Normal Force Calibration for Optical Based Silicone Tactile Sensor

The need for calibration is important as ancient humankind at B.C. age pioneered calibration for measurable items such as length, weight, frequency and other basic measurement. In the robotic application, the precision of movement and the sensitivity of reaction also based on the calibration of its sensors and actuators. Therefore it is vital for a newly developed sensor to be calibrated thoroughly before it can be used. In this paper, the authors proposed a calibration of a new optical based silicone tactile sensor developed in our lab. Measurable item which is normal force is relates to the blob area of image recorded in the inner side of optical based silicone tactile sensor. The normal force acquired from digital force sensor in experiment conducted. The experiment produced 9 images. The 9 images acquired is processed in WiT 8.2 image processing software to find the area of the specific spot as known as blob image. A blob area VS normal force graph is plotted using experimental data. The graph is then interpolated using suitable curve fitting technique to get the optimum relationship. The result shows that the quadratic plot is the best suit for the data with the force range from 0 to 3.79 N.