초록 ▼

A method is disclosed wherein a flexible space craft may be slewed by the application of positive and negative acceleration forces applied about a slewing axis. The method is such that at the end of the application of the slewing forces there is no residual energy in the excited modes. By examinatio

A method is disclosed wherein a flexible space craft may be slewed by the application of positive and negative acceleration forces applied about a slewing axis. The method is such that at the end of the application of the slewing forces there is no residual energy in the excited modes. By examination of the response of an undamped and then damped structural mode to a sequence of step forces－entirely within the premises of structural dynamics discipline－a minimum-time zero-residual-energy torque profile with unequal intervening pulses is arrived at heuristically. Rigorous yet simple relationships are then established among the maneuver angle of a rest-to-rest slew, slew time, widths of the intervening pulses, and natural frequency and damping of a critical mode whose energy at the end of slew must be zero.

대표청구항 ▼

In a system for a flexible spacecraft, said spacecraft having jets applying positive acceleration forces for slewing said spacecraft about its slew-axis over a maneuver angle qf-qi, and having a central, principal moment of inertia I about the slew axis, and equal and opposite negative acceleration

In a system for a flexible spacecraft, said spacecraft having jets applying positive acceleration forces for slewing said spacecraft about its slew-axis over a maneuver angle qf-qi, and having a central, principal moment of inertia I about the slew axis, and equal and opposite negative acceleration forces for decelerating said slewing to stop said spacecraft at a given angular position, the method of applying said forces being such that at the end of said slewing there is no energy in the mode that is excited during the slew, said spacecraft having a low-frequency translational modal coefficient cmfmwmz0 to t1; apply a narrow pulse of said deceleration forces to said spacecraft for a period of time extending from t1 to t2; apply a narrow pulse of said acceleration forces to said spacecraft for a period of time extending from t2 to t3; apply wide pulse of said deceleration forces to said spacecraft for a period of time extending from t3 to tf; said periods of time of said narrow and wide pulses being determined in accordance with the following: Step 1. assume the absence of the narrow pulses, so that the normalized widths s1 and s2 of the narrow pulses, defined as s1=2(t2-t1)/tf s2=(t3-T2)/tf (1) are zero; Step 2. determine half slew time (tf/2) using the relationship: qf-qi=(Tmx/I) (tf/2)2(1-2s1s2) (2) Step 3. for the determined half slew time, tf/2, calculate the following quantities: [Figure] (3) Step 4. determine the amplitude A and phase gA={(c.ch-1)2+s2ㆍsh2}½ g-1 (c.ch-1)/(s.sh) (-pgp4) Step 5. determine the quantities xx2 in accordance with the following relationships: wmx-1[(sh2-s2)/2A]-gwmxwmx+2gp5) where x1 and x2 are the narrow with of the pulses between t1 and t2, and t2 and t3, respectively; Step 6. calculate x1=(t2-t1) and x2=(t3-t2).