基于PID算法的水稻直播机播量控制系统的设计与试验

【目的】为了解决现有的机械式水稻直播机镇压轮传动播种导致的漏播以及播量无法同步均匀调节的问题,实现水稻直播机播量自动精准调节。【方法】对现有苏南地区传统机械式水稻直播机进行自动化改造,设计了基于PID调速算法的水稻直播机播量控制系统。该系统在田间播种作业时,由设计的测速轮采集机具作业速度,结合设定的目标播种量和机具作业速度,依据播量控制策略得到排种轴理论转速;利用PID调速算法和编码器测到的排种轴反馈转速对直流电机进行闭环控制,可在线无极调节播量,从而实现精准播种。【结果】该系统排种电机空载时转速调整时间小于0.63 s,最大超调量8.21%,施加12.5 N·m负载时,排种电机最长回调时间为0.32 s。目标设计播量对应转速范围内,转速控制误差最大值小于7.21%,转速误差小于5.21%,田间播量误差小于4.92%。田间车速阶梯变化时,排种转速跟随响应及时,具有较高的排种同步性,与传统机械式水稻直播机相比播量调节性能显著提高。【结论】该系统自动化改造简便,重点改进了播量调节机构,提高了传统播种机播种性能,对传统机械直播机具有较高适配性。

Design and experiment of sowing control system for rice direct seeder based on PID algorithm

Objective In order to solve the problem of the missed sowing and the uniform adjustment for sowing amount by the driven wheel existing in traditional mechanical rice direct seeder, and realize automatic and precise adjustment to the sowing amount of rice direct seeder.Method A traditional mechanical rice direct seeder, commonly used in the Southern Jiangsu area, was modified by incorporating an automatic seeding control system based on the PID speed control algorithm. During sowing, the working speed of implement was obtained by the designed speedometer. The theoretical rotational speed of sorting shaft was obtained according to sowing control strategy combining the set target sowing amount with the operational speed. The measured feedback speed of seeding axis closed the control loop of the DC motor using a PID speed regulation algorithm and an encoder, which could be adjusted on-line to achieve accurate seeding.Result The speed adjustment time of seeding motor without load was less than 0.63 s and the maximum overshoot was 8.21%. The longest time for the motors to be recharged was 0.32 s when a load of 12.5 N·m was applied to the device. For the target sowing amount, the maximum value of speed control error was less than 7.21%, speed error was less than 5.21%, and sowing amount error in field was less than 4.92%. When field speed of vehicle varied in step, the seeding speed responded in time and the vehicle had a higher seeding synchronization. The seeding adjustment performance was significantly improved using the automatic release meter compared with the conventional direct seeder.Conclusion The automation transformation of this system is easy, which focuses on improving the adjustment mechanism of sowing amount, improves the sowing performance of traditional seeder, and has a high adaptability to traditional rice direct seeder machine.