Study On The Picking Strategy And Walking Trajectory Planning Of Blueberry Picker

As the health benefits form the natural antioxidant fruit such as blueberry are getting known, demand for the blueberries is also growing. Blueberry is widly used in food, medicine, chemical industry and other fields. So it is obvious that the economic benefits to cultivated blueberry is great, and it will be an inevitable trend to expand the planting area. Because the blueberry harvesting is depent on entirely manual labor in our country, and the harvesting season is short, picking cost is large and the picking efficiency is low, the economic losses are always causes because the fruits could not be harvested in time. The blueberry fields could not be expanse because the same reason. So developing picking machine is a urgent task in our country.In order to realize the mechanization and automation of blueberry picking, a kind of high efficient and intelligent blueberry picking machine should be studied, and its key technologies should be overcome. Two key technologies will be studied here, the first is the picking strategy. In order to realize efficient and safe picking, the picking strategy must be confirmed,which includes the vibration magnitude and direction,motion parameters of picking machine and so on. The3-d growth model of blueberry plants is establish with the measured data, and the mechanical model and vibration model of blueberry tree could also be established. All these will become a foundation for designing the picking machine. The second key technology is track navigation of the picking machine. Because of unilateral traction, the sunken ground, the specific planting condition and other reasons, a deflection occurs a lot when blueberry walking along the planting ridge. Because the distance of strain and the ridging are fixed, the picking space of the machine is restricted, a slight deflection may cause blueberry plants overwhelmed even roots scratch. It is very necessary to guide walking path of the picking machine.The morphological structure model of blueberry plant is analyzed and set up with the measured data and abstract simplification. According to the theory of virtual plant, the plant model is established on the purpose for trees dynamic analysis. With L system theory and3-d modeling software ProE, with the VRML and OpenGL virtual reality technology, and based on the characteristic of blueberry tree structure, the virtual model of blueberry plants is established and achieved, the visualization simulation of blueberry picking process is realized.After the vibration characterastics of the blueberry branches are analyzed, such as complex, multi-freedom, nonlinear, blueberry branches were simplified as variable cross-section continuous vibration system, the axial and radial vibration models are established, then the vibration models are simulated with Matlab, the source of vibration that separate the fruits and branchs is confirmed. The stresses on blueberry branches in picking machine work space are analysed in different position and different angle, the extra picking vibration need in picking ripe fruit is evaluated. Thus the design for picking machine structure and working parameters will be provided from these.According to the environment of the blueberry planting farm, the sequence of identifying and locating of blueberries and the trees is conformed, the methods for image segmentation, out-noising, filtering, binary are studied according to blueberry characteristics. The blueberry trees outline is got with the Canny edge detection according to the principle of image segmentation, then the centerline of the blueberry tree is got to heading the direction of the blueberry picking machine, so the track guide could be finished. According to the difference color between mature blueberry and background, the quantity of the ripe fruits of blueberry trees may be estimated, through which the picking parameters of blueberry machine could be adjusted, then the automatic picking strategies is confirm, and the intelligent picking propose is realized.According to the structure characteristic and movement characteristic of blueberry picking machine, the reasons of deflection and movement interference when the machine was walking were analyzed, and according to the planting condition and the size of the machine, the mathematical models for the track boundary conditions and the safe turning distance of the picking machine were got,and the picking track is planed and designed, a reasonable picking path of blueberry picking machine is achived.