A Review of Prosthetic Interface Stress Investigations

Over the last decade, numerous experimental and numerical analyses have been conducted to investigate the stress distribution between the residual limb and prosthetic socket of persons with lower limb amputation. The objectives of these analyses have been to improve our understanding of the residual limb/prosthetic socket system, to evaluate the influence of prosthetic design parameters and alignment variations on the interface stress distribution, and to evaluate prosthetic fit. The purpose of this paper is to summarize these experimental investigations and identify associated limitations. In addition, this paper presents an overview of various computer models used to investigate the residual limb interface, and discusses the differences and potential ramifications of the various modeling formulations. Finally, the potential and future applications of these experimental and numerical analyses in prosthetic design are presented

Ergonomic Models of Anthropometry, Human Biomechanics and Operator-Equipment Interfaces

The Committee on Human Factors was established in October 1980 by the Commission on Behavioral and Social Sciences and Education of the National Research Council. The committee is sponsored by the Office of Naval Research, the Air Force Office of Scientific Research, the Army Research Institute for the Behavioral and Social Sciences, the National Aeronautics and Space Administration, and the National Science Foundation. The workshop discussed the following: anthropometric models; biomechanical models; human-machine interface models; and research recommendations. A 17-page bibliography is included

In-vehicle vibration study of child safety seats

This paper reports experimental measurements of the in-vehicle vibrational behaviour of stage 0&1 child safety seats. Road tests were performed for eight combinations of child, child seat and automobile. Four accelerometers were installed in the vehicles and orientated to measure as closely as possible in the vertical direction; two were attached to the floor and two located at the human interfaces. An SAE pad was placed under the ischial tuberosities of the driver at the seat cushion and a child pad, designed for the purpose of this study, was placed under the child. 4 test runs were made over a pave’ (cobblestone) surface for the driver’s seat and 4 for the child seat at both 20 km/h and 40 km/h. Power spectral densities were determined for all measurement points and acceleration transmissibility functions (ATFs) were estimated from the floor of the vehicle to the human interfaces. The system composed of automobile seat, child seat and child was found to transmit greater vibration than the system composed of automobile seat and driver. The ensemble mean transmissibility in the frequency range from 1 to 60 Hz was found to be 77% for the child seat systems as opposed to 61% for the driver’s seats. The acceleration transmissibility for the child seat system was found to be higher than that of the driver’s seat at most frequencies above 10 Hz for all eight systems tested. The measured ATFs suggest that the principal whole-body vibration resonance of the children occurred at a mean frequency of 8.5, rather than the 3.5 to 5.0 Hz typically found in the case of seated adults. It can be concluded that current belt-fastened child seats are less effective than the vehicle primary seating systems in attenuating vibrational disturbances. The results also suggest the potential inability of evaluating child comfort by means of existing whole-body vibration standards

How a Diverse Research Ecosystem Has Generated New Rehabilitation Technologies: Review of NIDILRR’s Rehabilitation Engineering Research Centers

Over 50 million United States citizens (1 in 6 people in the US) have a developmental, acquired, or degenerative disability. The average US citizen can expect to live 20% of his or her life with a disability. Rehabilitation technologies play a major role in improving the quality of life for people with a disability, yet widespread and highly challenging needs remain. Within the US, a major effort aimed at the creation and evaluation of rehabilitation technology has been the Rehabilitation Engineering Research Centers (RERCs) sponsored by the National Institute on Disability, Independent Living, and Rehabilitation Research. As envisioned at their conception by a panel of the National Academy of Science in 1970, these centers were intended to take a “total approach to rehabilitation”, combining medicine, engineering, and related science, to improve the quality of life of individuals with a disability. Here, we review the scope, achievements, and ongoing projects of an unbiased sample of 19 currently active or recently terminated RERCs. Specifically, for each center, we briefly explain the needs it targets, summarize key historical advances, identify emerging innovations, and consider future directions. Our assessment from this review is that the RERC program indeed involves a multidisciplinary approach, with 36 professional fields involved, although 70% of research and development staff are in engineering fields, 23% in clinical fields, and only 7% in basic science fields; significantly, 11% of the professional staff have a disability related to their research. We observe that the RERC program has substantially diversified the scope of its work since the 1970’s, addressing more types of disabilities using more technologies, and, in particular, often now focusing on information technologies. RERC work also now often views users as integrated into an interdependent society through technologies that both people with and without disabilities co-use (such as the internet, wireless communication, and architecture). In addition, RERC research has evolved to view users as able at improving outcomes through learning, exercise, and plasticity (rather than being static), which can be optimally timed. We provide examples of rehabilitation technology innovation produced by the RERCs that illustrate this increasingly diversifying scope and evolving perspective. We conclude by discussing growth opportunities and possible future directions of the RERC program

Real time integration of user preferences into virtual prototypes

Within new product development (NPD), both virtual prototypes and physical prototypes play important roles in creating, testing and modifying designs. However, in the current design process, these two forms of prototyping methods are normally used independently and converted from one to the other during different design phases. This conversion process is time consuming and expensive and also introduces potential information loss/corruption problems. If the design process requires many iterations, it may simply be impractical to generate all the conversions that are theoretically required. Therefore, the integration of virtual and physical prototyping may offer a possible solution where the design definition is maintained simultaneously in both the virtual and physical environment. The overall aim of this research was to develop an interface or a tool that achieves real time integration of physical and virtual prototyping. “Real time integration” here means changes to the virtual prototypes will reflect any changes that have been made contemporaneously to the physical prototypes, and vice versa. Thus, conversion of the prototype from physical to virtual (or vice versa) will be achieved immediately, hence saving time and cost. A review of the literature was undertaken to determine what previous research has been conducted in this area. The result of the review shows the research in this area is still in its infancy. The research hypothesis was developed through the use of a questionnaire survey. Totally 102 questionnaires were sent to designers, design directors or design managers to address the issue: will industrial designers want to make use of real time integration and if so, how? The outcome from the literature review drove further development of the research hypothesis and an initial pilot experiment to test this. The pilot trial was designed to address the research questions: • Can real time physical and virtual prototyping integration be conveniently demonstrated? • Will designers and users be comfortable using the integration method? • Will users recognise the benefits of the integration? The results showed that real time integration between physical and virtual prototyping is necessary in helping designers develop new products and for getting users more closely involved. The future research suggested is that more investigations and experiments are needed to explore a proper method that simultaneously employing these two types of prototyping in product development process. Keywords: Physical Prototyping; Virtual Prototyping; Integration; Real Time.</p

Human comfort in relation to sinusoidal vibration

An investigation was made to assess the overall subjective comfort levels to sinusoidal excitations over the range 1 to 19 Hz using a two axis electrohydraulic vibration simulator. Exposure durations of 16 minutes, 25 minutes, 1 hour, and 2.5 hours have been considered. Subjects were not exposed over such durations, but were instructed to estimate the overall comfort levels preferred had they been constantly subjected to vibration over such durations

Interface tool for human communication to integrate psychophysical inputs with rapid manufacturing technologies

People with Special Needs (PSN) are people conscious or unconscious with limited motor skills (possibly owing to a post-surgical situation). A large number of these persons have problems in body areas in contact with support surfaces. They do not have the capacity for autonomous movement, which results in excessive skin pressure and restricted blood circulation. This can lead to the development of pressure ulcers (PU). These people do not have the opportunity to communicate their needs to qualified care givers/helpers in the area to obtain appropriate products based on recent technologies. It is important to have integrated tools which allow PSN to interact with the technologies that surround them. This system permits strategies that allow personal psychophysical data to be analysed by a specialised technician (highlighting the user’s verbal and nonverbal signs), originating data that can be of assistance in the process of conversion into 3D computer aided design (CAD) models. From these models is expected a shape/base with better pressure distribution and able to be manufactured using technologies such as rapid manufacturing. This analysis considers user communication with a specialised technique based on pressure measurements, dynamic body posture and comfort/discomfort as verbal or nonverbal signs. The aim is to create an integration system that induces human communication, as a bridge between psychophysical data and a technique to use rapid manufacturing technologies for highly personalised product development

Automated biowaste sampling system improved feces collection, mass measurement and sampling

The capability of the basic automated Biowaste Sampling System (ABSS) hardware was extended and improved through the design, fabrication and test of breadboard hardware. A preliminary system design effort established the feasibility of integrating the breadboard concepts into the ABSS

The ISO standard: Guide for the evaluation of human exposure to whole-body vibration

The international guideline is discussed in terms of safety and human tolerance. Charts for equal subjective vibration intensity, subjective judgement of equal fatigue, and severe discomfort boundaries are included