Collision Response Of Surface Modeled Organs For Virtual Laparoscopic Surgery

Laparoscopic surgery is a modern surgical procedure in which, operations are performed in the abdomen by monitoring the image from a laparoscope: a telescopic rod lens system, which is usually connected to a video camera with a halogen or xenon light source, and is inserted into the abdomen through a small incision. Generally, laparoscopic surgeries are chosen over open surgery because of lower pain and speedier recovery process. However, the surgeon needs additional training in performing such surgery since laparoscopic camera reflects 2D mirror image of hand movement and depth information of the scene is harder for the surgeon to judge. Hence, surgical trainers for laparoscopic surgery are very important. Virtual Reality based surgical simulators in particular are becoming popular.This thesis describes a virtual reality based surgical simulator and examines the problem of collision response that occurs during the interaction of a surgical instrument with deformable tissue. Collision detection algorithms are discrete-time algorithms and take few milliseconds on average to detect and report a collision. The processing of multiple collisions detection further complicates the matter. There is also a high change of missing the exact instant of collision. This research mainly investigates the unseemly interpenetration of the objects caused by such discrete time collision detection. It then proposes an innovative method of using the bounding volume of the object in runtime to find collision information to overcome such interpenetration. The propose algorithm is implemented and validated in an existing surgical simulator at the Virtual Environment Laboratory.