Attitude control for space vehicle

Method of providing control for a space vehicle having thrust-producing means producing thrust for imparting momentum upon the vehicle thereby imparting motion upon the vehicle or reducing existing motion or reversing movement, further having control means for the thrust producing means causing the thrust producing means to produce thrust bursts or pulses, so that a controlled particular momentum is imparted upon the vehicle with each burst or pulse, such thrust burst being triggered by the control means respectively when the vehicle tends to move beyond selected descrete deviations and error positions from a desired position, said descrete deviations establishing descrete position levels which in turn establish respectively levels for control and triggering of a thrust burst, one of the position levels being the highest one, comprising:

• selecting the descrete position levels as levels for control triggering so that the highest one of said position levels, one in either direction as to deviation from the said desired position, are limit levels, defining a range of positional deviation tolerance;
• operating the thrust producing means so that a relatively small momentum is produced when the vehicle tends to move past either of said limit levels;
• operating the thrust producing means on particular levels of error positions within said range for producing momentum on each one of said levels
• (1) at a magnitude that is smaller than the sum of momenta to be produced on all position levels higher than said one level;
• (2) only after momenta have been produced for all selected smaller position levels;
• (3) only once for each sequence of thrust bursts leading to a residual error cycle wherein the vehicle is caused to oscillate within the range of tolerance with reversal occuring on each range limit and caused by said small momentum triggered in each instance when one of the range limits is reached.