Design And Analysis Of The Control System Of MRI-Compatible Breast Intervention Robot

With the high incidence of breast cancer, the therapeutic method is more and more important. Minimally invasive intervention operation based on image-guided is widely used. Among the image navigation technologies, MRI(magnetic resonance imaging) has the best imaging effect, the highest detection rate. Therefore, the study on breast intervention robot which can work in MRI environment and the control system of it has an important significance. However,due to the special environment of MRI, the robot has to work in strong magnetic environment. In addition, high positioning accuracy is required. Therefore, this poses a problem for the design and research of the control system of breast interventional robot which can work under the condition of nuclear magnetic resonance. In this thesis, based on the breast intervention robot, the control rule of it is researched. The main contents are as follows:Firstly, the structure characteristics of breast intervention robot is analyzed and the link coordinate system is established based on D-H method. According to the kinematics knowledge, joint variables and geometric parameters of the robot are obtained. And according to the method of direct and inverse kinematic analysis, the transformation matrix of direct solution and the implicit equation of inverse solution are obtained. Then, the relationship between the joint variables,the geometric parameters and the relative position of the end parts of the robot are achieved.Secondly, according to the work requirements of the robot, the overall control scheme in the form of “PC + SCM”(“ Personal Computer + Single Chip Microcomputer”) is designed. The master computer and the slave computer are included in this scheme. Arduino Mega 2560 microcontroller is chosen as the control unit. And the power supply circuit, communication circuit and some other circuit are designed. Stepper motor, motor driver and other hardware parts of thecontrol system are obtained, Stepper motor system simulation model is established by using MATLAB/Simulink, and current subdivision module of it is researched. The way of connection between all the components is illuminated,hardware of control system had been established. The microcontroller control program is made by using Arduino IDE. PC control interface is designed by using Lab VIEW 2012, and communication with the Arduino Mega 2560 microcontroller through the serial port is achieved.Finally, the experimental platform is built according to the whole structure and the characteristics of the motion of the breast intervention robot. Robot position control experiment has been carried out. The case of deviation which are from the experiment is analyzed. The same experiment has been carried out again after data-fitting and pulse compensation. Control precision is improved. And the result of the second experiment shows that the robot control system designed in this thesis can meet the requirements. This research lays a good foundation for further research and application.