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At least 199 records · Page 11

Design Considerations for Miniaturized Control Moment Gyroscopes for Rapid Retargeting and Precision Pointing of Small Satellites

This paper presents the design as well as characterization of a practical control moment gyroscope (CMG) based attitude control system (ACS) for small satellites in the 15-20 kilogram mass range performing rapid retargeting and precision pointing maneuvers. The paper focuses on the approach taken in the design of miniaturized CMGs while considering the constraints imposed by the use of commercial off-the-shelf (COTS) components as well as the size of the satellite. It is shown that a hybrid mode is more suitable for COTS based moment exchange actuators; a mode that uses the torque amplification of CMGs for rapid retargeting and direct torque capabilities of the flywheel motors for precision pointing. A simulation is provided to demonstrate on-orbit slew and pointing performance.

Patankar, Kunal↗

Simulation of Malfunctions for the ISS Double-Gimbal Control Moment Gyroscope

This paper presents a simplified approach to simulation of malfunctions of the Control Moment Gyroscope (CMG) on board the International Space Station (ISS). These malfunctions will be used as part of flight training of CMG failure scenarios in the guidance navigation control (GNC) subsystem of the Training Systems for 21st Century (TS21) simulator. The CMG malfunctions are grouped under mechanical, thermal and electrical categories. A malfunction can be as simple as one which only affects the telemetry or a complex one that changes the state and behavior of the CMG model. In both cases, the ISS GNC flight software will read the telemetry and respond accordingly. The user executes these malfunctions by supplying conditional data which modify internal model states and then elicit a response as seen on the user displays. Ground operators and crew on board the ISS use CMG malfunction procedures to better understand and respond to anomalies observed within the CMG subsystem.

Inampudi, Ravi↗

Fast Light Optical Gyroscopes

Next-generation space missions are currently constrained by existing spacecraft navigation systems which are not fully autonomous. These systems suffer from accumulated dead-reckoning errors and must therefore rely on periodic corrections provided by supplementary technologies that depend on line-of-sight signals from Earth, satellites, or other celestial bodies for absolute attitude and position determination, which can be spoofed, incorrectly identified, occluded, obscured, attenuated, or insufficiently available. These dead-reckoning errors originate in the ring laser gyros themselves, which constitute inertial measurement units. Increasing the time for standalone spacecraft navigation therefore requires fundamental improvements in gyroscope technologies. One promising solution to enhance gyro sensitivity is to place an anomalous dispersion or fast light material inside the gyro cavity. The fast light essentially provides a positive feedback to the gyro response, resulting in a larger measured beat frequency for a given rotation rate as shown in figure 1. Game Changing Development has been investing in this idea through the Fast Light Optical Gyros (FLOG) project, a collaborative effort which began in FY 2013 between NASA Marshall Space Flight Center (MSFC), the U.S. Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC), and Northwestern University. MSFC and AMRDEC are working on the development of a passive FLOG (PFLOG), while Northwestern is developing an active FLOG (AFLOG). The project has demonstrated new benchmarks in the state of the art for scale factor sensitivity enhancement. Recent results show cavity scale factor enhancements of approx.100 for passive cavities.

Smith, David D.↗

Carbon Nanotube Tape Vibrating Gyroscope

A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

Tucker, Dennis Stephen↗

Non-Hermitian Gyroscopes: Can Exceptional Points Increase Sensor Precision

We show that exceptional points in conservatively coupled systems can increase the quantum-limited precision of laser gyroscopes as a result of gain saturation, but that this requires recovery of the beat note by interference with an auxiliary mode, with consequences for the quantum and classical noise that depend on the particular recovery scheme.

David D Smith↗

MEMS metal-quartz gyroscope

The present disclosure relates to a gyroscope that makes use of a shuttle having a first plurality of fingers, a stator having a second plurality of fingers, at least one fixed support structure, and a plurality of flexors for supporting the shuttle for vibratory motion relative to the stator. The fingers of the shuttle are able to move in a vibratory motion adjacent the fingers of the stator without contacting the fingers of the stator. Portions of the fingers of at least one of the shuttle and the stator also make use of a grounded metal material layer to reduce parasitic capacitive coupling between the fingers of the shuttle and the fingers of the stator.

Park, Sangtae↗

Some effects of vibration and rotation on the drift of gyroscopic instruments

It is the purpose of this paper to describe and indicate possible analytical approaches to some of the most significant mechanisms by which vibration induced drifts may occur, and to indicate, where possible, some means of alleviating them. In all cases we will not consider gimbal bearing friction, mass unbalance or other sources of steady extraneous torques on the gyro rotor. The mechanisms to be discussed are: Non-Newtonian viscosity in single degree of freedom (SDF) integrating-rate gyros, nonisoelasticity in SDF gyros, noncommutative effects for SDF stabilized platform, gimbal inertia effects, 2 DF gyros, and spin axis torque coupling in 2 DF gyros. High-frequency elastic resonances are not discussed explicitly in detail, because they are a more familiar problem and one which depends strongly on the details of each particular gyro design.

Viscous Torque↗

Report on a cryogenic gyroscope

Report summarizes the principal problems encountered in sphere fabrication, magnetic field losses in superconductors, configurations for the supporting field, damping oscillations, refrigeration, techniques for accelerating the sphere, read-out, and testing the stability of the gyro.

Harding, J. T.↗