The paper addresses the development of a mathematical model that integrates generalized equations of motion for describing the self-propulsion and dynamics of Unmanned Ground Vehicles (UGVs), motion resistance models for various surface types, longitudinal stability criteria, and a comparative energy model between pure electric and hybrid propulsion. As a novel contribution, the paper introduces the Propulsive Efficiency Index (PEI), a dimensionless parameter for the objective comparison of propulsion architectures, and a hysteresis-based energy management strategy for controlling a combustion engine used as a range extender, combined with regenerative braking.

The research methodology combines analytical modeling with numerical simulation implemented in MATLAB, and proposes two complementary levels of analysis of the series-hybrid architecture. The theoretical model mathematically demonstrates that a combustion engine supplying exactly one third of the total electrical power required at the wheel invariably produces a 50% increase in range, independent of terrain type. The realistic model employs a fixed-power combustion engine, achieving a 42% increase in range on the most demanding scenario, and identifies a design threshold: the combustion engine power must exceed the electrical power demand on the mission's predominant terrain. The sensitivity analysis of the combustion engine activation threshold identifies an optimal interval that maximises range without excessively increasing fuel consumption, while the stability analysis demonstrates that the critical traction loss angle varies significantly depending on surface type, with the wheel slip constraint being consistently more restrictive than the geometric rollover constraint.