RESNA 28th Annual Conference - Atlanta, Georgia
Figure 1 shows the schematic diagram of the entire experimental system, which consists of a wheelchair seat with an adjustable footrest, a strain gage based force plate, strain gages at the chair posts and the amplifier, a general-purpose digital video camera, a LED, a data acquisition system and a PC. The PC generates commands for data acquisition and digital out for triggering via a multi-function I/O board. To synchronize the video measurements with the force measurement, the LED is triggered simultaneously with the starting time of force measurement. This figure also shows the developed programs, including the LabVIEW TM based data acquisition program, the video image processing program and the inverse dynamic analysis program, both developed with MATLAB ®. The image processing program tracks the markers attached to the human subject so as to generate coordinates of the joints and other points of interest. The estimated joint coordinates are further used to estimate the other coordinates, for example, angles of body segments, from the kinematic relations and to determine the unmeasured forces and torques from the inverse dynamic analysis. The data acquisition and processing program converts analog force signals into digital data. The inverse dynamic analysis program inputs the estimated joint angles and the digital force data and to result in the unmeasured forces and torques.