Pushtracker

---- PROTOTYPE --------- PURPOSE: To create a prototype tracking device (PushTracker) to monitor activity levels of individuals with lower extremity and mobility disabilities, spinal cord injury and others who use manual wheelchairs. The PushTracker allows manual wheelchair users to monitor their activity on an hourly, daily, and monthly level and includes data on average cadence, push distance, and total number of pushes. This device allows a manual wheelchair user to measure how he or she pushes in the natural environment and access his or her propulsion technique in comparison to PVA Clinical Practice Guidelines for the Preservation of Upper Limb Health following Spinal Cord Injury. Commercial bike cyclometers and pedometers were tested and found incapable of identifying the necessary information related to push and acceleration. The PushTracker combines an accelerometer and a wheel mounted magnet system to detect pushes and measure distance. A custom printed circuit board (PCB) with an onboard ARM7 microcontroller was created to read and power the accelerometer. The microcontroller used an algorithm specifically designed for this project that filters and interprets the accelerometer’s output in real time to detect pushes. The PCB contained a battery recharge circuit, which allowed the device to be recharged with a computer’s USB port. Additionally, the PCB also held an onboard microSD card to store data and an OLED screen to display data. An attached thumb knob allowed users to cycle through a menu showing their cadence, distance, and number of pushes over time periods ranging from hours to months. The microcontroller pins were set to either sense switch closures from the magnet during use or were switched to USB data transfer mode when downloading data to the computer for additional viewing. The magnet and magnet sensor arrangement was developed to mimic a cyclometer. The system used a small plastic ring with embedded magnets. The ring was placed on the outer face of the wheel bearing and held in place by its own magnetic force. The magnet ring spun around with wheel as it rotated. A magnet sensor was then placed at the distal end of the axle receiver and secured in place. In the case of this design, the magnet sensor was integrated into a a plastic enclosure that wass threaded onto the end of the axle receiver. Because the magnet sensor was above the axle tube and within the wheelchair frame, it was protected during transport. The magnet sensor could be connected to the PushTracker via a USB cable, allowing it to be easily disconnected and reconnected for viewing. The PushTracker prototype was tested and evaluated compared to the values obtained by an OptiPush commercial device. The PushTracker prototype allows users the ability to monitor their pushing habits over time. The capacity to monitor trends empowers users to take control of their own health and mobility in connection with his or her treatment team. This device was entered into the RESNA 2011 Student Design Competition where it placed as a semi-finalist under the outcome & quantitative measurement (OUT) category. TITLE: The PushTracker: An Activity Monitor for Manual Wheelchair Users. JOURNAL: RESNA Student Design Competition. REF: http://aac-rerc.psu.edu/wordpressmu/RESNA-SDC/2011/04/28/the-pushtracker....