Research On Fruit Peeling Technology Based On Line Structured Light Stereo Vision

With the improvement of the quality of life,people eat more and more fruits,especially the healthy and fast drinks represented by freshly squeezed juice are more and more popular.For the sake of health and hygiene,as well as the taste of juice,the dirt on the skin of the fruit needs to be removed before juice,or even the peel is directly removed.At present,fruit juicers generally use the skin to squeeze the fruit after washing.The mechanical peeling technology used in some applications,its peeling effect and efficiency are not satisfactory,which affects the popularization and application of automatic juice extraction technology.With the development of non-contact measurement technology represented by machine vision,scanning technology based on line structured light has been widely used in the production and processing process.Therefore,according to the difference in the peeling process parameters of thin-skinned fruits represented by apples and thick-skinned fruits represented by oranges,this paper carried out a research on an automatic fruit peeling system based on line structured light stereo vision to measure the shape characteristics of fruits.The main research contents are as follows:(1)Design the overall scheme and work flow of the automatic fruit peeling system for the established application scenarios,scope of use and accuracy requirements,and use Solidworks to establish a three-dimensional model of the experimental device.According to the fixed position and diameter of the apple in the three-dimensional model,determine the stroke of the motion module,determine the reasonable arrangement of the binocular camera and the line laser;then select the industrial camera with the appropriate focal length,and ensure that the two cameras have clear imaging and the effective image area is moderate;Determine the structural design of the tool;select a reasonable PLC controller;realize the construction of the entire experimental platform.(2)In-depth study of the principle and method of 3D reconstruction of fruit shape based on line structured light.First complete the camera parameter calibration experiment in the vision system,analyze the internal and external parameters and distortion coefficients in the camera calibration,and perform stereo correction of the camera;then use the line structured light scanning technology to realize the three-dimensional reconstruction of the fruit,and propose a combination of the gray barycentric method and the Steger method The improved method of obtaining a high-precision light bar center;the calibration of the rotation axis coordinates of the turntable is achieved through the stereo target,and the conversion of the left camera coordinate system to the rotation axis coordinate system is achieved,and the laser stripes are established in the rotation axis coordinate system to complete the fruit.3D point cloud reconstruction,the results are compared with the actual measured value,the error is within ±0.5mm;finally,according to the established 3D point cloud model,the path points of the peeling tool are extracted and generated.(3)Aiming at the thickness of thick-skinned fruits such as oranges,in order to ensure the peeling effect,the distribution law between the outer contour characteristics of the orange peel and the thickness of the orange peel was analyzed,and a model of the thickness distribution of the orange peel was established.The inner and outer contour features of orange peel are automatically extracted to obtain the peel thickness data of a specific batch and variety of thick-skinned fruits.(4)The control system of the fruit peeling device based on line structured light is designed.The three-dimensional model of the fruit,the thickness distribution law of the peel,the cutter structure and the peeling trajectory are automatically measured by the PC host and the PLC controller according to the structured light stereo vision technology.Point,control the cutter to realize reasonable continuous feeding and tangential feeding for thin-skinned apples and thick-skinned oranges,and complete peel cutting.The research in this article is helpful to reduce the waste water produced by fruit washing in the industrial field,improve the utilization rate of fruit pulp,improve the efficiency of fruit cutting,and provide necessary technical support for the promotion and application of fruit automatic juice extraction technology.