Dynamic positioning sensing system for estimating size and depth of embedded object

Abstract

In this study, we developed a dynamic positioning sensing (DPS) system for estimating size and depth of embedded objects. The DPS System is comprised of a tactile imaging sensor (TIS), a near infrared diffuse optical imaging (DOI) unit. The TIS have a flexible and transparent sensing probe, a LED (light emitting diode) module, and a CCD camera with lens. The light from the LED-illuminated probe is scattered when a force is applied to the probe, and captured by the camera as a tactile image. TIS determined the tumor size by correlating applied force, depth and number of pixel in tactile image. On the other hand, using a near infrared laser as source and the CCD camera as detector, we obtained the diffuse optical images. From these images, we computed the absorption coefficient of the embedded tumor phantom. We maneuvered the source-detector simultaneously for collecting diffuse optics information. We termed this maneuver as dynamic positioning. The TIS provided a priori location information. The combination of the absorption coefficient, tactile data, and dynamic positioning method improved the size and depth estimation. The experimental results showed that the TIS estimated the tumor phantom size with 7.23% error, while the DPS System measured the size with 0.8% error. The TIS depth estimation error was 41.83%, and the DPS System reduced depth measurement error to 20.67%.