基于视觉引导的平面并联棉花打顶装置设计与试验

Design and Experiment of Vision-guided Planar Parallel Cotton Topping Device

摘要:

棉花打顶是抑制顶端优势、促进棉桃生长、提高产量的重要农艺措施。为实现棉花打顶作业智能化与精准化，本文设计了一种基于视觉引导的平面并联棉花打顶装置，由机器视觉系统、平面并联定位机构、末端执行器和控制系统组成。引入轻量化平面并联五杆机构作为定位执行机构，兼顾高刚度与快速响应特性，工作空间覆盖典型顶尖生长区域;基于YOLO 11n目标检测模型，结合RGB-D相机采集的棉花冠层图像，实现棉花顶尖识别与空间定位;使用视觉粗定位和光栅精触发的混合定位策略，并基于STM32单片机构建有限状态机控制逻辑，确保作业时序，降低末端执行器垂直定位偏差。以打顶期棉花为对象开展了试验，结果表明，平面并联定位机构水平面定位误差为7.92 mm，垂直定位误差为1.88 mm;田间试验结果表明，当刀片转速为1 200 r/min、机具前进速度为0.2 m/s时，系统平均识别率为91.56%，平均打顶率为86.89%，实现全程自动化作业，验证了装置有效性与可行性。

Abstract:

Cotton topping is a crucial agronomic practice to suppress apical dominance, promote boll growth, and increase yield. To achieve intelligent and precise cotton topping operations, a vision-guided planar parallel cotton topping device was designed. The device consisted of a machine vision system, a planar parallel positioning mechanism, an end effector, and a control system. A lightweight planar parallel five-bar mechanism was introduced as the positioning actuator, combining high stiffness with fast response characteristics, with the workspace covering the typical apical growth region. Based on the YOLO 11n object detection model and cotton canopy images acquired by an RGB-D camera, recognition and spatial localization of cotton apices were achieved. A hybrid positioning strategy combining visual coarse localization and raster fine triggering was proposed, and a finite state machine control logic was implemented based on an STM32 microcontroller to ensure operational timing and reduce the vertical positioning deviation of the end effector. Experiments were conducted on cotton during the topping period. Results showed that the horizontal positioning error of the planar parallel positioning mechanism was 7.92 mm and the vertical positioning error was 1.88 mm. Preliminary field trials indicated that at blade speeds of 1 200 r/min and machine forward speeds of 0.2 m/s, the system achieved an average identification rate of 91.56% and an average topping rate of 86.89%, realizing full-process automated operation and verifying the effectiveness and feasibility of the device.