旋转式农机土槽试验台运行平稳性控制方法及试验验证

Running stability control method and test verification of soil groove test rig for rotary agricultural machine

为了解决旋转式土槽试验台的槽体和槽内土壤质量较大带来速度不容易控制和调节的问题,建立轮胎摩擦驱动的旋转式土槽试验台的数学模型。根据旋转式土槽交流伺服驱动器的特点设计了模糊控制器,对模糊控制进行优化并进行MATLAB仿真、对比。当交流伺服驱动器初始输入转速为300 r/min时,优化前后土槽在模糊控制策略下输出转速最终都稳定在3 r/min;优化后模糊控制下的土槽输出转速超调量小,最大转速为3.4 r/min,比优化前的3.7减小0.3 r/min,土槽输出转速稳定在3 r/min的时间由优化前的9.0减少到8.0 s,后期无振荡。试验结果表明:当旋转式土槽交流伺服驱动器输入转速320 r/min时,土槽运行稳定性误差由模糊控制的0.034降低到优化模糊控制的0.029,土槽从启动到进入稳定运行的时间由10.1缩短到7.9 s。该研究可提升后续利用该种试验台进行移栽和播种等农业机械试验的精度。

Indoor soil groove tester is a test platform of the agricultural and mechanical properties, and it can carry out tests conveniently and can not be limited by the seasons and if a whole machine has been developed, which is an important equipment in the process of agricultural machinery research and development and performance improvement. Existing soil groove test bench is basically linear soil tank, which universally has some problems, such as being not able to carry out continuous test（because of the limited length of the soil groove, if you want to test continuously, it must be pulled back to the starting point to test）, covering area too large and parameter test trouble（test instruments must move simultaneously with the measured object, in particular when the parameters of the trajectory and attitude are measured）. For this purpose, a rotating type of soil flume test rig, which can carry out the continuous test and has small area and convenient parameter test, is proposed. But after testing, it is found that due to large mass of the groove body and the soil in the groove, acceleration and deceleration is not easy to be controlled and regulated, leading to test velocity fluctuations. In order to further improve the running stability of the rotating earth groove, based on the movement characteristics and speed change rule of previous research test bed, the fuzzy control and PI（proportional integral controller） control strategy are compared, and it is found that the fuzzy control is more suitable for the operation control of rotary soil bin tester and test rig in the process of speed change by multiple parameters. For the multivariable complex system, this paper establishes the fuzzy control mathematical model of rotary soil bin test bench, and simulation analysis is carried out and control system is designed, according to the results of the simulation experiments. Through the simulation analysis and experimental verification of operation stability of rotary soil groove tester, it is found that the fuzzy controller of test bench is running more stably, and its steady error is within 3.2%, which is more suitable for the control of rotary type earth groove. Simulation results show that for the soil tank, a maximum speed of 3.4 r/min appears at the moment of 3.8 s when the input speed of optimized fuzzy servo control soil tank driving motor is 300 r/min; and after 8.0 s, soil groove slot output speed is stable at 3 r/min, without oscillation in the late stage. In experiments, the servo motors of rotary soil groove test bench under fuzzy optimal control and fuzzy control are respectively input with 5 groups of initial speeds（36.7-320 r/min）, the output speed and stability time of soil trough are measured, and the running stationarity error for soil trough is calculated. When the input speed of AC（alternating current） servo motor is maximum, the error of the running stationarity of the soil groove with the speed under fuzzy control is 0.034, and the error of the operation stationarity of the soil groove with optimized fuzzy control is 0.029. The improvement of the running stationarity of the rotary soil trough test bed can greatly improve the accuracy of the test of agricultural machinery on transplanting and sowing using the test bed.