Search NASA⌕ Search

Engineering topics

Breckenridge, W. G.

Publications and source records attributed to Breckenridge, W. G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Calibration and operation of a large space-based optical interferometer

The on-orbit calibration of the optics, structure, and control systems of the CSI Focus Mission Interferometer (FMI) is described. The calibration involves the estimation and propagation of both positional and rotational parameters and the propagation of both positional and rotational parameters at the nanometer/nanoradian level. It is shown that, given a nanometer class metrology system to monitor positional changes of critical optical elements, this calibration procedure should enable the FMI to perform 50 picoradian astrometry. The same Kalman filter that implements the initializing calibration of the interferometer baselines and internal pathlengths will also participate in the astrometric measurements of stellar positions.

Laskin, R. A.↗
NASA NTRS1989

Annihilation of angular momentum bias during thrusting and spinning-up maneuvers

During spinning-up and thrusting maneuvers of rockets and spacecraft, undesired transverse torques (from error sources such as thruster misalignment, center-of-mass offset and thruster mismatch) perturb the angular momentum vector from its original orientation. In this paper a maneuver scheme is presented which virtually annihilates the angular momentum vector bias, even though the magnitude and direction of the perturbing body-fixed torques are unknown. In the analysis it is assumed that the torques are small and constant and that the spacecraft or rocket can be approximated by a rigid body, which may be asymmetric. Typical maneuvers of the Galileo spacecraft are simulated to demonstrate the technique.

Longuski, J. M.↗
NASA NTRS1984

Quaternions for Galileo scan platform control

The application of quaternions for the articulation control of the Galileo scan platform is presented in this paper. The purpose of selecting quaternions is to minimize onboard computation time and program size. Attention has been focused on performing inertial pointing while the spacecraft is in a dual spin configuration. Target quaternion and relative target quaternion are introduced and used to specify the target position of the scan platform for point-to-point absolute slews and mosaic relative slews, respectively. The pointing error of the platform is represented by an error quaternion which is converted into gimbal angular errors defining the attitude change. For path control, a moving target quaternion is generated; the corresponding tracking error quaternion and the related spacecraft motion compensation capability are also addressed. A sample slew case is used to demonstrate the implementation of these concepts.

Breckenridge, W. G.↗
NASA NTRS1984

Annihilation of angular momentum drift during spinning-up and thrusting maneuvers of rigid bodies

A very simple, yet accurate, heuristic solution for the spiral path of the angular momentum vector during spin-up and spin-down maneuvers of rigid body spacecraft is presented. A two-burn scheme is proposed consisting of a burn, a coast, and a second burn of the spin thruster. The appropriate burn times are found by a transcendental equation similar to Kepler's equation. Numerical results verify the accuracy of the burn, coast, and burn times given by closed form expressions. The scheme can also be applied to the problem of axial thrusting during constant spin.

Longuski, J. M.↗
NASA NTRS1981

Command profile for Galileo scan platform control

A recursive command profile is developed for the control of a two-degree-of-freedom scan platform mounted on a flexible structure. Perfect sensors and actuators are assumed for development and testing, and structural vibrations are minimized by actuator torque commands following a smooth torque-time profile. The integral of the smooth torque profile, the rate profile, is recursively generated by a piecewise constant second derivation, and the torque applied by the closk actuator is divided into three components. Results show that the smooth platform motion in response to the command profiles is what the Galileo control systems needs to avoid stator structural vibrations. Position, rate and acceleration profiles are also presented, and the resulting motion of the scan platform in response to command profiles is illustrated.

Man, G. K.↗
NASA NTRS1981

Inertial attitude determination for a dual-spin planetary spacecraft

Design and performance evaluations of an onboard inertial attitude determination system for a dual-spin planetary spacecraft are presented. A quaternion integration algorithm and a rate estimator sequentially determine the scan platform's inertial attitude and rate from the drift and misalignment compensated gyro outputs. A least-squares estimator algorithm processes the star transit data from a rotor-mounted star scanner, and provides periodic updates of the scan platform's attitude as a means of correcting the drift of the quaternion integration algorithm. Computer simulated algorithm performance in the presence of nutation and sensor noise are presented.

Wong, E. C.↗
NASA NTRS1979

Interplanetary orbit determination

A general description of the Viking interplanetary orbit determination activity extending from launch to Mars encounter is given. The emphasis is on the technical fundamentals of the problem, basic strategies and data types used, quantitative results, and specific conclusions derived from the inflight experience. Special attention is given to the use of the spacecraft-based optical measurements and their first application as a principal navigational data type for an interplanetary mission. The optical-based orbit determination, in fact, was the primary contributor to the exceptional interplanetary navigation accuracy experienced by both Viking missions. The Viking application of optical orbit determination relied in large part on the technology developed and demonstrated by the Mariner 9 Optical Navigation Demonstration.

Rourke, K. H.↗
NASA NTRS1979

A model for testing centerfinding algorithms for automated optical navigation

An efficient software simulation of the imaging process for optical navigation is presented, illustrating results using simple examples. The problems of image definition and optical system modeling, including ideal image containing features and realistic models of optical filtering performed by the entire camera system, are examined. A digital signal processing technique is applied to the problem of developing methods of automated optical navigation and the subsequent mathematical formulation is presented. Specific objectives such as an analysis of the effects of camera defocusing on centerfinding of planar targets, addition of noise filtering to the algorithm, and implementation of multiple frame capability were investigated.

Griffin, M. D.↗
NASA NTRS1978

In-flight gyro drift rate calibration on the Viking Orbiters

The drift rates of the attitude control gyros on the Viking Orbiters were calibrated several times in flight. The process by which these rates were estimated as functions of time is novel for a space flight project, although relatively standard estimation techniques were used. The process is described fully and the results obtained from the twelve Viking single-axis gyros are analyzed. Although the possibility was explored, no significantly repeatable function of drift rate vs time or temperature was discovered; the overall mean was found to predict drift rate with acceptable accuracy.

Breckenridge, W. G.↗
NASA NTRS1977

Calibration of Viking imaging system pointing, image extraction, and optical navigation measure

Pointing control and knowledge accuracy of Viking Orbiter science instruments is controlled by the scan platform. Calibration of the scan platform and the imaging system was accomplished through mathematical models. The calibration procedure and results obtained for the two Viking spacecraft are described. Included are both ground and in-flight scan platform calibrations, and the additional calibrations unique to optical navigation.

Breckenridge, W. G.↗
NASA NTRS1977

In-flight gyro drift rate calibration on the Viking Orbiters

The drift rates of the attitude control gyros onboard the Viking Orbiters were calibrated several times during flight. The calibration was performed by engaging the gyro control of attitude for a six-hour period, recording the Viking Orbiter coordinates of the sun and the roll reference star as a function of time, and processing these data by a computer program. The computer program calculated drift rates for each data increment, and then smoothed the calculated rate versus the time function for all the data on the basis of a Gauss-Markov gyro-drift model. The effects of data noise were minimized by using a relatively long time constant in the Gauss-Markov model and by empirically determining a set of corrections for celestial inertial scale factor error differences. In this way the rms error of the data fit was lessened.

Breckenridge, W. G.↗
NASA NTRS1977

The determination of the interplanetary orbits of Vikings 1 and 2

A description is presented of the navigation-related events of the Viking Mars mission. Orbit determination system fundamentals are discussed, taking into account the trajectory models, observation models, radio data models, range considerations, optical data models, filter models, the orbit determination process, critical orbit determination inputs, and orbit determination errors. Attention is also given to questions of orbit determination strategy, orbit determination results, optical measurements processing, aspects of approach orbit determination evaluation, and the orbit determination software system.

Rourke, K. H.↗
NASA NTRS1974

Mariner Mars 1971 optical navigation demonstration

The feasibility of using a combination of spacecraft-based optical data and earth-based Doppler data to perform near-real-time approach navigation was demonstrated by the Mariner Mars 71 Project. The important findings, conclusions, and recommendations are documented. A summary along with publications and papers giving additional details on the objectives of the demonstration are provided. Instrument calibration and performance as well as navigation and science results are reported.

Born, G. H.↗
NASA NTRS1973

Interplanetary orbit determination

The logistical aspects of orbit determination (OD) in the interplanetary phase of the Mariner Mars 1971 mission are described and the working arrangements for the OD personnel, both within the Navigation Team and with outside groups are given. Various types of data used in the OD process are presented along with sources of the data. Functional descriptions of the individual elements of the OD software and brief sketches of their modes of operation are provided.

Zielenbach, J. W.↗
NASA NTRS1972

A detailed analysis of Mariner nine TV navigation data.

Mariner 9 data analysis showed a good performance of the Mars probe planetary approach navigation systems and a good agreement between measured and predicted probe-approach characteristics. It was found that all operations were completed on time and that the calibration of the instruments and the observation of a greater-than-planned number of stars resulted in a higher-than-expected measurement accuracy. The key instruments of the Mariner were TV cameras taking pictures of Phobos and Deimos against a background of stars, calibrated sun and star sensors, and a scan platform. The error models used for optical navigation system elements, the calibration of the scan platform and of the TV cameras, and the image detection and location techniques are discussed in detail.

Breckenridge, W. G.↗