MATLAB-based elastomer surface profilometer using PC soundcard data acquisition and linear variable differential transformer

Abstract

This paper presents a MatLab-based 3D surface profilometer intended for elastomer materials. MatLab controls the x, y, z stepper motors via the printer's parallel port. The instrument utilizes a linear variable differential transformer (LVDT) as its depth sensor, interfaced to the computer through the soundcard. Three tests were done to observe the stability of the LVDT response and the correlation of manually obtained data using VOM and soundcard data. Soundcard data varied linearly with VOM data by a factor of 13. The profilometer has a vertical sensitivity of 1.379 mm/V and step distance of 0.0184 mm in the x and y directions. It has a linear operating range of 6.895 mm extending to 11.031 mm with slight non-linearity. An optimum location for the cylindrical core was found to minimize the number of spikes in test line scans. Test scans show a vertical resolution of 10 microns at a scan speed of 0.184 mm/s.