超声波测距温室苗架喷淋车牵引导向系统研究

Towing Guidance System for Greenhouse Seedling Frame Sprinklers Based on Ultrasonic Distance Measurement

摘要:

温室大棚内人工喷淋作业存在劳动强度大、效率低下的问题,而顶部浇灌装置则成本高昂、利用率偏低,在此背景下,地面行走式喷淋车成为有效解决途径。 针对温室苗架喷淋车地面行走的导向难题,提出一种结构简易、成本低廉的循迹式前轮牵引导向系统技术方案,并结合场地条件与传感器特性,确定了循边导向系统的传感器选型方法及导向纠偏逻辑算法。 该系统以四轮独立驱动、前端或后端双轮同步转向的机构为本体,配备前后端超声波测距传感器及可编程逻辑控制器(Programmable logic controller,PLC)运算核心;通过变比例增益比例积分微分 (Proportional-Integral-Derivative,PID)控制模型完成纠偏导向运算后,系统向转向电机输出方向、偏摆角及转动速度等控制信号,驱动行走轮组向指定方向偏摆以实现精准纠偏。 此外,基于上述理论设计了一套导向行走控制系统,详细阐述测试平台勘测数据、系统硬件组成及底层硬件连线原理,并开展变比例增益 PID 模型的 Matlab 仿真、 关键数据关联验证、现场实测及测试效果评估。 试验结果表明,当系统以速度 5 m / min 行驶时,可精准识别预设纠偏边界,纠偏精度达 5 mm,且纠偏导向运动稳定平顺,全程无干涉、碰撞等异常问题。

Abstract:

Due to the high labor intensity and low efficiency of manual spraying operations in greenhouses, as well as the high cost and low utilization rate of spraying operations performed by overhead irrigation devices, ground-moving sprayers have become an effective solution. To address the guidance problem of greenhouse seedling frame sprayers moving on the ground, a technical solution for an edge- tracking front-wheel towing guidance system with simple structure and low cost was proposed. Meanwhile, a sensor selection method for the edge-tracking guidance system and a guidance-deviation-correction logic algorithm were put forward based on field conditions and sensor characteristics. The system was composed of a four-wheel mechanism with independent drive, a dual-wheel synchronous steering mechanism that can realize steering function at either the front or rear end, an information acquisition device equipped with ultrasonic sensors, and a PLC-based computing core. Upon completing guidance-deviation-correction via the variable proportional gain PID model, the system output direction, yaw angle, and rotation speed signals to the steering motor, which then yawed in the designated direction to realize deviation correction. In addition, based on the above theories, an implementation case of the edge-tracking front-wheel towing guidance system was provided, including survey data of the test platform, hardware composition of the system and its underlying hardware wiring principle. Furthermore, Matlab simulation of the variable proportional gain PID model, correlation verification of key data, field tests and test effect evaluation were carried out. Test results showed that when the system operated at a speed of 5 m / min, it can accurately identify the preset deviation-correction boundary, with a deviation correction accuracy of 5 mm. The deviation correction and guidance movement was stable and smooth, without any interference, collision or other problems throughout the process.