Instrumented Wheel for Wheelchair Propulsion Analysis
In this chapter the development of an instrumented wheel for use in a kinetic and kinematic study of manual wheelchair propulsion is presented. The instrumented wheel is a mechatronic device that is composed of a six-component load transducer and modules of signal conditioning, processing, and amplification. A slip ring is used for continuous operation and data transmission. The angular position of the wheel is measured by an encoder, and its resolution is mechanically amplified through a gear system. Two PCs are used in the system and are activated via a common mouse for consistent data acquisition in various tests. The loads applied by the wheelchair user on the handrim are calculated. The angular position of the wheelchair user’s hand on the handrim during the pushing phase (φ) is calculated by means of kinetic parameters without using a camera or a motion analysis system. The propulsion moment with respect to the hand coordinate system (Mhz) is calculated using φ. Next, a general uncertainty analysis is performed to determine the uncertainty equations for the local and global forces and moments, the local hand forces and moments, and the hand-contact angular position. The numerical uncertainty values for these parameters are calculated using the related equations. The results provide 4-2an estimate of the errors and uncertainties for the output of the instrumented wheel. Finally, a complete experimental procedure is performed to determine the specifications of the instrumented wheel. The static and dynamic test set-ups are designed, and tests are performed under different conditions. The results of the static and dynamic tests are used for both qualitative and quantitative verification of the system specifications.