Design and implementation of an automatic pressure-control system for a mobile sprayer for greenhouse applications

Abstract

This article presents the design and development of an embedded automatic pressure-control system for a mobile sprayer working in greenhouses. The pressure system is mounted on a commercial vehicle, it is composed of two on/off electrovalves and one proportional electrovalve. The hardware developed is based on an embedded microprocessor and provides a low-cost and robust solution. The resulting embedded system has been tested on a spraying system mounted on a manned vehicle. Furthermore, an easy-tuning non-linear PI (Proportional Integral) controller to achieve the desired pressure profile is designed and implemented in the embedded system. Many physical experiments show the best performance of such controller compared with a typical PI controller. Experiments covering the pressure range from 2 to 14 bar obtained a mean error less than 0.3 bar. Summing up, a low-cost automatic pressure-control system is developed, it ensures a uniform decomposition of the liquid sprayed on plants, and it works properly over a wide variable-pressure range.Additional key words: low-cost embedded hardware; non-linear PI controller; real-time operation; variable-pressure control. ResumenDiseño e implementación de un sistema de control automático para un pulverizador móvil para aplicaciones en invernaderos Este artículo presenta el diseño e implementación de un sistema de control de presión empotrado para un pulverizador móvil aplicado en invernaderos. El sistema de presión se ha montado en un vehículo comercial, está compuesto por dos electroválvulas todo/nada y una electroválvula proporcional. El hardware desarrollado se basa en un microprocesador empotrado y constituye una solución robusta y de bajo coste. El sistema empotrado desarrollado se ha probado en un sistema de pulverización montado en un vehículo guiado de forma manual. Además, se ha diseñado un algoritmo de control PI (Proporcional Integral) no lineal de fácil sintonía que permite asegurar el seguimiento del perfil de presión deseado y que ha sido implementado en el sistema empotrado propuesto. Numerosas pruebas reales han demostrado el mejor rendimiento de dicho controlador en comparación a un controlador de tipo PI. Experimentos realizados sobre un rango de presión de 2 a 14 bar demuestran un error medio menor a 0.3 bar. En definitiva se muestra un sistema de control de presión automático de bajo coste, que asegura una decomposición uniforme del líquido pulverizado, y funciona de forma correcta sobre un amplio rango de presión variable.Palabras clave adicionales: control de presión variable; controlador PI no lineal; hardware empotrado de bajo coste; operación en tiempo real.

Obstacle Detection System for Agricultural Mobile Robot Application Using RGB-D Cameras

“…As an example, the orchard’s robot navigation can be introduced, where the mobile robot needs to detect the path autonomously (e.g., defined as the position in the middle of the row) to accomplish their task (recollection, spraying, crops stand counting, plant phenotyping, etc.) [ 3 , 4 , 5 , 6 ]. In agricultural applications, the path detection and navigation strongly depend on the robotic task goals.…”

“…Blue cells are the correctly detected obstacles (TP). The cell (2,1) contains an obstacle that was not detected, and the closest map cell to it that represents the obstacle is(1,4). Therefore, the d min-obst = (2, 1) − (1, 4) 2 ≈ 3.16 m.…”

Design and Implementation of Low-Cost Field Crop Sprayer Electronic Flow Control System

“…Many types of fertilizers and chemicals applied in solid form in the past have been applied today through spraying activities in liquid form. Liquid chemicals are sprayed in a pulverized state on soil, plants or pests together with a little water through agricultural pesticide machines [6].…”

“…Andrade et al developed a virtual calibration module for temperature, pressure, and flow sensors in the spraying system using an Arduino that can read CAN protocol. In 2012, R. Gonzalez et al [6] developed a low-cost, and valid solution by controlling the embedded automatic pressure control system that works in greenhouses with a microprocessor. With the pressure-based sprayer control system, [15] Dickey-John SC1000 performed the operation with an application error of less than 5% at ground speeds ranging from 3.2 to 9.7 km / h. Chemical, fuel, and timesavings in spraying application were provided with precise guiding, and precise control of spraying.…”

Design and Experiment of a Variable Spray System for Unmanned Aerial Vehicles Based on PID and PWM Control

“…Compared with the high-speed flight of plant protection unmanned aerial vehicles (UAV), the response time of the electronic control valve has a greater impact on the system. Gonzalez et al [10] designed a nonlinear variable spray system based on pressure regulation. By establishing the transfer function of the open-loop system, the nonlinear control of the variable spray system was realized.…”