Singularity avoidance control laws for single gimbal control moment gyros
Abstract
Two singularity avoidance control laws are presented in this paper. These techniques are based upon the ability to calculate the exact instantaneous location of all singular gimbal angle sets. In the first control law, called the direct method, these gimbal angles are directly avoided by adding nullmotion that is in a sense opposite to the relative distance vector between the current set of gimbal angles and the most rapidly approaching singularity. This basic logic is followed unless the most rapidly approaching singularity happens to be on the saturation surface. In that situation, the algorithm attempts to steer towards the saturation singularity. The second control law, called the indirect method, is the second part of the first method. It always adds null motion in an attempt to steer the gimbal angle trajectories towards the saturation singularity. In the process of steering toward saturation, the gimbal angle trajectories indirectly avoid the remaining singularities. Computational results with both of these control laws show that these algorithms can successfully avoid internal singularities in cases where current control laws fail.
 Publication:

Guidance and Control Conference
 Pub Date:
 February 1979
 Bibcode:
 1979guco.conf...20C
 Keywords:

 Algorithms;
 Control Moment Gyroscopes;
 Control Theory;
 Gimbals;
 Instrument Errors;
 Singularity (Mathematics);
 Spacecraft Maneuvers;
 Avoidance;
 Block Diagrams;
 Computerized Simulation;
 Flow Charts;
 Satellite Attitude Control;
 Torque;
 Instrumentation and Photography