Showing papers on "Inertial reference unit published in 1979"

Kinematic inertial sensor

Abstract: A kinematic inertial sensor is provided for measuring angular velocity and position relative to inertial space about one or more measurement axes. The kinematic inertial sensor includes an angular rate sensor having a ring of conducting fluid contained in a housing, a set of gimbals for supporting the angular rate sensor, signal generating means, torque applying means, angle measuring means, resolver means, component processing means, and signal applying means.

Performance advantages of dynamically tuned gyroscopes in high accuracy spacecraft pointing and stabilization applications

Abstract: The paper compares and describes the advantages of dry tuned gyros over floated gyros for space applications. Attention is given to describing the Teledyne SDG-5 gyro and the second-generation NASA Standard Dry Rotor Inertial Reference Unit (DRIRU II). Certain tests which were conducted to evaluate the SDG-5 and DRIRU II for specific mission requirements are outlined, and their results are compared with published test results on other gyro types. Performance advantages are highlighted.

DRIRU II - The NASA standard high performance Inertial Reference Unit

Abstract: This paper discusses the design configuration, performance and environmental capability of NASA's Dry Rotor Inertial Reference Unit (DRIRU II) for use in spacecraft precision attitude stabilization systems. The system is a self-contained, strapdown, dual rate sensing unit for spacecraft requiring high accuracy, reliability and low power consumption. Modular construction of the basic unit, arrangement of gyros, electronic modules and power supplies, signal flow, and mounting are described. DRIRU II is designed to meet specified performance requirements for a minimum of two years of operating time in orbit and a reliability prediction analysis is presented. The characteristics of test equipment are given together with the results of the environmental, radiation, and magnetic field sensitivity tests. DRIRU II may be modified for unique requirements and the rate range and resolution options are tabulated. The flexibility of the unit afforded by the use of dry tuned gimbal gyros and its modular construction results in a system capable of satisfying the demanding requirements of a broad spectrum of future applications. The units are planned for the Solar Max, Landsat-D and ASPS missions in the 1980's.

DRIRU II Standard High Accuracy Inertial Reference Unit for Spacecraft Through the 1980's

Abstract: Until recently, space programs such as Viking used the “block redundancy” concept for spacecraft navigation/control, whereby multiple navigation units of the same configuration were packaged in different locations on the spacecraft. The desire for a more efficient and cost effective approach to redundant spacecraft navigation systems prompted NASA to fund the development of a redundant Inertial Reference Unit (DRIRU I) based on the utilization of three dry, tuned-gimbal, two-degree-of-freedom gyroscopes. Each gyroscope, together with its associated electronics and power supply, comprises a “gyro channel” which provides two axes of angular rate information and is totally independent from the other two gyro channels. The first of these systems was successfully flown on the Voyager Program. More demanding space programs of the late 1970's and through the 1980's, such as SOLAR MAX, LANDSAT, ASPS, and SPACE TELESCOPE, have prompted the further development of a standardized high accuracy IRU (DRIRU II) based on the same design concepts and objectives stated above. This paper provides a comprehensive discussion of the system design configuration, performance capability, and environmental capability of the NASA Standard Redundant Dry Rotor Inertial Reference Unit (DRIRU II). Further, the design flexibility of the DRIRU II is discussed to allow potential users to consider adaptation of the unit to their unique space program requirements.

Low-cost inertial navigation for moderate-g missions

Abstract: A low cost inertial navigation system (INS) concept is described for flight missions characterized by moderate accelerations and limited attitude variations. These missions involve general aviation aircraft, helicopters, or remotely piloted vehicles. The significance of the moderate acceleration and limited attitude is reviewed with respect to platform mechanization and instrumentation. A hybrid mechanization, partially gimballed and partially strapdown, is presented. The INS is implemented by an unbalanced two axis gimbal system and controlled by a two degree of freedom gyro. The INS provides locally level two axis acceleration information along with pitch and roll measurements. Heading information is provided by a second gyro mounted in the inner gimbal. The system error model is equivalent to that of a conventional platform with a tilt error determined by the integral of the gyro drift rate and an equivalent accelerometer type errors are also cancelled. Rapid gyro-compassing, implemented with opened gimbal control loops, and a strapdown procedure provides calibration of gyro drift rate biases.