Showing papers on "Inertial measurement unit published in 1974"

Optimum Skewed Redundant Inertial Navigators

Abstract: The problem of proper placement of the inertial sensors to optimize system performance is important to system designers. This is especially true of redundant strapdown systems that employ more sensors than the conventional, mutually orthogonal sets of three. In systems designed for a free fall environment and with no preferred direction, such as for spacecraft attitude reference, the sensor input axes should divide the three-space equally, and can thus be viewed as being normal to the faces of regular polyhedra.' In Earth-bound inertial navigators, the effect of gravity-dependent sensor errors and the generally reduced effect of azimuth errors on navigation accuracy significantly alter the situation. Both effects tend to decrease sensor elevation angles in an optimized system. Formulas are derived and curves are drawn for optimum sensor elevation and azimuth angles vs a 0-sensitive sensor error parameter, and a mission relative azimuth error parameter. Tetrad, pentad, and hexad arrays are analyzed, affording a dramatic improvement in accuracy as well as autonomous fault isolation and/or detection capability.

Redundant inertial measurement system configuration

Abstract: A redundant inertial measuring system includes three strapdown platforms each having two inertial sensors. The sensitive axes of the sensors are discretely disposed relative to the faces of a dodecahedron. The sensors and their associated electronics are physically and electrically separated from each other within each of the platforms.

Drift Compensation and Acceleration Resolution for a Rotating Platform IMU

Abstract: Theme T Delco Carousel IMU in the Titan IIIC vehicle is similar to the conventional inertial platform except that two sets of the inertial instruments are mounted on a platform which rotates at 1 rpm about an inertially fixed axis. Derivations of navigation equations for acceleration resolution and drift compensation for the IMU are presented. The equations have been checked out and implemented in the flight computer.

Inertial Navigation Theory (Autonomous Systems)

Abstract: : The main attention is devoted to the equations of ideal operations (unperturbed functioning) of inertial systems, which determine their structure, and to equations of inertial navigation system errors, an analysis of which permits evaluation of the operating stability of the system and establishment of the relationship between the errors of the elements and the accuracy of determining the navigational parameters of the object: the current coordinates of position and its orientation in space. Problems of autonomous preparation of inertial systems for operation are also considered. The book is devoted to the theory of autonomous inertial systems.

IMU Self-Alignment Techniques

Abstract: : This report presents the results of a study on platform self- alignment performed at the Guidance and Control Directorate, US Army Missile Research, Development and Engineering Laboratory, Redstone Arsenal, Alabama. The study was initiated to explore the latest techniques in platform self- alignment and to develop new and novel approaches which would enhance the successful application of self-alignment principles to the PERSHING 2 platform alignment problem with its unique accuracy and reaction time constraints. A significant result of this study is the development of a new gyrocompassing algorithm which provides improved self-alignment performance.

Digital IMUE Study.

Abstract: : Three applications of digital technology to an Inertial Measurement Unit (IMU) were studied - the stabilization servo, sinewave generation, and temperature control. The SHIP (Small Hardened Inertial Platform) served as a vehicle for this study, but the techniques developed are applicable to a wide range of guidance systems.

Autonomous orbital navigation using Kepler's equation

Abstract: A simple method of determining the six elements of elliptic satellite orbits has been developed for use aboard manned and unmanned spacecraft orbiting the earth, moon, or any planet. The system requires the use of a horizon sensor or other device for determining the local vertical, a precision clock or timing device, and Apollo-type navigation equipment including an inertial measurement unit (IMU), a digital computer, and a coupling data unit. The three elements defining the in-plane motion are obtained from simultaneous measurements of central angle traversed around the planet and elapsed flight time using a linearization of Kepler's equation about a reference orbit. It is shown how Kalman filter theory may also be used to determine the in-plane orbital elements. The three elements defining the orbit orientation are obtained from position angles in celestial coordinates derived from the IMU with the spacecraft vertically oriented after alignment of the IMU to a known inertial coordinate frame.

High-resolution width-modulated pulse rebalance electronics for strapdown gyroscopes and accelerometers

Abstract: Three different rebalance electronic loops were designed, implemented, and evaluated. The loops were width-modulated binary types using a 614.4 kHz keying signal; they were developed to accommodate the following three inertial sensors with the indicated resolution values: (1) Kearfott 2412 accelerometer - resolution = 260 micro-g/data pulse, (2) Honeywell GG334 gyroscope - resolution = 3.9 milli-arc-sec/data pulse, (3) Kearfott 2401-009 accelerometer - resolution = 144 milli-g/data pulse. Design theory, details of the design implementation, and experimental results for each loop are presented.

Attitude Determination Techniques for Rockets with Inertial Measuring Systems

Abstract: : The implementation of procedures used to calculate the attitude of a rocket from its transmitted gyroscopic roll, pitch, and yaw signals is discussed The differences and the angular conversions of the output from various inertial attitude systems are presented Also, a synopsis of the mathematical analysis used to compute attitude is presented In addition, analyses and data reduction techniques are developed to determine the attitude of the Ute-Tomahawk rocket A09209-1, fired 16 April 1973 at White Sands Missile Range, New Mexico