Research On Accuracy About A 5-DOF Framework For Minimally Invasive Cerebral Surgery

Minimally invasive cerebral surgery is one of advanced technologies of cerebral surgery. Compared with traditional cerebral surgery, minimally invasive cerebral surgery's process is more direct, more safe and accurate, and it makes less wound of brain. A 5-DOF frame-structure surgical system, shown in this paper, is a new type of surgical robot system and with low cost and reasonable accuracy. It is specially designed for minimally invasive cerebral surgery. The executed accuracy of the 5-DOF surgical framework is focused on by this paper.Firstly, structural components of the surgical system, its functional characteristics and the surgery process are introduced briefly. It is indicated that all the errors caused by the main parts of the stereospecific surgery system, such as focus image recognition system, registration system and surgical framework and so on, will affect end-component's executed accuracy of the surgical framework. The errors rooted in every DOF of the surgical framework are emphatically analyzed, and this analysis provides a basis for single DOF's error calibration and the establishment of error model.Secondly, the method and final results of single DOF calibrations are introduced in detail, and synthesized error of the 5-DOF surgical framework is estimated based on the results of the above calibrations. On the basis of the 5-DOF surgical framework's structure, its system of coordinates is set and its kinematics model based on D-H model is put forward. A special template used for establishing error model of the 5-DOF surgical framework is introduced in the paper. The distance between two marks on this template is measured twice respectively by CMM and surgical framework. Then, the difference of two measured results is used for establishing the error model of the surgical framework.Therefore, the parameter errors of the 5-DOF surgical framework are obtained finally. At last, the design and calibration of a measure apparatus which be used for measuring the end-component's error, is introduced. And then, the end-component's accuracy before and after error compensation of the 5-DOF surgical framework and the established error model are appraised by means of this apparatus.