Research On Intelligent Irrigation Control System In Intelligent Production Of Facility Vegetables

This paper relies on "Tianjin Agricultural Science and technology achievements transformation and promotion project","Tianjin Science and technology plan and promotion project" and "Tianjin Innovation research and experiment of young researchers in Academy of the Agricultural Sciences project".This paper mainly aims at the problems of low utilization coefficient of water resources,poor irrigation precision and unsatisfactory irrigation effect caused by the backward irrigation technology in the traditional vegetable planting.Based on the analysis of the current situation of facility agriculture irrigation,a set of facility vegetable intelligent irrigation control system was designed by combining wireless communication technology,artificial intelligence technology and database technology.The purpose of the system is to improve the irrigation technology of facility vegetables and realize the intelligent irrigation of farmland.Based on the analysis and summary of a variety of farmland irrigation control systems at home and abroad,combined with the needs of facility vegetable irrigation,the design scheme of irrigation system with soil water potential(SWP)as the control objective was proposed.Based on the software and hardware platform and fuzzy expert control method,the intelligent irrigation control system was designed,and the search method for the best control objective was proposed.First of all,the soil water potential distributed collection and monitoring system was designed.The system applies electronic soil water potential measuring instrument and 433 MHz wireless data transmission unit to realize data transmission.The sensing node of the distributed collection network is composed to transmit the soil water potential data of farmland to the field centralized control center in real time,which includes the field centralized control computer and PLC.The field centralized control computer transmits the data to the cloud through My SQL database,which realizes the remote monitoring of root user.Through 3G network and intelligent remote control terminal GRM500,the system can communicate with on-site executive control mechanism PLC to realize relevant operation.Secondly,the fuzzy comprehensive evaluation method based on AHP(analytic hierarchy process)and entropy weight method was proposed to achieve the optimization of the best control objective.Taking cucumber as an example,in order to get the best irrigation index of different vegetables,the growth under water stress was researched.The water consumption index,growth index,physiological index and quality index of Cucumber under different water gradients were obtained,and the best soil water potential suitable for cucumber growth was concluded,which was the basic work for realizing intelligent irrigation.Thirdly,taking the soil water potential as the control target,the fuzzy expert control is used to generate the control strategy of the system.And on the basis of a lot of irrigation experience,combined with expert irrigation advice,in the form of natural language in the control rules.The knowledge base,comprehensive database and knowledge acquisition mechanism were designed.The double input and single output fuzzy controller is selected as the inference engine.That is to say,the real-time soil water potential and ideal water potential difference(E)and difference change rate(EC)are selected as the input and the optimal irrigation time(U)as the output,which are designed and implemented on the Lab VIEW platform.In order to verify the control effect of the fuzzy controller,a field experiment was carried out with the traditional irrigation method,which verified the rationality and feasibility of the control strategy.In order to improve the human-computer interaction ability of the system,the field centralized control center uses Lab VIEW software to develop the management platform,establishes the communication connection between Lab VIEW and My SQL database and PLC,and designs the PLC function.In the practical application,the data acquisition of the control system is timely and accurate,the transmission is stable,the performance index and the design requirements are met,and it has strong adaptability to different types of soil.