. The forces applied on the fingertip during grasping are calculated. The hand model is also analysed using ANSYS to evaluate the stresses being developed at various points in the thumb and fingers. This analysis was made for the hand considering two different hand materials i.e. aluminium alloy and structural steel. The solution obtained from the forward kinematic analysis of the hand determines the maximum size for differently shaped objects while the solution to the inverse kinematic problem indicates the configurations of the thumb and the fingers inside the workspace of the hand. The solutions are predicted in which all joint angles are within their respective ranges. The results of the stress analysis of the hand model show that the structure of the fingers and the hand as a whole is capable of handling the selected objects. The robot hand under investigation can be realized and can be a very useful tool for many critical areas such as fine manipulation of objects, combating orthopaedic or neurological impediments, service robotics, entertainment robotics etc. The dissertation concludes with a summary of the contribution and the scope of further work

Human-centered Electric Prosthetic (HELP) Hand

In developing countries such as India, there is a higher rate of amputations among the population but a lack of viable, low cost solutions. Through a partnership with Indian non-profit Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS), the team designed a functional, robust, and low cost electrically powered prosthetic hand that communicates with people with unilateral, transradial amputations in urban India through a biointerface. The device uses compliant tendon actuation, small linear servos, and a wearable sleeve outfitted with electromyography (EMG) sensors to produce a device that, once placed inside a prosthetic glove, is anthropomorphic in both look and feel. The hand is capable of forming three grips through the use of a manually adjustable opposable thumb: the key, pinch, and wrap grips. The hand also provides vibrotactile user feedback upon completion of a grip. The design includes a prosthetic gel liner to provide a layer of cushion and comfort for safe use by the user. These results show that it is possible to create a low cost, electrically powered prosthetic hand for users in developing countries without sacrificing functionality. In order for this design to be truly adjustable to each user, the creation of an easily navigable graphical user interface (GUI) will have to be a future goal. The prosthesis prototype was developed such that future groups can design for manufacturing and distribution in India

Comparison of the vocabularies of the Gregg shorthand dictionary and Horn-Peterson's basic vocabulary of business letters

This study is a comparative analysis of the vocabularies of Horn and Peterson's The Basic Vocabulary of Business Letters1 and the Gregg Shorthand Dictionary.2 Both books purport to present a list of words most frequently encountered by stenographers and students of shorthand. The, Basic Vocabulary of Business Letters, published "in answer to repeated requests for data on the words appearing most frequently in business letters,"3 is a frequency list specific to business writing. Although the book carries the copyright date of 1943, the vocabulary was compiled much earlier. The listings constitute a part of the data used in the preparation of the 10,000 words making up the ranked frequency list compiled by Ernest Horn and staff and published in 1926 under the title of A Basic Writing Vocabulary: 10,000 Words Lost Commonly Used in Writing. The introduction to that publication gives credit to Miss Cora Crowder for the contribution of her Master's study at the University of Minnesota concerning words found in business writing. With additional data from supplementary sources, the complete listing represents twenty-six classes of business, as follows 1. Miscellaneous 2. Florists 3. Automobile manufacturers and sales companie

Synthetic finger phalanx with lifelike skin compliance

10.1007/978-3-642-16587-0_46Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)6425 LNAIPART 2498-50