Pursuit of a Moving Ground Target on a Graph Using Partial Information
K. Kalyanam and M. Pachter
https://doi.org/10.19124/ima.2015.001.04
Abstract
The optimal control of a “blind” pursuer searching for an evader moving on a road network toward a set of goal vertices is considered. The evader’s speed is time-varying and not known to the pursuer; although upper and lower bounds on the speed are assumed known. To aid the pursuer, certain roads in the network have been instrumented with Unattended Ground Sensors (UGSs) that detect the evader’s passage. When the pursuer arrives at an instrumented node, the UGS therein informs the pursuer if and when the evader visited the node. The pursuer’s motion is not restricted to the road network. In addition, the pursuer can choose to wait/loiter at any UGS location/node. At time 0, the evader passes by an entry node and proceeds towards one of the exit nodes. The pursuer also arrives at this entry node after some delay and is thus informed about the presence of the intruder/evader in the network, whereupon the chase is on. Capture entails the pursuer and evader being co-located at an UGS location. If this happens, the UGS is triggered and this information is instantaneously relayed to the pursuer, thereby enabling capture. On the other hand, if the evader reaches one of the exit nodes without being captured, he is deemed to have escaped. We provide an algorithm that computes the maximum initial delay at the entry node for which capture is guaranteed and the corresponding optimal pursuit policy.