丘陵小型农机三点悬挂倾角前馈控制系统研究OA
Feedforward Control System for Inclination Angle of Three-Point Hitch Mechanism of Small Agricultural Machines in Hilly Areas
[目的]针对丘陵小型无人驾驶拖拉机配挂轻型属具在硬质地块作业时,由于采用液压开关阀及强压作业模式导致的三点悬挂系统液压延时大、控制精度低及惯性超调剧烈等问题,设计一种基于分段补偿预模型的前馈CP-bang-bang提升控制系统.[方法]该系统利用安装于车身与下拉杆的倾角传感器,通过车身姿态反馈补偿方法实时获取提升角度,自动抵消地形起伏造成的机身俯仰干扰,建立三点悬挂一维几何控制模型.针对液压系统在上升与下降工况下的动力学非对称性,采用面积辨识法分别建立系统的开环传递函数,并据此构建CP补偿预模型.该模型通过预测系统运动惯性产生的滑行量,对开关阀的关断时机进行前馈补偿,并结合bang-bang控制策略构建CP-bang-bang控制器.[结果]在相同工况下,改进后的CP-bang-bang控制器性能显著优于传统bang-bang控制器.试验数据显示,与bang-bang控制相比,CP-bang-bang控制器的平均绝对定位误差由2.00°降低至0.87°,停杆精度提升56.5%;平均调节时间由2.84 s缩短至2.62 s.[结论]在应用常规液压开关阀的前提下,通过分段补偿前馈方法可有效克服液压延时与系统非对称性,实现悬挂高度的快速精准调控,对丘陵智能化农机装备的性能优化具有重要意义.
[Objective]To address the problems of large hydraulic delay,low control accuracy,and severe inertial overshoot in the three-point hitch system of small unmanned tractors equipped with light implements when operating on hard terrain,due to the use of hydraulic on-off valves and strong pressure operation mode,this paper studies and designs a feedforward CP-bang-bang lift control system based on a piecewise compensation pre-model.[Methods]This system uses inclination sensors installed on the vehicle body and the lower pull rod to obtain the real time lift angle through the vehicle body attitude feedback compensation method,and automatically offsets the body pitch disturbance caused by terrain undulations,and establishes a one-dimensional geometric control model of the three-point hitch.Considering the dynamic asymmetry of the hydraulic system in the lifting and lowering conditions,the area identification method is used to establish the open-loop transfer functions of the system respectively,and a CP compensation pre-model is constructed based on this.This model predicts the sliding amount caused by the system's motion inertia and performs feedforward compensation on the timing of the on-off valve's closure,and combines the bang-bang control strategy to construct a CP-bang-bang controller.[Results]Simulation and field comparison test results show that under the same conditions,the perfor-mance of the improved CP-bang-bang controller is significantly better than that of the traditional bang-bang controller.Test data show that compared with bang-bang control,the average absolute positioning error of the CP-bang-bang controller is reduced from 2.00° to 0.87°,and the stop bar accuracy is improved by 56.5%;the average adjustment time is shortened from 2.84s to 2.62s.[Conclusion]This study proves that under the premise of using conventional hydraulic on-off valves,the piecewise compensation feedforward method can effectively overcome hydraulic delay and system asymmetry,achieving rapid and precise control of the hitch height,which is of great significance for the performance optimization of intelligent agricultural machinery equipment in hilly areas.
张闻宇;蔡希扬;曾山;孙杨;卢一鸣;郑乐;高巧明
华南农业大学 工程学院,广州 510642华南农业大学 工程学院,广州 510642华南农业大学 工程学院,广州 510642广西科技大学 汽车与机械工程学院,广西 柳州 545066华南农业大学 工程学院,广州 510642贵州大学 机械工程学院,贵阳 550025广西科技大学 汽车与机械工程学院,广西 柳州 545066
农业科技
三点悬挂CP-bang-bang控制液压延时动力学非对称性前馈控制
three-point hitchCP-bang-bang controlhydraulic delaydynamic asymmetryfeedforward control
《沈阳农业大学学报》 2026 (4)
97-111,15
贵州科技计划项目(黔科合支撑[2024]100)广东省基础与应用基础研究基金项目(2025A1515012286)山东省重点研发计划项目(2022SFGC0202)华南农业大学创新训练项目(X202510564128)华南农业大学工程学院创新创业项目(2024105641198)
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