Universidad de Almería

Rural Engineer Department

6LoWPAN for Precision Agriculture

6LoWSoft_20 for Precision Agriculture

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6LoWSoft_20

Welcome to the Website for 6LoWSoft project.

One of the changes more important that have been produced in the last years in the Almeria east is the intensive crops exploit especially in the green houses. In this type of crop is very important the use of technics and technologies to improve the performance in the farm. In this work is presented an advanced monitoring system to collect the variables applied on the precision agriculture. The monitoring system in its transport layer is made up wireless sensor network (WSN) which employ 6LoWPAN and RPL, it measure the humidity, temperature, light in the air and the volumetric water content in the soil (VWC). The WSN sends the collected data to a embedded device which store the data in a Data Base, and through the web platform allow see in fashion graphic and in real time the values obtained in the plantations.

We have used Tmote Sky and compatible "TelosB" motes.

The sensors are responsible for collect the values of the environmental variables in the air and in the soil inside the area which occupies the zone crop and transport it to the sink mote. Is used integrated sensors to the motes and soil sensors external attached to the motes.

The soil sensor Decagon EC-20 measures the volumetric content water and is attached to the expansion conector of 10 pins in the Telosb mote. The soil sensor bare wire is conected to the TelosB mote's ground pin, the excitation wire with the Vcc pin and its analog out with the ADC pin. Since the soil sensor have an audio connector, is used an audio jack as interface to the interconection between the soil sensor and the TelosB mote.

Such as is depicted in the figure below, the system is made up by three elements: a) the sensors which read the enviromental information, b) the WSN which transport the data and c) the server which receives, stores and shows the data.

   

Although is possible to use any device what complies with the server function is used a embedded device because it has more portability, a better integration in the greenhouse, and a more energy saving. Has been employed a "plug computer" called "Sheevaplug" which operates with a ARM proccessor of 1.2 GHz and a GNU/Linux system embedded (Debian 6.0). Initially the Sheevaplug has a intern memory of 512 MB, but to increase its DB capacity storage is used a SD memory of 8 GB.

In the figure below, appears the "Sheevaplug" server with its USB connection to the sink mote (TelosB mote), the network cable for its access to Internet, a SD memory which stores the information in the Data Base and its power cord. In a way comparative is showed a 5 cents coin of Euro.

   

Among the soil sensors more used and studied nowadays there are the manufatured by Decagon Company. Has several model, I.e. EC-5, EC-10 and EC-20 with visible difference in the size of its soil probe. Is used the model EC-20 due that it has the soil probe with the major longitude (20 cm) and offers the deepest soil study. But the mean reason is because the EC-20 model has a lower consume of energy,which is around 2mA to 2.5V meanwhile the EC-5 is 10 mA to 2.5V, relevant aspect when working together with the WSN since the soil sensor is communicated and feeded directly from the TelosB mote,in such sense a lower energy consumption allowed a life time long in the mote's batteries.

The soil sensor (EC-20) measures the volumetric water content and is communicated to the 10 pin expansion connector of the TelosB mote.

In the next figure, is showed the soil sensor connected to the Telosb mote, in the laboratory and in the university soccer field.

   

The Routing (TinyRPL)

Since the WSN is a network that could work with multi-hop links is used to this purpose the RPL protocol (IPv6 Routing Protocol for Low power and Lossy Networks) that in the TinyOS implementations is called TinyRPL. It is added in the configuration for all the motes. Even though TinyRPL has a little time developed, tests done indicates that it has a similar performance than CTP (Collection Tree Protocol) the de-facto routing protocol standard for TinyOS.

In its integration with TinyRPL, BLIP initiates the TinyRPL operations once a node is assigned a global address. After TinyRPL sets a route using ICMPv6 pertaining to RPL is added the route into the Blip routing table. Therefore TinyRPL will find routes in an automatic fashion without necessity of create it manually, which gives a more realistic approach at the moment of implement in any place since don't import the node position making the project replicable in any agriculture field without take account the WSN distribution.