The Study Of Greenhouse Environment Control System Based On CAN Bus

Greenhouse iS the important part of installation agriculture.Crop production in domestic and overseas greenhouses shows that advanced automation and management system for greenhouse will improve the efficiency of agriculture production.In this thesis,the characteristies of greenhouse system are summarized,such as nonlinearity. 1arge delay,strong coupling.With the introduction of the CAN bus into the field of the greenhouse environment,a CAN bus based field level monitor and control system was designed by employing the techniques of fuzzy control,computer technology, information and network technology.The primary factors affecting the greenhouse environment were analyzed and the whole design plan has been offered.Then three kinds intelligent CAN bus nodes. including analog signal collection,digital signal collection and on—ofr control ones, were developed using the modular design method.and the data was transmitted bv 1-wire.The hardware circuit of the field level greenhouse monitor and control system was introduced.In the end,the software of the whole system was disigned.The system adopted the CAN bus method to realize the communication between the IPC and the intelligent CAN bus nodes.The communication protocol,together with the communication program module including CAN module initialization.CAN data reception and transmission,was designed based on the frame structure using CAN2.OA standard.In the system,The IPC takes the initiative role in controlling the greenhouse environment by sending commands to the inte l ligent CAN nodes for date collection and other operations.The fuzzy control method was used in the system as the control strategy according to the characteristics of greenhouse environment.Based on the analysis of the inputs,outputs and the contr01 rules of the geenhouse environment.a fuzzy controller was designed for the control system.After that.the contr01 method was applied to a test base.In the end,the outcome of fuzzy control was compared with that of PIDcontr01.It was confirmed that the fuzzy control with a smal 1 er overshoot and adjusting timeconstant is superior to the PID contr01.