Test method for empirically determining inertial properties of manual wheelchairs

Eicholtz, Matthew; Caspall, Jayme J.; Dao, Phuc V.; Sprigle, Stephen; Ferri, Al

doi:10.1682/jrrd.2011.03.0045

Cited by 18 publications

(14 citation statements)

References 9 publications

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“…Testing using objects with analytically determined inertias found error within 0.82 percent. Other than this modification, the iMachine used in this study was identical to the apparatus reported in Eicholtz et al, and specific information about the design and technique can be found there [9].…”

Section: Inertial Measurementsmentioning

confidence: 98%

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Changes in inertia and effect on turning effort across different wheelchair configurations

et al. 2013

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Abstract-When executing turning maneuvers, manual wheelchair users must overcome the rotational inertia of the wheelchair system. Differences in wheelchair rotational inertia can result in increases in torque required to maneuver, resulting in greater propulsion effort and stress on the shoulder joints. The inertias of various configurations of an ultralightweight wheelchair were measured using a rotational inertia-measuring device. Adjustments in axle position, changes in wheel and tire type, and the addition of several accessories had various effects on rotational inertias. The configuration with the highest rotational inertia (solid tires, mag wheels with rearward axle) exceeded the configuration with the lowest (pneumatic tires, spoke wheels with forward axle) by 28%. The greater inertia requires increased torque to accelerate the wheelchair during turning. At a representative maximum acceleration, the reactive torque spanned the range of 11.7 to 15.0 N-m across the wheelchair configurations. At higher accelerations, these torques exceeded that required to overcome caster scrub during turning. These results indicate that a wheelchair's rotational inertia can significantly influence the torque required during turning and that this influence will affect active users who turn at higher speeds. Categorizing wheelchairs using both mass and rotational inertia would better represent differences in effort during wheelchair maneuvers.

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Section: Inertial Measurementsmentioning

confidence: 98%

“…For this reason, I WC was measured experimentally using the inertia measurement device called the iMachine [9]. We developed the iMachine to measure I WC for irregularly-shaped rigid bodies, specifically, an occupied wheelchair rotating about the yaw axis.…”

Section: Inertial Measurementsmentioning

confidence: 99%

Changes in inertia and effect on turning effort across different wheelchair configurations

et al. 2013

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“…Inertial properties such as the location of the center of gravity (COM) and moment of inertia about the COM were measured using a pendulum platform (Eicholtz et al 2012). Table 1 presents the measured geometric and inertial properties of the AMPS-wheelchair combination used in the experiments in this work.…”

Section: System Specificationsmentioning

confidence: 99%

Influence of rolling resistance on manual wheelchair dynamics and mechanical efficiency

Teran

Ueda

2017

Int J Intell Robot Appl

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The anatomical model propulsion system (AMPS) was designed to propel manual wheelchairs in a highly repeatable manner while emulating human weight distribution and force application. This paper details the development of two control systems for the AMPS and their application on several sets of experiments. The first system allows the AMPS to maneuver with precision along straight and curvilinear trajectories. The second system mimics human pulsatile propulsion of a manual wheelchair for tests on a dynamometer. In both cases, the controller used an estimation of input forces provided by a model along with real-time feedback to create an appropriate maneuver control of the wheelchair. Several studies have measured rolling resistance using diverse methodologies and equipment including dynamometers, treadmills, and instrumented wheelchairs. A new approach for testing rolling resistance by using the AMPS is presented in this work. This new approach was able to test the wheelchair behavior on actual floor while all wheels are making contact, with precise control on velocity and acceleration, a combination unattainable with previous methods. Results confirm other researchers' conclusion that rolling resistance increases with velocity, but also add new evidence that rolling resistance increases significantly with acceleration on a manual wheelchair. The AMPS was also used to estimate turning resistance in manual wheelchairs. Results offer new evidence that turning resistance increases as the instantaneous radius of rotation of the trajectory shortens. Additionally, the AMPS was provided with the ability to propel a manual wheelchair emulating human pulsatile propulsion on a single-roller dynamometer. Various pushing frequencies and duration of pulses were tested to compare the efficiency of different propulsion techniques. Two indices, energy conversion efficiency (g) and cost of transport (COT), were used to quantify wheelchair mechanical efficiency due to their relevance for vehicles. Energy conversion efficiency was found to vary significantly for different values of acceleration. COT was found to increase as linear velocity increased and the radius of curvature was reduced. Initial findings on COT for these pulsatile propulsion experiments suggest propelling techniques might have an effect in overall mechanical efficiency. Wheelchair mechanical efficiency could be used to compare the performance of different wheelchair models over common maneuvers, helping clinicians do more informed decisions for their patients. Further development and exhaustive testing of the system presented in this work could potentially become a standard for the manual wheelchair industry.

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“…Mass, yaw inertia of the MWC (I G ), and the location of the CoM were measured experimentally using a device called the iMachine [25]. The device consists of a turntable mounted to a single axle.…”

Section: System and Wheel Inertiamentioning

confidence: 99%

Evaluation of wheelchair resistive forces during straight and turning trajectories across different wheelchair configurations using free-wheeling coast-down test

Lin¹,

Huang²,

Sprigle³

2015

J Rehabil Res Dev

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Abstract-The purpose of this study was to develop a simple approach to evaluate resistive frictional forces acting on manual wheelchairs (MWCs) during straight and turning maneuvers. Using a dummy-occupied MWC, decelerations were measured via axle-mounted encoders during a coast-down protocol that included straight trajectories and fixed-wheel turns. Eight coast-down trials were conducted to test repeatability and repeated on separate days to evaluate reliability. Without changing the inertia of the MWC system, three tire inflations were chosen to evaluate the sensitivity in discerning deceleration differences using effect sizes. The technique was also deployed to investigate the effect of different MWC masses and weight distributions on resistive forces. Results showed that the proposed coast-down technique had good repeatability and reliability in measuring decelerations and had good sensitivity in discerning differences in tire inflation, especially during turning. The results also indicated that increased loading on drive wheels reduced resistive losses in straight trajectories while increasing resistive losses during turning. During turning trajectories, the presence of tire scrub contributes significantly to the amount of resistive force. Overall, this new coast-down technique demonstrates satisfactory repeatability and sensitivity for detecting deceleration changes during straight and turning trajectories, indicating that it can be used to evaluate resistive loss of different MWC configurations and maneuvers.

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Test method for empirically determining inertial properties of manual wheelchairs

Cited by 18 publications

References 9 publications

Changes in inertia and effect on turning effort across different wheelchair configurations

Changes in inertia and effect on turning effort across different wheelchair configurations

Influence of rolling resistance on manual wheelchair dynamics and mechanical efficiency

Evaluation of wheelchair resistive forces during straight and turning trajectories across different wheelchair configurations using free-wheeling coast-down test

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