An Intelligent Wireless Sensor and Actuator Network System for Greenhouse Microenvironment Control and Assessment

Abstract

Purpose: As application-specific wireless sensor networks are gaining popularity, this paper discusses the development and field performance of the GHAN, a greenhouse area network system to monitor, control, and access greenhouse microenvironments. GHAN, which is an upgraded system, has many new functions. It is an intelligent wireless sensor and actuator network (WSAN) system for next-generation greenhouses, which enhances the state of the art of greenhouse automation systems and helps growers by providing them valuable information not available otherwise. Apart from providing online spatial and temporal monitoring of the greenhouse microclimate, GHAN has a modified vapor pressure deficit (VPD) fuzzy controller with an adaptive-selective mechanism that provides better control of the greenhouse crop VPD with energy optimization. Using the latest soil-matrix potential sensors, the GHAN system also ascertains when, where, and how much to irrigate and spatially manages the irrigation schedule within the greenhouse grids. Further, given the need to understand the microclimate control dynamics of a greenhouse during the crop season or a specific time, a statistical assessment tool to estimate the degree of optimality and spatial variability is proposed and implemented. Methods: Apart from the development work, the system was field-tested in a commercial greenhouse situated in the region of Punjab, India, under different outside weather conditions for a long period of time. Conclusions: Day results of the greenhouse microclimate control dynamics were recorded and analyzed, and they proved the successful operation of the system in keeping the greenhouse climate optimal and uniform most of the time, with high control performance. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Keywords IntroductionThe wireless sensor network (WSN) is one of the upcoming, multidisciplinary, and pervasive computing technologies of the 21st century (Estrin et al., 2002). With its wide range of application potential, it is invading environments and bridging the gap between the real physical world of sensory data and the digital world of computers and internet. WSN is achieving the high-end goal of creating real sensor webs, which may be called the "next-generation internet" (Zhao and Guibas, 2004). A typical WSN consists of a number of sensor nodes, spatially distributed into an application environment, that cooperatively monitor the phenomenon of interest and communicate data to the gateway node via a low-power true-mesh multihop routing for end user access (Sohraby et al., 2007). Each sensor node is embedded with sensing, computing, and wireless communication capabilities to form a data collection network. The utility of WSN is further enhanced by integrating it with an actuator network...