Sensitivity of cooperative target geolocalization to orbit coordination

This article investigates the sensitivity of target geolocalization by a team of two unmanned aircraft to orbit coordination. Using an uncertain, deterministic target model, a nondimensional optimality criterion based on the Cramer-Rao lower bound of the geolocalization problem is defined. The optimal sensing configuration is specified by two parameters, allowing for a general sensitivity study using parameter sweeps of the range of the unmanned aircraft to the target and their transverse separation in a polar coordinate system fixed on the target. Orbit coordination to maintain the optimal configuration is often infeasible given limitations on unmanned aircraft dynamics, motion of the target vehicle, and background wind. Therefore, orbit coordination policies that trade angular separation for range must be used. The sensitivity analysis of the optimal configuration is extended to orbit coordination over a finite time horizon for static and constant-velocity targets. Three orbit coordination policies (one that maintains angular separation while allowing range to the target to vary, one that maintains range while allowing angular separation to vary, and one that allows both angular separation and range to vary) are compared against an ideal policy that maintains the optimal configuration for all time. The sensitivity analysis; performed here shows that different orbit coordination policies should be applied in different sensor regimes. However, policies that maintain the optimal range while allowing the angular separation to vary are more robust over the entire set of possible sensor characteristics than approaches that maintain optimal angular separation at the expense of range.