Mechanism Design And Laparoscope's Following/Forecasting Kinematics Method Study On Slave System Of A Laparoscopic Minimally Invasive Surgical Robot

With the development of robotic technology and application of minimally invasive surgery (MIS), the laparoscopic minimally invasive surgical robotic system is developed based on robotics and minimally medical science as the key technologies, the advantages include precise object positioning, easy to realize MIS, performing master-slave control and remote surgery, significant reductions of patients' pain and recovery time.Through the further research on the composition of master-slave laparoscopic minimally invasive surgical robotic system,the overall system scheme is established,and proposing a slave system which is consist of two instrument arms and one laparoscope arm. Based on the analysis of the three robotic arms' operation space, in order to realize good versatility of the robotic arms, an 8 degrees of freedom (DOFs) redundant versatil mechanical arm and 3 DOFs micro device are designed and trial complete the key experimental prototype. Discussing the composition of one-armed 8 DOFs robot assisted laparoscopic surgery navigation system and 11 DOFs robot assisted surgical system, as well as the combination scheme of 3-arms slave system.According to the characteristics of 8 DOFs laparoscope arm and 11 DOFs instrument arms,the kinematics coordinate systems and the forward/inverse kinematics models are established based on D-H method, the only inverse solutions are calculated according to the active joints' range of movement. Then the kinematics simulation models of laparoscope arm and instrument arm are established using the Simulink toolbox of Matlab, and verifying the correctness of forward/inverse kinematics,and analyzing the operation space of laparoscope arm and instrument arm.Proposing a kinematics algorithm for the laparoscope visual window's automatic tracking instrument arms' the mark points, in order to guarantee the micro devices'distribution ratio in the area of the visual window, the doctor does not switch the master-slave control object and can keep the visual window's tracking movement effectively. The general base coordinate system is established, through deep analysis the robotic kinematics and space analytic geometry, the mathematical expressions of the laparoscope following movement algorithm is calculated; meanwhile, the simulation program is wrote using the function M-file of Matlab, inputting two set of mark points' typical trajectory curve, and outputting the automatic following trajectory curve of laparoscope's end, and the condition determination angles are presented to illustrate the feasibility and correctness the of this kinematics method.Establishing a kind of forecasting kinematics algorithm for laparoscope, firstly discreting mark points' trajectory curve into sequence position vector, using the adjacent 6 elements Verhulst grey model to predict the mark points' position vector,then using the laparoscope's following kinematics algorithm to calculate the forecasting trajectory curve of laparoscope's end. Finishing simulation program using the function M-file of Matlab,analysis the forecasting trajectory curve and relative error under different discretization sampling times,the simulation results show that there are some mutation values near the trajectory inflection point, the following algorithm is inaccuracy; therefore, establishing a prediction correction algorithm,through a large number of simulation, compared the simulation results,this prediction correction algorithm is turned out to be effective and feasible,the prediction accuracy of laparoscope's trajectory curve is greatly increased, the continuous and smooth of the curve is enough to macth the demands of the actual system performance.