SIMULATION OF A SATELLITE GYROSCOPIC ATTITUDE CONTROL SYSTEM WITH ORBITAL PITCH RATE.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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A satellite gyroscopic attitude control system using four single-degree-of-freedom control gyros is analyzed by signal flow graphs, and simulated on an IBM 7094 computer using a digital analog simulation subroutine. A signal flow graph is first developed for one gyro, and then extended to the four gyro configuration. A transfer function is derived for each axis from the signal flow graph, and coefficients are chosen to optimize performance about the X and Y axes which have equal moments of inertia. The Z axis has a moment of inertia one-fortieth of the other two, and the resulting higher natural frequency is compensated by a Z axis angular accelerometer. Digital simulation demonstrated that the system is capable of correcting step and rate errors about each axis. Orbital pitch rate is introduced causing the net gyro spin momentum vector to precess. The simulated flight computer torqued the gyros to correct for the precession. This maintained the spin momentum vector fixed in inertial space while the vehicle maintained its pitch rate. The MIDAS program and five sample data runs are included. Author