A modular laser gyro incorporating a laser gyro with a digital control processor. The digital control processor safely and quickly starts the laser gyro. The microprocessor also executes tests on the gyro and provides a health signal. Optional start-up operations may be performed including the calibration of volts per mode and system configuration. Various information including gyro parameter load commands, gyro control commands, gyro status commands, and gyro calibration and diagnostic commands may be provided to an inertial navigation system. A high voltage start circuit includes a high voltage start module and high voltage pulse generator apparatus. The high voltage start circuit is contained within a modular laser gyro housing. A direct digital dither drive for a dither motor controls the dithering of the gyro to prevent lock in of the laser beams. A dither stripper controls the stripping of the dither signal. A bias drift rate improvement system, as well as a random drift rate improvement system reduces errors. A lifetime prediction mechanism incorporates a memory model that stores worst case performance parameters and evaluates them against predetermined failure criteria. An active current control controls lasing current to prolong life and enhance performance. A single transformer power supply powers the modular gyro.

Modular laser gyro

A laser gyro start up apparatus and method that safely and quickly starts up a laser gyro. A microprocessor sequences the mechanical and electrical systems of the laser gyro such that the gyro is started up quickly in the proper sequence. The microprocessor also executes tests on the gyro and provides a health signal in the timing sequence. The start up apparatus starts the laser block dither, laser discharge and acquires the path length controllers. Optical start up operations may be performed including the calibration of volts per mode.

Laser gyro microprocessor start up control method and apparatus

Of the various non-linearity sources in a ring laser gyroscope (RLG), the most limiting one is the "mode-locking" or "lock-in" phenomenon. To avoid the mode-locking, the laser cavity is subjected to a fixed frequency to-and-fro motion, called mechanical dithering. This forces the RLG to stay outside the lock-in zone. The RLG output, however, reflects the dither rate as an additive noise, which must be removed to obtain the true body rate. The dither removal is by far the most important task in RLG signal processing, as the dither residue limits the accuracy with which the RLG measures angular rate and hence angular position. Two dither removal techniques commonly used in RLGs are: (1) the dither-stripping scheme using dither pick-off sensor; and (2) the dither removal by digital filtering scheme. Both techniques have their own strengths and weaknesses and hence are not applicable in all RLG-based positioning and tracking problems. This paper proposes a "third alternative scheme" for dither removal that essentially combines the strengths of the two existing schemes, provides comparable measurement accuracy and meets the time constraint in typical RLG-based applications. A comparative study of the three schemes with online single axis RLG data is also presented.

An improved dither-stripping scheme for strapdown ring laser gyroscopes

The design of a rapid and robust transfer alignment system for advanced kinetic energy missiles (ADKEMs) is presented in this paper. Owing to the high acceleration level and the reduced engagement time of ADKEMs, the transfer alignment which aligns the salve (missile) inertial measurement unit (IMU) with the master (ground launch vehicle) IMU must be accomplished in a short time with high accuracy. The scope of transfer alignment system design presented in this paper includes the assessment of inertial guidance accuracy, transfer alignment formulation, simulation environment development, maneuver scenario evaluation, system error analysis, tradeoff study, and filter robustness and sensitivity analysis.

Transfer alignment design and evaluation

/pdf/performance-modeling-of-ring-laser-gyro-in-inertial-628djqbieb.pdf

Performance Modeling of Ring Laser Gyro in Inertial

The GG1308 ring laser gyro (RLG) inertial measurement systems represent the smallest-volume, lightest-weight, and lowest-cost RLG systems. These systems are designed to provide the functions required for inertial guidance, aided or midcourse navigation, and vehicle stabilization and control to a wide variety of tactical missiles, standoff weapons, unmanned aerial vehicles, torpedoes, and manned rotorcraft. GG1308 inertial systems achieve their low cost as a result of several significant development thrusts. Low-cost inertial sensors must be utilized. The GG1308 RLG is a true design-to-cost device with producibility and the cost of parts, materials, assembly labor, and manufacturing automation being the dominant design drivers. Additionally, these GG1308 inertial systems use a commonality design approach. This philosophy has made it possible to develop several generic hardware elements which need only be repackaged to provide an inertial system in the form factor required for specific programs. It also provides the system with an adaptability and intelligence to improve its performance throughout its useful life by making software improvements which do not affect the hardware design or production process. >

L.O. Thielman

Papers

GG1308 ring laser gyro inertial measurement systems: Honeywell's low-cost solution for tactical applications