Sensor Localization Using Hybrid RF/Optical Wireless Communications for an Aerial Data Mule

In this paper we consider the problem of pairing a ground sensor with an aerial vehicle, both equipped with a hybrid communication system - radio frequency for non-line of sight transmission and optical for line-of-sight transmission. These communication technologies are complementary and by coordinating them it is possible to mitigate their respective weaknesses. A challenging problem is positioning the flying robot within optical communication range, especially when the distance is large and the sensor location is unknown. In this work, we propose a solution to the problem of autonomously localizing the sensor node relative to the aerial vehicle. We take advantage of the hybrid communication scheme by developing a control strategy that uses the radio signal to guide the aerial platform to the sensor node. Once the optical-based signal strength is over a desired threshold the robot hovers within optical range. The control strategy is demonstrated through simulations that incorporate a realistic model for the hybrid communication link.