Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2009
Publication Date: 3/1/2010
Citation: O'Shaughnessy, S.A., Evett, S.R. 2010. Developing wireless sensor networks for monitoring crop canopy temperature using a moving sprinkler system as a platform. Applied Engineering in Agriculture. 26(2):331-341. Interpretive Summary: Canopy temperatures can provide information on the status of a crop. Infrared thermometers are a means to monitor canopy temperature remotely. Wireless infrared thermometers provide a grower with the ability to mount the sensors on a center pivot system and monitor the field as the pivot moves. Over a two-year period, we developed two generations of electronic circuits to connect industrial infrared thermometers to radio modules. The second generation of interface circuit boards were much smaller, used 96% less power, and reduced the cost of parts by 50%.We established three wireless sensor networks of infrared thermometers. One network was placed on a six-span center pivot arm to form a moving network. A second network was established in the field below the six-span pivot, and a third network was established under a three-span center pivot. The reliability, advantages, and disadvantages of the networks were compared. The networks in the field were more reliable than the network on the pivot arm. Data loss from the network on the pivot arm was mainly due to interference from the steel trusses and towers of the pivot. The difference in the performance of the two field wireless sensor networks resulted from timing issues. Future work is necessary to refine sensor network capabilities, but mesh networking provides a promising method for wireless communication when using a moving sprinkler as a platform.
Technical Abstract: The objectives of this study were to characterize wireless sensor nodes that we developed in terms of power consumption and functionality, and compare the performance of mesh and non-mesh wireless sensor networks (WSNs) comprised mainly of infrared thermometer thermocouples located on a center pivot lateral and in the field below. The sensor nodes mounted on masts fixed to the lateral arm of a center pivot irrigation system functioned to monitor crop canopy temperatures while the system moved; the sensor nodes established in the field below the pivot were to provide stationary reference canopy temperatures. The WSNs located in cropped fields independent of the irrigation system functioned in a highly reliable manner [packet reception percentage (PRP) > 94]. Mesh-networking was the single communication protocol that provided functionality for the WSN located on the center pivot lateral. Its PRP was 84 and 87 during the 2007 and 2008 growing seasons, respectively. Future research is required for thorough testing and optimizing of WSNs for automatic control and irrigation scheduling of a center pivot system.