(Georgia Institute of Technology, 2018-11)
Huang, Morris; Misch, Jacob; Sprigle, Stephen
The 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.
(Georgia Institute of Technology, 2014)
Liles, Howard; Huang, Morris; Caspall, Jayme; Sprigle, Stephen
A 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.