XV. Wheelchairs and Powered Vehicles


A. General



Rory A. Cooper, PhD; Michael L. Boninger, MD; Mark A. Baldwin, BS
Human Engineering Research Laboratories, VA Pittsburgh Health Care System, Pittsburgh, PA 15206; Departments of Rehabilitation Science and Technology, and Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261; email: rcooper+@pitt.edu; mlboning+@pitt.edu; mbaldwin+@pitt.edu

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #B869-2RA)

PURPOSE--The purpose of this project has been 1) to identify specific biomechanical factors that differentiate manual wheelchair users (MWUs) with and without pathological or clinical findings in the upper limbs; 2) to further define the prevalence of upper limb pain and pathology in MWUs and its relation to length of time with disability; and 3) to gain further insight into the progression over time of upper limb injuries in individuals with a new disability.

METHODOLOGY--Before the experimental trials, subjects volunteered and gave written consent for wheelchair propulsion testing. Bilateral kinematic and kinetic data were collected during several speed trials, with each subject propelling his/her own wheelchair secured to a computer-controlled dynamometer. After a brief acclimation period, subjects were instructed to propel during four separate 20-s trials at a self-selected speed (0.9 m/s, 1.8 m/s) and for a ramp up to maximum speed. After each subject reached a steady-state speed during each trial, propulsion kinetics, and kinematics were collected. Subjects were allowed to rest between each trial.

  Bilateral kinematic data was collected using an OPTOTRAK (Northern Digital Inc.) motion analysis system. Fourteen LED markers were used to identify anatomical landmarks on each of the upper limbs, including the acromion process, lateral epicondyle, olecranon process, ulnar and radial styloids, and the third and fifth metacarpophalangeal joint. An additional carbon fiber rigid body with three LED markers mounted on it was strapped to the subject's sternum to track trunk motion. Kinetic data were collected by fitting each subject's wheelchair with SMARTWheels, which measure 3-D global forces (Fx, Fy, Fz) and moments (Mx, My, Mz). These forces and moments were transformed into pushrim, wrist, and shoulder local coordinate systems, using Matlab programs. Visual feedback during propulsion trials has been added with a speedometer and wheel differential to ensure subjects stayed near suggested speeds. Nerve conduction studies and MRIs were performed on each subject for secondary injury investigation.

PRELIMINARY RESULTS--To date, we have tested over 60 MWUs. We have performed extensive analysis on the motion, forces, and moments occurring at the pushrim, at the wrist, and at the shoulder during steady-state propulsion. In addition, we investigated relationships between wheelchair propulsion parameters and the results from the nerve conduction studies and MRIs. From these relationships, we have been able to identify key aspects of wheelchair propulsion that may lead to the development of secondary injuries in the upper limbs, such as carpal tunnel syndrome and shoulder tendonitis. For the first time, these findings have allowed us to draw a direct relationship between secondary injuries and wheelchair propulsion.

FUTURE PLANS--The next phase of our research is to expand our analysis of wheelchair propulsion by looking for more relationships between propulsion characteristics, different wheelchair setups, and assistive device attachments and secondary injuries. With the findings of this research, we intend to have the ability to make recommendations on proper wheelchair setup and propulsion technique to prevent injuries such as carpal tunnel syndrome and shoulder tendonitis that are very prevalent in the manual wheelchair user population.




Lucas H.V. van der Woude, PhD; Annet J Dallmeijer, PhD; A Peter Hollander, PhD; Leonard Rozendaal, PhD; Dirkjan Veeger, PhD
Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Faculty of Human Movement Sciences, Van der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands, email: L_H_V_van_der_Woude@FBW.VU.NL

Sponsor: Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Faculty of Human Movement Sciences, Van der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands

PURPOSE--We are conducting a systematic analysis of manual wheelchair propulsion from a combined biomechanical and physiogical perspective, eventually with the objective of improving the mobility of the wheelchair/user combination. Our central areas of interest are: 1) the impact of wheelchair design characteristics upon the physiology and biomechanics of the user, with special reference to functional load and mechanical efficiency and kinetics, and the loading of structures during mere manual wheelchair propulsion. From this approach a set of theoretically based guidelines for wheelchair design and fitting emerges. 2) The factors which determine work capacity and power output (among others: functionality and propulsion technique) of the user. This should lead to guidelines of wheelchair training and exercise in sports and rehabilitation, and additionaly should serve in the development of design and fitting guidelines.

METHODOLOGY--Wheelchair propulsion is studied during standardized (sub-)maximal aerobic wheelchair exercise and sprint tests on a motor-driven treadmill and during simulated conditions on different computer-controlled wheelchair ergometers. During the treadmill tests (used in studies on prototype evaluation, performance capacity, and propulsion technique), physiological measures are combined with kinematics (3-D) and electromyography. Force measurements and kinematics during propulsion on special purpose wheelchair ergometers enable an additional 3-D reconstruction of the movement pattern of arms and trunk, in close conjunction with detailed force and power production. Together with electromyography of upper extremity and trunk muscles and overall physiology, phenomena of the low and varying mechanical efficiency in manual wheelchair propulsion is studied from a combined physiological and biomechanical perspective.

  A detailed model of the shoulder-arm complex allows calculation of the contribution of different muscles on power production during static and dynamic activity of shoulder and elbow in wheelchair arm work and other tasks. Thus the high prevalence of repetitive strain injuries (RSI) in the shoulder and hand-wrist areas among the user population may be understood more clearly. Currently, we have implemented a wrist system that allows the ambulant measurement of 3-D wrist excursions during wheelchair propulsion.

  Arm work during different forms (lever, crank, hubcrank, and hand rim) of manual wheelchair propulsion is also studied. Co-ordinative aspects of 'simple' cyclic motions in hubcrank and lever propulsion are subject to study, primarily to help understand co-ordinative 'problems' in that area.

PROGRESS--Detailed studies were conducted on lever and synchronic and asynchronic crank propulsion in relation to different gear ratios. Results on crank propulsion indicated a significantly better performance using the synchronic mode. The levers showed a better performance when using a 'high resistance/low speed' condition. Overall, levers and cranks are much less straining and more efficient than handrims. The latter also holds true for hubcrank propulsion. A first study of hand-wrist motions indicated large excursions around the flexi on/extension axis and ulnar/radial deviation axis.

FUTURE PLANS--We plan further refinement of fitting quidelines for groups of disabled subjects, also during the process of rehabilitation. Detailed analysis of wheelchair arm work during hubcrank and handrim propulsion must contribute to a further understanding of the mechanisms and risks of RSI and possible preventive measures in terms of wheelchair design or propulsion technique.




Thomas Adams, ME; Steven Reger, PhD, CP; Edgardo Cordona; Joseph Takacs, Jr.; Vinod Sahgal, MD
Department of Rehabilitation Medicine, Cleveland Clinic Foundation, Cleveland OH 44195 Kinedyne Corporation, Lawrence KS; email: regers@cesmtp.ccf.org

Sponsor: STTR Program, National Institutes of Health, Bethesda, MD 20832

PURPOSE--Transportation providers must be able to secure all wheelchairs, including scooters, to the vehicle for stability and safety. Belt-type securement systems are the most common design used in public-transit and school buses because they can be used with a wide variety of wheelchair styles. Difficult access to the belts, however, has been a source of continued frustration. This project focuses on a near-term solution to adapt the current technology to better meet the needs of public transit and wheelchair users by addressing securement of the wheelchair to the vehicle, and leaving occupant restraint to be addressed by separate restraint systems.

METHODOLOGY--We worked with wheelchair users and transportation providers to develop design criteria for a commercially feasible wheelchair securement system. These quantitative criteria included securement time, operational forces and motions, component locations, wheelchair stability, and crashworthiness. A prototype system was developed and mounted on a 16-passenger minibus. Wheelchair users and transit operators evaluated the operation of the system. Stability of a secured wheelchair during driving maneuvers was tested using a tilt-table that allows for highly reproducible simulation of the inertial forces experienced during turning and braking. Crashworthiness was demonstrated through sled impact simulation.

  The designed pretensioning system consists of four webbing retracting units mounted to the vehicle floor. A locking mechanism in each retractor unit provides for webbing withdrawal during attachment, and locking after the belts are attached to the wheelchair. Through electronic control a single switch simultaneously locks and pretensions all four belts. Optional belt end-fittings were developed to provide a captive fitting that can be rapidly attached to the wheelchair with one hand and minimal dexterity. The belts are held off the floor when the system is not in use so that the wheelchair user or assistant can easily access them.

PROGRESS--Positive feedback from wheelchair users and transit providers indicated that the pretensioning system was a significant improvement over the current securement systems. No major obstacles to widespread acceptance of the device were seen. Although independent use of the system by individuals seated in wheelchairs was not included in the design criteria, it was a desired objective. Approximately half of the wheelchair users with intact hand and arm function were able to perform the entire securement within 3 min without any assistance. The secured wheelchairs moved less than 5 cm during simulated "normal operating conditions," as required by the Americans with Disabilities Act. These results were similar to those obtained using commercial wheelchair securement systems. Sled impact testing was successfully completed, demonstrating compliance with SAE Recommended Practice Wheelchair Tiedown and Occupant Restraint Systems for Use in Motor Vehicles (SAE J2249). Additional testing showed that the system could also safely secure a three-wheel scooter during a 20-g, 30-mph simulated impact.

FUTURE PLANS--The encouraging results have led to an additional 2-yr project to review the design and make the necessary changes to prepare for commercial production. National field testing will be performed to evaluate the acceptance of the pretensioning system with a variety of climates and regional travel patterns. The 15-mo field test will demonstrate the durability of the design in the harsh transit environment.



Rory A. Cooper, PhD; Albert Vangura Jr., AS, BS; Lucy Spruill, MA
Human Engineering Research Laboratories, VA Pittsburgh Health Care System, Pittsburgh, PA 15206; Department of Rehabilitation Science and Technology, School of Health and Rehabilitation Science, and the Department of Bioengineering, School of Engineering, University of Pittsburgh, Pittsburgh, PA 15206; email: rcooper+@pitt.edu; alvst11+@pitt.edu; lspruill+@pitt.edu

Sponsor: Paralyzed Veterans of America, Washington, DC 20420; Yamaha Motor Corporation, U.S.A., Research and Development California, Cypress, CA 90630

PURPOSE--Long-term life expectancy for wheelchair users approaches that of the general population at this time; but more emphasis must be placed on quality of life and health issues surrounding long-term wheelchair use. One important issue for wheelchair users is injury, pain, and loss of function related to propelling a manual wheelchair. The upper limbs are not designed for mobility and weight-bearing and their use for these activities can result in loss of mobility, need for surgical intervention, and potential loss of independence. The purpose of this study is to evaluate the Yamaha JWII electric-powered, add-on unit for a manual wheelchair. This unit is easily attached to any manual wheelchair and provides additional power to the main wheels, based upon the amount of force applied to the pushrim by the user. This additional power is expected to reduce the energy expenditure required to propel a manual wheelchair and provide added comfort to users that actively experience upper extremity pain and dysfunction.

METHODOLOGY--This evaluation consists of three components: 1) mechanical testing based on ANSI/RESNA Wheelchair Standards, 2) metabolic energy expenditure comparisons with five nonimpaired subjects (controls) and 3) Activities of Daily Living (ADL) course using 10 experienced, manual wheelchair users (MWU).

  One Quickie GP wheelchair equipped with a JWII is currently being tested to current ANSI/RESNA Wheelchair Standards (Vol. 1, Sect. 1, 5, 7 and 8; Vol. 2, Sect. 2, 3, 4, 6, 9 and 10) at the Human Engineering Research Laboratories (HERL). Upon successful completion of mechanical testing, five controls will sign informed consent and propel a JWII equipped, manual wheelchair attached to a computer-controlled wheelchair ergometer through five resistance conditions. During propulsion, expired gases, heart rate, and cadence will be analyzed. After completion of metabolic testing, MWUs will sign informed consent and propel a Quickie GP manual wheelchair with and without the device through an ADL course. Each trial will be repeated three times for each wheelchair condition. Upon completion of a condition, the subject will then rate the chair on a number of subjective scales on a survey developed at HERL.

  The inclusion/exclusion criteria for this evaluation for all subjects is that they can propel a manual wheelchair and are between the ages of 18 and 65 years. The MWUs will be required to have at least 3-months experience.

PROGRESS--We have specified and inventoried the wheelchairs and JWIIs for testing. We are in the process of performing the ANSI/RESNA tests for this wheelchair system. We have designed the test machine modifications to accommodate the unique features of the JWII. We have begun subject recruitment for testing the device. Thus far, the JWII appears to offer some valuable features that will benefit wheelchair users.

FUTURE PLANS/IMPLICATIONS--The high incidence of arm pain among manual wheelchair users causes concern among health care professionals and may alter people's life-styles. Researchers have worked for several years to improve the design of manual wheelchairs, and significant progress has been made. However, some people continue to experience arm degeneration. This has resulted in the more frequent use of electric-powered wheelchairs by individuals with paraplegia. This often requires altering activities and extensive vehicle and home modifications. An alternative is to use an electric-powered add-on unit. This research will lead to add-on units that provide effective mobility in a manner natural to the user without requiring major modifications to the home or personal vehicle.



Rory A. Cooper, PhD; Michael L. Boninger, MD; Andrew J. Rentschler
Human Engineering Research Laboratories, VA Pittsburgh Health Care System, Pittsburgh, PA 15206; Departments of Rehabilitation Science and Technology, and Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261; email: rcooper+@pitt.edu; mlboning+@pitt.edu; ajrst22+@pitt.edu

Sponsor: Paralyzed Veterans of America, Washington, DC 20420

PURPOSE--The purpose of this study is to evaluate the performance of five different brands of power wheelchairs to allow for a comparison between the different power wheelchairs based on durability, stability, cost effectiveness, and other factors. Currently, such information about these wheelchairs is not readily available for clinicians or wheelchair users.

METHODOLOGY--A total of 15 power wheelchairs were selected to undergo testing according to the ANSI/RESNA Wheelchair Standards. Five different types were purchased: the Quickie P200, Invacare Action Storm, Permobil Chairman, Pride Jazzy, and the Everest and Jennings Lancer 2000. An outside source was used to purchase the wheelchairs to insure that the manufacturers took no steps to modify them. Three chairs of each type were purchased so that any statistical significance between wheelchairs could be determined.

  The chairs were randomly assigned a testing order for the study. The ANSI/RESNA Standards which were included in the study encompass parts 01 (Static Stability), 02 (Dynamic Stability), 03 (Effectiveness of Brakes), 04 (Energy Consumption), 05 (Overall Dimensions, Mass, and Turning Space), 06 (Speed, Acceleration, and Retardation), 07 (Seating Dimensions), 08 (Static, Impact, and Fatigue Strength), 09 (Climatic Tests), 10 (Obstacle-Climbing Ability), and 14 (Power and Control Systems). In addition, after all of the wheelchairs have completed ANSI/RESNA testing, they will be cycled back through part 08 until a Class III failure occurs. Part 08 involves testing the wheelchair on the double-drum machine for 200,000 cycles. If the wheelchair passes this test without any Class III failures then it is placed on the curb-drop machine for 6,666 cycles. The wheelchairs will be cycled through these tests until a Class III failure occurs. A Class III failure is defined as permanent damage, deformation, or failure that significantly affects operability of the wheelchair.

PROGRESS--Currently, all have completed parts 01 through 07. The first round of testing should be completed by January 1999. Completion of the study depends on the number of fatigue cycles required to produce a Class III failure for all 15 wheelchairs.

PRELIMINARY RESULTS--Initial results demonstrate that there are performance differences among the wheelchairs in parts 02 and 03, dynamic stability and efficiency of braking. The results of most interest will be those obtained from testing each wheelchair to Class III failure. This will allow for the comparison of durability and cost effectiveness between different types of power wheelchairs.

FUTURE PLANS--Additional studies may be conducted to include a broader expanse of power wheelchairs. Also, electric scooters are becoming more popular, and the FDA has recently included them in the same group as power wheelchairs. Therefore, a comparison study among scooters may be applicable, because the results can also be compared to the power wheelchair study.



Michael J. Dvorznak, BS; Rory A. Cooper, PhD; Thomas J. O'Connor, MS; Michael L. Boninger, MD
Human Engineering Research Laboratories, VA Pittsburgh Health Care System Pittsburgh, PA 15206; Departments of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA 15261; Division of Physical Medicine and Rehabilitation, Department of Orthopedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213-3221; email: mjdst47@pitt.edu

Sponsor: Paralyzed Veterans of America, Washington, DC 20006; Eastern Paralyzed Veterans of America, Jackson Heights, New York 11370; Centers for Disease Control, Atlanta, GA 30333

PURPOSE--Improvements to wheelchair design and technology, along with increased public accessibility, have advanced the role of electric-powered wheelchairs as a mobility device in the community. With this comes the potential risk of tips and falls when traversing obstacles encountered during activities of daily living. This study will help to determine if an optimal wheelchair fit and use of a seatbelt will reduce the frequency and severity of electric-powered wheelchair accidents.

METHODOLOGY--A 50th-percentile Hybrid III test dummy with force and moment sensing instrumentation will be randomly seated in six electric-powered wheelchairs from three manufacturers. Infrared emitting markers for use with a Selspot motion analysis system will be fixed to its joints and to the chair for kinematic measurement. To determine the effects of design and fit of the chair to the occupant, seating support and seatbelt usage will be altered. The wheelchair will be operated via radio control model airplane controller over a series of 10 obstacles representing common obstructions that would be encountered during daily living. Motion and kinetic data will be collected while driving over each obstacle for each condition. From the kinetic data, we can acquire information as to whether bones will be broken during falls or whether restraining devices might put users at risk to injury.

PROGRESS--The dummy has been instrumented with load cells in the neck, lumbar spine, knees, lower, and upper tibia of both legs. Collection boards have been fabricated and tested. Load cells will be recalibrated due to signal amplifying gain resistors in the collection circuit.

PRELIMINARY RESULTS--Preliminary results show that the set-up of the wheelchair influences driver safety. A previous study with eight wheelchairs involving only kinematic parameters showed that the use of a seatbelt reduced the risk of falling from a wheelchair, and properly adjusted legrests can reduce the risk of injury to the driver. A parallel study uses kinematic data in conjunction with inertial information and computer modeling to investigate impact forces during braking trials.

IMPLICATIONS--We expect that our discoveries will reduce the frequency and severity of electric-powered wheelchair accidents, thus reducing medical costs and enabling power wheelchair users to achieve their full potential in society.




Thomas Adams, ME; Steven Reger, PhD, CP; Lance Watt; Vinod Sahgal, MD
Department of Rehabilitation Medicine, Cleveland Clinic Foundation, Cleveland OH 44195; email: regers@cesmtp.ccf.org

Sponsor: TRANSIT-IDEA Program, Transportation Research Board, National Academy of Sciences

PURPOSE--The current practice of floor-mounted lap belts has proven to be highly impractical for wheelchair users, as the frame of the wheelchair interferes with the path of the belt from the pelvis to the floor. This difficulty has led to the dangerous practices of relying on wheelchair-mounted lap belts for crash protection or placing the lap belts over the arm rests and abdomen. To overcome these problems and provide a safe and practical solution, a system has been developed that provides adjustable lap belt anchorages that are secured to the vehicle but can be located next to the pelvis of the rider seated in a wheelchair.

METHODOLOGY--Since this new technology is a radical departure from the current methods, information was collected from wheelchair users and transportation providers regarding the design features needed for its success. Data collection techniques included surveys, focus groups, and human factors measurements. A panel of experts then confirmed the validity of the resulting design criteria. A prototype was then constructed for trial by transit personnel and wheelchair users.

  The restraint system is built into a single structure replacing the existing wheelchair barrier or modesty panel mounted on vehicles at the rear of the wheelchair bay. Two hook-shaped, length-adjustable arms extend and rotate forward out of this panel, one on either side of the wheelchair. Half of the lap belt is anchored to the end of each arm. When properly positioned, the arms come up at approximately 45° from near the floor under the panel, hook around the wheelchair armrest, and position the lap belt anchorage immediately next to the passenger's hip. All adjustments in angle and length are made while grasping the arm and compressing a lever. Once the grip is released, the extendable arms and lap belt anchorages are held firmly in place by the fully mechanical system.

  In some cases, the wheelchair user will be able to operate the system independently, while some assistance will be needed for individuals with impaired hand or arm function. In any event, the person assisting, usually the driver, will no longer need to reach around the passenger's hips, reach down to the floor, or search for loose or missing lap belts. The extendable arms will locate the lap belt anchorages and can be positioned from a standing posture next to the wheelchair.

PROGRESS--The system has been built and fitted in a city bus. The operation of the system is reliable, and can be achieved by individuals seated in a wheelchair. User trials are ongoing; a final strength test scheduled for fall 1998. Successful test results will demonstrate the feasibility of this concept, and further funding and industrial collaboration will be sought for commercial dissemination of the feasibility model.

FUTURE PLANS--To comply with the Americans with Disabilities Act, the lap belt anchorages must meet the Federal Motor Vehicle Safety Standards for Seat Belt Anchorages (FMVSS 210). This standard specifies that the anchorage points must withstand a 5,000-lb forward force to assure crash protection. Complying with this standard (although the loads are thought to be unrealistic for transit buses) requires using large structural members. Further design improvements are needed to overcome the high operation forces resulting from the size of the structural members to make it easier for wheelchair users to use the system independently.


B. Powered Controllers



Pascal Malassigné, MID, IDSA; Audrey L. Nelson, RN, PhD; Mark W. Cors, BFA; Carl H. Sutton, MD; Rosemary Bonifay, MS; Thomas L. Amerson, PhD
Research Service, 151, and the Spinal Cord Injury Center, Clement J. Zablocki VA Medical Center, Milwaukee, WI 53295-1000; Nursing Service, James. A. Haley VA Medical Center, Tampa FL 33612-4798; Department of Physical Medicine and Rehabilitation, Medical College of Wisconsin, Milwaukee, WI 53226; email: pascal@execpc.com; nelson.audrey_l@tampa.va.gov

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #B1522-3DA)

PURPOSE--The goal of this project was to develop a new motorized prone cart. This was the last phase in the design of new prone carts by these investigators.

  Prone carts are used for mobility by individuals with spinal cord injuries (SCI) who have pressure sores on the sacral region and the legs. Once pressure ulcers develop, the patient must stay off affected areas until they are healed. In most instances this precludes the use of a wheelchair. Prone carts provide an altemative to prolonged bed immobilization.

  Motorized prone carts are used by individuals with SCI who have limited, or no, arm and hand functions (quadriplegics), while manual prone carts are used by individuals with arm and hand functions (paraplegics).

METHODOLOGY--This project was accomplished in three phases. First, two motorized prone carts were designed and fabricated with OrthoKinetics, the collaborating manufacturer for the manual prone carts. Each cart was equipped with a different controller system from Dynamics Controls. The carts are presently under clinical evaluation with patients at the Milwaukee and Tampa SCI Centers as well as in wheelchair-accessible homes. This evaluation includes a combination of questionnaires, interviews, and photography to validate the prototypes. Finally, the cart will be tested with applicable ANSI/RESNA Electric Wheelchair Standards: determination of dynamic stability (WC/02); determination of efficiency of brakes (WC/03); determination of energy consumption (WC/04); determination of overall dimensions, mass, and turning space (WC/05); determination of maximum speed, acceleration, and retardation (WC/1)6); static, impact, and fatigue strength tests (WC/07); climatic test (WC/09); determination of the obstacle-climbing ability (WC/10); testing of power and control systems (WC/14); and detenmination of flammability.

PROGRESS--The carts are presently being clinically evaluated at the Milwaukee and Tampa SCI Centers.

FUTURE PLANS--Following the clinical evaluation and testing with applicable ANSI RESNA Electric Wheelchair Standards, the motorized prone cart will be manufactured by Everett & Jennings and made commercially available to SCI Centers.


C. Seating Systems



Rory A. Cooper, PhD; Carmen P. DiGiovine, BS; Michael L. Boninger, MD; Andy Rentschler, BS; Dehou Liu, MS, Changfeng Tai, PHD
Human Engineering Research Laboratories, VA Pittsburgh Health Care System, Pittsburgh, PA 15206; Departments of Rehabilitation Science and Technology, and Bioengineering, Schools of Health and Rehabilitation Science, Engineering, and Medicine, University of Pittsburgh, Pittsburgh, PA 15261; Division of Physical Medicine and Rehabilitation, Department of Orthopedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213-3221; email: rcooper+@pitt.edu; mlboning+@pitt.edu

Sponsor: Department of Veterans Affairs, VA Rehabilitation Research and Development Service, Washington, DC 20420
(Project #B805-4RA)

PURPOSE--The goals of this research into different cushions and back supports are to determine the changes in comfort with them; the changes in vibration of a wheelchair user with respect to the wheelchair structure with them; the change in vibrations and loads of an ISO test dummy while on a double-drum tester and a curb-drop tester with respect to the wheelchair structure with them; and to suggest improvements of the ISO tests. The long-term aim of this project is to improve the design and selection process of cushions and back supports, thus reducing the incidence of pain and spinal deformities in wheelchair users as a result of poor dynamic positioning and vibrations/loads transmitted through the wheelchair, back support, and cushions.

METHODOLOGY--This is a complex study addressing wheelchair design in a comprehensive way. Surveys and accelerometry data are being used to assess wheelchair rider comfort. Four different cushions and four different back supports, accounting for 16 unique seating systems, are being evaluated. Subjects use their own wheelchairs with one of the seating systems over a predefined obstacle course that has events similar to those encountered during normal activities of daily living. The individual's wheelchair is instrumented with an accelerometer, and their caster and rear wheel are replaced with instrumented versions. Upon completion of the course, each subject is asked to complete a survey about the individual obstacles and the course as a whole.

  Accelerometer data are collected from the seat and bite-bar (head) in three dimensions. The data are used to develop periodograms and transfer functions. This information is being used to determine whether some seating systems are better at attenuating impacts and vibrations from the ground. It is also being compared to reported rider comfort.

  Road load data are being collected to determine the actual loads experienced by users and their seating system, data critical for innovative design using computer-aided engineering. Actual road load data are being compared to that collected with the same instrumentation on ANSI/RESNA test machines. These data will be useful in the development and testing of wheelchairs and seating systems, in order to create a set of standards which is complimentary to the existing standards for manual wheelchairs.

PROGRESS--The instrumentation in order to collect the accelerometer and road load data have been developed and thoroughly tested. Ride comfort data have been collected using methods adopted from ISO 2631, and a survey on the different seating systems evaluated by two individuals who use a manual wheelchair. Improvements to the reliability and ease of use of the system have been incorporated into the protocol.

FUTURE PLANS--We plan to continue increasing our sample size, to compare the results obtained from this study with results obtained from a previous study, and to determine the relationship between road and test loads. Currently, the focus has been on manual wheelchairs. It is important to extend this work to powered wheelchairs and scooters. Very little comfort, load, or testing data are available for these devices. Modifications to the ANSI/RESNA fatigue tests may be appropriate to obtain results more similar to those obtained during actual use. Of course, the test procedures must take into account the accelerated time frame required of standards testing in order to be useful for design and evaluation. This line of research shows promise to benefit people who use wheelchairs, and the results have opened several areas for more intense investigation.




Steve Ryan, BESc, PEng; Susan Mulholland, MSc(Rehab), OT(C); John Hancock; Michael Doell, AOCA
Bloorview MacMillan Centre, Toronto, ON, M4G 1R8

Sponsor: Lever Foundation

PURPOSE--The goal of this project is to investigate the acceptance of a proposed standardized adapter/receiver system for custom seats that allows a child to take part in various recreational activities. The envisaged system allows caregivers to take custom seats from wheelchairs to use as positioning devices on many commercial products such as swings, wagons, and toboggans. Issues such as safety, durability, projected cost, and usability of the system are being considered with input from consumers and others during the early feasibility phases.

PROGRESS--Two discussion groups were organized to evaluate a working prototype of the recreation adapter/receiver system. One session was held with the Lifeskills staff at Bloorview MacMillan and a facilitated focus group was held with recreation staff from Variety Village--an integrated sport training and fitness centre in Scarborough, Ontario--and members of Bloorview MacMillan's Youth Advisory Council. Participants in both groups were very positive about the working prototype developed. The group agreed that recreation for younger children meant enabling a child to participate in activities as others do. Furthermore, they identified the importance of being able to access both personal and public recreation equipment and activities. The ability to use this system in public locations (e.g., on amusement rides, school auditorium seats, movie cinema seats, hockey bleachers) was also identified as important.



Steve Ryan, BESc, PEng; Michael Doell, AOCA; Gloria Leibel BSc, PT; Jan Polgar, PhD, OT(C); Dianna Lee, MA, OT(C); Martin Mifsud; Rick Taylor; Bill Bennett, BASc, PEng
Bloorview MacMillan Centre, Toronto, ON, M4G 1R8; University of Western Ontario, School of Occupational Therapy, Elborn College, London, Ontario, Canada, N6G 1H1; Occupational Therapy and Assistive Technology Consulting, Waterloo, ON; Variety Ability Systems Incorporated, Scarborough, Ontario; Ontario Rehabilitation Technology Consortium, Toronto, ON, M4G 1R8; email: jpolgar@julian.uwo.ca; ortcsr@oise.utoronto.ca

Sponsor: Ontario Rehabilitation Technology Consortium (funded by the Ontario Ministry of Health); Variety Ability Systems Incorporated, Scarborough, Ontario.

PURPOSE--Toiletting is an area of concern for many parents of children with physical disabilities. Unless appropriate postural support is provided on a secure base, this event can be frightening for the child and disconcerting for the parent. Research was conducted to support the development of an adaptive toiletting system that positions children better and addresses concerns raised by both parents and clinicians. The new commercial product developed through this research and manufactured by Variety Ability Systems Incorporated (VASI) is called AquanautTM.

PROGRESS--Project team members oversaw the development of production tooling by VASI's subcontractors and identified and resolved preproduction run problems. Family trials and other consumer tests were coordinated to evaluate pre-production units and a draft of the Aquanaut owner's manual. Working together with VASI, marketing literature and promotional products were developed and distributed. In concert with the ORTC's Technology Transfer Unit, international patent and design registration activities were coordinated to protect the commercial value of the product. Aquanaut was successfully launched in fall 1997 at the Canadian Seating and Mobility Conference in Toronto and was showcased at both MedTrade Home Healthcare Show in New Orleans and Reha in Dusseldorf, Germany in October 1997.




Steve Ryan, BESc, PEng; Patty Rigby, MHSc, OT(C); Michael Doell, AOCA; Devin Ostrom, BASc; Susan Mulholland, MSc(Rehab), OT(C)
Bloorview MacMillan Centre, Toronto, ON, Canada M4G 1R8; University of Toronto, Department of Occupational Therapy, Toronto, Ontario, M5T 1W5; email: ortcsr@oise.utoronto.ca; patty.rigby@utoronto.ca

Sponsor: Ontario Rehabilitation Technology Consortium (funded by the Ontario Ministry of Health)

PURPOSE--The purpose of this research project is to develop a modular, customizable seating system that can adapt to child growth with minimal work while providing the necessary support and features of a custom seat.

PROGRESS--Since the inception of this project, progress has been made through the use of consumer focus groups and the collection of anthropometric data. This was critical to identify the necessary features and growth/adjustment ranges needed to accommodate an age group of children between the ages of 6 and 12. Following this investigation, a decisive description of the desired seating system was created, and an initial prototype was constructed for fitting trials with children at Bloorview MacMillan Centre School. Design criteria were refined from this trial, and a second seating prototype was constructed according to the modified data.

FUTURE PLANS--The new prototype will be tested by two families over one-week trials. The seating system design will be improved for the construction of six newer seats. These third generation seats will undergo further testing by clinicians and individual families during the summer 1998.



Patty Rigby, MHSc, OT(C); Denise Reid, PhD, OT(C), Steve Ryan, BESc, PEng; Susan Mulholland, MSc(Rehab), OT(C); Devin Ostrom, BASc, PEng; Michael Doell, AOCA
Bloorview MacMillan Centre, Toronto, ON, Canada M4G 1R8; The University of Toronto, Department of Occupational Therapy, University of Toronto, Toronto, ON, M5T 1W5; email: ortcsr@oise.utoronto.ca; d.reid@utoronto.ca; patty.rigby@utoronto.ca

Sponsor: Ontario Rehabilitation Technology Consortium (funded by the Ontario Ministry of Health); Canadian Occupational Therapy Foundation

PURPOSE--To address consumer concerns about the function and operation of postural belts on wheelchair seats, new strategies for stabilizing the pelvis were investigated. As an outcome of this investigation, numerous prototype devices were developed and evaluated with the assistance of clinicians and parents. Work is now underway to both commercialize and integrate promising products into the new pediatric seating system under development.

PROGRESS--In Fiscal 97/98, two product prototypes were developed further and evaluated during family trials: a) HipHuggersTM was developed to improve the fit of wheelchair lap belts. HipHuggers redirects the pull of the lap belt so more of it wraps around the pelvic area of the child. This results in an intimate fit that helps to provide better stabilization of the pelvis. An application for third party funding approval of HipHuggers was made by the project team. The Ministry of Health's Assistive Devices Program approved funding 75 percent of the cost of the device. With this support, the cost is more in line with what consumers are willing to pay for this product. b) Rigid Pelvic Stabilizer (RPS) System was designed to replace postural belts entirely, particularly for children with difficult seating problems. The RPS design evolved through four design stages. The most recent version was packaged with instructions and sent to five different seating centers across Ontario and in the United States. Results of the trials suggested minor modifications to improve the reliability of the devices. RPS prototypes were enthusiastically accepted by both clinicians and parents whose children used them.

FUTURE PLANS--In Fiscal 98/99, a short production run of HipHuggers will be made and consumer interest monitored. If this proves favorable, a manufacturer will be sought to transfer the design. Plans are underway to incorporate a modified version of the RPS system into the Modular Paediatric Seating (MPS) system design. Research funding from the Canadian Occupational Therapy Foundation was received to investigate further the clinical effectiveness of the RPS in a school setting. The study began March 1998 and is due to be completed summer 1999.



Steve Ryan, PEng; Patty Rigby, MHSc, OT(C); Michael Doell, AOCA; Ihsan Al-Temen, PEng; John Hancock
Bloorview MacMillan Centre, Toronto, ON, Canada M4G 1R8; email: ortcsr@oise.on.ca

Sponsor: Rotary Club of Leaside (Toronto) and Ontario Rehabilitation Technology Consortium (funded by the Ontario Ministry of Health)

PURPOSE--A prototype transportation restraint carrier was developed for school-aged children unable to sit unsupported while travelling in a motor vehicle. The carrier converts a custom wheelchair seat into a child restraint system so as to reduce the risk of personal injury caused by a motor vehicle collision. To transfer children safely into and out of the family car, a portable lift and transfer device was also developed and tested.

PROGRESS--New strategies were developed to interest potential manufacturers in the two transportation products--the child restraint carrier and lift and transfer device--now called TranSit SystemTM. A patent application was submitted in the United States, both to protect its commercial value and allow for disclosure of its novel features at international business venues.

  A demonstration of the technology was presented to prospective manufacturers through a pre-release product flyer and a short video presentation. Discussions are being sought with companies who expressed an interest in this new technology.

FUTURE PLANS--In fiscal 1998/99, we shall continue to seek business partnerships with interested companies. The project team will provide development support as necessary. Furthermore, the team will ensure that federal regulatory requirements are met and commercial interests are maintained.



Jonathan M. Owens; Beth A. Todd, PhD; James F. Cuttino, PhD
The University of Alabama, Tuscaloosa, AL 35487-0276; email: jowens@eng.ua.edu; btodd@coe.eng.ua.edu; jcuttino@coe.eng.ua.edu

Sponsor: The University of Alabama, College of Engineering, Tuscaloosa, AL 35487

PURPOSE--Using computer modeling, the behavior of human soft tissues can be more easily observed and predicted over a large range than when using less efficient physical tests. The goal of this project is to refine the FE model that has been created to utilize data obtained on the nonlinear behavior of the adipose and muscular tissues of the seating area to create seating systems that reduce the occurrence of decubitus ulcers.

METHODOLOGY--The initial model was modified from a simple hemispherical section into two separate models that represented male and female subjects. The tissue properties were based on experimental data previously collected for these subjects. Load versus displacement data were analyzed to determine the stiffness for the muscle and adipose tissue separately. The male model represented a body type with a very low percentage of body fat, and the female model represented a higher percentage body fat. The dimensions of the model were based on MRI data where the thicknesses of the muscle and adipose tissue for both subjects were determined. On male model, the thickness of the fatty layer was 13.7 mm while the muscle layer was 45.1 mm below the ischial tuberosity. On the female, the fatty layer was 25.5 mm and the muscle layer was 15.6 mm below the ischial tuberosity.

  Both models were loaded with 29 percent of the total body weight, which resulted in 211 N for the male and 167.5 N for the female. Both loads were applied to the lower quarter of the hemispherical region to represent sitting on a contoured cushion.

PROGRESS--With the initial model yielding results similar to those in the literature, the new models are advancing our understanding of the behavior of the two tissue types at their interfaces. This includes the interface between the adipose tissue and the muscle tissue within the buttocks, the interface between the muscle tissue and the bony prominence represented by a constrained core, and finally, the interface between the outer layer of fatty tissue and the seating surface.

PRELIMINARY RESULTS--The stiffness for the muscle layer was experimentally determined to be 1.8 N/mm and the stiffness for the fatty layer was determined to be 1.2 N/mm. The elastic modulus for the muscle layer was calculated to be 0.55 N/mm2 and that for the fatty layer was 0.16 N/mm2. These values for the moduli of elasticity were input into the FE model where the von Mises stresses and strains were determined. The von Mises stress distributions were very similar despite the varying layer thickness and body weights. The highest magnitude in the male was 231 Pa and 220 Pa for the female. Both maximum stresses occurred in the tissue adjacent to the bottom of the ischial tuberosity.

  The stiffer muscle region of the male model introduced an increase in the surface strain (0.14 N/mm) of the more pliable thin layer of fatty tissue at the seat interface, while the female had lower surface strain (0.11 N/mm).

FUTURE PLANS--The model is being moved to a new platform where nonlinear FEA can be used to incorporate the nonlinear behavior of the muscle and adipose layers of tissue. The new software will also be used to create a seating surface that represents the frictional forces present when it deflects under load.


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Last revised Thu 04/29/1999