Intruder Isolation on a General Road Network Under Partial Information

The intruder isolation problem (IIP) involves using an unmanned aerial vehicle (UAV) to isolate an intruder traveling along a road network. The UAV has no visibility of the intruder and can obtain the information only about the intruder’s location from unattended ground sensors (UGSs) preinstalled on the road network. An UGS detects a passing intruder and records the time of passage. It can also upload the time-stamped information to the UAV directly overhead. This paper focuses on finding the optimal sequence of UGSs for the UAV to visit and the corresponding waiting time around each UGS to achieve isolation for the two variants of the IIP. This task is challenging due to the continuous movement of the intruder along the road network and the partial information scenario. To address these challenges, we propose an unfolding strategy to transform the road network to a decision tree, which describes all possible routes that the intruder may select to follow. Based on the decision tree, the optimal solution to the isolation problem is computed via dynamic programming (DP). To alleviate the computational complexity of DP, an UGS ranking scheme is proposed. Numerical implementations based on a real road network are presented to demonstrate the effectiveness of the proposed solution approach.