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ANALYSIS OF VIBRATION AND COMPARISON OF FOUR WHEELCHAIR CUSHIONS DURING MANUAL WHEELCHAIR PROPULSION

Authors:
Carmen P. Digiovine at The Ohio State University
Carmen P. Digiovine
Erik J Wolf at Walter Reed National Military Medical Center
Erik J Wolf
James Hosfield
James Hosfield
James Hosfield
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Thomas Corfman
Thomas Corfman
Thomas Corfman
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ANALYSIS OF VIBRATION AND COMPARISON OF
FOUR WHEELCHAIR CUSHIONS DURING
MANUAL WHEELCHAIR PROPULSION
Carmen P. DiGiovine B.S., Rory A. Cooper Ph.D., Erik J. Wolf, James Hoseld, and
Thomas Corfman, M.S.
Human Eng. Res. Lab., Center of Excellence in Wheelchairs and Related Technologies,
Dept. of Phys. Med. and Rehab. Dept. of Rehab. Sci. and Tech.,
Univ. of Pittsburgh., PA 15261
Reprinted With Permission
RESNA July 17, 2000
Compliments of:
A Division of Cascade Designs, Inc.
4000 1st Avenue South
Seattle, WA 98134
Phone: (800) VARILITE (827-4548)
Fax: (206) 343-5795
www.varilite.com
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Cascade Designs, Limited
Dwyer Road, Midleton, Co. Cork
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ANALYSIS OF VIBRATION AND COMPARISON OF FOUR WHEELCHAIR CUSHIONS
DURING MANUAL WHEELCHAIR PROPULSION
Carmen P. DiGiovine B.S., Rory A. Cooper Ph.D., Erik J. Wolf, James Hosfield, and Thomas
Corfman, M.S.
Human Eng. Res. Lab., Center of Excellence in Wheelchairs and Related Technologies,
Dept. of Phys. Med. And Rehab. Dept. of Rehab. Sci. and Tech., Univ. of Pgh., Pgh., PA 15261
ABSTRACT
The purpose of this study was to compare four cushions, a Jay Active (JA), and PinDot Comfort-Mate
(PDCM), a Roho Low Profile (RLP), and a Varilite Solo (VS), based on their ability to minimize
the vibrations transmitted from the wheelchair to the individual during manual wheelchair
propulsion (MWP). Accelerometers measured the vibrations at the wheelchair/cushion interface and
at the individual’s head as the individual traversed an obstacle course. The VS performed the best,
followed by the PDCM, the RLP and finally the JA, suggesting that a combination of foam and air
minimizes the transmission of vibration. Cushions designed for static pressure relief may not
perform well in other areas potentially related to secondary injuries such as vibration.
INTRODUCTION
Typically, cushions are prescribed by clinicians based on the cushion’s pressure distribution
Properties, especially under the ischial tuberosities and the sacrum. Active individuals may need a
firm cushion (e.g. foam based rather than air based) in order to perform independent transfers, or a
light cushion in order to minimize the weight of the wheelchair/seating system.
The ability of the cushion to minimize impact (shock) and cyclic (repetitive) vibrations an
individual experiences is typically not considered. Whole-body vibration experienced during
manual wheelchair propulsion (MWP) can decrease an individual’s comfort and increase the rate of
fatigue [1]. Exposure to whole-body vibration has been shown to exceed the comfort and fatigue
thresholds during MWP [2, 3]. This may adversely affect the physical performance of the
individual. It may lead to social inactivity since the individual becomes fatigued faster. Finally, it
may lead to poor body mechanics during MWP, transfers, or other activities of daily living,
consequently increasing the individual’s susceptibility to developing a secondary injury.
The purpose of this study was to compare four cushions, a Jay Active (JA), a PinDot Comfort-
Mate (PDCM), a Roho Low Profile (RLP), and a Varilite Solo (VS), based on their ability to
minimize vibration transmission from the wheelchair to the individual during MWP. Determining
the cushion that minimizes vibrations provides clinicians additional information when
recommending the most appropriate cushion. This is especially relevant in today’s healthcare
environment where letters of medical necessity are required by the majority of funding agencies.
METHODS
A triaxial accelerometer (Analog Devices ADXL05, ±4g) was mounted on a seat-plate which
rested on the wheelchair’s seat tubes (rails). The cushion was then affixed on top of the seat-plate.
The accelerometer was positioned midway between the ischial tuberosities, directly below the
sacrum. A second triaxial accelerometer was mounted on a bite-bar. The bite-bar was held between
the individual’s teeth, with a mouth guard to protect his/her teeth. This accelerometer measured the
vibration experienced by the individual at his/her head. The acceleration signals were sampled at
200 Hz via a battery powered custom-designed data acquisition system [4].
A total of 10 unimpaired individuals propelled an instrumented wheelchair (Invacare XTR)
while negotiating nine obstacles 48 times (four cushions by four back supports by three trials). Only
the cushions were examined in this study, rather than the back supports or complete seating
systems. The nine obstacles consisted of a unidirectional (a.k.a. rumble) strip, a ramp (1:25 slope), a
curb drop (5 cm), a simulated door threshold, three sinusoidal bumps of varying height, a strip of
truncated domes (a.k.a. dimple strip), and carpet.
RESNA 2000 • June 28 – July 2, 2000 429
The seat-plate and bite-bar accelerations were compared using the following equations:
max (BB) – min (BB)
RR = --------------------------- (1)
max (SP) – min (SP)
RMS (BB)
RMSR = ----------------- (2)
RMS (SP)
where max (BB) and max(SP) are the maximum vertical accelerations recorded at the bite-bar and
seat-plate, respectively, min(BB) and min(SP) are the minimum vertical accelerations recorded at
the bite-bar and seat-plate, respectively, RR is the range ratio comparing the range of bite-bar
vertical accelerations to the range of seat-plate vertical accelerations, and RMSR is the root-mean-
squared (RMS) ration comparing the RMS of the bite-bar vertical accelerations to the RMS of the
seat-plate accelerations. The RR describes the cushion/human system’s (CHS) ability to minimize
peak vibrations, which are primarily due to impact vibrations (e.g. traversing the curb drop). The
RMSR describes the CHS’s ability to minimize the cyclic vibrations (e.g. traversing the
unidirectional strip or repetitive motions of MWP). For both ratios, a value below one indicates the
CHS reduces the vibrations, whereas, a value above one indicates the CHS amplifies the vibrations.
The cushions were compared for significant differences using a mixed-model ANOVA with a
Bonferroni post-hoc test (p<0.05). The mean RR and RMSR values for each cushion were
determined by averaging these values across the backs and trials. The RR and RMSR means were
used as data points in the statistical analysis. The mixed-model ANOVA was implemented in order to
account for the fact that the data for each cushion was obtained from the same group of individuals.
A single-factor ANOVA could not be implemented because the data violates the assumption that
the groups of individuals were independent.
RESULTS
The mean plus/minus the standard deviation of RR and RMSR across ten participants are listed
in Table I. The cushion with the lowest (i.e. best) ratios was the VS, followed by the PDCM, the
RLP, and finally, the JA. The RR and RMSR of the VS were significantly different than the other
three cushions (p<0.05). The RR of the PDCM was significantly different from the JA (p<0.05).
The CHS reduced the range of peak accelerations (RR<1) and amplified the RMS accelerations
(RMSR>1).
Table I. Mean ± Standard Deviation (n=10) of the Range Ratio (RR) and the RMS Ratio (RMSR)
for the four cushions. The letters A, B, C, or D indicate a significant difference at the p<0.05 level.
Cushions
Range Ration (RR) RMS Ratio (RMSR)
A. Varilite Solo (VS) 0.4l±0.088: B, C, D 1.32±0.16: B, C, D
B. PinDot Comfort-Mate (PDCM) 0.48±0.095: A, D 1.39±0.16: A
C. Roho Low Profile (RLP) 0.48±0.094: A 1.41±0.19: A
D. Jay Active (JA) 0.52±0.10: A, B 1.43±0.18: A
DISCUSSION
The RR and RMSR for the VS is significantly less than the other three cushions used in this
study (Table I). The VS is composed of a foam base below an adjustable air pocket. This
combination minimized the transmission of impact vibrations (i.e. due to shock), as described by the
RR, and cyclic vibrations (i.e. due to repetitive motions), as described by the RMSR. The PDCM
(foam only) and RLP (air only), had similar results, but were in contrast to the results of the VS
(foam and air), suggesting that vibrations are minimized by the interaction of the air and foam,
rather than one or the other.
The results obtained by the JA cushion, which generated the largest (i.e. worst) RMSR and RR
values, can be explained by the material properties of the cushion. This cushion consists of a
430 RESNA 2000 • June 28 – July 2, 2000
contoured foam base below a gel layer. Gel has inadequate reactive properties, that is, it feels like a
solid object when the individual encounters impact vibrations. This is because it is designed to
provide pressure relief in static or pseudo-static situations, rather than to absorb vibrations. Since
the gel is extremely stiff during impact and cyclic vibrations, the foam base is the only component
which has the ability to minimize the vibrations transferred to the individual, likely producing poor
results relative to the other cushions.
Currently, the main focus of cushion design is on appropriate pressure distribution, especially
under the ischial tuberosities and the sacrum. The JA and RLP are typically used by clinicians for
individuals who are at a greater risk of developing pressure sores. However, the RLP and JA may
not be the ideal cushions for active users, especially in minimizing vibration. As described in the
introduction the amount of vibration an individual experiences will directly affect the individual’s
comfort and rate of fatigue. This could compromise the individual’s ability to actively participate in
the community and independently perform activities of daily living.
The RMSR and RR are accurate metrics to determine a cushions ability to minimize the
vibration transmitted to the individual. Both parameters were consistent in rating the cushions, and
in discriminating that the VS was significantly better than the other three cushions (Table I). The
RR indicated that all the CHSs were able to reduce the range of vibrations experienced by the
individual (RR<l). Upon initial examination of the RMSR it appeared that the CHS increased
vibration transmission (RMSR>l). This is due to the fact that the vibrations experienced during
MWP were in the same frequency range as the natural frequencies of the human body [6]. Therefore
it is appropriate to suggest that the RMSR parameter was greater than one due to the properties of
the human body rather than the cushion. Since the individuals remained constant across groups, and
differences in the RMSR were a direct result of the different cushions used in this study.
Future investigations will examine the RMSR and RR parameters on an obstacle by obstacle
basis, will compare back supports and seating systems rather than just cushions, will examine
parameters in the frequency domain rather than the time domain, and will include individuals who
use a manual wheelchair as their primary form of mobility.
REFERENCES
l. ______, (1985). Evaluation of Human Exposure to Whole-Body Vibration – Part l: General
Requirements, ISO 2631/1
,Washington DC: ANSI Press.
2. DiGiovine CP & Cooper RA, (1999). Analysis of Whole-body Vibration during Manual
Wheelchair Propulsion using ISO Standard 2631. Proceedings of the 22
nd
Annual RESNA
Conference
, Long Beach, CA, 242-244.
3. Tai C, Liu D, Cooper RA, DiGiovine MM, & Boninger ML, (1998). Analysis of Vibrations
during Manual Wheelchair Use. Saudi J Disabil Rehabil
, 4, 186-191.
4. VanSickle DP, Cooper RA, & Gonzalez J, (1997). Smart Accelerometer: A Device to Measure
Three-Axis Acceleration for the Purpose of Evaluating wheelchair Ride Comfort, Proceedings
of the 20
th
Annual RESNA Conference, Pittsburgh, PA, 245-247.
5. ________, SAS
, ver. 7, SAS Institute, Inc., 1990.
6. DiGiovine CP, Cooper RA, & Boninger ML, (1999). Comparison of Absorbed Power to
Vertical Acceleration when Measuring Whole-body Vibration during Wheelchair Propulsion.
Proceedings of the 21
st
Annual International Conference of the IEEE-EMGS, Atlanta, GA, 610.
ACKNOWLEDGEMENTS
This project was supported through a grant from the U.S. Dept. of Veterans Affairs (B805-RA).
ADDRESS
Carmen P. DiGiovine
7180 Highland Drive, 151R-1, Building 4, Room 058E
Pittsburgh, PA 15206
cpdst11@pitt.edu
RESNA 2000 • June 28 – July 2, 2000 431
REPRINTED WITH PERMISSION
JULY 17, 2000
... Regarding TVDV [40][41][42], Tw-RMS [41,56], or transfer function between the floor and the seat [30], all articles reported value above one (see Table 5), which reveals that the MWC/user system tends to amplify the amount of vibration. Regarding Tf-Acc through the cushion, Garcia-Mendez et al. [54] obtained values between 1 and 1.2. ...
... Regarding Tf-Acc through the cushion, Garcia-Mendez et al. [54] obtained values between 1 and 1.2. On the other hand, Digiovine et al. [56] reported that Tt-Acc between the seat and the head was lower than one. Hence, the user/cushion system can reduce the shock amplitude, but not the vibration transmissibility (i.e., 0.4-0.5 and 1.3-1.4, ...
... Hence, the user/cushion system can reduce the shock amplitude, but not the vibration transmissibility (i.e., 0.4-0.5 and 1.3-1.4, for Tt-Acc and Ta-RMS, respectively) [56]. ...
Vibration Transmission during Manual Wheelchair Propulsion: A Systematic Review
Article
Full-text available
  • Jun 2021
Manual wheelchair (MWC) propulsion can expose the user to significant vibration. Human body exposure to certain vibrations can be detrimental to health, and a source of discomfort and fatigue. Therefore, identifying vibration exposure and key parameters influencing vibration transmissibility during MWC propulsion is crucial to protect MWC users from vibration risks. For that purpose, a systematic review using PRISMA recommendations was realizedtosynthesizethe current knowledge regarding vibration transmissibility during MWC propulsion. The 35 retrieved articles were classified into three groups: Vibration content, parameters influencing vibration transmission, and vibration transmission modeling. The review highlighted that MWC users experience vibration in the frequency range detrimental/uncomfortable for human vibration transmission during MWC propulsion depends on many parameters and is still scarcely studied and understood. A modeling and simulation approach would be an interesting way to assist physicians in selecting the best settings for a specific user, but many works (modeling, properties identification, etc.) must be done before being effective for clinical and industrial purposes.
View
... Other studies that compared the ability of seat cushions to minimize vibration exposure during manual WC propulsion support these results. For instance, Wolf et al. and DiGiovine et al. suggest that cushions made with a combination of foam and air transmit fewer impact and cyclic vibrations1920. These studies also provide important findings about how vibrations are transmitted. ...
... They found that high-impact shocks were reduced whereas cyclic vibrations were amplified when accelerations at the head were compared with those measured under the seat cushion. These results demonstrated that the human body and seating system absorb the energy of high-impact vibrations, while cyclic vibrations in the same frequency range as the natural frequencies of the human body appear to be amplified [20]. Although the research cited previously provides some evidence that WBV exposure may contribute to back and neck pain among WC users, the individual role of the cushion, which would be the first line of protection against WBV, is not well understood. ...
... Although the research cited previously provides some evidence that WBV exposure may contribute to back and neck pain among WC users, the individual role of the cushion, which would be the first line of protection against WBV, is not well understood. This is because in previous studies that assessed vibration exposure in WC users, measurements were collected below the seat cushion and in some cases at the head [9,1920, which combines the cushion and subject into one mechanical unit. These methods attempt to represent WC cushion transmissibility by the input acceleration below the WC cushion under the output acceleration measured at the head, which underestimates the energy absorbed by the human body. ...
GDynamic stiffness and transmissibility of commercially available wheelchair cushions using a laboratory test method
Article
  • Feb 2012
  • J REHABIL RES DEV
Evidence suggests that wheelchair (WC) users are exposed to unhealthy levels of vibration during WC use. Health risks associated with vibration exposure include vertebral disc degeneration and back pain, which may consequently decrease the function and independence of WC users. Some evidence suggests that the cushions used in WCs may amplify vibrations, although conclusive evidence has not been presented in the literature. This study evaluated and compared the transmissibility of commercially available WC cushions with two laboratory test methods: (1) direct measurement of transmissibility while human subjects propelled a WC over a road course with different cushions and (2) characterization of cushions with a material testing system (MTS) combined with mathematical models of the apparent mass of the human body. Results showed that although dynamic characterization of WC cushions is possible with an MTS, the results did not correlate well with the transmissibility obtained in the WC road course. Significant differences were found for transmissibility among the cushions tested, with the air-based cushions having lower transmissibility than the foam- or gel-based cushions.
View
... However, when moving in a wheelchair, a disabled person is exposed to whole-body vibrations. Studies show that constant exposure to vibration can lead to poor body posture, with the consequence that the wheelchair user is more susceptible to additional injuries [1][2][3][4]. The amount of vibration received also depends on the type of construction and additional equipment for the wheelchair, such as shock absorbers or seat cushions. ...
... An example of this is the system of reduction in plate structural vibrations (solid body) by piezoelectric elements (electric field) to minimize sound radiation (acoustic field). An interesting type of vehicle is the wheelchair [1,4]. On the one side, its construction should be simple and lightweight to make it a user-friendly system of car/train transport and home storage. ...
Application of Polyurethane Foam as a Material for Reducing Vibration of Wheelchair User
Article
Full-text available
  • Mar 2025
In this article, an attempt was made to model the body of a person moving in a passive manner (movement forced by another person) in a wheelchair. For this purpose, the Wan–Schimmels model was modified by 4 DOF, supplementing it with the weight of the wheelchair and a polyurethane cushion. The study was designed to test the effectiveness of utilizing a polyurethane cushion to reduce the whole-body vibration acting on a person while moving in a wheelchair. The study used a rheological model of polyurethane (PU) foam with concentrated parameters. Harmonic and random vibration analysis was carried out for this model. At the same time, the model with 5 DOF seems to be sufficient to describe vibrations transmitted to wheelchair users. The model presented in this paper can become a tool for future analysis of vibrations of people of different weights, moving passively on various types of wheelchairs on surfaces whose irregularities can be given by an appropriate form of kinematic excitation. The approach used in this study is likely to be useful in selecting a wheelchair and seat cushion so as to counteract and minimize vibrations perceived by humans.
View
... This excess can be considered particularly dangerous due to the fact that these are low frequencies, which are the natural frequencies of internal organs, including the spine . This may explain the fact that wheelchair users complain of pain in the lumbar spine [10], [17], [24], [37]. Thus, it is important to reduce these whole body vibrations to ensure the safety and comfort of wheelchair users. ...
... For low frequencies in the range up to 10 Hz, signal amplification is observed due to the use of a seat cushion, regardless of the thickness of the polyurethane cushion. A similar relationship, i.e., the amplification of vibrations in the frequency range harmful to the human body (4-12 Hz), was found in [15], [17], [24]. However, according to the tests carried out, the limit given by the ISO standard is exceeded for frequencies above 10 Hz. ...
Experimental study of the influence of using polyurethane cushion to reduce vibration received by a wheelchair user
Article
Full-text available
  • Jan 2023
  • Acta Bioeng Biomech
Purpose Experimental studies on comparing the ability of polyurethane cushions of three arbitrary selected thicknesses to minimize vibrations transmitted from the wheelchair to its user. Methods Measurements were made during passive motion on five different surfaces often found in public spaces. Two tests were carried out during the measurements. In the first test, the sensor was located directly on the surface of the wheelchair seat. In the second test, a polyurethane cushion was placed on the seat, on which the measuring sensor was then placed. Results The study showed that regardless of the surface on which the wheelchair user moves, the threshold defined in the ISO standard for frequencies in the range from 4 to 40 Hz is exceeded. However, thanks to the use of polyurethane cushions, vibration damping is visible for frequencies ranging from 10 to 40 Hz. The impact of the user’s weight on the magnitude of the perceived vibrations was also observed. Conclusions Studies show that wheelchair users are exposed to whole body vibration that can negatively affect their health. Cushions made of polyurethane seems to be a promising solution to reduce whole body vibration in the frequency range that is burdensome and harmful to human health.
View
... Health risks associated with exposure to vibration include vertebrae, disc degeneration, and back pain, which may result in decreased activity and independence of users [6,[15][16][17]. DiGiovine et al. [18] also reports that people in wheelchairs often report back pain, which reduces their level of activity and participation in society. ...
Experimental identification of the subjective reception of external stimuli during wheelchair driving
Article
Full-text available
  • Dec 2021
The aim of this article is identification of the subjective reception of external stimuli during wheelchair driving by analyses of vibration signals obtained from measurements. The identification concerns the impact of vibrations generated during crossing various types of pavements on the discomfort feelings of the selected human body parts (mainly the spine). The identification used the measurements of the whole body vibrations received by the user of the wheelchair. The research focuses mainly on the analysis in the frequency ranges corresponding to the vibration resonance of the spine. It is because respondents of the conducted surveys selected the spine as one of the most sensitive parts of the body.
View
... Early studies on wheelchair-vibrations [1][2][3] have shown that on certain road conditions the accelerations experienced by the wheelchair-user exceed the standardized levels set for the general population [4]. The primary health concern that is associated with whole-body vibrations is back pain [5][6][7]. ...
Modeling Wheelchair-Users Undergoing Vibrations
Article
Full-text available
  • Jul 2017
A procedure for modeling wheelchair-users undergoing vibrations was developed. Experimental data acquired with a wheelchair simulator was used to develop a model of a seated wheelchair user. Maximum Likelihood estimation procedure was used to determine model complexity required to characterize wheelchair-user's response. It was determined that a two segment rotational link model is adequate for characterization of vibratory response. The parameters of the proposed model were identified using experimental data and verified using additional experimental results. The proposed approach can be used to develop subject-specific design criteria for wheelchair seating and suspension.
View
... Studies carried out to evaluate the effectiveness of seating systems to reduce vibration transmission to WC users have demonstrated that cushions are not effective in reducing vibration transmitted to the riders, and in some cases may amplify it. 2,[14][15][16][17][18] In addition, WC users may not be provided with the most effective seating systems in terms of vibration suppression. 14 The potential discomfort caused by prolonged WC riding and vibration exposure has motivated the development of WC suspension systems to reduce external reaction forces transmitted to WC users during daily WC use. ...
Health risks of vibration exposure to wheelchair users in the community
Article
  • Jul 2013
The purpose of this study was to evaluate whole-body vibration (WBV) exposure to wheelchair (WC) users in their communities and to determine the effect of WC frame type (folding, rigid, and suspension) in reducing WBV transmitted to the person. An observational case-control study of the WBV exposure levels among WC users. Thirty-seven WC users, with no pressure sores, 18 years old or older and able to perform independent transfers. WC users were monitored for 2 weeks to collect WBV exposure, as well as activity levels, by using custom vibration and activity data-loggers. Vibration levels were evaluated using ISO 2631-1 methods. All WC users who participated in this study were continuously exposed to WBV levels at the seat that were within and above the health caution zone specified by ISO 2631-1 during their day-to-day activities (0.83 ± 0.17 m/second(2), weighted root-mean-squared acceleration, for 13.07 ± 3.85 hours duration of exposure). WCs with suspension did not attenuate vibration transmitted to WC users (V = 0.180, F(8, 56) = 0.692, P = 0.697). Conclusions WBV exposure to WC users exceeds international standards. Suspension systems need to be improved to reduce vibrations transmitted to the users.
View
Seat & footrest vibrations in manual wheelchairs
Article
  • Jan 2002
Newer manual wheelchairs have incorporated suspension systems in the hopes of decreasing harmful shock and vibration transmission. This study examined differences in the shock and vibration transmitted to a manual wheelchair occupant with and without suspension caster forks and with and without rear suspension systems. Significant differences were found in the peak accelerations at the seat (p = 0.0004) and footrest (p = 0.0007) between the wheelchairs when using the OEM caster forks versus the suspension casters. The wheelchairs with suspension had significantly different frequencies at which the peak accelerations occurred for both the seat (p = 0.01) and footrest (p = 0.0001). The wheelchairs that had the suspension caster forks had lower total power per octave than the wheelchairs with the OEM caster forks. For the footrest vibrations, significant differences were found between the types of caster forks for all octaves except those associated with frequencies above 78.75 Hz. There were significant differences for wheelchairs with and without rear suspension for total power per octave of seat vibrations in the octaves between 7.81 Hz and 9.84 Hz (p = 0.01), and 12.40 Hz. and 15.63 Hz (p = 0.008). Suspension caster forks reduce the shock and vibration exposure to the user of a manual wheelchair. Rear suspension systems reduce some of the factors related to shock and vibration exposure, but they are not clearly superior to traditional designs.
View
Vibration exposure of individuals using wheelchairs over concrete paver surfaces
Article
Full-text available
According to the International Standards Organization 2631-1 standard on human vibration, individuals in a seated position are at risk of injury due to whole-body vibrations when exposed for long periods of time. Wheelchair users fit this description perfectly, however little research has been conducted to evaluate the amount of vibration transmitted to a wheelchair user. The vibration exposure was produced by traversing nine pavement surfaces with 10 individuals without disabilities in a manual and powered wheelchair. The surfaces included poured, jointed concrete and concrete and clay pavers with chamfers from 0 to 8 mm wide and two herringbone laying patterns for selected surfaces. Power wheelchair results: The standard poured concrete surface was used as a norm and compared to the other surfaces. Two surfaces resulted in higher vibration exposure than the standard; an 8mm wide chamfer concrete paver in a 90 degree herringbone pattern and a 6mm wide chamfer pavers 90 degree herringbone pattern. Manual wheelchair results: Three surfaces resulted in higher vibration exposure than the standard surface; the 8mm wide chamfer surface in a 90 degree herringbone pattern, and the two 6mm wide chamfer surfaces placed in 90 and 45 degree patterns. Recommendations: Smaller chamfer widths on pavers exposes individuals using wheelchairs to less vibration. Also, pavers installed in a 90 degree herringbone pattern produced lower vibration exposures. It is recommended that only pavers of 6 mm wide chamfers or less be used with a 90 degree herringbone pattern.
View
Trends and Issues in Wheelchair Technologies
Article
  • Jun 2008
There is an overwhelming need for wheelchairs and the research and development required to make them safer, more effective, and widely available. The following areas are of particular importance: practitioner credentials, accreditation, device evaluation, device user training, patient education, clinical prescribing criteria, national contracts, and access to new technology. There are over 170 U.S. wheelchair manufacturers with a total reported income of 1.33billion.However,ofthesecompanies,onlyfivehadsalesinexcessof1.33 billion. However, of these companies, only five had sales in excess of 100 million. Wheelchairs account for about 1% of Medicare spending. Use of assistive technology is an increasingly common way of adapting to a disability. The emergence of advanced mobility devices shows promise for the contribution of engineering to the amelioration of mobility impairments for millions of people who have disabilities or who are elderly. Some of the trends in wheelchairs are going to require new service delivery mechanisms, changes to public policy, and certainly greater coordination between consumers, policy makers, manufacturers, researchers, and service providers.
View
Guide for the Evaluation of Human Exposure to Whole-Body Vibration
Article
  • Dec 1975
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.
View
Smart Accelerometer: A Device to Measure Three-Axis Acceleration for the Purpose of Evaluating wheelchair Ride Comfort
  • Jan 1997
  • 245-247
  • D P Vansickle
  • R A Cooper
  • J Gonzalez
VanSickle DP, Cooper RA, & Gonzalez J, (1997). Smart Accelerometer: A Device to Measure Three-Axis Acceleration for the Purpose of Evaluating wheelchair Ride Comfort, Proceedings of the 20 th Annual RESNA Conference, Pittsburgh, PA, 245-247.
Analysis of Vibrations during Manual Wheelchair Use
  • Jan 1998
  • 186-191
  • C Tai
  • D Liu
  • R A Cooper
  • M M Digiovine
  • M L Boninger
Tai C, Liu D, Cooper RA, DiGiovine MM, & Boninger ML, (1998). Analysis of Vibrations during Manual Wheelchair Use. Saudi J Disabil Rehabil, 4, 186-191.
Analysis of Whole-body Vibration during Manual Wheelchair Propulsion using ISO Standard 2631
  • 242-244
  • Digiovine
  • Cooper
DiGiovine CP & Cooper RA, (1999). Analysis of Whole-body Vibration during Manual Wheelchair Propulsion using ISO Standard 2631. Proceedings of the 22nd Annual RESNA Conference, Long Beach, CA, 242-244
Comparison of Absorbed Power to Vertical Acceleration when Measuring Whole-body Vibration during Wheelchair Propulsion
  • Jan 1999
  • 610
  • C P Digiovine
  • R A Cooper
  • M L Boninger
DiGiovine CP, Cooper RA, & Boninger ML, (1999). Comparison of Absorbed Power to Vertical Acceleration when Measuring Whole-body Vibration during Wheelchair Propulsion. Proceedings of the 21 st Annual International Conference of the IEEE-EMGS, Atlanta, GA, 610.
Evaluation of Human Exposure to Whole-Body Vibration -Part l: General Requirements, ISO 2631/1
  • Jan 1985
______, (1985). Evaluation of Human Exposure to Whole-Body Vibration -Part l: General Requirements, ISO 2631/1,Washington DC: ANSI Press.