COMPUTATION OF NEAR-MINIMUM-TIME MANEUVERS OF FLEXIBLE STRUCTURES BY PARAMETER OPTIMIZATION

Near-minimum-time attitude maneuvers of space structures as well as gr ound-based test articles are considered. The switching nature of the c ontrols for rigid-body maneuvers is illustrated using a control cube a nd a critical control axis. The presence of torque smoothing and, wher e appropriate, gravitational effects and connections to other bodies a re explicitly included in the mathematical models of the systems to be optimized. A maximum fuel consumption constraint is included along wi th the required terminal conditions on attitude and angular velocities . The switch times, maximum thrust magnitudes, and smoothing parameter s are determined using the sequential quadratic programming method for parameter optimization. Results indicating attitude and angular veloc ity histories, thruster forces, and structural vibrations are presente d for three, four, and five switch maneuvers, as well as maneuvers tha t involve large coasting arcs.