Theme A SINGLE axis attitude control system, employing -/man integral pulse frequency modulator and thrusters having unsymmetrical force characteristics, is analyzed for the stability of its ultimate motion around a small equilibrium region, and for convergence of the system trajectory from large initial states to this region. A type of motion, which for practical purposes is equivalent to a two-pulse limit cycle, is defined and referred to here as Relationships among the several system parameters are established and these ensure the existence of favorable motion. To establish the convergence from large initial states, a function similar to a Lyapunov function, but involving the concept of the minimum distance between a point and a set, is used as an analytical tool. The analytical results are displayed conveniently on a single graph and are verified by experiments on a computer simulation.