New Approach to the Open Loop Control for Surgical Robots Navigation

Robotic and computer-assisted technology are increasingly being developed for use in surgery to aid surgeons in providing more precision and accuracy, especially during procedures requiring fine movements. Moreover, reproducibility is another important aspect to be considered to achieve better results. This paper presents a navigation system developed to assist orthopaedic surgery with application in open loop control of the robots used for femur drilling procedures. Although it may have other applications, the system was thought to be used in Hip Resurfacing (HR) prosthesis surgery to implant the initial guide tool. The navigation system does not require any marker implanted in the patient, unlike current systems. The location of the bone in the operating room is obtained through the information from ultrasound (US) images and Computer Tomography (CT) images, obtained respectively in the intra-operative and pre-operative scenarios. During the surgery the bone position and orientation is obtained through a registration process between the US and CT, using an optical measurement system (Polaris) to measure the 3D position of passive markers attached to the US probe and to the drill. The system description, image processing, calibration procedures and results with real experiments are presented and described to illustrate the system in operation.