Exposure of variable speed targets through a sensor field

In order to monitor a region for target intrusion, sensors can be deployed to perform collaborative target detection. To adequately deploy sensors, metrics need to be define to measure the ability of a given deployment to successfully complete this task. Recently, the measure of exposure was defined to evaluate the coverage of the region by a sensor network. Exposure is a versatile metric that is expected to provide a pertinent measure of the region coverage for various scenarios. This paper develops a method to find the minimum exposure of a target traversing the region at variable speed. It also introduces target activities different from region traversal for which the coverage by the sensors remains not well defined. Finally, the problem of coverage in the presence of obstacles in the region is identified. Exposure is expected to provide a good coverage measure for these various problems.