ABSTRACT
The data acquisition card was selected in consideration of sampling frequency and required channels. In order to get evenly sampled series along its walking displacement, an external clock was assigned by another encoder. The encoder was fixed to a wheel of the device, it could provide 1000 pulses while the wheel rotated a circle. Then the data acquisition card kept acquiring samples according to the encoder pulses. When the device stopped walking, a data acquisition process was done. The data acquisition card sent these data to the touchscreen computer. However, the signal data acquired contained fake and disturb signals. Digital filtering progress was quite necessary. Because the digital filtering program is professional and complex, it is feasible to handle the digital filtering program with a professional toolkit, such as Matlab software. The bridge communication between Matlab and main programming tool, selected as Visual Studio, could be finished by a DLL (dynamic link library) file, as shown in Fig. 2.
