An Automatic Microinjection System Of Zebrafish Larva Heart Based On Visual Localisation

Zebrafish(Danio rerio)is the best model for the study of physiological and pathological processes.It has always been playing an important role in embryo,genetics,biology and genomics.Previous studies have focused on embryo injection or cell injection,but few studies have been done on zebrafish,such as drug screening,disease models,reproductive endocrinology,and neuroscience.In this thesis,based on the design of a juvenile microinjection system,visua l positioning,image processing,motion control and other means are used on the study of heart automatic microinjection of zebrafish larva.In the past,the targets of microinjection,such as animal cells or embryos with a spherical structure,which are relatively convenient for fixation and positioning.At the same time,it is very difficult to recognize the contour of the zebrafish because of the pigment deposition in the epidermis of zebrafish.Compared with the cells,zebrafish larvae are irregular in shape and have been fully differentiated,and higher requirements have been put forward for injection targets and injection directions.The mechanical platform is the foundation of automatic micr oinjection.In order to have quick,stable and reliable micromanipulation process,we need a mechanical platform with fast response speed,reliable stability,high precision.This thesis designs a more precise 3D micro mechanical platform and a rotary mechanism for juvenile attitude adjustment,with visual system mod ule,optical microscope,micro injection pump,vertical computer modules complete the automatic process of microinjection of zebrafish larvae.In the visual processing part,the optical image microscope CCD is used to process the image information in the host computer.The collected images are gray,two valued,and median filtering,which is convenient for subsequent processing.In order to inject several young fish,template matching and K mean clustering algorithm were used to obtain the number of young fish and the position of the center of gravity of each young fish.The body posture of young fish was obtained by flood filling algorithm and image chain code.According to the posture of the juvenile fish,the movement of the juvenile fish can be adjusted to the desired attitude with the movement control part of the system.The position of the heart can be estimated according to the contour and posture of the young fish,and the heart can be easily injected into the heart.The motion control system is mainly for control of micro 3D platform,so that the suction needle tip position according to the visual feedback in accordance with the preset trajectory well,and retention,fixation and adjustment of juvenile zebrafish posture in the tip,the reason mainly lies in the convenient injection needle to juvenile heart injection according to the same attitude,improve the success rate of automatic injection.In this section,an adaptive sliding mode controller is used to track the tip trajectory and simulate it.Simulation results show that the system output can well follow the desired output trajectory,which proves the effectiveness of the control system design.According to the design of the 3D platform system based on the visual image processing module controller and adaptive sliding mode,we carried out the research of cardiac microinjection experiments on zebrafish juveniles,analyzed the comprehensive performance of the system,which proved the rationality of the system.