Donald M. Spaeth

Assessing mobility characteristics and activity levels of manual wheelchair users

Although engaging in an active lifestyle is beneficial for maintaining quality of life, a majority of wheelchair users are inactive. This study investigated the mobility characteristics and activity levels of manual wheelchair users in the residential setting and at the National Veterans Wheelchair Games (NVWG). Demographic factors that may have influenced activity in the home environment were also identified. Fifty-two manual wheelchair users completed a brief survey, and their activity was monitored with a custom data logger over a period of 13 or 20 days. We found that they traveled a mean +/- standard deviation of 2,457.0 +/- 1,195.7 m/d at a speed of 0.79 +/- 0.19 m/s for 8.3 +/- 3.3 h/d while using their primary wheelchair in the home environment. No significant differences in mobility characteristics or activity levels were found for level of spinal cord injury or disability. We also found that subjects traveled significantly farther and faster and were active for more hours during an average day at the NVWG than in the home environment (p < 0.001). We found that manual wheelchair users who were employed covered more distance, accumulated more minutes, and traveled a greater average maximum distance between consecutive stops than those who were unemployed. Results from this study provide a better understanding of the activity levels achieved by manual wheelchair users and insight into factors that may influence this activity.

Performance assessment of a pushrim-activated power-assisted wheelchair control system

Wheelchairs are an important form of mobility for people with disabilities. For many years, there have only been three wheelchair varieties: electric-powered wheelchairs, scooters and manual wheelchairs. Recently, wheelchairs have been developed that use a combination of human power and electric power. The human power is delivered by the arms through the pushrims while the electric power is delivered by a battery through two electric motors. The shared control system for a pushrim-activated power-assisted wheelchair (PAPAW) must account for the human behavior and the interaction with the device. The PAPAW uses a form of gain scheduling based upon events recorded from the pushrim torque. The control system significantly altered (p<0.05) selected variables from pushrim torque curves for manual wheelchair propulsion and PAPAW operation as desired. The peak torque was reduced by over 50%, and the time on the rim was nearly doubled with the PAPAW. The PAPAW provided intuitive control and was capable of significantly reducing the strain on the upper extremities commonly associated with secondary disabling conditions among manual wheelchair users.

Engineering Better Wheelchairs to Enhance Community Participation

With about 2.2 million Americans currently using wheeled mobility devices, wheelchairs are frequently provided to people with impaired mobility to provide accessibility to the community. Individuals with spinal cord injuries, arthritis, balance disorders, and other conditions or diseases are typical users of wheelchairs. However, secondary injuries and wheelchair-related accidents are risks introduced by wheelchairs. Research is underway to advance wheelchair design to prevent or accommodate secondary injuries related to propulsion and transfer biomechanics, while improving safe, functional performance and accessibility to the community. This paper summarizes research and development underway aimed at enhancing safety and optimizing wheelchair design

Comparison of virtual and real electric powered wheelchair driving using a position sensing joystick and an isometric joystick

There are limited interface options for electric powered wheelchairs, which results in the inability of some individuals to drive independently. In addition, the development of new interface technologies will necessitate the development of alternative training methods. This study compares a conventional position sensing joystick to a novel isometric joystick during a driving task in a virtual environment and a real environment. The results revealed that there were few differences in task completion time and root-mean-square error (RMSE) between the two types of joysticks. There were significant correlations between the RMSE in the virtual environment and the real environment for both types of joysticks. The data indicate that performance in the virtual environment was representative of driving ability in the real environment, and the isometric joystick performed comparably to the position sensing joystick.

Quantifying wheelchair activity of children: a pilot study.

Cooper RA, Tolerico M, Kaminski BA, Spaeth D, Ding D, Cooper R: Quantifying wheelchair activity of children: a pilot study. Am J Phys Med Rehabil 2008;87:977–983. Objective:The purpose of this study was to investigate mobility-related wheelchair activity of children in their community setting. Design:Mobility-related wheelchair activity data from 18 community- dwelling children (9 manual and 9 electric powered) were collected using custom-designed data logging devices. The children were between 8 and 17 yrs of age and independently used a wheelchair as their primary means of mobility. A data logging device was installed on their wheelchair for 7 days. However, because the device was attached and removed at different times of the day, the first and last days of the study period were not analyzed. Therefore, a total of 5 days of data were used to investigate wheelchair activity. Results:Overall, the children who used manual wheelchairs traveled on an average of 1602.31 m/day (SD, 976.78) at a speed of 0.67 m/sec (SD, 0.12), and the children who used electric-powered wheelchairs drove 1752.42 m/day (SD, 835.14) at a speed of 0.75 m/sec (SD, 0.35). It was also calculated that the average daily number of starts/ stops per thousand meters the manual and electric-powered wheelchair users completed were 166.77 (SD, 64.32) and 112.53 (SD, 62.27), respectively. A comparison of mobility-related wheelchair activity revealed a significant (P = 0.008) difference in the average daily distance traveled between genders, with the boys traveling further than the girls. Conclusions:The mobility data obtained from the children wheelchair users suggest that one possible factor of variability among wheelchair activity is between genders. The data collected provide us with direction for future research in this area.

Virtual Reality and Computer-Enhanced Training Applied to Wheeled Mobility: An Overview of Work in Pittsburgh

Some aspects of assistive technology can be enhanced by the application of virtual reality. Although virtual simulation offers a range of new possibilities, learning to navigate in a virtual environment is not equivalent to learning to navigate in the real world. Therefore, virtual reality simulation is advocated as a useful preparation for assessment and training within the physical environment. We are engaged in several efforts to develop virtual environments and devices for mobility skills assessment and training, exercise training, and environment assessment. Virtual reality offers wheelchair users a training tool in different risk-free environments without any indoor (e.g., walls, furniture, and stairs) and outdoor (e.g., curb cuts, uneven terrain, and street traffic) physical constraints. Virtual reality technology will probably become more common in the field of assistive technology, especially given the rapid expansion of gaming technology and the continued exponential growth of computing power.

Development of a Wheelchair Virtual Driving Environment: Trials With Subjects With Traumatic Brain Injury

OBJECTIVE To develop and test a wheelchair virtual driving environment that can provide quantifiable measures of driving ability, offer driver training, and measure the performance of alternative controls. DESIGN A virtual driving environment was developed. The wheelchair icon is displayed in a 2-dimensional, birds eye view and has realistic steering and inertial properties. Eight subjects were recruited to test the virtual driving environment. They were clinically evaluated for range of motion, muscle strength, and visual field function. Driving capacity was assessed by a brief trial with an actual wheelchair. During virtual trials, subjects were seated in a stationary wheelchair; a standard motion sensing joystick (MSJ) was compared with an experimental isometric joystick by using a repeated-measures design. SETTING Subjects made 2 laboratory visits. The first visit included clinical evaluation, tuning the isometric joystick, familiarization with virtual driving environment, and 4 driving tasks. The second visit included 40 trials with each joystick. PARTICIPANTS Subjects (n=8; 7 men, 1 woman) with a mean age of 22.65+/-2y and traumatic brain injury, both ambulatory and nonambulatory, were recruited. INTERVENTIONS The MSJ used factory settings. A tuning program customized the isometric joystick transfer functions during visit 1. During the second visit, subjects performed 40 trials with each joystick. MAIN OUTCOME MEASURE The root mean square error (RMSE) was defined as the average deviation from track centerline (in meters) and speed (in m/s). RESULTS Data analysis from the first 8 subjects showed no statistically significant differences between joysticks. RMSE averaged .12 to .21m; speed averaged .75m/s. For all tasks and joysticks, driving in reverse resulted in a higher RMSE and more virtual collisions than forward driving. RMSE rates were greater in left and right turns than straight and docking tasks. CONCLUSIONS Testing with instrumented real wheelchairs can validate the virtual driving environment and assess whether virtual driving skills transfer to actual driving.

Comparison of virtual wheelchair driving performance of people with traumatic brain injury using an isometric and a conventional joystick

UNLABELLED Cooper RA. Comparison of virtual wheelchair driving performance of people with traumatic brain injury using an isometric and a conventional joystick. OBJECTIVE To compare wheelchair driving performance in a driving simulator using a conventional joystick and an isometric joystick. DESIGN Randomized, cohort study. SETTING A research facility based in a hospital or in an independent living center. PARTICIPANTS Participants (N=20; 12 men, 8 women; mean age ± SD, 30.62±10.91 y) who were at least 1 year post-TBI. INTERVENTIONS Driving performance using an isometric joystick compared with a conventional movement joystick. MAIN OUTCOME MEASURES Average trial completion time, and trajectory-specific measures measured orthogonal to the center of driving tasks: root mean squared error, movement offset, movement error, and number of significant changes in heading. RESULTS After statistically controlling for driving speed, participants were able to complete the driving tasks faster with an isometric joystick than while using a conventional movement joystick. Compared with the conventional joystick, an isometric joystick used for driving forward demonstrated fewer driving errors. During reverse driving the conventional joystick performed better. CONCLUSIONS The customizable isometric joystick seems to be a promising interface for driving a powered wheelchair for individuals with TBI.

The development and preliminary evaluation of a training device for wheelchair users: The GAMEWheels system

Purpose. Training of appropriate wheelchair propulsion methods may be beneficial to the individual who uses a wheelchair by reducing the incidence of pain and improving ones quality of life. This paper discusses the development and initial testing of a training device that was developed to aid in wheelchair propulsion techniques: GAMEWheels System. Methods. Two separate models of GAMEWheels have been developed: a GAMEWheels Clinical and a GAMEWheels Trainer. Details of the development process and the refinement have been included in this manuscript. To verify and compare the practicality and functionality of the two GAMEWheels systems, several focus groups were conducted: first to determine whether the systems could be set-up with informational materials and second to determine if the systems could be taught to novice users. Results. Results from the focus group indicate that the overall impressions of the systems were that they were ‘fun’ to play. Suggestions were raised to improve the design, which have been incorporated into further refinement of the GAMEWheels systems. Conclusions. This paper provides an overview of the development of a wheelchair-training device. Valuable information was gained to improve the design of the GAMEWheels systems.

Optimized joystick controller

The purpose of the study was to develop an optimized joystick control interface for electric powered wheelchairs and thus provide safe and effective control of electric powered wheelchairs to people with severe physical disabilities. The interface enables clinicians to tune joystick parameters for each individual subject through selecting templates, dead zones, and bias axes. In terms of hand tremor usually associated with people with traumatic brain injury, cerebral palsy, and multiple sclerosis, fuzzy logic rules were applied to suppress erratic hand movements and extract the intended motion from the joystick. Simulation results were presented to show the graphical tuning interface as well as the performance of the fuzzy logic controller.