Online Planning for Data Collection in Multi-Robot Systems

Wireless sensors networks have been used for data collection in various civil and military applications. We consider a system where a group of mobile robots and a set of stationary wireless sensor nodes are sparsely deployed in a large unbounded area. In such scenarios, all sensor nodes may not be connected via a communication network. Furthermore, no pair of sensor nodes may be within the transmission range of each other. Therefore, many relay nodes are needed to guarantee the connectivity of the network. However, this approach will affect the lifetime of the system due to the energy consumption by data transmission. In this paper, we study the problem of data collection from the deployed sensors utilizing the robots. The robots do not know the locations of each other and the sensor nodes. Moreover, the sensor nodes do not know the locations of each other and the robots. We propose an online algorithm in which the robot explores the area to find the sensor nodes and collect their stored data. Depending on whether the number of robots is known by the robots in advance or not, we investigate and compare two cases of the problem. In simulations, we empirically evaluate the performance of our algorithm and show that it quantifies as a function of the environment size, the number of robots, and the communication range when both the number of robots and the number of sensors are not known in advance.