DE2217949

A controlled momentum change is given to the space vehicle in bursts of thrust producer operation, the bursts being triggered when the vehicle moves beyond given deviations from desired position. Discrete position levels are selected as levels for control triggering so that the highest levels, one in either deviation direction are limit levels. A relatively small momentum is produced when the vehicle moves past either limit. Particular levels of error position within the range of tolerance cause thrust producer operation at a magnitude smaller than the sum of momenta at all higher levels, only after momenta production for all smaller levels and only once for each sequence. The vehicle oscillates with reversal at each limit caused by the small momentum change.