Study On Precision Movement Control In Laser Capture Microdissection

Laser microdissection technology enables biological embryos,cells,and tissues to be cut and captured effectively.Therefore,this technology has been used widely in major research fields of life sciences such as embryo genetics,transgenics,and tumors.Due to the size limitation of the microscope,large-area dissection compromises the precision,which can not meet the needs of researchers.Coordinate calibration of screen and moving module and trajectory planning was studied to improve precision movement control in laser microdissection.In order to increase the microdissection precision especially in large-area,a five-point partition coordinate calibration method is proposed.This method is based on errors-in-variables(EIV)for laser microdissection,and was used to improve the conversion relationship between the screen coordinates and the motion model coordinates.In order to establish the EIV adjustment model,the quaternion was adopted.Besides this,Gauss-Helmet(GH)model was employed to help to realize the EIV model and the coordinate transformation obtained by the Total Least Squares(TLS)under the framework of variable error model.The precision of coordinate calibration is improved by optimizing the choice of calibration coordinate points and their relative screen positions.The results show that the precision of the five-point partition in the area of middle of the screen is the best – about 6 times higher than that of the linear calibration method,and verifies high effectiveness.A trajectory planning approach based on the nonlinear error compensation for laser microdissection was proposed to improve the microdissection accuracy in a large-area.The impact of selection of value points on trajectory planning was studied using CSS(Curvature Scale Space)corner detection.A method of B-spline trajectory planning was established by detecting the turning points of the motor and corner point of trajectory.When considering dynamic model of the cambered control device and motor constraint parameters,the trajectory planning strategy of complementary control of systematic errors without cumulative errors and with acceleration mutation is established on the condition of problem formulation of the cambered control device and motor constraint parameters.Further,simulation and experimental model show that the proposed method is similar as that of the equal proportion algorithm.However,the accuracy of this method is more than 4 times higher than that of the equal proportion algorithm in the case of the same numerical value point,and the risk of out-of-step is also smaller.The nonlinear problem of the system is fully considered in calibration and trajectory planning in this paper,and the precision of laser microdissection is further improved by algorithm optimization,which provides a powerful research and clinical application for major diseases.