Efficient Actuator Failure Avoidance Mobile Charging for Wireless Sensor and Actuator Networks

Actuators and sensors are two types of important nodes in wireless sensor and actuator networks (WSANs). Actuators consume a large amount of energy for driving themselves move, handling events, communicating with each other, and computation. Hence, the sensors and actuators all suffer from a serious energy-constrained problem in WSANs. Recently, many excellent energy recharging works are proposed for wireless sensor networks (WSNs). However, the wireless energy delivery issue for WSANs is rarely addressed. In this paper, by deeply analyzing the characteristics of WSANs, we discuss the wireless mobile recharging issue for WSANs and present a novel actuator failure avoidance online charging scheme (AFAC). To prevent as many sensors failure as possible while ensuring no actuator failure, AFAC always tries to select the node that not only makes no actuator failure but also brings about the least number of nonfunctional sensors as the next target. Furthermore, since charging the actuators takes a long time, maximum charging threshold is set for actuators to prevent sensor nodes failure in the network. The simulation results demonstrate that our scheme gets the lowest sensor failure ratio with low charging cost and charging delay in comparison with other wireless charging schemes for WSANs.