基于双测速模式的玉米追肥机控制系统设计与试验

针对玉米追肥机北斗单点测速方式存在延时，造成测速准确性低的问题，提出了北斗单点测速与地轮测速相结合的双测速模式。搭建了玉米追肥机控制系统并开发配套控制界面，完成了双测速模式规则建立及控制器程序设计。重点对加减速过程判定与地轮稳定测速的速度范围进行了研究，试验确定了双测速模式切换条件，并验证了双测速模式的可行性。试验结果表明，地轮稳定测速的最大速度为6.0km/h，地轮测速队列长度N的最佳值为5，模式切换速度变异系数临界值为4.2%；3.5、5.5、6.0、8.0km/h 4种不同目标速度测速性能对比试验结果表明，双测速模式与北斗单点测速在加速阶段相对响应时间均值为1.6s，减速阶段均值为1.8s，实际施肥延时距离平均减小0.55m。田间施肥性能试验结果表明，双测速模式加速阶段速度切换造成的排肥转速差均值为1.5r/min，减速阶段排肥转速差在8.0km/h速度条件下最大，均值为7.1r/min。减速阶段控制结果表明，系统平均响应时间为1.3s，平均稳态误差均值为0.8r/min，系统平均超调量为8.7%。双测速模式切换准确率为100%，满足精准施肥的需要。

Design and Experiment of Double Speed Measurement Mode of Corn Topdressing Control System Based on Spectral Information

In order to solve the problem of low accuracy caused by the delay of Beidou single point speed measurement of corn topdressing machine, a double speed measurement mode combining Beidou single point speed measurement with ground wheel speed measurement was proposed. The control system of corn topdressing machine was set up and the corresponding control interface was developed. The double speed measurement mode rule was established and the controller program was designed. The speed range of acceleration and deceleration process judgment and stable speed measurement of ground wheel were studied. The switching conditions of dual speed measurement mode were determined by experiment, and the feasibility of dual speed measurement mode was verified. The test results showed that the maximum speed of the ground wheel was 6.0km/h, the optimal value of the ground wheel speed measurement queue N was 5, and the critical value of mode switching speed variation coefficient was 4.2%. The speed measurement performance comparison test results of four different target speeds of 3.5km/h, 5.5km/h, 6.0km/h and 8.0km/h showed that the average response time of double speed measurement mode was 1.6s earlier than that of Beidou single point speed measurement, and the deceleration phase was 1.8s earlier. The actual fertilization distance was reduced by 0.55m. The results of field fertilization performance test showed that the average speed difference of fertilizer application was 1.5r/min in the acceleration stage of double speed measurement mode, and the maximum speed difference was 7.1r/min at the speed of 8.0km/h in deceleration stage. The results showed that the average response time of the system was 1.3s, the average steady-state error was 0.8r/min and the average overshoot was 8.7%. The accuracy of double speed mode switching was 100%, which met the needs of precision fertilization.