农业机械导航路径跟踪控制方法研究进展

    Research progress on the path tracking control methods for agricultural machinery navigation

    • 摘要: 路径跟踪控制技术作为农业机械导航的核心,是提高控制系统控制精度和对环境适应性的关键,可提高农机具作业精度和效率,同时可避免重复作业和遗漏现象,减少农业生产资料浪费。该文根据农业机械导航路径跟踪控制方法中是否涉及农机模型,将路径跟踪控制技术分为与农机运动学模型相关、与农机动力学模型相关以及与模型无关的路径跟踪控制方法。通过对原理的解析明确了各类控制方法的优缺点,及对现有解决方案进行了总结分析,指出了现有方案存在共性或个性问题,由此完成了对现阶段国内外针对农业机械导航路径跟踪控制方法的研究进展的阐述。通过对各类控制方法适用性及农机导航产品发展现状的分析,提出了农机导航路径跟踪控制方法的发展展望,以期为后续路径跟踪控制方法的研究提供指导性方向和有针对性的参考,具体如下:1)明确了现有模型对农机运动过程描述的局限性,指出高精度农机模型研究的必要性;2)为提升控制方法自适应性和鲁棒性,研究需从常规工况向极限工况和复杂工况拓展;3)明确单一控制方法的局限性,明确多方法融合控制的发展趋势。

       

      Abstract: Agricultural production mode has been required for the intelligence and digitization of agricultural machinery. An automatic control system has gradually been the research interest of agricultural machinery in recent years. Among them, the navigation system with path tracking control can be expected to improve the accuracy of the agricultural machinery and the adaptability to the environment. Specifically, the accuracy and efficiency of agricultural production can be improved to realize more complex tasks, in order to avoid the wide crop coverage due to leakage testing. In this review, the types of agricultural machinery models were evaluated with/without the navigation path tracking control system. Three categories were also divided into the path-tracking control system with the kinematic or dynamic models, as well as the model-independent path-tracking control. Agricultural machinery was assumed as a rigid or single rigid body system for control with the kinematic model. The kinematic model of agricultural machinery included pure tracking, linear quadratic optimal control, and the model predictive control. By contrast, the dynamic model of agricultural machinery considered the influence of the mass and inertia of agricultural machinery on the control, particularly with the sliding mode variable structure control. The path-tracking control method unrelated to the agricultural machinery model was utilized to directly extract the features from the sensor data or visual information. The PID, and fuzzy control were the widely-used path-tracking control systems in the path-tracking control methods unrelated to the agricultural machinery model. The optimal path-tracking control of the agricultural machinery was achieved to correct the control system using the error between the sensor feedback and reference input values. The pros and cons of various control methods were clarified to evaluate the existing solutions. The current research progress was reviewed on the general and specific existing solutions to the navigation path tracking control of agricultural machinery. The applicability of various control methods was also evaluated for the current development status of agricultural machinery navigation products. The development prospects were then proposed for a navigation path tracking control of agricultural machinery. Some recommendations were as follows: 1) The current model was limited to describing the motion process of agricultural machinery. There was a high demand for the high precision model research of agricultural machinery; 2) In order to improve the adaptability and robustness of the control method, the research should be extended from the conventional to extreme and complex conditions; 3) The single control method was confined in the navigation path tracking control method of agricultural machinery. It can be expected to require the development trend of multi-method fusion control. This finding can provide strong references for subsequent research on the path-tracking control methods, particularly for the intelligent development of agricultural machinery in China.

       

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