Design of a Robotic System to Measure Propulsion Work of Over-Ground Wheelchair Maneuvers.

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.

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

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.

Partitioning kinetic energy during freewheeling wheelchair maneuvers.

This paper describes a systematic method to partition the kinetic energy (KE) of a free-wheeling wheelchair. An ultralightweight rigid frame wheelchair was instrumented with two axle-mounted encoders and data acquisition equipment to accurately measure the velocity of the drive wheels. A mathematical model was created combining physical specifications and geometry of the wheelchair and its components.

Validation of an accelerometer-based method to measure the use of manual wheelchairs.

The goal of this project was to develop and validate a methodology for measuring manual wheelchair movement. The ability to study wheelchair movement is necessary across a number of clinical and research topics in rehabilitation, including the outcomes of rehabilitation interventions, the long-term effects of wheelchair propulsion on shoulder health, and improved wheelchair prescription and design. This study used a wheel-mounted accelerometer to continuously measure distance wheeled, and to continuously determine if the wheelchair is moving.

Test method for empirically determining inertial properties of manual wheelchairs.

The iMachine is a spring-loaded turntable used to measure inertial properties of irregularly shaped rigid bodies, specifically manual wheelchairs. We used a Newton-Euler approach to calculate wheelchair mass and center of mass (CM) location from static force measurements using load cells. We determined the moment of inertia about the vertical axis from the natural frequency of the system in simple harmonic motion.

Assessment of an ultrasonic dermal scanner for skin thickness measurements.

The measurement precision of a 20 MHz ultrasound dermal scanning system, Episcan, manufactured by Longport Inc. was investigated for its use in the measurement of skin thickness. Results from measurements of relatively ideal homogeneous, uniformly thick plastic plates indicate that the scanner can accurately measure to depths of 8-34 mm from the surface of the transducer or approximately 18 mm from the surface of the latex probe-cover with a high level of precision, less than 1% of the mean thickness.