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Rehabilitation Engineering and Applied Research Lab (REAR Lab)
Rehabilitation Engineering and Applied Research Lab (REAR Lab)
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ItemModeling manual wheelchair propulsion cost during straight and curvilinear trajectories dataset(Georgia Institute of Technology, 2020-05-11) Misch, Jacob ; Huang, Morris ; Sprigle, StephenMinimizing the effort to propel a manual wheelchair is important to all users in order to optimize the efficiency of maneuvering throughout the day. Assessing the propulsion cost of wheelchairs as a mechanical system is a key aspect of understanding the influences of wheelchair design and configuration. The objective of this study was to model the relationships between inertial and energy-loss parameters to the mechanical propulsion cost across different wheelchair configurations during straight and curvilinear trajectories. Inertial parameters of an occupied wheelchair and energy loss parameters of drive wheels and casters were entered into regression models representing three different maneuvers. A wheelchair-propelling robot was used to measure propulsion cost. General linear models showed strong relationships (R2 > 0.84) between the system-level costs of propulsion and the selected predictor variables representing sources of energy loss and inertial influences. System energy loss parameters were significant predictors in all three maneuvers. Yaw inertia was also a significant predictor during zero-radius turns. The results indicate that simple energy loss measurements can predict system-level performance, and inertial influences are mostly overshadowed by the increased resistive losses caused by added mass, though weight distribution can mitigate some of this added cost. Videos of the test methods used to collect this dataset (wheelchair-propelling robot performing the three maneuvers, coast-down cart test for rolling resistance, and the scrub torque test rig) can be found here: http://hdl.handle.net/1853/60553
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ItemVideo Demonstrations of Component- and Systems-Level Test Methods for Wheelchair Propulsion Characterization(Georgia Institute of Technology, 2018-11) Huang, Morris ; Misch, Jacob ; Sprigle, StephenThe five videos included in this repository demonstrate the fundamental test methods used to characterize performance of various wheelchair components. The Anatomical Model Propulsion System (AMPS) was designed to emulate the weight distribution and force application of a human wheelchair user. Three canonical maneuvers were identified to quantify the effects of rolling resistance, drive wheel scrub, and caster swivel. The ‘AMPS straight.mp4’ file shows the straight maneuver. ‘AMPS left FW turn.mp4’ demonstrates a fixed-wheel turn, where one wheel is locked and scrubbing against the floor as the chair drives the other wheel. The ‘AMPS CCW.mp4’ shows an alternating zero-radius maneuver designed to cause caster swivel by driving the wheels in opposing directions. Also included in this directory are videos representing the standalone coast-down and scrub torque component tests. ‘Caster Wheel Coast-down Test Video.m4v’ shows the coast-down cart loaded with weights and instrumented with accelerometers to log the deceleration of the cart. This test measures the force of rolling resistance acting on the cart. The final video, ‘scrub test demo.mp4’, shows the test rig used to measure scrub torque. A ZwickRoell materials testing machine pulls the steel cable attached to a pulley system, which rotates the load arm and effectively scrubs the tile or carpet swatch against the fixed wheel. These videos were taken in 2017 to use as demonstrations for future researchers and collaborators. More information can be found in Morris Huang’s dissertation located at http://hdl.handle.net/1853/59253.
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ItemDevelopment of component and system level test methods to characterize manual wheelchair propulsion cost(Georgia Institute of Technology, 2017-11-10) Huang, MorrisThe current approach to manual wheelchair design lacks a sound and objective connection to metrics for wheelchair performance. The objective of this research was three-fold: 1) to characterize the inertial and resistive properties of different wheelchair components and configurations, 2) to characterize the systems-level wheelchair propulsion cost, and 3) to model wheelchair propulsion cost as a function of measured component and configuration properties. Scientific tools developed include 1) a series of instruments and methodologies to evaluate the rotational inertia, rolling resistance, and scrub torque of wheelchair casters and drive wheels on various surface types, and 2) a wheelchair-propelling robot capable of measuring propulsion cost across a collection of maneuvers representative of everyday wheelchair mobility. This suite of tools were used to demonstrate the variance manifested in the resistive properties of 8 casters and 4 drive wheels, and the impact/tradeoffs of these components (as well as mass and weight distribution) on system-level wheelchair propulsion cost. Coupling these findings with a theoretical framework describing wheelchair dynamics resulted in two empirical models linking system propulsion cost to component resistive properties. The outcomes of this research empower clinicians and users to make more informed wheelchair selections, as well as offer manufacturers a basis by which to optimize their wheelchair designs.
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ItemDesign of a Robotic System to Measure Propulsion Work of Over-ground Wheelchair Maneuvers(Georgia Institute of Technology, 2014) Liles, Howard ; Huang, Morris ; Caspall, Jayme ; Sprigle, StephenA wheelchair-propelling robot has been developed to measure the efficiency of manual wheelchairs. The use of a robot has certain advantages compared to the use of human operators with respect to repeatability of measurements and the ability to compare many more wheelchair configurations than possible with human operators. Its design and implementation required significant engineering and validation of hardware and control systems. The robot can propel a wheelchair according to pre-programmed accelerations and velocities and measures the forces required to achieve these maneuvers. Wheel velocities were within 0.1 m/s of programmed values and coefficients of variation (CV) < 2%. Torque measurements were also repeatable with CV <10%. By determining the propulsion torque required to propel the wheelchair through a series of canonical maneuvers, task-dependent input work for various wheelchairs and configurations can be compared. This metric would serve to quantify the combined inertial and frictional resistance of the mechanical system.