Incorporating Plug and Play Technology into Measurement and Control Systems for Irrigation Management

Past experience has demonstrated that the control needed to implement site-specific irrigation management with center pivot irrigation systems requires extensive computing capability distributed over large spatial areas. The coordination of control and instrumentation data is most effectively managed using data networks and low-cost microcontrollers. These systems have historically been propriety one of a kind designs. In each instance when sensors or actuators change, new hardware designs and extensive software modification is required to previous or existing systems. Adopting a standard interface for all sensors and actuators would allow reuse of common hardware such as network interfaces and control algorithm hardware and software. The IEEE 1451 instrumentation and control standard provides a well-documented protocol for integrating smart sensors and actuators into a distributed control environment. This standard provides for a mechanism to implement an instrumentation plug and play network that is similar in concept to PC peripherals that use the USB interface for easy and seamless integration. Studies have shown that the bandwidth and response constraints imposed by the hardware needed to implement the IEEE 1451 protocol is well within the requirements needed for spatial and temporal site-specific irrigation management using a center pivot irrigation system. Advantages of "plug and play" technology allow alternate sensors to be easily and simply incorporated in to a common control system. Designs for smart soil moisture sensors and sprinkler valve controllers are explored and evaluated to determine if the additional cost of implementing a plug and play IEEE 1451 is justifiable. Different actuator and instrumentation configurations are explored to demonstrate how systems can be scaled to satisfy the requirements for each specific application without sacrificing economy.