Inertial gyroscope system application considerations

Criteria for designing inertial gyroscope system

Evaluation of selected strapdown inertial instruments and pulse torque loops, volume 1

Design, operational and performance variations between ternary, binary and forced-binary pulse torque loops are presented. A fill-in binary loop which combines the constant power advantage of binary with the low sampling error of ternary is also discussed. The effects of different output-axis supports on the performance of a single-degree-of-freedom, floated gyroscope under a strapdown environment are illustrated. Three types of output-axis supports are discussed: pivot-dithered jewel, ball bearing and electromagnetic. A test evaluation on a Kearfott 2544 single-degree-of-freedom, strapdown gyroscope operating with a pulse torque loop, under constant rates and angular oscillatory inputs is described and the results presented. Contributions of the gyroscope's torque generator and the torque-to-balance electronics on scale factor variation with rate are illustrated for a SDF 18 IRIG Mod-B strapdown gyroscope operating with various pulse rebalance loops. Also discussed are methods of reducing this scale factor variation with rate by adjusting the tuning network which shunts the torque coil. A simplified analysis illustrating the principles of operation of the Teledyne two-degree-of-freedom, elastically-supported, tuned gyroscope and the results of a static and constant rate test evaluation of that instrument are presented

Floated pallet definition study. Volume 4: Summary volume

The conceptual design of a suspension system for the Floated Pallet and a retention system to support the pallet during launch, maneuvering and descent are described. In addition, a control moment gyroscope support equipment configuration study including installation and an experiment mount and erection study was performed. The impact of these separate hardware studies on the existing pallet configuration was assessed and a modified pallet common module defined

Application of inertial instruments for DSN antenna pointing and tracking

The feasibility of using inertial instruments to determine the pointing attitude of the NASA Deep Space Network antennas is examined. The objective is to obtain 1 mdeg pointing knowledge in both blind pointing and tracking modes to facilitate operation of the Deep Space Network 70 m antennas at 32 GHz. A measurement system employing accelerometers, an inclinometer, and optical gyroscopes is proposed. The initial pointing attitude is established by determining the direction of the local gravity vector using the accelerometers and the inclinometer, and the Earth's spin axis using the gyroscopes. Pointing during long-term tracking is maintained by integrating the gyroscope rates and augmenting these measurements with knowledge of the local gravity vector. A minimum-variance estimator is used to combine measurements to obtain the antenna pointing attitude. A key feature of the algorithm is its ability to recalibrate accelerometer parameters during operation. A survey of available inertial instrument technologies is also given

SIRU development. Volume 1: System development

A complete description of the development and initial evaluation of the Strapdown Inertial Reference Unit (SIRU) system is reported. System development documents the system mechanization with the analytic formulation for fault detection and isolation processing structure; the hardware redundancy design and the individual modularity features; the computational structure and facilities; and the initial subsystem evaluation results

Mission definition study for Stanford relativity satellite. Volume 2: Engineering flight test program

The need is examined for orbital flight tests of gyroscope, dewar, and other components, in order to reduce the technical and financial risk in performing the relativity experiment. A program is described that would generate engineering data to permit prediction of final performance. Two flight tests are recommended. The first flight would test a dewar smaller than that required for the final flight, but of size and form sufficient to allow extrapolation to the final design. The second flight would use the same dewar design to carry a set of three gyroscopes, which would be evaluated for spinup and drift characteristics for a period of a month or more. A proportional gas control system using boiloff helium gas from the dewar, and having the ability to prevent sloshing of liquid helium, would also be tested

A bibliography /with abstracts/ on gas-lubricated bearings Interim report

Gas lubricated bearings - annotated bibliograph

Fluidic mechanism for dual-axis gyroscope

In this paper, we report a further study of flow-network generating four jet flows which circulate in a sealed device to experimentally investigate the feasibility and efficiency of a dual-axis gyroscope. The experiment is carried out successfully and the experimental results reasonably agreed with those obtained by numerical analysis using OpenFOAM. The flow rectifying coefficient is determined using the mathematical lump model for a vibrating system, which takes into account of the device geometry and resonant frequency. Experimental and numerical results demonstrate that the coefficient of the new system developed in this study is significantly higher than those of conventional designs. The hotwire-integrated device which can function as a dual-axis gyroscope is tested using a turntable with speeds up to 1900 rpm. The scale factor and cross-sensitivity of the system are 0.26 microV s/o and 1.2%, respectively. The cross-sensitivity and the effects of linear acceleration, actuating voltage on the diaphragm, heating power and position of hotwires are also investigated

MEMS Gyroscopes for Consumers and Industrial Applications

none2mixedAntonello, Riccardo; Oboe, RobertoAntonello, Riccardo; Oboe, Robert

Space infrared telescope pointing control system. Infrared telescope tracking in the presence of target motion

The use of charge-coupled-devices, or CCD's, has been documented by a number of sources as an effective means of providing a measurement of spacecraft attitude with respect to the stars. A method exists of defocussing and interpolation of the resulting shape of a star image over a small subsection of a large CCD array. This yields an increase in the accuracy of the device by better than an order of magnitude over the case when the star image is focussed upon a single CCD pixel. This research examines the effect that image motion has upon the overall precision of this star sensor when applied to an orbiting infrared observatory. While CCD's collect energy within the visible spectrum of light, the targets of scientific interest may well have no appreciable visible emissions. Image motion has the effect of smearing the image of the star in the direction of motion during a particular sampling interval. The presence of image motion is incorporated into a Kalman filter for the system, and it is shown that the addition of a gyro command term is adequate to compensate for the effect of image motion in the measurement. The updated gyro model is included in this analysis, but has natural frequencies faster than the projected star tracker sample rate for dim stars. The system state equations are reduced by modelling gyro drift as a white noise process. There exists a tradeoff in selected star tracker sample time between the CCD, which has improved noise characteristics as sample time increases, and the gyro, which will potentially drift further between long attitude updates. A sample time which minimizes pointing estimation error exists for the random drift gyro model as well as for a random walk gyro model