基于智能手机的手持式树上苹果果径测量系统设计与试验

In-situ Handheld Fruit Diameter Measurement System on Apple Trees Based on Smart Phone

摘要:

为解决现有接触式果径测量过程耗时，长时间测量精度容易受试验人员主观影响的问题，结合机械设计、串口通信、自动控制等技术设计了一款手持式树上苹果果径测量系统。该系统由手持式果径测量工具和数据接收APP两部分组成。在果园树上果径测量作业时，试验人员手持果径测量工具的握柄，通过按压握柄带动传动模块，夹持爪随之张开，从而实现夹持爪与被测果实表面贴合及果径测量，并通过蓝牙通讯来将数据传输到手机端APP以进行保存、删减、位置信息绑定及批量导出等操作。为衡量手持式果径测量工具精度，分别进行公制块规和苹果果径测量试验。公制块规测量试验结果表明，本文所提出的尺寸测量工具实现了亚毫米级别精度测量。苹果果径测量试验结果表明，测量误差随着果实尺寸的增加而增加，在测量成熟期果实时，尺寸测量工具获取结果的平均绝对误差（Mean square error，MAE）及均方根误差（Root mean squared error，RMSE）仍可控制在0.45mm以下，可满足苹果果径测量精度需求。

Abstract:

To solve the problem that the existing contact fruit diameter measurement process is tedious and time-consuming, as well as the susceptibility to record errors influenced by the subjective judgments of experimenters during prolonged measurement, a handheld apple tree fruit diameter measurement system was designed. The system incorporated technologies such as mechanical design, serial communication, and automatic control. It consisted of a handheld fruit diameter measurement tool and a corresponding data-receiving mobile APP. During orchard operations for measuring tree fruit diameter, experimenters held the grip of the fruit diameter measurement tool. By pressing the handle, the transmission module was activated, causing the clamps to open, allowing them to grip and measure the diameter of the tested fruit surface. The data was then transmitted to the mobile APP via Bluetooth for operations such as saving, editing, binding location information, and batch exporting. To assess the precision of the handheld fruit diameter measurement tool, metric block gauge measurements and apple diameter measurement experiments were conducted. Results of the metric block gauge measurement experiment demonstrated that the proposed measurement tool achieved sub-millimeter-level precision. Apple diameter measurement experiment results indicated that the proposed measurement tool achieved a more satisfactory accuracy in measuring apple tree diameters compared with vernier caliper. Even when measuring the diameters of mature fruit, the majority of the measured fruit diameters had mean square error (MAE) and root mean squared error (RMSE) controlled below 0.45mm, meeting the precision requirements for apple fruit diameter measurement.