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    果园高位自动调平作业平台设计及仿真

    Design and simulation of the automatic-leveling high-position platform in orchards

    • 摘要:
        目的  我国果园机械化程度低,尤其缺少丘陵山地果园的机械,目前果园疏花疏果、套袋、采摘等繁重工作主要依靠人工架梯完成。设计一款适用于丘陵山区苹果园的高位自动调平平台,可以提高果园采收机械的采收效率、安全性和稳定性。
        方法  根据果园地形特点和果树高度确定平台设计要求和调平方式,确定俯仰、侧倾不同部分尺寸关系,液压缸所需推力、平台角度和液压缸位移量的关系;建立平台控制系统数学模型,使用增量式PID控制器,以不同干扰信号在Simulink中仿真控制调平性能;在Adams中设计极限倾翻坡度实验,平台在不同姿态、不同升降高度和不同载质量情况下仿真验证其安全性。
        结果  建立各部分的数学关系,确定各部分基本尺寸,从而建立了平台三维模型。在控制系统仿真中,俯仰、侧倾控制系统在阶跃干扰信号下能使工作台很快回到水平位置,调平时间分别为1.6、2.1 s,超调量均为0;俯仰、侧倾控制系统在正弦干扰信号下能使工作台始终保持在0°附近,波动范围分别在0.15°、0.19°内。平台极限倾翻坡度仿真实验表明平台的倾翻稳定性随着举升高度和载质量的增加而降低,相比无调平时,有调平时的最小极限倾翻坡度增加了24.77%,平台安全性明显提高。
        结论  设计的果园高位自动调平平台能够在不同干扰下始终保持水平,具有较好的抗倾翻能力,安全可靠,能够满足丘陵山地果园的使用需求。

       

      Abstract:
        Objective  There is a low degree of mechanization in China, especially the lack of machinery for hilly orchards. At present, the flower thinning, fruit-separated, bagging, picking and other heavy works of orchards mainly rely on artificial ladders. In order to improve the harvest efficiency, safety and stability of orchard harvesting machinery, we designed an automatic-leveling high-position platform suitable for apple orchards in hilly areas.
        Method  Based on the characteristics of orchard terrain and the height of fruit trees, the design requirements and leveling methods of the platform, the size of different parts of pitch and roll, the thrust required by the hydraulic cylinder, the relationship between platform angle and the displacement of hydraulic cylinder were determined. A mathematical model of the platform control system was established. Then, we used an incremental PID controller to simulate the control leveling performance in Simulink with different interference signals. An extreme inclination slope experiment in Adams was designed, where the platform was simulated to verify the safety under different postures, different lifting heights and varied loads.
        Result  The mathematical relationship of each part was established, and the basic dimensions of each part were determined so as to establish the three-dimensional model of the platform. In the control system simulation, the pitch and roll control systems can quickly return the platform to the horizontal position under the step interference signal. The leveling time was 1.6 and 2.1 s, respectively, and the overshoot was 0. Under the sinusoidal interference signal, the pitch and roll control system can keep the platform near 0°, and the fluctuation range was between 0.15° and 0.19°. The limit tilting slope simulation experiment of the platform revealed that the platform’s tilting stability decreased with the increase of lifting height and load. Compared with the case without leveling, the minimum limit tilt angle with leveling increased by 24.77%, so the safety of platform significantly improved.
        Conclusion  The designed automatic leveling high-position platform in orchards can always maintain level under different interferences, with good anti-tilting ability, safety and reliability, and can meet the needs of hilly orchards.

       

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