| In recent years,facility agriculture has developed rapidly with the annual increase of greenhouse.The refinement and intellectualization of facility agriculture is one of the main ways to improve China’s agricultural modernization production.Real-time acquisition of navigation and positioning information is the key to realize intelligent and refined facility agriculture.GPS positioning technology is relatively mature,but the GPS signal is seriously attenuated by barriers such as walls,which can not be used in indoor environment.Therefore,it is of great significance to study a new wireless positioning technology suitable for greenhouse agriculture.The main contents are as follows:1、Design of positioning experiment platform based on UWBUltra-wideband(UWB)technology has attracted wide attention due to its strong penetration,high transmission rate and low power consumption.The positioning technology has the advantages of high accuracy,low energy consumption,simple design,low cost,convenient network node layout,no stringent requirements for site environment,and is suitable for indoor environment such as greenhouse.Time difference of arrival(TDOA)location algorithm has the following advantages:(1)there is no phase ambiguity in positioning system and the baseline of direction finding can be unrestricted;(2)the structure of positioning system is simple;(3)the accuracy of positioning system is high.Considering the above reasons,in this paper,UWB was selected as wireless carrier communication technology and TDOA was used as positioning method to design positioning test platform based on greenhouse environment.2、Collection and optimization of static positioning information for mobile platforms in greenhousesAiming at the measurement errors caused by single positioning algorithm and environmental factors,several static optimization algorithms are selected to collect and optimize the static positioning information of greenhouse mobile platform.When the mobile platform is statically measuring coordinates,UWB positioning test platform transmits pulse signals to transmit data.Under the interference of measurement errors,for the same position,in a period of time,the measured coordinate data will be distributed around the real point with certain measurement errors.Clustering algorithm is used to make the processed points close to the real point,which can improve the positioning accuracy.Based on the energy consumption in greenhouse agricultural engineering and the location requirements of single or multiple mobile platforms,in this paper,the design of clustering location optimization algorithms for different situations was designed.The experimental results showed that the least square method was used for static optimization of single mobile platform,K-Means algorithm was used for static optimization of multiple known platforms,and DBSCAN algorithm was used for static optimization of multiple unknown platforms,which could achieve better optimization results.3、Collection and optimization of dynamic positioning information for mobile platform in GreenhouseBecause the accuracy of coordinate data measured by UWB test platform is not ideal,the dynamic positioning optimization of greenhouse mobile platform was focused in this paper.In the process of tag movement,at a certain time,the data measured by the device is unique,so the clustering algorithm can not be applied to this scenario.In this paper,Kalman filter algorithm and maximum likelihood estimation were used to collect and optimize the dynamic positioning data,and the optimal results were compared to select the most suitable dynamic positioning optimization algorithm with greenhouse environment.The experimental results showed that the Kalman filter was better than the maximum likelihood estimation algorithm.4、Real-time visualization of location information of mobile platform in GreenhouseOn the basis of the above research,the optimized positioning information collected by the equipment on the compute was visually displayed on the computer.Firstly,.NET API technology was used to collect information for positioning devices.Then,the location information was optimized according to the status of the target.Finally,location information and path could be real-time displayed while the function of human-computer interaction was realized. |
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