Study On Control System Of Variable Rate Fertilizer Applicator Based On GPS\GPRS

Precision Agriculture (PA) is well recognized as a sustainable method for development of agriculture and has obvious economic and environmental benefits. Variable Rate Fertilization (VRF) is an important part of Precision Agriculture and is an efficient method to solve the farm fertilization problems, including unreasonable structure, low average utilization ratio of fertilizer, agricultural environment pollution. As the foundation and carrier of VRF, the variable rate fertilization applicator has significant theoretical and practical values.Based on the control principle of VRF applicator and design requirement, a control system of VRF applicator with the core of farming computer and grooved sheave controller is researched and developed. Firstly, based on the analysis of farming computer structure, the control of faming computer is studied, including the acceptance of GPS information, the methods of prescription storage and resolving, the application of GPRS wireless data transfer technology in the VRF for the first time. Secondly, with grooved sheave characteristics, the control of grooved sheave is discussed. A new control model with two parameters is established. The functions related to the opening and rotate speed of grooved sheave and capacity of fertilizer discharge is derived with Least Squares Techniques (LST) according to the experiment data. The control rule combining accuracy and energy saving was developed. Two different kinds of driving methods based on hydraulics and motors are studied.To prove the correctness of theory and work performance of control system of VRF applicator, the calibration experiment and field experiment are done and the result indicates that the control system is reasonable and feasible. It is easy...