Greenhouse Environmental Monitoring and Control
Greenhouse Wireless Sensor Network
Greenhouse facilities are being rapidly developed and expanded. The environmental conditions of a greenhouse directly affect the growth of crops. Therefore, the realtime monitoring and control of such type of indoor environment is important. Environmental automatic control technology is an effective means to improve the control technology of a greenhouse environment. Wireless sensor network (WSN) can form a useful part of the automation system architecture in modern greenhouses. A WSN is a group of small sensing devices, or nodes, that capture data in a given location. These nodes then send the raw data to a base station in the network, which transmits the data to a central computer that performs analysis and extracts meaningful information. This system enables concerned personnel to conveniently monitor various real-time data through the network-monitoring platform. Wireless communication can be used to collect the measurements, such as the temperature, light levels, carbon dioxide, and humidity. Compared to the cabled systems, the installation of WSN is fast, cheap, and easy. Moreover, it is easy to relocate the measurement points when needed by just moving sensor nodes from one location to another within a communication range of the coordinator device. For instance, if the greenhouse flora is high and dense, the small and light-weight nodes can even be hanged up to the plants’ branches. A distinct advantage of these WSNs is that they are both scalable (i.e. nodes and sensors can easily be added to the network) and the nodes are also reconfigurable. This means that a greenhouse operation can start with a small WSN system and gradually work up to larger systems when needed. A small WSN (minimal two or three nodes with a base station) can be deployed and used for monitoring until a level of understanding and comfort is reached by the user.
Base Station
The base station, which is the network coordinator, manages the activities of individual nodes by periodically requesting data. In addition to data aggregation and analysis, the base station acts as a door to the Internet (typically a local area network), providing operators with remote access to the WSN’s data.
Sensor Nodes
A wireless sensor network (WSN) generally consists of a large number of low-cost and low-power multifunctional sensor nodes that are deployed throughout the greenhouse. A typical sensor node in a WSN consists of a wireless communication unit, a microprocessor, a data acquisition unit, memory unit, and sensors.
Sensors
A sensor can be defined as any instrument that measures some type of physical or chemical characteristic and converts that measurement into a signal that can be read by an observer or automated data collection system. As stated in the sections above, all greenhouse control systems require information on the variables that define the greenhouse environment. Sensors provide the information. Traditionally, the growers have acted as the system's integrated “sensor”, directly feeling greenhouse conditions which they tried to relate his crop's growth and development. Today, there are many sophisticated electronic sensors available to the grower for monitoring greenhouse conditions and providing input data for automatically making increasingly subtle and efficient control decisions.
User Interface
The user interface is arguably the most important part of this system as it allows the growers to use the data and derive maximum benefit from this system. The user interface mainly includes realtime data display, statistical data analysis, real-time warning system, historical data query, and other functions.
Data Logging
Data history is valuable in identifying patterns and trends in environmental conditions. However, manually monitoring and recording environmental parameters takes a significant amount of personnel time and detracts from other, important workplace demands. Many monitoring systems automatically save information, recording tens of thousands of data points, dates and times.
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