Quantifying prosthetic and intact limb use in upper limb amputees via egocentric video: an unsupervised, at-home study

Analysis of the manipulation strategies employed by upper-limb prosthetic device users can provide valuable insights into the shortcomings of current prosthetic technology or therapeutic interventions. Typically, this problem has been approached with survey or lab-based studies, whose prehensile-grasp-focused results do not necessarily give accurate representations of daily activity. In this work, we capture prosthesis-user behavior in the unstructured and familiar environments of the participants own homes. Compact head-mounted video cameras recorded ego-centric views of the hands during self-selected household chores. Over 60 hours of video was recorded from 8 persons with unilateral amputation or limb difference (6 transradial, 1 transhumeral, 1 shoulder). Of this, almost 16 hours of video data was analyzed by human experts using the 22-category ‘TULIP’ custom manipulation taxonomy, producing the type and duration of over 27,000 prehensile and non-prehensile manipulation tags on both upper limbs, permitting a level of objective analysis not previously possible with this population. Our analysis included unique observations on non-prehensile manipulations occurrence, determining that 79% of transradial body-powered device manipulations were non-prehensile, compared to 60% for transradial myoelectric devices. Conversely, only 16-19% of intact limb activity was non-prehensile. Additionally, multi-grasp terminal devices did not lead to increased activity compared to 1DOF devices

Design of an affordable anthropomorphic mechanical prosthetic hand

Includes bibliographical references.This dissertation outlines the conceptualisation, design, manufacture, assembly and experimental testing of an affordable anthropomorphic mechanical hand prosthesis. In many countries, upper-limb amputees lack access to prosthetic hand devices. Furthermore, currently available mechanical devices require a large amount of effort to actuate; fatiguing and frustrating patients who have no other alternative but to use them. Consequently, a need has arisen to provide a mechanical device that is affordable enough to be accessible to low and middle-income patients, is functional enough to allow users to easily perform their Activities of Daily Living (ADLs), and is aesthetically appealing enough to ensure that patients feel comfortable and confident when wearing it. Concept solutions of several mechanisms were identified and evaluated from which the final design was selected. Analytical force analysis was used to generate a mathematical model to analyse the response of each dynamic member in the hand. A linear relationship between the input-force and applied grasp-forces of the hand was identified. Finite Element Analysis (FEA) used to investigate the lateral and hyperextensive loading limits of the phalanges, generated results that corresponded well to the experimental outcomes. Amongst the utilised actuation mechanisms (levers, pulleys, tendon-wires, bearings and springs), the tendon-wires were of concern due to their repetitive tensile loading and relative movement with the phalanges. Tensile testing of various tendon-wires and endurance testing of the phalangeal tendon-channels, yielded a combination which surpassed the infinite life requirement of 1,200,000 loading cycles; with carbon-nylon contact wearing at the lowest rate as confirmed by gravimetric tests in accordance with ASTM F2025 (2000). Manufacture of the hand used rapid prototyping in combination with traditional machining methods and standard components, enabling a fully-assembled cost of R 11,628.37; below the required R 18,000 limit. Various power and precision grasping configurations were achieved and the contact forces satisfactorily maintained, using the hand’s built-in locking mechanism. Feedback gathered from the prosthetist and patients suggested making slight alterations to the hand’s aesthetics and to address minor functional challenges, such as the control of the closing trajectory for precision grasps

Technology for monitoring everyday prosthesis use: a systematic review

BACKGROUND Understanding how prostheses are used in everyday life is central to the design, provision and evaluation of prosthetic devices and associated services. This paper reviews the scientific literature on methodologies and technologies that have been used to assess the daily use of both upper- and lower-limb prostheses. It discusses the types of studies that have been undertaken, the technologies used to monitor physical activity, the benefits of monitoring daily living and the barriers to long-term monitoring. METHODS A systematic literature search was conducted in PubMed, Web of Science, Scopus, CINAHL and EMBASE of studies that monitored the activity of prosthesis-users during daily-living. RESULTS 60 lower-limb studies and 9 upper-limb studies were identified for inclusion in the review. The first studies in the lower-limb field date from the 1990s and the number has increased steadily since the early 2000s. In contrast, the studies in the upper-limb field have only begun to emerge over the past few years. The early lower-limb studies focused on the development or validation of actimeters, algorithms and/or scores for activity classification. However, most of the recent lower-limb studies used activity monitoring to compare prosthetic components. The lower-limb studies mainly used step-counts as their only measure of activity, focusing on the amount of activity, not the type and quality of movements. In comparison, the small number of upper-limb studies were fairly evenly spread between development of algorithms, comparison of everyday activity to clinical scores, and comparison of different prosthesis user populations. Most upper-limb papers reported the degree of symmetry in activity levels between the arm with the prosthesis and the intact arm. CONCLUSIONS Activity monitoring technology used in conjunction with clinical scores and user feedback, offers significant insights into how prostheses are used and whether they meet the user’s requirements. However, the cost, limited battery-life and lack of availability in many countries mean that using sensors to understand the daily use of prostheses and the types of activity being performed has not yet become a feasible standard clinical practice. This review provides recommendations for the research and clinical communities to advance this area for the benefit of prosthesis users

Investigation of upper limb prosthesis functionality using quantitative design tools

Upper limb prostheses offer those with limb loss a solution to restore some of their lost functionality by allowing them to participate in bilateral tasks, especially those required for daily living. Whilst there is a wide range of upper limb prostheses available, there remain high device rejection rates. Low functionality and discomfort are major factors in prosthesis rejection, which had been identified as challenges more than 60 years ago. These issues have not been effectively addressed due the lack of design tools for engineers and clinicians. Upper limb prostheses have seen greater technological advances than the methods to evaluate them effectively, which has resulted in over-engineered designs which do not meet the needs of their user. In this thesis , I aim to improve future upper limb prostheses through the development of three design tools. These design tools seek to quantify the functionality of prosthetic devices using motion capture analysis, virtual environments, and joint optimisation. By developing these tools, there is greater opportunity to optimise prostheses earlier in the design cycle which can result in improved functionality. It is anticipated that improvements in functionality will increase user satisfaction and therefore reduce device rejection rates Motion capture analysis was used to study the compensatory movements that arise from operating an upper limb prosthesis. Using a motion capture suit, the motor strategy of a participant was compared between using their biological hand and using a prosthesis through the use of an able-bodied adaptor. It was found that the shoulder and trunk had to make the most compensatory movements to complete several grasping tasks due to the lack of degrees of freedom at the distal end of the prosthesis. Without forearm supination/pronation and wrist extension/flexion, the participant had to approach the grasping tasks from a different angle, sometimes having to lean backwards and abduct their upper arm. The methodology of utilising a motion capture suit as a design tool to quantitatively assess the compensatory movements caused by a prosthetic device was successfully demonstrated. Virtual environments, in conjunction with quantitative grasp quality metrics, can be used to assess the performance of the upper limb prosthesis extremity alone, uninfluenced by user bias. A dynamic virtual environment is presented to simulate several grasping tasks with five upper limb prosthetic devices. Contact information from these grasping tasks are used to calculate the quality of the grasp and provide an overall grasping functionality score. From the simulation results, it was found that more degrees of freedom do not necessary equate to better grasping performance. The positions of force vectors during grasp formation are vital and they must be well- balanced in order to result in stable grasps. Simulated grasping and quantitative analysis in a virtual environment has been demonstrated, which can be used to better plan grasping paths and therefore improve the grasping functionality of upper limb prosthesis designs. Prosthesis users desire their devices to have a low mass, have a low cost, and have high functionality. However, these are conflicting design objectives and decisions must be made to which design considerations to prioritise. A multi-objective model was used to balance these three objectives and select the most suitable components that make up a prosthesis. A modularity scheme was used to divide an upper limb prosthesis into three categories: socket, forearm, and terminal device. In each category, several components were considered which can either be manufactured by conventional engineering or additive manufacturing. Each component would provide a unique value determined by a several quantitative utility functions. Based on satisfaction studies in the literature, the multi-objective optimisation model found that a Split Hook terminal device with an additively manufactured socket and forearm was the optimal design as it provided a low mass and excellent grasping functionality. This model has been demonstrated to work with different user requirements to intelligently select the most appropriate upper limb components within the modularity scheme. Overall, methods were developed which covered aspects of prosthesis design from clinical testing of prosthetic devices, functionality assessments of Computer Aided Design models, and intelligent selection of prosthesis components for individual requirements. It is hoped that these design tools may enable better communication between engineers and clinicians to ensure that users receive devices that are to their satisfaction

Optimizing 3D Printed Prosthetic Hand and Simulator

The purpose of this study is to examine the position and use of an upper extremity prosthetic simulator on non-amputees. To see how a 3D printed prosthetic simulator can be optimized to serve the user correctly and accurately. In addition, this study examines the improvement of the Hosmer 5X Prosthetic Hook with the addition of newly designed trusses on to the prosthetic, as well as utilizing a new manufacturing method known as 3D printing. These topics are important because there is no standardized prosthetic simulator for schools and research facilities to use. Off the shelf prosthetic simulator cost upwards of $2000, often too expensive for early stage research. By optimizing the Hosmer 5X Prosthetic Hook with 3D printing, this new opportunity could allow amputees, from a range of income classes, to have access to a wide variety of prosthetics that are strong enough to support everyday living activities. A low-cost prosthetic that is easily distributable and accessible can give people a chance to regain their independence by giving them different options of efficient prosthetic devices, without having to spend so much. The devices in this project were design and analyzed on SOLIDWORKS, 3D scanned on the Artec Space Spider, and surfaced on Geomagic Wrap. Key results include developing a low-cost, robust prosthetic simulator capable of operating a Hosmer 5X Prosthetic hook, as well as developing a lighter version of the Hosmer 5X Prosthetic Hook that is more cost efficient and easily obtainable to the population around the world

Mechatronic design and optimisation of a low-cost prosthetic hand.

M. Sc. Eng. University of KwaZulu-Natal, Pietermaritzburg 2015.The Touch Hand II was developed to improve on the first version, addressing the lack of low cost myoelectric controlled hand prostheses. The improvements included a lower materials cost of $ 635.14, an aesthetically appealing human{like form factor, a reduced total mass of 486 g (including the wrist and electronics), a 211 % increase in grip strength, and a 3.83 times higher allowable palm load with a 1.7 factor of safety. Costs were reduced predominantly due to 3D printing and using sensorless technology, based on speed and torque estimation through brushed dc motor back-emf and current measurements. The compact design was accomplished by using a unique finger actuation and trajectory concept, and integrating a custom PCB. An intuitive command selection protocol was developed with the aid of a GUI. A finite state machine was used to successfully switch between speed and grip force control depending on whether an object was in contact with the fingers during a close/open command. The design has accommodated the future addition of myoelectric control, sensors, and sensory feedback

Design and Analysis of a Body-Powered Underactuated Prosthetic Hand

As affordable and efficient 3-D printers became widely available, researchers are focusing on developing prosthetic hands that are reasonably priced and effective at the same time. By allowing anyone with a 3-D printer to build their body powered prosthetic hands, many people could build their own prosthetic hand. However, one of the major problems with the current designs is the user must bend and hold their wrist in an awkward position to grasp an object. The primary goal of this thesis is to present the design process and analysis of a mechanical operated, underactuated prosthetic hand with a novel ratcheting mechanism that locks the finger automatically at a desired position. The prosthetic hand is composed of the following components: a frame for the hand and forearm, ratcheting mechanism, finger mount, rack, pawl and stopper for ratchet, cable, springs, rigidly supporting finger and a compliant finger. The compliant finger was manufactured using shape deposition manufacturing. The joints of the finger were made using PMC 780, polyurethane material, and the finger pads were made of Polydimethylsiloxane(PDMS). To estimate how a compliant finger behaves on the actual system with the ratcheting mechanism and how much force is required to operate this finger, the preshaping analysis was conducted. The preshaping analysis data was verified by loading and unloading weights to the tendon cable and taking pictures of the finger each time the cable force was varied. Then, the pictures were processed using MATLAB image processing tools to calculate joint angles. Additionally, the contact force analysis was performed to determine the effects of the contact location and finger joint angles on the magnitude of contact force given the tension of the cable. Using the contact force analysis, it would be possible to estimate how much load the hand can hold. Finally, the hand was tested to hold various shapes of objects to prove how well it can grasp. Based on the experiment, the hand had a higher success rate of grasping objects that are lightweight (less than 500g) and cylindrical or circular shaped

Data-driven Mechanical Design and Control Method of Dexterous Upper-Limb Prosthesis

With an increasing number of people, 320,000 per year, suffering from impaired upper limb function due to various medical conditions like stroke and blunt trauma, the demand for highly functional upper limb prostheses is increasing; however, the rates of rejection of prostheses are high due to factors such as lack of functionality, high cost, weight, and lack of sensory feedback. Modern robotics has led to the development of more affordable and dexterous upper limb prostheses with mostly anthropomorphic designs. However, due to the highly sophisticated ergonomics of anthropomorphic hands, most are economically prohibitive and suffer from control complexity due to increased cognitive load on the user. Thus, this thesis work aims to design a prosthesis that relies on the emulation of the kinematics and contact forces involved in grasping tasks with healthy human hands rather than on biomimicry for reduction of mechanical complexity and utilization of technologically advanced engineering components. This is accomplished by 1) experimentally characterizing human grasp kinematics and kinetics as a basis for data-driven prosthesis design. Using the grasp data, steps are taken to 2) develop a data-driven design and control method of an upper limb prosthesis that shares the kinematics and kinetics required for healthy human grasps without taking the anthropomorphic design. This thesis demonstrates an approach to decrease the gap between the functionality of the human hand and robotic upper limb prostheses by introducing a method to optimize the design and control method of an upper limb prosthesis. This is accomplished by first, collecting grasp data from human subjects with a motion and force capture glove. The collected data are used to minimize control complexity by reducing the dimensionality of the device while fulfilling the kinematic and kinetic requirements of daily grasping tasks. Using these techniques, a task-oriented upper limb prosthesis is prototyped and tested in simulation and physical environment.Ph.D

Design and development of robust hands for humanoid robots

Design and development of robust hands for humanoid robot

Investigation into the control of an upper-limb myoelectric prosthesis

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