植物工厂立体栽培系统多功能作业平台优化与试验

    Optimization and experiment of the multifunctional operation platform of the stereo cultivation system for plant factory

    • 摘要: 植物工厂中多采用立体栽培架进行育苗与栽培,立体栽培架上的栽培床搬运是其中重要一环。目前,栽培床多为人工搬运,存在劳动强度大、自动化水平低等问题。针对此问题,该研究研制了一种多功能作业平台,可实现自主循迹、定位和栽培床的自动搬运和输送。根据栽培床质量和立体栽培架高度要求,设计了升降机构,并确定了关键参数;研究了栽培床自动对接和自动输送机构,实现了栽培床的自动装卸;确定了基于RFID(Radio Frequency Identification)传感器的定位系统方案。采用STM32单片机作为自动控制系统的主控制器,自动控制系统主要包括导航系统、定位系统、通信系统、行走系统、升降系统、自动对接系统和自动输送系统等部分,并基于Android平台设计了人机交互界面,通过设置相应指令实时监控多功能作业平台的运动状态和作业参数。为评价多功能作业平台作业效果,以升降机构高度范围、前后定位偏差、高度定位偏差和平台与立体栽培架对接成功率为试验指标,进行了性能试验。试验结果表明,多功能作业平台升降高度范围为833~2 460 mm,前后定位偏差小于9 mm,高度定位偏差小于5 mm,对接成功率不小于96%,满足作业要求。该研究为进一步提高植物工厂立体栽培自动化水平提供了参考。

       

      Abstract: Stereo cultivation is usually used in plant factories for seedling and cultivation. Transportation of cultivation bed is an important part of the stereo cultivation automation. At present, cultivation bed is mostly handled manually, which has problems such as high labor intensity and low level of automation. To solve this problem, a multifunctional operation platform, which had the functions of autonomous tracking, automatic positioning, and automatic conveying of cultivation bed, was developed in this paper. The multifunctional operation platform mainly consists of navigation system, positioning system, communication system, walking system, lifting system, automatic docking system, and automatic conveying system. The working principle and technical parameters of the multifunctional work platform were introduced. During operation, the cultivation bed was transported from nursery workshop to greenhouse by the multifunctional operation platform firstly. Then,the multifunctional operation platform reached the target stereo cultivation rack through the road reserved in greenhouse and lifted the cultivation bed to the target height. The automatic conveying mechanism started to push cultivation bed to stereo cultivation rack by automatic docking mechanism. The cultivation bed was transported to stereo cultivation rack when the proximity switch installed on stereo cultivation rack detected the cultivation bed. Finally, the multifunctional operation platform stopped working and go back to the charger area. When the crops were mature, the multifunctional operation platform would automatically transport the cultivation bed to the picking area, so as the logistics automation of the crop production process was realized by the multifunctional operation platform. To meet the requirements of multi-layer cultivation of stereo cultivation rack, the lifting mechanism was designed based on principle of virtual displacement according to the weight of the cultivation bed and the height of the stereo cultivation rack. Single hydraulic cylinder driving and two scissor lift mechanisms were chosen. The maximum driving force of the hydraulic cylinder was about 15 443.9 N through theoretical analysis. The length, stroke, outer diameter and inner diameter of the hydraulic cylinder were determined to 940, 360, 63, and 35 mm respectively. The automatic docking and automatic conveying mechanism of the cultivation bed were studied. The automatic docking was realized between the multifunctional operation platform and stereo cultivation rack by automatic docking mechanism, and two-way transportation of the cultivation bed was realized by automatic conveying mechanism. Thus, the automatic loading and unloading of the cultivation bed was realized. The positioning system based on the RFID (Radio Frequency Identification) sensor was determined. Walking system and the lifting mechanism of the working platform would stop working when the RFID sensor detected the electronic labels on the ground and stereo cultivation rack.STM32 was used as the main controller of the automatic control system. The software and hardware of the control system were designed. A human-machine interaction interface was designed based on the Android. It was to monitor the motion status and operating parameters of the multifunctional operation platform in real time. To evaluate the operation performance of the multifunctional operation platform, the experiments were conducted. The test indexes were the height range of the lifting mechanism, the front and rear positioning deviation, the height positioning deviation, and the success rate of the platform and the stereo cultivation frame docking. The experiment results show that the height range and effective lift height of the multifunctional mobile platform was 833-2 460 mm and 1 627 mm. The front and rear positioning deviation is less than 9 mm, average value was 4.5 mm. The height positioning deviation was less than 5 mm, average value was 3.7 mm. And the docking success rate was not less than 96%, which meet the requirements of the operation. This study provides a reference for further improving the automation level of stereo cultivation of plant factories.

       

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