Effect of estimation on the performance of an integrated missile guidance and control system

Motivated by spectral separation, guidance and control systems of interceptors are traditionally designed separately. However, interception of highly maneuverable targets and increased interception accuracy requirements lead to intense maneuvering during the last phase of the engagement, thus violating the spectral separation assumption of the conventional two-loop design. This has boosted the interest in integrated guidance-control designs that demonstrate superior interception accuracies by accounting for the coupling between the kinematics and dynamics of the problem. One of the approaches used for the integrated design is the sliding mode control (SMC) methodology. The results presented so far assumed full state information. We examine the effect of estimation on the performance of the integrated sliding mode controller design. In particular, a sliding mode observer/differentiator (SMOD) is used to estimate the target states. Through an intensive numerical study it is shown that the integrated guidance-control approach has a clear advantage over a conventional separated two-loop design. This advantage is attributed to the robustness of the integrated sliding mode controller design that better deals with the estimation errors and measurements noises.