基于区间分析的自动移栽机苗盘定位控制方法

苗盘输送部件是自动移栽机的关键部分，由于国内标准塑料苗盘易变形造成苗盘外表面的光反射率不稳定，导致单个光电传感器识别苗盘到位信息误差大，苗盘定位不准确。针对这一问题，该研究设计了一种推杆平移输送、双传感器融合定位的苗盘输送装置，并提出一种苗盘精确定位控制方法。该方法首先通过双传感器分别感知苗盘与推杆的到位信息，并融合输送装置的结构信息，得到苗盘从起始位置输送至取苗位置的精确输送距离；然后设计了一种苗盘与推杆之间放置位置的判定方法，判定苗盘当前放置位置后输入对应的位移量将苗盘输送至取苗位置，最后驱动伺服电机实现苗盘输送的精确控制。以128穴标准PVC硬塑苗盘为测试对象，开展了苗盘输送定位及取苗性能试验，结果表明：控制系统可以准确判定苗盘任意放置在输送链推杆上的具体位置，在苗盘不同放置位置及不同输送速度下，电机脉冲频率越快，定位偏差越大。当电机脉冲频率为800 Hz时，输送定位偏差最大值为1.35 mm，最小值为0.79 mm，此时定位偏差平均值最大为1.07 mm，定位偏差变异系数最大为14.1%。在不同输送速度下，取苗成功率均达100%，满足精确输送定位要求，解决了单个光电传感器定位不...

Positioning control method for the seedling tray of automatic transplanters based on interval analysis

Abstract: The seedling tray conveying is one of the most components in an automatic transplanting machine. However, a large error can be found to identify the position of the seedling tray using a single photoelectric sensor. The reason can be the unstable light reflectivity of the outer surface on the seedling tray, due mainly to the easy deformation of the standard plastic tray. It is a high demand to accurately and rapidly position the seedling tray. In this study, a seedling tray conveying device was designed with fusion positioning using the push-rod translational conveying and dual sensor. A precise positioning control system was also proposed for the seedling trays. Firstly, the dual sensors were used to identify the in-position information of the seedling tray and the push rod, and then to fuse the structural information of the conveying device. A calculation model was also established to transport from the initial position to the given position for the seedling picking. As such, a seedling tray and push rod were designed after calculation. Secondly, an accurate evaluation was performed on the placement category between the push rods. The interval of each category was determined through normalized data processing. After that, an optimal displacement was given to the seedling tray using each placement category. The seedling tray was transported to the given position for the seedlings picking. Finally, the servo motor was used to drive the precise control of seedling tray delivery. Taking the 128-hole standard PVC hard plastic seedling tray as the test object, a series of performance tests were carried out for the positioning and seedling of the seedling tray conveying device. The results show that the control system was accurately determined the specific category of the seedling tray that placed arbitrarily on the push rod of the conveyor chain. Specifically, the faster the motor running pulse frequency was, the greater the positioning deviation was under different placement categories and conveying speeds. When the motor running pulse frequency was 800 Hz, the maximum conveying positioning deviation was 1.35 mm, the minimum value was 0.79 mm, the maximum average value of the positioning deviation was 1.07 mm, and the maximum coefficient of variation of the positioning deviation was 14.1%. Under different conveying speeds, the success rate of picking seedlings with the claws and holes was 100%, fully meeting the requirements of precise conveying and positioning. Therefore, the improved device can be expected to avoid the inaccurate and unstable positioning of a single photoelectric sensor. The finding can provide a technical guarantee for the automatic transplanter suitable for the standard plastic seedling tray.