Interaction with the surrounding environment is an essential element of ever day life. For individuals with severe motor and communicative disabilities, single switch scanning is used as method to control their environment and communicate. Despite being very slow, it is often the only option for individuals who cannot use other interfaces. The alteration of timing parameters and scanning system configurations impacts the communication rate of those using single switch scanning. The ability to select and recommend an efficient configuration for an individual with a disability is essential. Predictive models could assist in the goal of achieving the best possible match between user and assistive technology device, but consideration of an individuals single switch scanning tendencies has not been included in communication rate prediction models. Modeling software developed as part of this research study utilizes scan settings, switch settings, error tendencies, error correction strategies, and the matrix configuration to calculate and predict a communication rate. Five participants with disabilities who use single switch scanning were recruited for this study. Participants were asked to transcribe sentences using an on-screen keyboard configured with settings used on their own communication devices. The participants error types, frequencies, and correction methods were acquired as well as their text entry rate (TER) during sentence transcription. These individual tendencies and system configuration were used as baseline input parameters to a scanning model application that calculated a TER based upon those parameters. The scanning model was used with the participants tendencies and at least three varied system configurations. Participants were asked to transcribe sentences with these three configurations The predicted TERs of the model were compared to the actual TERs observed during sentence transcription for accuracy. Results showed that prediction were 90% accurate on average. Model TER predictions were less than one character per minute different from observed baseline TER for each participant. Average model predictions for configuration scenarios were less than one character per minute different from observed configuration TER.

A primary objective of the study was to determine the validity of a SenseWear (SW) activity monitor (AM) in assessing Energy Expenditure (EE) of manual wheelchair users with spinal cord Injury (SCI) while resting and performing three types of physical activities including wheelchair propulsion, arm-ergometer exercise, and deskwork. A secondary objective of the study was to build and validate a new EE prediction model for a SW AM for the physical activities performed in the study. A tertiary objective was to examine the relationship between the criterion EE and three activity monitors including the ActiGraph, the RT3 on arm, and RT3 on waist. Ten manual wheelchair users with SCI were recruited to participate in this pilot study. The results indicate that EE estimated by SenseWear AM with the default EE equationfor resting was close (0.2%) to the criterion EE in manual wheelchair users with SCI. However, the SW AM overestimated EE during deskwork, wheelchair propulsion and arm-ergometry exercise by 6.5%, 105% and 32%, respectively. From the investigation, we found that the EE estimated by SW AM using the new regression equation model significantly improved its performance in manual wheelchair users with SCI. The Intraclass Correlation Coefficient of EE estimated by SW using new prediction equation and the criterion EE were excellent (0.90) and moderate (0.74) with percent errors reduced to 17.4% and 7.0% for wheelchair propulsion and arm-ergometry exercise, respectively. The new prediction equation for SW AM was able to differentiate and discriminate (sensitive)EE estimation in physical activities like wheelchair propulsion and arm-ergometer exercises in manual wheelchair users with SCI indicating that it has a potential to be used in manual wheelchair users with SCI. In addition, the variance explained by RT3 (R2 = 0.68, p<0.001) on arm and the ActiGraph (R2 = 0.59, p<0.001) on the wrist wrist indicate that AMs placed on an arm or wrist may be able to better predict EE compared to the AM on the waist.

The Functional Mobility Assessment (FMA) instrument is a self-report outcome tool, designed to measure the effectiveness of Wheeled Mobility and Seating (WMS) interventions for people with disabilities (PWD). To describe the psychometric properties of the FMAs test-retest reliability, a repeated-measures cohort study was conducted. The specific aims of the study included examining the test-retest reliability of the FMA and determining to what extent each self-reported performance item remained stable when clients responded twice to the same questions over a time period of no less than one week and no more than three weeks. Participants were recruited from the University of Pittsburgh Medical Centers (UPMC) Center for Assistive Technology (CAT). The study sample involved 20 participants who were non-wheelchair or scooter users but in the process of being evaluated for a device (Non-WMS users) and 21 participants who were being evaluated for a replacement device (Existing WMS users). These 41 participants completed an initial FMA questionnaire. After obtaining the initial assessment, the FMA was administered a second time, within 7-21 days. Intra-class correlation coefficients (ICC) were computed to determine agreement between the two scores. Test-retest reliability scores for all items and participants were above the acceptable value of > 0.80 for a clinical assessment tool, except Health Needs and Reach for the Non-WMS users, and Transfers and Carry out daily routine for Existing WMS users. Existing WMS users had higher total scores (greater satisfaction) on the FMA than Non-WMS users. Results indicate that the FMA was a reliable and stable tool for assessing satisfaction of individuals who use or need WMS interventions. Future studies should include larger samples and recruit participants from multiple sites.

While technological developments over the past several decades have greatly enhanced the lives of people with mobility impairments, between 10 and 40 percent of clients who desired powered mobility found it very difficult to operate electric powered wheelchairs (EPWs) safely because of sensory impairments, poor motor function, or cognitive deficits [1]. The aim of this research is to improve control of personalized mobility for those with multiple sclerosis (MS) by examining isometric and movement joystick interfaces with customizable algorithms. A variable compliance joystick (VCJ) with tuning software was designed and built to provide a single platform for isometric and movement, or compliant, interfaces with enhanced programming capabilities. The VCJ with three different algorithms (basic, personalized, personalized with fatigue adaptation) was evaluated with four subjects with MS (mean age 58.7±5.0 yrs; years since diagnosis 28.2±16.1 yrs) in a virtual environment. A randomized, two-group, repeated-measures experimental design was used, where two subjects used the VCJ in isometric mode and two in compliant mode. While still too early to draw conclusions about the performance of the joystick interfaces and algorithms, the VCJ was a functional platform for collecting information. Inspection of the data shows that the learning curve may be long for this system. Also, while subjects may have low trial times, low times could be related to more deviation from the target path.

When an electric powered wheelchair (EPW) user leaves the confines of their home and ventures into the outdoors, they are confronted with a wide variety of terrain and driving conditions. Very little research has been done in trying to understand the difficulties EPW users face when driving outdoors. The first section describes a focus group study of 31 EPW users with the objective of assessing EPW users comfort level when driving in various outdoor conditions. Questionnaire and focus group transcripts showed that the EPW users top concerns were slipping, getting stuck, and tipping. The driving conditions most avoided were in the general themes of soft surfaces, angled surfaces, and adverse conditions. The second section presents in detail the electronic and mechanical design of an advanced controller for an EPW. A single board computer provides the computational power and storage space needed to execute normal operations, complex safety algorithms, and extensive data logging. Sensors provide feedback on velocity and inertia. A rugged aluminum enclosure protects the electronics. The advanced controller is used to research better ways to provide safety and customization for the EPW user. The outcome of this project as a whole was to demonstrate what can be done with an EPW to enhance the mobility and safety of its occupant.

As prevalence of wheelchair usage has increased, wheelchair manufactures are required to provide more and better wheelchairs because of secondary injuries such as pressure sores and repetitive strain injuries. Better qualified wheelchairs provide more adjustment, so wheelchair components have been developed to provide that adjustment. Among the wheelchair components, a backrest is one of critical components of the wheelchair due to the importance of seating position and appropriate trunk support. The Lightweight Durable Adjustable Composite (LWDAC) Backrest Mounting project consisted of three design iterations, prototypes, durability testing, and user evaluation. The backrest mounting is adaptable to most ultralight manual wheelchairs. The backrest is designed with features including height, width and backrest angle adjustment. The angle adjustment adds adjustability and flexibility to a rigid backrest and can be operated with only one hand, without high strength or dexterous manipulation. The LWDAC was tested with ANSI/RESNA durability and fatigue test standards and passed impact test, static stability test and durability test, but not fatigue test. This study also included focus groups to gather user and clinician feedback regarding backrest characteristics. The backrest had overall positive response from participants. The participants agreed the backrest mounting can be operated with one hand, felt comfort when seated, and wheelchair users were interested in purchasing the backrest and clinicians indicated they would recommend the LWDAC backrest.

Lateral ankle sprains are a common injury among all levels of athletic competition and can lead to the development of functional ankle instability (FAI). Individuals with FAI often display postural stability deficits. Numerous ankle questionnaires have been developed to classify subjects with FAI; however, the relationship between ankle questionnaires and postural stability is limited and warrants investigation. The primary purpose of this study was to compare measures of static and dynamic postural stability between FAI and healthy controls. The secondary purpose was to identify the relationship between ankle questionnaires and postural stability in FAI subjects. A total of 24 recreationally active subjects, 12 FAI and 12 healthy controls, between the ages of 18-35 were recruited to participate in this study. Static postural stability was assessed during eyes open and eyes closed single-leg stance. Dynamic postural stability was assessed during single-leg jump landings in the anterior and lateral directions. The ankle questionnaires included the Functional Ankle Disability Index, Ankle Instability Instrument, Ankle Joint Functional Assessment Tool, and Cumberland Ankle Instability Tool. Demographic, postural stability and questionnaire variables were compared using independent samples t-tests. A series of Pearson correlation coefficients were computed to determine the relationship between ankle questionnaires and measures of static and dynamic postural stability. The FAI subjects demonstrated worse (greater perceived symptoms of functional instability) scores on the Functional Ankle Disability Index-Sport, Ankle Instability Instrument, Ankle Joint Functional Assessment Tool, and Cumberland Ankle Instability Tool than the healthy controls. Additionally, FAI subjects demonstrated worse (higher) scores for the medial/lateral ground reaction force standard deviation during eyes closed single-leg stance, vertical stability index, and DPSI during anterior and lateral jumps. Significant correlations were observed between the medial lateral stability index and Ankle Joint Functional Assessment Tool and Cumberland Ankle Instability Tool during lateral jumps. The results of the study demonstrate FAI subjects have static and dynamic postural stability deficits compared to healthy controls. Additionally, the ankle questionnaires were poorly correlated with static and dynamic postural stability suggesting the ankle questionnaires may be inadequate at detecting postural stability deficits in FAI subjects.

For individuals who rely on wheeled mobility devices (WMD), performing transfers is essential to independence with activities of daily living at home and participation in the community. Transfers are required for getting to and from the device to bed, bath tub, car seat, among others. The United States Access Board develops guidelines and maintains design criteria for the built environment to maximize accessibility to public places. The objective of this study was to analyze the impact of transfer setup on performance of independent transfers. The first aim of the study was to perform an expert review of the current knowledge regarding transfers and the impact of setup. Results showed a consensus among studies that transferring to a higher surface implies greater exertion of the upper limb. Yet, there is no evidence concerning height differences, horizontal distance, and space needed next to the target surface so it can be accessible by a majority of WMD users. The second aim was to compare the current guidelines for amusement park rides with the results obtained by evaluating the impact of setup on transfer performance using a custom-built transfer station. We evaluated community-dwelling WMD users who were able to transfer independently and who represented a broad spectrum of disabilities. We evaluated the impact of height differential, gap, placement of a non removable armrest, and the effect of a grab bar. Results showed that height differentials above and below WMD height, gaps and obstacles pose serious transfer-related accessibility problems for WMD users. Current guidelines for amusement park rides fall short in terms of height recommendations and space available for the WMD and could exclude up to 72% of our sample. The third aim was to evaluate the relationship between functional performance (i.e. upper limb strength and trunk control) and transfer ability in people with spinal cord injury. Results found that trunk stability and gender are significant predictors of transfer ability. Rehabilitation plans should include balance training and core strengthening in addition to upper limb conditioning when teaching transfer skills. Improving transfer ability has the potential to increase community participation and independence among WMD users.

This thesis is composed of two studies related to wheelchair propulsion biomechanics. The first study investigated the impact of cross-slope and surface roughness on wheelchair propulsion. Fifteen manual wheelchair users propelled across a five-meter platform which were set to level, 1°, or 2° cross slope, and attached with one of three surfaces including Teflon (slippery), wood (normal), and blind guide (rough). The study found main effects of both cross slope and surface roughness on stroke number and sum of work, and a main effect of cross slope on velocity. Subjects travelled slower, used more strokes, and expended more work with increasing cross slope. Subjects also used more strokes when propelling on the slippery and rough surfaces than on the level surface. They expended more work when propelling on the rough surface than on the level surface. When looking into bilateral propulsion parameters, we found that peak resultant force, peak wheel torque, and sum of work became significantly asymmetrical with the increase of cross slopes. Exposure to biomechanics loading can be reduced by avoiding slippery, rough, and cross slopes when possible. The second study consisted of a preliminary analysis on the validity of a wheelchair propulsion monitor (WPM) in estimating wheelchair propulsion biomechanics. The WPM integrates three devices including a wheel rotation datalogger, and an accelerometry-based device on the upper arm and underneath the wheelchair seat, respectively. Five wheelchair users were asked to push their own wheelchairs fitted with a SMARTWheel over level and sloped surfaces on two separate visits. The estimated stroke number and cadence by the WPM were consistent with the criterion measures by the SMARTWheel (ICC= 0.99 for stroke number, ICC=0.97 for cadence) with less than 5% absolute percentage errors for stroke number and 9% for cadence. The peak resultant force and wheel torque could be predicted to some extent by acceleration features on an individual subject basis. The study demonstrated the potential of the WPM in tracking wheelchair propulsion characteristics in the natural environment of wheelchair users.

This thesis describes the history of the Endeavor folding wheelchair. In its current incarnation, it is an adjustable folding manual wheelchair conceptually based on a diamond shaped truss (similar to a bicycle). By disconnecting this truss at two points, the chair is able to fold flat enough to fit in the overhead bin of an airplane. It also features "airplane wheels" for maneuvering down the aisle of an airplane, taking the place of a boarding chair. The main part of the study was a clinical trial to gain feedback on the current chair design. The first phase of the study involved users performing obstacles encountered on a daily basis using the Endeavor and their personal chair. In the second phase, users took the chair home to see how the chair would function in their everyday lives. Because participants were comparing the Endeavor to their personal chairs, much of the feedback received was based primarily on the differences between the geometry and options of the Endeavor and their personal chairs. Based on the clinical results, the most important features that the Endeavor is lacking are: a more forgiving seatpan, and a more effective range of adjustability. In the future, a more organized approach based on product development methods should be used to develop better design criteria. The results of this study showed that in its current form, the Endeavor folding wheelchair may best be a special-purpose chair. By addressing all of the safety concerns, improving the ranges of adjustability to match the dimensions of the users in our focus group, and adding usability related options the chair may be able to function as an everyday wheelchair for many users. When our take-home participants were asked if they would like their chair better if they had "airplane wheels" five of the nine agreed. With some redesign to increase ease of use and decrease weight they could be marketed as their own product.