Design And Study Of Infrared Optical Positioning System In Surgical Navigation Based On Fpga

In recent years, modern medical surgery is developing towards the direction of precision and minimally invasive, thus leading to the research in surgical navigation system. Optical positioning system using CMOS sensor benefits from capability of both passive and active tracking, consequently become the main direction of development.This thesis gives an intensive study to the positioning theory of binocular vision and hardware properties of embedded systems, sets up an infrared optical positioning system based on FPGA and SOPC, achieves the marker locating and tracking in real-time. The main contents of this thesis are as follows: [1] Introducing the direct linear transform (DLT) method and epipolar constraint method to 3-D coordinates reconstruction based on CMOS sensor, also gives and demonstrates how to calculate the inner and outer parameters besides calibrating the positioning system. [2] Design and develop an infrared optical positioning system prototype according to the binocular theory, complete the hardware and software design. System implementation starts from the CMOS sensor at the front end, image sensor driver as well as the centroid extraction of the markers are all accomplished by FPGA. Image cache and VGA display are designed to facilitate system debug. In addition, the mechanical structure is developed for fixing and packaging the system. [3] In order to overcome the lack of computation ability on Nios II processor, hardware acceleration for 3D reconstruction computation is proposed and calculating speed gets a significant promotion, this makes the 3D reconstruction work can be done by embedded hardware platform. [4]A high accuracy platform is established to calibrate the system and a fine experiment result is acquired. Some key problems such as image storage during the calibration flow are also solved. In summary, for the special application of positioning and tracking during the surgical navigation, this thesis has accomplished the research and development of the real-time, high precise 3-D optical positioning system for multiple markers tracking. The test result indicates that the system has got a submillimeter positioning accuracy and update rate of 60Hz.