Optimal Sample Number for Autonomous and Central Wireless Sensor Actuator Network

摘要

Applying distributed system concept with wireless communication in sensor and actuator network for process automation applications is led to developing autonomous wireless sensor actuator network. One of the requirements for this development is determining the sample number. Because of the hardware and power supply limitations, wireless sensors are applied to discrete control system. In wireless sensor network the highest sample number in comparison to the wired network is restricted. Moreover, the lowest sample number is also constrained by the limitations imposed by the control limits values. In this chapter, firstly the central structure is reviewed and then autonomous structure is introduced. Afterwards relations between sample number and actuator frequency drift in discrete domain is formulated and presented. In addition, ways to trade off the sample number with the actuator frequency and control limits value are acknowledged. One approach to find the optimal sample rate for each network structure is proposed. It is shown when the sensor network becomes larger, autonomous network can partly compensate communication number and energy consumption increase by adding the sample number whereas central network does not support this feature.