The great developments in applied mathematics and computational capabilities facilitate the design and implementation of robust control. In addition, the huge developments in nanotechnology and its availability in civilian level with less cost, size and weight attract many of the researchers allover the world towards embedded systems especially the embedded flight control. Among the real applications are the guided missiles especially the antitank guided missile systems which are commanded to the line of sight (CLOS) against ground and short range targets. The present work is concerned with improving the performance of an antitank guided missile system belonging to the first generation via robust synthesis of autopilot and guidance systems. The design and analysis necessitates somehow accurate model with different uncertainties (objective of Part-1 of the paper) for the system, a robust autopilot design (objective of Part-2 of the paper) and implementation via hardware in the loop (HIL) simulation (objective of Part-3 of the paper). This part of the paper is devoted to the derivation of the system equations of motion clarifying different sources of uncertainty including thrust aging, anomalies in aerodynamic coefficients and derivatives and wind velocity effects. The solution of these equations is described in the form of modules programmed within the C++ and MATLAB environments to form the baseline for
subsequent design and analysis. The simulation is conducted with different engagement scenarios and different levels of uncertainty in thrust, aerodynamics and wind velocity. The simulation results are validated against reference data and verified for performance requirements including the time of flight, miss distance, control currents, normal acceleration and angles of attack. This investigation clarified the closeness of the designed model performance to the reference and its appropriateness for autopilot design and HIL simulation in the next parts of the paper.