Analysis of mechanical and electrical noise interfacing the instrument during data acquisition: development of a machine for assessing surface properties of fibers

A new compression test unit was developed for the assessment of the surface properties of fibers. In order to measure the variation in the compression force during a test, a full bridge load cell was developed. It was seen that the signal coming from the strain gages was superimposed with noise. It was also found that the noise was from both electrical and mechanical sources. An extensive mathematical analysis of mechanical noise and the application of a mechanical noise reduction technique minimized the mechanical noise component. Analysis of electrical noise showed that the motion control card was interfacing with the data acquisition (DAQ) card via both the RS232 and the AC power line. It was necessary to separate the motion control unit and the DAQ unit in order to eliminate the electrical noise problem present in the system. After eliminating the noise from the unit, the calibration of the strain gages has been performed. The coefficient of correlation was found 1.00 with a cubic model.