Organization:
Spacecraft Research and Design Center (SRDC)

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The research in our center is progressing in several challenging areas, such as flexible spacecraft control, acquisition, tracking and pointing, optical beam control, adaptive optics, beam jitter, adaptive control, control moment gyros control, and spacecraft design. The center has several state-of-art laboratories for instruction and research.
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Publication Search Results

Now showing 1 - 10 of 73
  • Publication
    Robust Closed-loop Control Design for Spacecraft Slew Maneuver Using Thrusters
    (1995) Bang, H.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    In this paper, a closed-loop switching function for on-off thruster firings is proposed to provide good attitude control performance in the presence of modeling errors for single-axis slew maneuver of a rigid spacecraft and to eliminate double-sided thruster firings. The size of a single-sided deadband in the switching function provides the capability of a tradeoff between maneuver time and fuel expenditure. The application of this switching function for the single-axis slew maneuvers of flexible spacecraft is also analyzed. The analytical simulations and experimental results demonstrate that the proposed switching function provides significant improvement in the slew maneuver performance. In this paper, a closed-loop switching function for on-off thruster firings is proposed to provide good attitude control performance in the presence of modeling errors for single-axis slew maneuver of a rigid spacecraft and to eliminate double-sided thruster firings. The size of a single-sided deadband in the switching function provides the capability of a tradeoff between maneuver time and fuel expenditure. The application of this switching function for the single-axis slew maneuvers of flexible spacecraft is also analyzed. The analytical simulations and experimental results demonstrate that the proposed switching function provides significant improvement in the slew maneuver performance. In this paper, a closed-loop switching function for on-off thruster firings is proposed to provide good attitude control performance in the presence of modeling errors for single-axis slew maneuver of a rigid spacecraft and to eliminate double-sided thruster firings. The size of a single-sided deadband in the switching function provides the capability of a tradeoff between maneuver time and fuel expenditure. The application of this switching function for the single-axis slew maneuvers of flexible spacecraft is also analyzed. The analytical simulations and experimental results demonstrate that the proposed switching function provides significant improvement in the slew maneuver performance. In this paper, a closed-loop switching function for on-off thruster firings is proposed to provide good attitude control performance in the presence of modeling errors for single-axis slew maneuver of a rigid spacecraft and to eliminate double-sided thruster firings. The size of a single-sided deadband in the switching function provides the capability of a tradeoff between maneuver time and fuel expenditure. The application of this switching function for the single-axis slew maneuvers of flexible spacecraft is also analyzed. The analytical simulations and experimental results demonstrate that the proposed switching function provides significant improvement in the slew maneuver performance. In this paper, a closed-loop switching function for on-off thruster firings is proposed to provide good attitude control performance in the presence of modeling errors for single-axis slew maneuver of a rigid spacecraft and to eliminate double-sided thruster firings. The size of a single-sided deadband in the switching function provides the capability of a tradeoff between maneuver time and fuel expenditure. The application of this switching function for the single-axis slew maneuvers of flexible spacecraft is also analyzed. The analytical simulations and experimental results demonstrate that the proposed switching function provides significant improvement in the slew maneuver performance.
  • Publication
    Adaptive Control of Uncertain Hamiltonian Multi-Input Multi-Output Systems: with Application to Spacecraft Control
    (2008) Yoon, H.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    A novel adaptive tracking control law for nonlinear Hamiltonian multi-input–multi-output (MIMO) systems with uncertain parameters in the actuator modeling as well as the inertia and/or the Coriolis and centrifugal terms is developed. The physical properties of the Hamiltonian systems are effectively used in the control design and the stability analysis. The number of the parameter estimates is significantly lowered as compared to the conventional adaptive control methods which are based on the statespace form. The developed control scheme is applied for attitude control of a spacecraft with both the inertia and the actuator uncertainties, and numerical examples show that the controller successfully deals with the unknown inertia/actuator parameters.
  • Publication
    Topaz II Nuclear Powered SAR Satellite
    (1994) Feuerstein, M.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modulcs provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk. The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modulcs provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk. The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modulcs provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk. The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modules provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk. The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modulcs provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk. The AA4871 Spacecraft Design course is the capstone class for the M.S. in Astronautics at the Naval Postgraduate School. Thc design team integrated a Topaz If nuclear power system with an EOS Synthetic Aperture Radar to design a low Earth orbit, three axis stabilized satellite flying in a gravity gradient stable orientation. The SAR is a high resolution, electronically stecrable, Earth science data collector for glaciology, hydrology, vegetation, occauography and geology which penetrates clouds, foliage and shallow soil layers. The antenna modulcs provide global, regional, and local high resolution mapping. Tradeoffs were analyzed to optimize coverage, satisfy nuclear safety issues, and to satisfy defined revisit and resolution requircmcnts. The design emphasized use of qualified and readily available components and subsystems. The satellite features a cylindrical monocoquc alumiiium structure, and a sun synchronous orbit simplifying thermal control design. It has a momentum bias attitude control system with momentum wheels and thrusters. The antenna has microstrip radiating elements on a honeycomb metal and composite structure and is articulated with respect to the spacecraft via an electric gimbal motor. Existing satcllitc control and data processing and distribution facilitics and an existing launch vehicle and launch site limit cost and tcchnical risk.
  • Publication
    Adaptive Antenna Shape Control Using Piezoelectric Actuators
    (1997) Agrawal, B.N.; Elshafei, M.A.; Song, G.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    This paper presents improved techniques for the shape control of composite material plates using piezoelectric actuators. The application of this work is for the shape control of spacecraft antenna to correct surface errors introduced by manufacturing, in-orbit thermal distortion, and moisture. A finite element model has been developed for a composite plate with distributed piezoelectric actuators and sensors. To improve the accuracy of the prediction of plate deformation, a simple higher-order deformation theory is used. The electric potential is treated as a generalized coordinate, allowing it to vary over the element. The applied voltages to the actuators are optimized to minimize the error between the desired shape and the deformed shape. Based on these techniques, two computer programs were developed on finite element modeling and optimization. The analytical results demonstrate the use of piezo-electric actuators for the active shape control of spacecraft antennas.
  • Publication
    Spacecraft Vibration Using Pulse-Width Pulse-Frequency Modulated Input Shaper
    (1997) Song, G.; N. Buck; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    Minimizing vibrations of a exible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the rst study of pulse-width pulse-frequency modulated thruster control using command input shaping. Input shaping is a technique that uses a shaped command to ensure zero residual vibration of a exible structure. Pulse-width pulse-frequency modulation is a control method that provides pseudolinear operation for an on-off thruster. The proposed method takesfull advantage of the pseudolinear property of a pulse-width pulse-frequency modulator and integrates it with a command shaper to minimize the vibration of a exible spacecraft induced by on-offthruster ring. Compared to other methods, this new approachhas numerous advantages:1) effectiveness in vibration suppression, 2) dependence only on modal frequency and damping, 3) robustness to variationsin modal frequency and damping, and 4) easy computation. Numerical simulations performed on an eight-mode model of the Flexible Spacecraft Simulator in the Spacecraft Research and Design Center at the U.S. Naval Postgraduate School demonstrate the ef cacy and robustness of the method. Minimizing vibrations of a exible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the rst study of pulse-width pulse-frequency modulated thruster control using command input shaping. Input shaping is a technique that uses a shaped command to ensure zero residual vibration of a exible structure. Pulse-width pulse-frequency modulation is a control method that provides pseudolinear operation for an on-off thruster. The proposed method takesfull advantage of the pseudolinear property of a pulse-width pulse-frequency modulator and integrates it with a command shaper to minimize the vibration of a exible spacecraft induced by on-offthruster ring. Compared to other methods, this new approachhas numerous advantages:1) effectiveness in vibration suppression, 2) dependence only on modal frequency and damping, 3) robustness to variationsin modal frequency and damping, and 4) easy computation. Numerical simulations performed on an eight-mode model of the Flexible Spacecraft Simulator in the Spacecraft Research and Design Center at the U.S. Naval Postgraduate School demonstrate the ef cacy and robustness of the method. Minimizing vibrations of a exible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the rst study of pulse-width pulse-frequency modulated thruster control using command input shaping. Input shaping is a technique that uses a shaped command to ensure zero residual vibration of a exible structure. Pulse-width pulse-frequency modulation is a control method that provides pseudolinear operation for an on-off thruster. The proposed method takesfull advantage of the pseudolinear property of a pulse-width pulse-frequency modulator and integrates it with a command shaper to minimize the vibration of a exible spacecraft induced by on-offthruster ring. Compared to other methods, this new approachhas numerous advantages:1) effectiveness in vibration suppression, 2) dependence only on modal frequency and damping, 3) robustness to variationsin modal frequency and damping, and 4) easy computation. Numerical simulations performed on an eight-mode model of the Flexible Spacecraft Simulator in the Spacecraft Research and Design Center at the U.S. Naval Postgraduate School demonstrate the ef cacy and robustness of the method. Minimizing vibrations of a exible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the rst study of pulse-width pulse-frequency modulated thruster control using command input shaping. Input shaping is a technique that uses a shaped command to ensure zero residual vibration of a exible structure. Pulse-width pulse-frequency modulation is a control method that provides pseudolinear operation for an on-off thruster. The proposed method takesfull advantage of the pseudolinear property of a pulse-width pulse-frequency modulator and integrates it with a command shaper to minimize the vibration of a exible spacecraft induced by on-offthruster ring. Compared to other methods, this new approachhas numerous advantages:1) effectiveness in vibration suppression, 2) dependence only on modal frequency and damping, 3) robustness to variationsin modal frequency and damping, and 4) easy computation. Numerical simulations performed on an eight-mode model of the Flexible Spacecraft Simulator in the Spacecraft Research and Design Center at the U.S. Naval Postgraduate School demonstrate the ef cacy and robustness of the method.
  • Publication
    Active Vibration Suppression of a Flexible Structure Using Smart Material and a Modular Control Patch
    (2000) Song, G.; S.P. Schmidt; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
  • Publication
    Star Tracker Attitude Estimation for an Indoor Ground-Based Spacecraft Simulator
    (2011) Tappe, J.; Kim, J.J.; Jordan,A.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    This paper presents a study of star tracker attitude estimation algorithms and implementation on an indoor ground-based Three Axis Spacecraft Simulator (TASS). Angle, Planar Triangle, and Spherical Triangle algorithms are studied for star pattern recognition. Least squares, QUEST and TRIAD algorithms are studied for attitude determination. A star field image is suspended above TASS. The indoor laboratory environment restricts the placement of the star field to be in close proximity to TASS. This restriction adds some additional complication to the standard attitude determination problem. An iterative solution handles this complication. Experimental verification is also performed for the proposed iterative solution. This paper presents a study of star tracker attitude estimation algorithms and implementation on an indoor ground-based Three Axis Spacecraft Simulator (TASS). Angle, Planar Triangle, and Spherical Triangle algorithms are studied for star pattern recognition. Least squares, QUEST and TRIAD algorithms are studied for attitude determination. A star field image is suspended above TASS. The indoor laboratory environment restricts the placement of the star field to be in close proximity to TASS. This restriction adds some additional complication to the standard attitude determination problem. An iterative solution handles this complication. Experimental verification is also performed for the proposed iterative solution. This paper presents a study of star tracker attitude estimation algorithms and implementation on an indoor ground-based Three Axis Spacecraft Simulator (TASS). Angle, Planar Triangle, and Spherical Triangle algorithms are studied for star pattern recognition. Least squares, QUEST and TRIAD algorithms are studied for attitude determination. A star field image is suspended above TASS. The indoor laboratory environment restricts the placement of the star field to be in close proximity to TASS. This restriction adds some additional complication to the standard attitude determination problem. An iterative solution handles this complication. Experimental verification is also performed for the proposed iterative solution.
  • Publication
    Acquisition, Tracking and Pointing Technology Development for Bifocal Relay Mirror Spacecraft
    (2007) Kim, J.J.; Sands, T.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    The purpose of the research is to develop acquisition, tracking, and pointing technologies for the Bifocal Relay Mirror Spacecraft and verify these technologies with the experimental test-bed. Because of the stringent accuracy requirement of the laser beam and the agile maneuverability requirement, significant research is needed to develop acquisition, tracking, and pointing technologies for the Bifocal Relay Mirror Spacecraft. In this paper, development of the Bifocal Relay Mirror Spacecraft experimental test-bed is presented in detail. The current operational results are also presented including precision attitude control of the spacecraft for fine tracking and pointing. The purpose of the research is to develop acquisition, tracking, and pointing technologies for the Bifocal Relay Mirror Spacecraft and verify these technologies with the experimental test-bed. Because of the stringent accuracy requirement of the laser beam and the agile maneuverability requirement, significant research is needed to develop acquisition, tracking, and pointing technologies for the Bifocal Relay Mirror Spacecraft. In this paper, development of the Bifocal Relay Mirror Spacecraft experimental test-bed is presented in detail. The current operational results are also presented including precision attitude control of the spacecraft for fine tracking and pointing.
  • Publication
    2H Singularity-Free Momentum Generation with Non-Redundant Single Gimbaled Control Moment Gyroscopes
    (2006) Sands, T.; Kim, J.J.; Agrawal, B.N.; Spacecraft Research and Design Center (SRDC); Department of Mechanical and Aerospace Engineering
    Two objectives dominate consideration of control moment gyroscopes (CMGs) for spacecraft maneuvers: High torque (equivalently momentum) and singularity-free operations. This paper adds to the significant body of research towards these two goals utilizing a minimal 3-CMG array to rovide 646% singularity-free momentum performance increase spherically, compared to the ubiquitous pyramid arrangement skewed at 54.730. Spherical 1H (1 CMGs-worth (momentum) singularity free momentum is established with birectional 1H and 2H in the third direction in a baseline configuration. Lastly, momentum space reshaping is shown via mixed skew angles. These claims are demonstrated analytically, then heuristically, and finally validated experimentally. Two objectives dominate consideration of control moment gyroscopes (CMGs) for spacecraft maneuvers: High torque (equivalently momentum) and singularity-free operations. This paper adds to the significant body of research towards these two goals utilizing a minimal 3-CMG array to rovide 646% singularity-free momentum performance increase spherically, compared to the ubiquitous pyramid arrangement skewed at 54.730. Spherical 1H (1 CMGs-worth (momentum) singularity free momentum is established with birectional 1H and 2H in the third direction in a baseline configuration. Lastly, momentum space reshaping is shown via mixed skew angles. These claims are demonstrated analytically, then heuristically, and finally validated experimentally.
  • Publication
    Vibration Reduction for Flexible Spacecraft Attitude Control Using PWPF Modulator and Smart Structures
    (1999) Song, Gangbing; Agrawal, Brij N.; Spacecraft Research and Design Center (SRDC); Aeronautics and Astronautics
    This paper presents a new approach to vibration reduction of flexible spacecraft during attitude control by using Pulse Width Pulse Frequency (PWPF) Modulator for thruster firing and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)'s Flexible Spacecraft Simulator (FSS), which consists of a central rigid body and an L-shape flexible appendage. A pair of on-off thrusters are used to reorient the FSS. To actively suppress vibrations introduced to the flexible appendage, embedded piezoelectric ceramic patches are used as both sensors and actuators to detect and counter react to the induced vibration. For active vibration suppression using the piezoelectric ceramic patches, Positive Position Feedback (PPF) control targeting at the first two flexible modes of the FSS system is used. Experimental results demonstrate the effectiveness of the control strategy of PWPF modulation for attitude control and PPF for active vibration suppression. This paper presents a new approach to vibration reduction of flexible spacecraft during attitude control by using Pulse Width Pulse Frequency (PWPF) Modulator for thruster firing and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)'s Flexible Spacecraft Simulator (FSS), which consists of a central rigid body and an L-shape flexible appendage. A pair of on-off thrusters are used to reorient the FSS. To actively suppress vibrations introduced to the flexible appendage, embedded piezoelectric ceramic patches are used as both sensors and actuators to detect and counter react to the induced vibration. For active vibration suppression using the piezoelectric ceramic patches, Positive Position Feedback (PPF) control targeting at the first two flexible modes of the FSS system is used. Experimental results demonstrate the effectiveness of the control strategy of PWPF modulation for attitude control and PPF for active vibration suppression. This paper presents a new approach to vibration reduction of flexible spacecraft during attitude control by using Pulse Width Pulse Frequency (PWPF) Modulator for thruster firing and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)'s Flexible Spacecraft Simulator (FSS), which consists of a central rigid body and an L-shape flexible appendage. A pair of on-off thrusters are used to reorient the FSS. To actively suppress vibrations introduced to the flexible appendage, embedded piezoelectric ceramic patches are used as both sensors and actuators to detect and counter react to the induced vibration. For active vibration suppression using the piezoelectric ceramic patches, Positive Position Feedback (PPF) control targeting at the first two flexible modes of the FSS system is used. Experimental results demonstrate the effectiveness of the control strategy of PWPF modulation for attitude control and PPF for active vibration suppression. This paper presents a new approach to vibration reduction of flexible spacecraft during attitude control by using Pulse Width Pulse Frequency (PWPF) Modulator for thruster firing and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)'s Flexible Spacecraft Simulator (FSS), which consists of a central rigid body and an L-shape flexible appendage. A pair of on-off thrusters are used to reorient the FSS. To actively suppress vibrations introduced to the flexible appendage, embedded piezoelectric ceramic patches are used as both sensors and actuators to detect and counter react to the induced vibration. For active vibration suppression using the piezoelectric ceramic patches, Positive Position Feedback (PPF) control targeting at the first two flexible modes of the FSS system is used. Experimental results demonstrate the effectiveness of the control strategy of PWPF modulation for attitude control and PPF for active vibration suppression. This paper presents a new approach to vibration reduction of flexible spacecraft during attitude control by using Pulse Width Pulse Frequency (PWPF) Modulator for thruster firing and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)'s Flexible Spacecraft Simulator (FSS), which consists of a central rigid body and an L-shape flexible appendage. A pair of on-off thrusters are used to reorient the FSS. To actively suppress vibrations introduced to the flexible appendage, embedded piezoelectric ceramic patches are used as both sensors and actuators to detect and counter react to the induced vibration. For active vibration suppression using the piezoelectric ceramic patches, Positive Position Feedback (PPF) control targeting at the first two flexible modes of the FSS system is used. Experimental results demonstrate the effectiveness of the control strategy of PWPF modulation for attitude control and PPF for active vibration suppression.