Continuous-time intruder isolation using Unattended Ground Sensors on graphs

This paper studies the continuous-time intruder isolation problem on a general road network graph under delayed information scenario. Several Unattended Ground Sensors (UGSs) are pre-installed along certain edges of the graph for detecting intruder motion and recording the detection time. Measurements of a UGS can only be obtained when the UAV is within its communication range. The goal of this paper is to find the optimal path for the UAV to follow in order to capture the intruder within the shortest time, based on the delayed information from the visited UGSs. We propose an unfolding strategy to transform the road network graph to a decision tree incorporating delayed measurement information. Based on the decision tree, both optimal and sub-optimal min-max solutions are developed. Several interesting properties of the corresponding optimal value function are also derived. Numerical simulations based on a real road network are presented to demonstrate the effectiveness of the proposed strategies.