Showing papers on "Inertial measurement unit published in 1996"

Portable tracking apparatus for continuous position determination of criminal offenders and victims

Abstract: A portable locator or tracking apparatus is provided for continuous location determination of subjects which communicates with a body-worn, non-removable, tamper resistant transceiver and a central data-base system. The portable tracking apparatus has a Global Position System (GPS) receiver and inertial sensors for determining location, microprocessors for logic and mathematical algorithm processing, memory for programs and data, a wireless transceiver for communications with the body-worn device, a wireless transceiver for communicating with the central data-base system, an alpha-numeric display for displaying text messages sent to the subject acoustic speaker and microphone for voice and tone messages with subjects, electronic tamper sensors, motion sensors, attitude position sensor, batteries and external connectors for power, recharge, communications and auxiliary antennas.

Hybrid GPS/inertially aided platform stabilization system

Abstract: A hybrid system for stabilizing the attitude of an instrument relative to a dynamic platform includes a plurality of (roll, pitch and yaw) inertial rate sensors, whose outputs are sampled at a rate sufficient to provide real time tracking of changes in orientation of the platform, and a global positioning system (GPS) receiver, whose precision platform attitude output is updated periodically, but at a rate less than the rate of change of attitude of the platform. The inertial rate sensors provide effectively continuous motion (e.g., angular rate) data signals representative of three-dimensional changes in attitude (position derivative signals) of the platform. The inertial rate output are integrated to provide output signals representative of the dynamic orientation of the platform. Sequential outputs of the integration-processing circuitry are also coupled to a sample buffer, which is controllably read-out in accordance with the periodic updates from the GPS receiver. The integrated inertial sensor (attitude) data is compared with the GPS update data to generate error signals which are used to adjust the inertial sensor data. By employing a sample buffer in an inertial sensor output integration feedback loop with the GPS receiver, the hybrid system of the present invention avoids what would otherwise be a staleness problem with the data provided by the GPS receiver.

Inertial proprioceptive devices: self-motion-sensing toys and tools

Abstract: One of the current goals of technology is to redirect computation and communication capabilities from within the traditional computer and into everyday objects and devices—to make devices. one important function of smart devices is motion sensing. a proprioceptive device has a sense of its own motion and position. this ability can allow pens to remember what they have written, cameras to record their positions along with images, and baseball bats to communicate to batters information about their swing. in this paper, inertial sensing is introduced as the logical choice for unobtrusive, fully general motion sensing. example proprioceptive device applications are presented along with their sensing ranges and sensitivities. finally, the technologies used in implementing inertial sensors are described, and a survey of commercially available accelerometers and gyroscopes is presented.

Airborne imaging system using global positioning system (GPS) and inertial measurement unit (IMU) data

Abstract: A remote data collection system, which may be used in a vehicle such as an aircraft or a ground vehicle, includes a directional sensor, such as one or more cameras, for sensing a characteristic of interest and providing sensor data. The system further includes a global positioning system (GPS) receiver for providing GPS data representative of the position of the sensor, an inertial measurement unit (IMU) for providing IMU data representative of the attitude of the sensor, a processing unit and a storage unit. The processing unit determines geographic data referenced to the sensor data in response to the GPS data and the IMU data. The processing unit may utilize an error model to determine IMU errors which may be used in determining the geographic data with high accuracy. The sensor data and the geographic data are stored in the data storage unit for subsequent use. The system may include a stabilized platform on which the sensor and the IMU are mounted. The stabilized platform is rotated about at least one axis of rotation to control the sensing direction of the sensor as the vehicle moves.

Integrated gps/inertial navigation apparatus providing improved heading estimates

Abstract: The integrated GPS/inertial navigation apparatus utilizes satellite signals received with two spatially-separated antennas to achieve improved heading estimates for a mobile platform. Each satellite signal comprises one or more component signals with each component signal having a different carrier frequency. The integrated GPS/inertial navigation apparatus consists of a receiver and an inertial navigation system. The receiver measures the carrier phase of each of one or more component signals of one or more satellite signals received by each of the two antennas during successive time periods of duration Tp. Phase measured during a Tp time period is called Tp-phase. Only one component signal of one satellite signal received by one antenna is measured during any Tp time period. The receiver utilizes the Tp-phases of each component signal obtained during a Tk time period to estimate the phase of the component signal at the end of the Tk time period, the estimated phase at the end of the Tk time period being called the Tk-phase. The inertial navigation system, comprising inertial sensors and a digital processor, utilizes the Tk-phases in determining the heading of the vehicle and the displacement of each of the two antennas from the inertial sensors of the inertial navigation system. The measured phase of a component signal is subject to error as a result of the satellite signal traversing the ionosphere. The inertial navigation system achieves more accurate estimates of heading and antenna displacements by utilizing the Tk-phases in determining ionospheric corrections to phase.

Introduction to avionics

Abstract: Air data and air data systems introduction to aerodynamics and aircraft control fly-by-wire flight control inertial sensors and systems navigation systems displays and MMI auto-pilots and flight management systems integrated avionics.

Apparatus and method for sensing motionlessness in a vehicle

Abstract: An apparatus and method for sensing motionlessness for sensing motionlessness in a land-based vehicle is provided. The apparatus can include an inertial measurement unit (IMU) mounted in a predetermined orientation on the vehicle and a programmable computer. The IMU can have an inertial sensor which generates a plurality of motion signals. More than one inertial sensor can be used and, in that case, each of the sensors can be mounted in a second predetermined orientation with respect to the others, such as an orthogonal orientation, thereby creating a selected spatial reference frame. The inertial sensor can be one or more accelerometers, or one or more gyroscopes, or an accelerometer-gyroscope combination. The computer receives the motion signals and determining a motion state of the vehicle therefrom. The computer provides the motion state to a target application which acts in accordance therewith. The method can include sensing a reference sample of motion signals during a reference period; extracting a reference characteristic signal from the reference sample; sensing an operational sample during an operational period; extracting an operational characteristic signal from the operational sample; determining the current motion state by comparing the operational characteristic signal to the reference characteristic signal; reporting the motion state to a target application in the vehicle, the application acting in accordance therewith.

Attitude determination and control of clementine during lunar mapping

Abstract: The Clementine spacecraft, launched in early 1994, recently completed a two-month lunar mapping mission in which it recorded high-resolution images over the entire surface of the moon. The attitude determination and control subsystems developed for the mapping phase of the mission are described. The vehicle's attitude determination subsystem consisted of a simple fixed-gain Kalman filter, uncoupled about each spacecraft axis, combining rate inputs from two solid-state optical gyros and attitude inputs from two wide field-of-view star trackers. The attitude control subsystem consisted of a simple proportional-integral-derivative algorithm operating on quaternion and rate feedback signals to provide pointing, tracking, and slewing functions. The primary actuating devices were three reaction wheels used for feedback error compensation and 12 thrusters used for occasional momentum dumping. During lunar mapping the attitude determination and control subsystems maintained vehicle pointing to within a three-axis rss value of 0.05 deg. On-orbit results are provided from outputs of the attitude determination filter, the lunar nadir-tracking controller, and the large-angle slew generator. Additionally, results are provided from a novel inertia estimator, which utilized sensor outputs during two slew maneuvers.

New approach to coarse alignment

Abstract: Two different methods for coarse alignment are discussed. One of them (direct method) utilizes both accelerometers and gyros output for continuously tracking attitude estimation while the other (gyrocompassing) utilizes gyro outputs for continuously tracking attitude system and accelerometers for attitude estimation. The standard approach is gyrocompassing in spite of the fact that it is not always the most accurate. The rule for selecting an appropriate algorithm is obtained. Our approach is based on DCM instead of Euler angles estimation, a fact which allows us to solve the nonlinear problem.

An Integrated Low Cost GPS/INS Attitude Determination and Position Location System

Abstract: Advances in the technology of low cost solid-state inertial sensors have brought the price for a inertial measurement unit (IMU) down to the $ 10,000 level. Such an IMU, Systron Donners’ MotionPakTM, has been purchased by the Institute of Geodesy and Navigation (BEN) in order to develop an integrated GPS/INS attitude determination system. As GPS component for the integrated system, IfEN has selected the Trimble Advanced Navigation Sensor (TANS) Vector receiver system, which is a multi antenna attitude determination and position location system. IfEN has developed a realtime navigation software to calculate position, “velocity and attitude from the outputs of the MotionPak gyroscopes and accelerometers. These computed values are integrated with position, velocity and attitude information from the TANS Vector in a Kalman filter. Test results show that this system can achieve up to 0.1 degrees attitude accuracy (RMS). This Paper describes the low cost integrated GPS/INS System, including GPS and INS hardware, data acquisition and software.

Micromachining inertial instruments

Abstract: Draper Laboratory, using silicon microfabrication techniques to achieve high yields by batch processing, has been developing miniature microelectromechanical instruments for over 10 years. During this time, considerable progress has been made in the development and fabrication of micromechanical gyroscopes, accelerometers, and acoustic sensors. Inertial instruments have become a worldwide research and commercial topic. Draper gyroscopes and accelerometers have been fabricated with measurement ranges from 50 to 500 deg/s and 10 to 100,000 g, respectively. In gyroscopes, stabilities are 20 deg/h in room temperature tests and 4.4 deg/h applying 0.3 degrees C thermal control. For accelerometers, less than 1 mg has been demonstrated in room temperature tests. These units have performed successfully across a temperature range of -40 to 85 degrees C, and have survived 80,000- to 120,000-g shock tests along all axes. Continuing development activities are expected to yield over an order of magnitude in performance enhancement. These micromechanical instruments are built using a silicon wafer process that results in crystal silicon structures that are anodically bonded on a Pyrex substrate that contains sensing and control electrodes. This silicon-on-glass configuration has low stray capacitance, and is ideally suited for hybrid or flip-chip bonding technology. Draper's inertial sensors incorporate excellent fabrication, however, building the silicon and Pyrex sensor chip is only one of many important contributions in a complete sensor system. Other equally important steps include: 1) electronics and application-specific integrated circuits (ASICs) 2) packaging, 3) test, and 4) modeling and analysis. This presentation focuses on sensor fabrication. Draper's accelerometers and gyroscopes and the dissolved wafer fabrication process are described. The evolution of gyro design, fabrication, and performance is summarized. Garnered through experience in both conventional and micromachined inertial sensors, rules of thumb that have guided Draper's micromachining efforts are discussed.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Weapon IMU transfer alignment using aircraft position from actual flight tests

Abstract: This paper presents results from a study of weapon inertial measurement unit (IMU) transfer alignment using the aircraft's navigation system position data. The alignment process consists of first establishing a navigation solution (position, velocity and attitude) using the raw IMU outputs, then via a Kalman filter algorithm estimate errors in the weapon navigation data using aircraft navigation system data as observations. The aircraft's navigation system data is used to initialize the weapon's navigation solution. The results presented in this paper are based on using the aircraft's position data as the filter algorithm's observation. Using flight data, it is shown that a weapon's navigation frame can be aligned to an accuracy of less than 1 milliradian. The alignment error is determined by assuming that the total difference between the weapon's post-alignment free-inertial position and the aircraft's position is the result of horizontal navigation frame tilt error alone. The affect of the aircraft's flexible structure during higher maneuver levels is illustrated.

The 1996 MIT/Boston University/Draper Laboratory autonomous helicopter system

Abstract: The Massachusetts Institute of Technology, Boston University and Draper Laboratory have cooperated to develop an autonomous aerial vehicle that won the 1996 International Aerial Robotics Competition. This paper describes the approach, system architecture and subsystem designs for the entry. This entry represents a combination of many technology areas: navigation, guidance, control, vision processing, human factors, packaging, power, real-time software, and many others. The aerial vehicle, an autonomous helicopter, performs navigation and control functions using multiple sensors: differential GPS, inertial measurement unit, sonar altimeter, and a flux compass. The aerial transmits video imagery to the ground. A ground based vision processor converts the image data into target position and classification estimates. The system was designed, built, and flown in less than one year and has provided many lessons about autonomous vehicle systems, several of which are discussed.

Evaluation of an integrated GPS/INS system for shallow-water AUV navigation (SANS)

Abstract: Many possible autonomous underwater vehicle (AUV) missions require a high degree of navigational accuracy. The Global Positioning System (GPS) is capable of providing this accuracy. However, intermittent reception caused by either wave action or deliberate submergence will cause the loss of GPS position fix information for periods extending from several seconds to minutes. The SANS system is designed to demonstrate the feasibility of using a low-cost strapped-down inertial measurement unit to navigate between GPS fixes. It is anticipated that navigational accuracy comparable to GPS is possible between fixes.

Stellar inertial attitude determination for LEO spacecraft

Abstract: This paper describes the normal mode attitude determination algorithm for the low earth orbit (LEO) spacecraft using stellar inertial sensors. Included in the algorithm is a 6-state extended Kalman filter (EKF) which corrects the spacecraft attitude error as well as gyro bias error using celestial observations from star trackers. The detailed derivation of the EKF using a quaternion formulation is given in the paper. Time-domain simulations are presented to show the predicted filter performance which is a function of star density (or number of stars seen), star catalog error, star tracker noise, and gyro noises. Covariance analysis indicates that precision attitude with accuracy better than 12 arc seconds (3 sigma) can be met with the proposed attitude determination and control system hardware components.

Characterization of membrane curvature in micromachined silicon accelerometers and gyroscopes using optical interferometry

Abstract: Micromachined silicon sensors often exhibit curvature of released membrane structures due to internal stresses, doping gradients, and crystalline defects. This curvature can be a significant source of error in inertial sensors such as accelerometers and gyroscopes. Development of process conditions that reduce curl requires a rapid, accurate method for obtaining high-resolution flatness data over a complex two-dimensional surface. This work reports on the use of a commercially-available, nondestructive optical characterization tool that provides high-resolution profiles of micromachined structures. This interferometry technique is shown to be a significant extension of traditional process development tools, such as scanning electron microscopy (SEM) and test structures. Statistical information on flatness of test structures, accelerometers, and gyroscopes is reported as a function of processing conditions. Unexpected and previously undetected phenomena are revealed by the interferometry measurement. Optimization of the diffusion-annealing cycle provides structures that are flat to within 0.1 micrometers. The flatter parts now being produced have contributed to recent advances in the performance of Draper Laboratory's inertial sensors.

Feedforward stabilization test bed

Abstract: The vast majority of gimbaled line-of-sight stabilization systems involve inertial angular rate sensors located on the gimbal assembly. These sensors are mounted to follow the line-of-sight as the gimbals move, thus allowing them to serve as direct feedback elements for the stabilization rate-control loops. For systems in which on-gimbal configurations are not possible, feedforward control configurations using strapdown inertial sensors are required. The gimbal control commands in these systems are calculated in real- time form the inertial sensor outputs and the transformation matrices between the sensor, gimbal, and line-of-sight reference frames. A testbed for the development and test of a feedforward line-of-sight stabilization systems is described. The system includes a three-axis, mirror-stabilized gimbal, a servoamplifier unit, and inertial measurement system, a digital controller, and a personal computer for software development.

GPS-aided retrotraverse for unmanned ground vehicles

Abstract: A computer controlled HMMWV automatically retraces a previously recorded path usingnavigation data, a process we have termed retrotraverse. AKalman filter combines the outputof two navigation systems, an inertial dead reckoning systems and a differential GPS both withand without carrier phase detection. During retrotraverse, the mobility controller uses a velocitycontroller and pure pursuit steering. Obstacles such as another vehicle can be detected with a laser range imaging device. Keywords: dead reckoning, GPS, inertial navigation, Kalman filter, LADAR, obstacle avoidance, purepursuit, retrotraverse, speed control, UGV 1. INTRODUCTION During 1994 and 1995 the U.S. Army brought a robotic vehicle to Ft. Hood, TX to participate in severalbrigade training exercises, mock battles involving hundreds of Ml tanks, Bradleys, and HMMWVs. Therobot vehicle, an actuated HMMWV, was assigned to the Mustang Battalion, thel-8th Cay, and performedcounter reconnaissance missions. There were two reasons to include the robot in their training exercises.First, it allowed military personnel to start thinking about unmanned ground vehicles and how to developstrategies involving them. Second, it gave technologists a chance to experience how military scouts perform

Low cost inertial/GPS integrated position and orientation system for marine applications

Abstract: This paper describes the low cost position and orientation system (LCPOS), comprising the integration of a low cost "tactical grade" inertial measurement unit with GPS position, velocity and heading aiding data. LCPOS was designed to be a cost-effective alternative to a high performance costly ship INS (SINS). The demonstrated accuracy of the LCPOS integrated navigation solution is comparable to that of the SINS.

Miniaturized, low-cost IFOG IMU for tactical weapon applications

Abstract: Honeywell, under contract to the US Air Force, has developed a 25 cubic-inch IFOG IMU brassboard which demonstrated performance of < deg/hr bias stability, < 0.05 deg/(root) hr random noise and < 250 ppm scale factor accuracy over the full military temperature range. To overcome the size constraint of 25 cubic-inch, the three-axis IFOG optical cluster was configured with the minimum IMU configuration having only eight optical components. Special loop-closure signal processing was developed to accommodate all three- axis sensor electronics within a single 3.4-inch electronic board. To achieve the IMU cost target of < 6000 dollars, the design utilizes a very lowest cost optical components such as an 830nm light source along with a 1300 nm single- mode fiber sensing coil. Further cost reduction was realized through the robust design which provides very relaxed gyro assembly tolerances. The 25 cubic-inch IFOG IMU will have sufficient performance, small size, ruggedness for high-g launch, and low unit production cost to be suitable for use in a wide variety of tactical weapon systems.

Application of inertial sensors and flux-gate magnetometer to real-time human body motion capture

Abstract: : Human body tracking for synthetic environment interface has become a significant human- computer interface challenge. There are several different types of motion capture systems currently available. Inherent problems, most resulting from the use of artificially-generated source signals, plague these systems. A proposed motion capture system is being developed at the Naval Postgraduate School which utilizes a combination of inertial sensors to overcome these difficulties. However, the current design exhibits azimuth drift errors resulting from the use of inertial sensors. This thesis proposes a new method of compensating for azimuth drift using a three-axis fluxgate magnetometer. The magnetometer capable of azimuth drift compensation since its sensitive axis is not collinear with the local vertical. This thesis includes a program for simulating the operation of a fluxgate magnetometer in C++. The included C++ code simulates a fluxgate magnetometer and provides an estimate of azimuth based on the magnetometer's output which is typically within five degrees of the actual azimuth. Real magnetometer data for testing and verification was accomplished by bench testing a real fluxgate magnetometer.

CCD star tracker for attitude determination and control of a satellite for a space VLBI mission

Abstract: This paper presents design and performance of a high- precision star tracker which has been developed for use in the attitude determination and control system of MUSES-B spacecraft; the space segment of space VLBI program called VSOP (equals VLBI Space Observation Program). The MUSES-B is being prepared for launch in September 1996. The attitude control system is required to fulfill an overall pointing accuracy of 0.01 degrees (3 sigma) of an 8 meter-diameter VLBI antenna mounted on the spacecraft. The onboard attitude determination system is based on a reset type Kalman filter that assures the overall attitude determination accuracy of 19 arcseconds, using outputs from the star trackers and the gyroscope-based inertial sensors. For this purpose, the star tracker is designed to provide star position detection accuracy of 4 arcsec random (1 sigma) plus 15 arcsec bias error. This paper describes the design of the STTs, the performance analyses, and ground test results of the Protoflight Model.

Guidance, navigation, and control from instrumentation to information management

Abstract: I. Classical Guidance, Navigation, and Control Systems T HE classical guidance, navigation, and control (GN&C) system, shown in Fig. 1, is a feedback system that includes three subsystems. These subsystems are defined as follows. Navigation is the determination of the position and velocity vectors of a moving platform in a specified coordinate frame. Guidance is the determination of a trajectory from a current position and velocity to a desired position and velocity, satisfying specified costs and constraints. Control is the determination of the commands to the vehicle actuators to implement the trajectory, preserving a stable feedback loop.

The position and orientation system (POS) for airborne survey applications

Abstract: The Position and Orientation System (POS) is an integrated inertial/GPS system that generates accurate position (latitude, longitude, altitude) and orientation (roll, pitch, heading) for airborne survey/mapping applications as well as various other land and marine applications. POS is a GPS-aided strapdown inertial navigator that uses a Kalman filter and a closed-loop error controller to provide an optimally blended position and orientation solution from inertial data from an IMU and aiding data from a GPS receiver. This paper gives a brief description of POS and compares it to other available technologies. It then describes the various application areas of POS for airborne vehicles (POS/AV). Some applications from other POS variants, POS/LV for Land Vehicles, POS/MV for Marine Vessels, are also described. 4 refs., 4 figs., 1 tab.

Integrated INS/GPS navigation systems for tactical applications

Abstract: Recent advances in navigation technology have led to an overall improvement in the ability to navigate to a predetermined location Availability of the United States Global Positioning System (GPS) has permitted high-accuracy integrated navigation performance with a wide range of inertial sensors Kearfott has developed a family of ring laser gyroscope angular displacement and linear acceleration sensors which have been integrated with GPS in various configurations to address the operational requirements and cost of ownership constraints for tactical applications This paper discusses the progress Kearfott has made in the development of its line of inertial measurement and inertial navigation products that have been integrated with GPS receiver sensors for tactical mission requirements The utilization of GPS aiding in the enhancement of the performance of the systems for short mission duration is presented Test data from the resultant INS/GPS configuration are compared to simulations of the system as designed vs utilization of the present operational GPS satellite constellation

An Integrated GPS/Micro-Mechanical IMU for 5 Navy Projectiles

Abstract: The Extended Range Guided Munition Demonstration Program is a joint technical effort between Draper laboratory and the Naval Surface Warfare Center, Dahlgren Division, with programmatic responsibility residing in the Naval Surface Fire Support Program Office, Naval Sea Systems Command. The program will culminate in four flight tests beginning in the Summer CE 1996 that demonstrate extended range and improved s:curacy over conventional Navy 5” projectiles. This paper describes the design, operation and critical performance issues of the ERGM Demonstration GPSMMIMU, which is the guidance system for the Navy’s 5” ERGM Demonstration Round. This guidance system combines GPS position data with micro- mechanical inertial sensor measurements to produce the navigation solution, and uses the navigation data with a prespecitied aimpoint location to generate guidance commands. In addition to the GPS receiver and the Micro-Mechanical Inertial Sensor Assembly, the system includes a g-hardened reference oscillator, the guidance and navigation electronics, and the power conversion electronics, all packaged in an 8 lbr cylindrical volume 8.4 inches long with a diameter of 4 inches.

Autonomous Local Vertical Determination for Guided Artillery Shells

Abstract: Accurate local vertical (roll angle) estimates are required for guided artillery shells in order to correctly implement guidance commands. Although GPS and IMU data will typically be merged in the navigation filter to estimate local vertical as well as position and velocity, it is desirable to estimate local vertical in the absence of GPS data since this data will not be available at the start of flight and could drop out or be corrupted during flight. This study was undertaken to evaluate the performance of local vertical estimators which use only inertia1 sensors. More specifically, we consider local vertical estimation using gravity turn rate (flight path angle rate induced by gravity) information obtained using only on-board strapdown micromechanical gyros. A four state Kalman filter has been developed and tested using a Monte Carlo simulation and a typical micromechanical gyro error budget. The choice of four states depends strongly on the assumption that the spin rate of the navigation base will by relatively low (a few Hz) throughout the flight. At extremely low or extremely high spin rates, other filters would be required and performance may be quite different. Results were simulated for an Extended Range Guided Munition (ERGM) she11 over a planar ballistic path with a range of 6.4 nautical miles and a flight time of 60 seconds. It was found that local vertical can be acquired in less than ten seconds and can be tracked to within an rms error of less than ten degrees throughout the flight. Versions of the filter based on both known and unknown flight path angle rates were developed and tested. The results indicate that both versions perform well, but that the filter using known flight path angle rate tends to produce smoother error histories. Robustness of the filter was demonstrated in the presence of realistic disturbances. Estimation with large roll gyro errors was considered (biases as high as 0.5 rad/sec). An extended Kalman filter was used to estimate roll gyro error in a five state filter and retain good performance.

INS/GPS space application for all flight dynamics - boost through landing

Abstract: This paper describes the evolutionary development of an expanded capability INS/GPS system with application for several high dynamic space vehicles, both existing and planned. The principle effort began approximately four years ago with the NASA decision to initiate a series of Space Shuttle GPS development flight tests using a space modified Collins 3M GPS receiver. The technological advances resulting from the highly successful Shuttle flight tests are being applied to and expanded on for both the successor to the 3M, the MAGR-S and a small card Collins GPS receiver modified for space (GEMIII-S). The GEMIII-S has been integrated with a Litton IMU. Since the initial Shuttle efforts, considerable progress has been made in the application of the all dynamic Collins GPS receivers for space and a common approach for integration into both existing and planned space type vehicles. This paper addresses the following three main topics that define that progress: 1) evolution of the GPS space receiver for civil and military applications; 2) integrated INS/GPS functions for various flight dynamic phases and vehicles; and 3) verification and test of the integrated system.

The Use of Informational Redundancy in INS with ESG

Abstract: A problem of using the redundant information in gimbaled inertial navigation systems (INS) based on two electrostatically suspended gyros (ESG) to calibrate the gyro drift models’ parameters is investigated. Two basic versions of an inertial measurement unit (IMU) construction are considered: with the ESG installed in individual gimbals or on a common gyrostabilized platform, It is shown that in both cases an additional autonomous measurement can be generated as a difference of cosines of the angle between the gyro momentums, expressed via body fixed and inertial components. On the basis of the derived measurement error models the observability of the gyro drift parameters is investigated. The increase in efficiency of the INS calibration at the INS initially and in operation with the use of the additional measurement (jointly with the conventional positional and velocity measurements) is justified analytically and by simulation.

Integration and testing of a low-cost land navigator for the army combined arms weapon system (TACAWS)

Abstract: The army combined arms weapon system (TACAWS) is currently being developed as a technology demonstration program at the US Army Missile Command (MICOM) located at Redstone Arsenal, AL. The thrust behind the development of TACAWS is to provide the 21st century Army a multi-purpose, multi-target, and multi-platform weapon system that can be easily deployed to any location in the world. The TACAWS land navigation system (LNS) incorporates data from 3 ring laser gyros, 3 quartz accelerometers, a precision lightweight GPS receiver (PLGR) and an odometer into the position and attitude solutions. The LNS is being installed on a modified M2 Bradley vehicle, for the purpose of navigation, targeting, data link attitude control, and missile initialization. Missile initialization includes the transfer of the LNS's north alignment accuracy to the missile's inertial measurement unit. The LNS test results reported include alignment accuracy (static and moving) and drift, inertial sensor error estimation, alignment transfer accuracy, and navigation accuracy with and without GPS data.