Data Acquisition System for a Medical Tracking Device based on a Novel Angular Sensor : How to Acquire and Process Data from the ASTRAS Tracking System

This research is part of the MIRACLE project (Minimally Invasive Robot-Assisted Computer-guided LaserosteotomE) dedicated to the development of a robotic endoscope to perform minimally invasive laser osteotomies (bone cutting). In this framework, we developed a novel angular sensor called ASTRAS (Angular Sensor for TRAcking Systems) to serve as basic element of a tracking system for articulated devices (e.g. an articulated robotic endoscope). At each joint of the articulated endoscope one ASTRAS sensor is positioned, so that its shape and the pose of its tip can be calculated from the angle measurements. In ASTRAS, the angle is evaluated with high precision by processing the image cast by a shadow mask onto an image sensor. For an articulated endoscope, the acquisition and processing electronics of its tracking system based on ASTRAS has to fulfill the following requirements: 1) acquire and synchronize raw-data from the image sensors; 2) process the images in real-time to compute the angles; 3) provide one channel per endoscope joint; 4) be embedded in a small electronic device (e.g. a single-board computer). In this paper, we propose a solution based on an Field Programmable Gate Array (FPGA) that can acquire raw data from the image sensors, synchronize, and process them. The proposed system has an embedded processor running an operating system (Linux) such that it can easily implement software solutions for both processing and communication. In addition, we also present the results of a preliminary test of the first prototype and show some novel ideas of development.