Accession Number : ADA325615

Title :   Minimum Vibration Maneuvers Using Input Shaping and Pulse-Width, Pulse-Frequency Modulated Thruster Control.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Buck, Nicholas V.

PDF Url : ADA325615

Report Date : DEC 1996

Pagination or Media Count : 164

Abstract : Minimizing the modal vibration induced by on-off thrusters is a challenging problem designers of flexible spacecraft. This thesis presents the first study of Pulse Width, Pulse Frequency (PWPF) modulated thruster control using the method of command input shaping. Input shaping systems with linear actuators has been successfully developed to reduce modal vibrations. Recently this method has been extended to systems with on-off actuators to some degree. However, exist approaches require complicated nonlinear optimization and result in bang-bang control action. Bang thruster operation on flexible spacecraft is propellant-intensive and causes frequent thru switches. In this thesis, a new approach integrating command input shaping with PWPF-modulated thruster control is developed to minimize residual vibration in maneuvers and to reduce propel consumption. To realize this approach, an in-depth analysis of the PWPF modulator is first conducted to recommend parameter settings. Next, command input shapers are designed and integrated with PWPF modulator. Simulation verifies the efficacy of this technique in reducing modal vibration. Lastly, robustness analyses are performed and demonstrate the method's insensitivity to frequency damping uncertainty.

Descriptors :   *VIBRATION, *SPACE TECHNOLOGY, *THRUST CONTROL, *PULSE FREQUENCY MODULATION, FREQUENCY, LINEAR SYSTEMS, INPUT, CONTROL, SIMULATION, UNCERTAINTY, OPTIMIZATION, SPACECRAFT, SHAPE, DAMPING, THESES, NONLINEAR SYSTEMS, PULSES, RESIDUALS, MANEUVERS, WIDTH, ACTUATORS, SLEWING, THRUSTERS, FLEXIBLE STRUCTURES, FREQUENCY MODULATORS.

Subject Categories : Mechanics
      Radiofrequency Wave Propagation
      Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE