Berry picking method based on negative pressure suction principle and determining method of rated output pressure value of power source

The invention provides a tree internal flow field change model in a berry picking method based on negative pressure suction. According to the model, a suction head in a power source fits the surface of a tree body to conduct berry suction work, wherein the rated output pressure value of the suction head is P0, and the rated output air speed is u0; the x axis is horizontal, the original point is at an air inlet of the suction head, and the direction in which the surface of the tree body points to the trunk serves as the positive direction; k0 represents the gas compression coefficient, the air density is rho0, and the pressure value P is the pressure value of a certain point, on the x axis, inside the tree body; the density coefficient of the tree body is k; the berry tree is subjected to a wind field test, the initial air speed u1 on the surface of the tree body, the air speed u at a certain point, on the x axis, inside the tree body and the x coordinate value of the point are measured, and according to an ai