Closed-loop drip irrigation control using a hybrid wireless sensor and actuator network

In this research, a closed-loop drip irrigation control hybrid wireless sensor and actuator network (HWSAN) prototype were developed and deployed in a crop field for soil property precise measurement and precision irrigation in accordance with the measured soil property. The HWSAN was composed of a wireless sensor and actuator network (WSAN) used for in-field soil property monitoring and irrigation control and a laboratory supervising system. The WSAN included ten sensor nodes, five irrigation control nodes, a central node, a gateway and a cellular modem. The laboratory supervising system was formed by a web-server. The system could automatically sample soil properties including soil moisture, electrical conductivity, and nearsurface temperature at four different depths underground and transmit field data through cellular network to the web-server. Closed-loop control was achieved through the control nodes listening uploading packets from its paired sensor nodes to control drip irrigation. Results from the quality of service (QoS) evaluation included: the data packet transmission rate was 84.76%, data accuracy rate was greater than 97% and no in-field data transmission errors.