Patent ID: 11878328
Assignee: JIANGSU UNIVERSITY
Field: Chemical engineering (Chemistry)
Classification: CPC B  G | IPC B  G

Claim 0:
1. A color sorting method for small-grain agricultural products combining an area scanning photoelectric characteristic and a line scanning photoelectric characteristic, characterized by comprising the following steps:
step I, performing area scanning identification on the small-grain agricultural products, comprising the following processes:
process I, erecting an area scan camera above an outlet of a conveyor belt of a material conveying device, setting a width of an area scan area of the area scan camera to be equal to a width W of the conveyor belt, and meanwhile setting a length of the area scan area of the area scan camera as L and setting a conveying speed of the conveyor belt as V0; and starting the area scan camera cyclically to obtain an area scan image I_t of the area scan area containing M×N pixels at each of different moments of t;
process II, analyzing the small-grain agricultural products in the area scan image I_t by using an image processing algorithm, extracting area array features of single-grain agricultural products in the area scan image one by one, identifying unqualified agricultural products in the area scan image I_t according to the area array features, and marking areas A_t_1, A_t_2, . . . , A_t_(n−1), and A_t_n corresponding to the unqualified agricultural products, wherein n is a number of particles of the unqualified agricultural products in the area scan image I_t, and a value of n is a natural number; and
process III, establishing a rectangular coordinate system by taking a y-axis of a conveying direction of the conveyor belt as a positive direction, a lower left vertex of the scan area of the area scan camera as a coordinate origin (0, 0), and a pixel point as a minimum unit of a coordinate scale; and locating center pixels P_t_i (x, y) of areas A_t_i corresponding to the unqualified agricultural products one by one, calculating time Δt1_i required for the unqualified agricultural products of the A_t_i to move from a position at a moment of t to a line scan area, and arrangement orders p_i of the unqualified agricultural products of the A_t_i along an x-axis direction in the current area scan image I_t so as to determine positioning parameters K_t_i (t, i, Δt1_i, p_i) corresponding to the unqualified agricultural products of the A_t_i, and feeding back the positioning parameters to a central control module, wherein i∈[1, n];
step II, performing line scanning positioning on the unqualified agricultural products during falling of the agricultural products, comprising the following processes:
process i, starting a line scan positioning camera by the central control module at moments of t+Δt1_i successively in an order of the Δt1_i from small to large according to the positioning parameters K_t_i (t, i, Δt1_i, p_i) corresponding to the area scan image I_t fed back in step I to obtain line scan signals L_t_i corresponding to the unqualified agricultural products of the A_t_i, wherein a number of pixels is H;
process ii, returning a signal value less than or equal to h in the L_t_i to 0 by taking the h as a denoising threshold, then calculating a peak width F_t_i corresponding to a (p_i)-th peak in the L_t_i, and calculating a pixel position D_t_i corresponding to a half-peak width (F_t_i)/2; and
process iii, determining a pneumatic sorting nozzle q_i corresponding to the unqualified agricultural products of the A_t_i in combination with the D_t_i according to a calibrated corresponding relationship between a line scan signal pixel and a position of the pneumatic sorting nozzle; and meanwhile, calculating time Δt2_i required for movement from a position of the unqualified agricultural products of the A_t_i to an action site of the pneumatic sorting nozzle at the moment of t+Δt1_i so as to determine sorting parameters Q_t_i (t, i, Δt1_i, Δt2_i, q_i) of the unqualified agricultural products of the A_t_i, and feeding the sorting parameters back to the central control module; and
step III, performing pneumatic sorting on the unqualified agricultural products, comprising the following processes:
controlling an airflow ejected from the (q_i)-th pneumatic sorting nozzle by the central control module at the moments of Δt1_i+Δt2_i successively in the order of Δt1_i+Δt2_i from small to large according to the sorting parameters Q_t_i (t, i, Δt1_i, Δt2_i, q_i) corresponding to the area scan image I_t fed back in step II to change a falling trajectory of the unqualified agricultural products of the A_t_i and realize pneumatic sorting on the unqualified agricultural products,
wherein in step I, a method for determining the time Δt1_i required for the unqualified agricultural products of the A_t_i to move from the position at the moment of t to the scan area of the line scan positioning camera comprises Δt1_i=Δt1_i_1+Δt1_i_2, wherein Δt1_i_1 is time required for uniform linear motion of the unqualified agricultural products of the A_t_i from the moment of t to an end of the conveyor belt, and Δt1_i_2 is time for horizontal projectile motion of the unqualified agricultural products of the A_t_i from the end of the conveyor belt to the line scan area,
wherein a method for determining the Δt1_i_2 is, Δt
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  ,, h1 is a height difference between a horizontal end of the conveyor belt and the line scan area, and a boundary line at the end of the conveyor belt is parallel to the line scan area; and g is a gravity acceleration of a located area of color sorting equipment.