基于GNSS的平地控制系统优化设计与试验

农田土地平整技术能够提高农田灌溉质量和改善土壤矿物质均匀度，以达到节水增产的目的，随着全球导航卫星系统（GNSS）的建立与完善，基于GNSS的农田土地精细平整技术得到广泛应用。针对当前使用GNSS定位数据进行高程闭环控制，容易产生平地铲超调问题，设计了一种基于GNSS的土地精平机电控制系统，提出一种可控制时长的滞环控制算法，通过控制电磁阀的通电时间，精确控制平地铲升降，以减少超调。试验结果表明:在低速作业状态下，平地铲可减少15%的振荡，高速作业状态下可减少23%的振荡；有效降低了平地铲高程的突变，在低速作业时减少30%，在高速作业时减少8%；无论是低速作业还是高速作业，完成作业后均能保证90%以上的点在±2 cm以内，满足土地平整的精度要求。 

Optimization Design and Test of GNSS Flat Control System

Farmland leveling technology can improve quality of farmland irrigation and uniformity of soil minerals，so as to achieve purpose of saving water and increasing production.With establishment and improvement of Global Navigation Satellite System（GNSS），fine formation technology of farmland land based on GNSS has been widely applied.The current use of GNSS positioning data for elevation closed-loop control is likely to cause overshoot of flat ground.A GNSS-based precision leveling electromechanical control system was designed，and a time-controlled hysteresis control algorithm was proposed.By controlling power-on time of solenoid valve，leveling scraper lift could be accurately controlled to reduce overadjustment.Experimental results showed that vibration of flat shovel could be reduced by 15% at low speed and 23% at high speed.At the same time，abrupt transition of flat spade elevation was effectively reduced，which was reduced by 30% at low speed and 8% at high speed.No matter low speed operation or high speed operation，more than 90% points could be guaranteed within±2 cm after completion of operation to meet precision requirements of land leveling.