Showing papers on "Inertial reference unit published in 1977"

Apparatus for computing the rate of change of energy of an aircraft

Abstract: A rate of change of energy computer utilizing signal processing of the inner vectorial product of inertial acceleration and inertial velocity wherein such parameters are derived utilizing outputs from the aircraft INS (inertial navigation system) and from body mounted accelerometers.

Inertial system having correction means for effects of gravitational anomalies

Abstract: Conventional first and second Schuler tuned inertial platforms, that are physically displaced from each other by a predetermined distance, are employed in an inertial system to reduce navigation errors caused by the uncertainty in the earth's gravitational field. In addition to the two Schuler tuned platforms, a conventional velocity measuring instrument is employed to provide damping to the inertial system. The invention takes advantage of the fact that for a pair of ideal platforms if the relative velocity between them as displaced sensors can be measured with moderate accuracy then performance rivaling that obtainable with a gradiometer aided inertial platform can be achieved.

Inertial attitude control of Voyager spacecraft using dry tuned rotor gyro

Abstract: The inertial attitude control system designed for the Voyager spacecraft, which will carry out flybys of Jupiter and Saturn in 1979 and 1981, respectively, is described. The attitude of the spacecraft in three-dimensional space will be measured by a Dry Inertial Reference Unit (DIRU) based on three identical two-degree-of-freedom dry gyros. A software estimation process has been developed to use DIRU data and other information to obtain optimum estimates of spacecraft position, velocity, and acceleration. The attitude of the spacecraft is corrected using these estimates by activating hydrazine thrusters. The operation of dry gyros is discussed, together with the network compensation techniques used in their associated capture loop to obtain a capture capability of 8 deg/sec and a frequency response of 10 Hz (3-dB point). The control law and estimation process are examined. Results of computer simulation studies of the performance of the attitude control system are presented.

Flight test results of the Strapdown hexad Inertial Reference Unit (SIRU). Volume 1: Flight test summary

Abstract: Flight test results of the strapdown inertial reference unit (SIRU) navigation system are presented. The fault-tolerant SIRU navigation system features a redundant inertial sensor unit and dual computers. System software provides for detection and isolation of inertial sensor failures and continued operation in the event of failures. Flight test results include assessments of the system's navigational performance and fault tolerance.

Flight-control/navigation inertial reference system

Abstract: The preliminary design of a redundant strapdown navigation system for integrated flight-control/navigation use has been completed. Based on application of tuned-gimbal gyros, a compact configuration (13 in x 13 in x 14 in) has been achieved for fail-operational/fail-operational redundancy. Test data are presented for strapdown system test programs including flight testing of the LN-50 tuned-gimbal gyro system. Testing of a redundant sensor configuration is currently in process. Strapdown gyro development also includes ring laser and nuclear magnetic resonance techniques.

Flight test results of the Strapdown hexad Inertial Reference Unit (SIRU). Volume 3: Appendices A-G

Abstract: Results of flight tests of the Strapdown Inertial Reference Unit (SIRU) navigation system are presented. The fault tolerant SIRU navigation system features a redundant inertial sensor unit and dual computers. System software provides for detection and isolation of inertial sensor failures and continued operation in the event of failures. Flight test results include assessments of the system's navigational performance and fault tolerance. Selected facets of the flight tests are also described in detail and include some of the following: (1) flight test plans and ground track plots; (2) navigation residual plots; (3) effects of approximations in navigation algorithms; (4) vibration spectrum of the CV-340 aircraft; and (5) modification of the statistical FDICR algorithm parameters for the flight environment.

Functional Requirements of the Interface Between the NAVSTAR GPS Receiver Model X and the Advanced Inertial Reference Sphere. Volume II.

Abstract: : The performance requirements for the GPS X-set impose difficult and conflicting design problems on the receiver. To accurately track the incoming signals in a high-dynamics environment, a wide-bandwidth tracking loop is required with a high-order tracking network. For best performance in the presence of noise, on the other hand, a narrow bandwidth tracking loop is desired. Techniques for utilizing an Inertial Measurement Unit (IMU), such as the Advanced Inertial Reference Sphere (AIRS), to aid the receiver tracking loops are studied. The IMU can provide accurate information on translational accelerations and orientation changes experienced by the receiver. By properly using the IMU data, the receiver bandwidth can be reduced without increasing the dynamics-induced tracking error. The end result is an improvement in performance in noisy or jamming situations.