支持转速现场标定的玉米精密排种器电驱控制系统研究

针对现有玉米精密电驱排种控制系统无法快速适应多类型排种器排种控制的问题,在玉米CAN总线电动排种的基础上,设计了一种对玉米排种器排种驱动进行现场标定的电驱控制系统。系统在排种驱动电动机控制信号与排种盘转速之间的对应关系中,采用分段线性插值的方法现场获取排种器驱动曲线,实现排种盘转速标定与控制。以国产气吸式玉米精密排种器和指夹式玉米精密排种器为试验对象,在模拟车速下,对系统排种盘转速现场标定的控制准确性进行试验。电驱气吸式排种器排种盘转速控制性能试验中,株距设定为25 cm,车速设定为3~12 km/h(间隔3 km/h),结果表明,系统调节时间最长为0.80 s,稳态误差最大为0.81 r/min,控制精度最低为97.42%。电驱指夹式排种器排种盘转速控制性能试验中,株距分别设定为20、25、32 cm,车速设定为4~9 km/h(间隔1 km/h),结果表明,总体排种盘转速平均调节时间为1.09 s,标准差为0.26 s;总体平均稳态误差为0.38 r/min,标准差为0.23 r/min;总体平均控制精度为98.30%,标准差为1.01%。与分段PID排种转速控制系统控制性能进行对比得出,支持转速现场标定的系统具有更好的适应性,平均调节时间减少0.51 s,平均稳态误差增大0.16 r/min,平均控制精度降低0.63个百分点。选用指夹式排种器,进行了播种均匀性田间试验,株距为20 cm,车速范围为4~7 km/h(间隔1 km/h),结果表明,播种合格指数大于等于84.26%,变异系数小于等于18.29%,说明系统能够完成对玉米精密排种器排种转速控制曲线的高控制精度现场标定,能够精准控制电驱排种转速。

Investigation on Motor-driving Maize Precision Seed Meter System Supporting On-site Calibration of Rotate Speed of Seed Plate

Facing the problem of existing maize precision planting control system cannot quickly drive the seed sowing of multiple types corn precision seed meters, an on-site seeding rate calibration system was designed based on the controller area network (CAN) bus motor-driving corn planting technology. From the corresponding relationship between the motor control signal and the rotate speed of seed plate, the system got the seed meter driving curve in the filed using piecewise linear interpolation to realize the seeding rate control. Taking a domestic corn air-suction seed meter and a corn finger pick-up seed meter as the test objects, the speed control performance of seed plate in simulative travel speed was respectively evaluated. In the experiment of rotate speed control performance of corn air-suction seed meter, the seed spacing was set to be 25cm and the travel speed was set to be 3~12km/h with increment of 3km/h, the greatest response time was 0.80s, the biggest steady-state error was 0.81r/min and the lowest accuracy of seed plate rotate speed control was 97.42%. In the experiment of rotate speed control performance of corn finer pick-up seed meter, the seed spacing was set to be 20cm, 25cm and 32cm and the travel speed was set to be 4~9km/h with increment of 1km/h, the results showed that the average response time of the whole rotate speed of seed meter was 1.09s with standard deviation of 0.26s;the average steady-state error of the whole experiments was 0.38r/min with standard deviation of 0.23r/min;the average accuracy of rotate speed control of the whole experiments was 98.30% with standard deviation of 1.01%. Compared the seed plate rotate speed control system with the sectional proportion integration differentiation (PID) method, the system supported seed plate rotate speed on-line calibration had a better adaptability, the average response time was decreased by 0.51s, the average steady-state error was increased by 0.16r/min and the average accuracy of rotate speed control was decreased by 0.63 percentage points. The planting uniformity experiment in field was performed, taking the finger pick-up seed meter as the material. In the experiment of planting uniformity in field, the seed spacing was set to be 20cm and the travel speed was 4~7km/h with increment of 1km/h, the results showed that the quality of feed index was greater or equal to 84.26%, and the coefficient of variation was less than or equal to 18.29%. The above results indicated that the system can precisely control the rotate speed of motor driving planting through the way of calibrating the planting rotate speed control curve of corn precision seed meter on site with high accuracy.