System and method for controlling continuous hole seeding of air-suction drum-type seed-metering device

Patent metadata

Field	Value
Publication number	US-12134524-B2
Application number	US-202217790516-A
Country	US
Kind code	B2
Filing date	Mar 7, 2022
Priority date	May 25, 2021
Publication date	Nov 5, 2024
Grant date	Nov 5, 2024

Abstract

A system includes a hollow shaft, a drum, an absolute encoder, a driving mechanism, a conveyor belt, a photoelectric sensor, and a controller. A structural optimization design method of the drum is provided on the basis of theoretical calculation of a seeding track of the drum-type seed-metering device, a theoretical model of a conveying position of a tray and a seed-metering angle is built with the aim of continuously sowing grains to the center of each hole, the conveying position of the tray and a rotating position of suction holes on the drum are monitored in real time on a seedling raising line, and a difference value between the actual position of the suction holes and the theoretical seed-metering angle and a change rate of the difference value are calculated and serve as input parameters to design a fuzzy controller of the rotation speed of the drum.

First claim

What is claimed is:

1. A method for controlling continuous hole seeding of an air-suction drum-type seed-metering device, comprising a system for controlling continuous hole seeding of the air-suction drum-type seed-metering device, wherein the system for controlling continuous hole seeding of the air-suction drum-type seed-metering device comprises a hollow shaft, a drum, an absolute encoder, a driving mechanism, a conveyor belt, a photoelectric sensor, and a controller;
the hollow shaft is horizontally mounted on a line frame, the drum is mounted on the hollow shaft, the drum and the hollow shaft have a common axis, and arrayed suction holes are disposed on the drum;
one end of the hollow shaft is connected to a negative pressure fan and the other end of the hollow shaft is connected to a positive pressure fan, a positive pressure end of the hollow shaft is provided with a vertical through pipe, a partition plate is mounted below the vertical through pipe, the partition plate is attached to an inner wall of the drum through a preloaded spring to form a closed positive pressure cavity, a plurality of through holes are disposed on a negative pressure end of the hollow shaft, and a negative pressure cavity is formed in the drum;
the absolute encoder is mounted on the drum and is used for measuring a rotation state of the drum, that is, a position angle of the suction holes in each row, the driving mechanism is connected to the drum, and the drum rotates about an axis of the hollow shaft;
the conveyor belt is located below the drum, and the photoelectric sensor is mounted on the conveyor belt and is used for detecting a position of a tray conveyed by the conveyor belt;
the controller is connected to the absolute encoder, the photoelectric sensor, and the driving mechanism;
the method comprises the following steps:
determining a seed-metering angle θ 0 and a contact height h between the partition plate and the drum;
establishing a matching relationship between a rotation speed of the drum and a conveying speed of the tray;
determining a theoretical model of a conveying position of the tray and the seed-metering angle;
recording a time when the photoelectric sensor detects the tray according to the theoretical model of the conveying position of the tray and the seed-metering angle;
measuring, by the absolute encoder, an actual angle of the corresponding suction holes on the drum, and calculating a deviation of the seed-metering angle and a deviation change rate of the drum;
inputting the deviation of the seed-metering angle and the deviation change rate into the controller to build a fuzzy controller of the rotation speed of the drum, that is, an adjustment control model of the rotation speed of the drum;
setting, by the controller, a speed of the conveyor belt and the rotation speed of the drum according to the matching relationship between the rotation speed of the drum and the conveying speed of the tray;
collecting, by the controller, output signals from the absolute encoder and the photoelectric sensor in real time and calculating the rotation speed of the drum according to the adjustment control model of the rotation speed of the drum; and
controlling, by the controller, the driving mechanism to adjust the rotation speed of the drum, so that an actual seed-metering angle is kept within a set range.

2. The method for controlling the continuous hole seeding of the air-suction drum-type seed-metering device according to claim 1 , wherein the structural optimization design of the drum comprises the following steps:
designing different sizes of the partition plates to obtain different seed-metering angles θ 0 , and building complete three-dimensional structure models of the drum-type seed-metering device;
theoretically calculating, by using a discrete element method (DEM)-computational fluid dynamics (CFD) gas-solid coupling method, a falling track of grains under a set rotation speed and positive and negative pressure differences;
recording a theoretical landing position as P 0 , setting the rotation speed ω, the positive pressure difference p+, and the negative pressure difference p· of the drum to fluctuate in ranges of Δω, Δp+, and Δp·, respectively, repeatedly calculating the falling track and a landing position P i of the grains, and calculating a deviation di between the landing positions P i and P 0 ;
building by fitting a mathematical model of the deviation δ i and the rotation speed ω, the positive pressure difference p+, and the negative pressure difference p· of the drum and recording the mathematical model as δ i =f(w, p+, p·);
calculating partial derivatives to obtain k=a 1 ·∂δ i /∂ω+a 2 ·∂δ i /∂p + +a 3 ·∂δ i /∂p − , wherein a 1 , a 2 , and a 3 are set weight coefficients;
calculating corresponding values of k according to the different seed-metering angles θ 0 , and establishing a fitting function of k and θ 0 ; and
determining the different seed-metering angles θ 0 and the contact height h between the partition plate and the drum with an aim of obtaining a minimum value of k.

3. The method for controlling the continuous hole seeding of the air-suction drum-type seed-metering device according to claim 2 , wherein the matching relationship between the rotation speed of the drum and the conveying speed of the tray is established by the following steps:
assuming that the conveying speed of the tray is v, a center distance between holes on the tray is l, and the suction holes on the drum form an angle of a, so that the rotation speed of the drum satisfies ω 0 =a·v/l, that is, the matching relationship between the conveying speed v of the tray and the rotation speed ω 0 of the drum.

4. The method for controlling the continuous hole seeding of the air-suction drum-type seed-metering device according to claim 3 , wherein the theoretical model of the conveying position of the tray and the seed-metering angle is determined by the following steps:
based on the matching relationship ω 0 =a·v/l between the conveying speed of the tray and the rotation speed of the drum and a determined optimal seed-metering angle θ 0 , obtaining through theoretical calculation a time Δt taken by the grains to fall from a seed-metering position to a horizontal position of the holes, so that the grains fall into a center of each hole when Δt=(L+l/2)/v, that is, the theoretical model of the conveying position of the tray and the seed-metering angle θ 0 , wherein l is the center distance between the holes on the tray and L is a horizontal distance between a mounting position of the photoelectric sensor and an axis of the drum.

5. The method for controlling the continuous hole seeding of the air-suction drum-type seed-metering device according to claim 4 , wherein the adjustment control model of the rotation speed of the drum is built by the following steps:
recording the time when the photoelectric sensor detects the tray as t 0 ;
measuring, by the absolute encoder, the actual angle θ t of the corresponding suction holes on the drum;
calculating the deviation of the seed-metering angle e=Δθ=θ t −θ 0 and the deviation change rate e c -de/dt of the drum according to the theoretical model of the conveying position of the tray and the seed-metering angle;
establishing a univariate two-dimensional fuzzy control algorithm with e and e c as inputs; and
outputting an adjustment value Δω of the rotation speed of the drum, so that the adjustment control model of the rotation speed of the drum is built.

6. The method for controlling the continuous hole seeding of the air-suction drum-type seed-metering device according to claim 1 , wherein the driving mechanism comprises a chain, a stepper motor, and a stepper motor driver;
a chain wheel is mounted on the drum, the chain wheel is driven by

Assignees

• Univ Jiangsu

Inventors

• Zhao Zhan
• Zhou Yue
• Zhou Jing

Classifications

• B65G2811/095

  Speed variation control means · CPC title

• B65G2203/044

  Optical · CPC title

• B65G2203/0233

  Position of the article · CPC title

• B65G2201/0202

  Agricultural and processed food products · CPC title

• B65G47/848

  the article-engaging elements being suction or magnetic means · CPC title