C . Taylor, A. C olchester (Ed.): M I C CAI´ 99, LNCS 1679, pp. 1125 -1132, 1999.  Springer-Verlag Berlin Heidelberg 1999 Image-Based Control of Interactive Robotics Systems Andreas Hein and Tim C. Lueth Surgical Robotics Lab (SRL) Clinic for Maxillofacial Surgery, Charité Virchow-Hospital, D-13353 Berlin, Germany {a.hein, t.lueth}@ieee.org http://www.charite.de/rv/mkg/srl/index.html Abstract. In this paper a robotics system is described which supports the sur- geon during drilling and shaping operations. The special feature of this system is the fusion of control commands by the surgeon and control commands derived directly in real-time from the image data of the patient. This interactive control of a robotics system leads to a cooperation between the surgeon and the robotics system. Because the robotics system can directly access to the image data within every control cycle it provides a higher accuracy and an enhanced safety of drilling operations. A tool for the quantitative analysis of the image data, the interactive control system of the robotics system and the first application in Anaplastology is presented. 1 Introduction Surgery is a relatively new and a rapidly growing field of application for robotics technology. Robots can be used to enhance the accuracy and the dexterity of a sur- geon, can decrease the tremble of the human hand and can amplify or reduce the movements and/or forces applied by the surgeon. Especially in fields of surgery where the human hand is the limiting factor for further optimization of the surgical tech- niques –like in neurosurgery, orthopedic and maxillofacial surgery– robotics technol- ogy can be applied. The drilling or shaping of bone structures is of great importance for surgery. In con- trary to soft tissue a static model of bone structures derived from CT images can be used. Currently, these operations are carried out by the surgeons free hand during an intervention. In the near of sensitive regions the manual handling can lead to compli- cations due to inaccuracies or shattering of the drill or shaper. Especially in maxillofacial surgery the accuracy of an intervention is of paramount importance due to the high social and aesthetic impact of the face. Therefore, the po- sitioning and moving of drills or shapers with a high accuracy is desirable. Additional difficulties in maxillofacial surgery are the restricted access to the bone structures through small incisions, the swelling of tissue during the intervention, and the small distance to vital organs or structures.