Abstract: An apparatus detects an air turbulence and wind shear encountered by an air vehicle having an accelerometer sensing air vehicle vertical acceleration. The apparatus includes a pressure sensor having a pressure sensing port for sensing a pressure parameter of a local air flow which changes with changes in the local airflow turbulence, and a fast time constant pressure transducer coupled to the pressure port for generating a transducer signal representative of the parameter. Differentiating means calculates a time derivative of the transducer signal and provides a turbulence signal representative of the time derivative. Subtracter means provides the difference between the turbulence signal and a vertical acceleration signal from the accelerometer, to provide a wind shear indicating signal indicative of an increase in air turbulence.

Abstract: One side of a primary flight display has an elongated vertically disposed airspeed dial display which provides global or macro airspeed information. A rolling drum display provides a digital display of a present value of airspeed. An elongated vertically disposed altitude dial display is located on a second side of the primary flight display. The second dial display is configured to provide a predetermined amount of rotation of the pointer for a lo predetermined change in altitude. A second rolling drum display provides a digital present value of altitude. The elongated dial displays provide greatly expanded display areas and improved readout resolution.

Abstract: A vertical position and gravity map aided INS is self contained (no external signals required); covert (no signals emanated); unrestricted in operating area; able to operate in quiet or active gravity regions; and able to be configured with proven instruments.

Abstract: The invention provides a route state filter for a vehicle route guidance system for improved tracking of vehicle position with respect to a preselected route. A set of position possibilities are derived by comparing a measured vehicle position to a database containing data representing a map of roads, the possibilities corresponding to possible positions on the roads within an error region around the measured position. A route guidance module receives the position possibilities, checks their validity and applies a filter to remove less likely possibilities. A current position is then selected from the remaining possibilities. An ON/OFF ROUTE status of the vehicle is determined by comparing the selected position with the selected route information in the database. A distance-based filter is utilized to provide improved continuity in the route status determination.

Abstract: A three axis, single degree of freedom gyroscope based rate sensing platform has restraining torque developed for the platform from a feedback loop that includes electronics that decouples individual gyroscope outputs from the rate inputs that correspond to axes other than the input axis for that gyroscope and provides an enhanced frequency response. The outputs from the various gyroscopes are processed in a compensator that estimates the platform rates on independent axes using either a Kalman filter estimator or a matrix inverse of the matrix equation of motion between platform input rate and gyroscope output. High bandwidth performance is obtained by an increased stiffness and prefiltering of the gyro torque inputs.

Abstract: A grade and acceleration sensor having a weight, a first sensor for measuring a first parameter of the weight due at least to the force of gravity to generate a first signal, a second sensor for measuring a second parameter of the weight due to both the force of gravity and the acceleration of the vehicle on which the sensor is mounted to generate a second signal, a grade angle generator generating the grade angle .theta. in response to the first and second signal, and an acceleration generation generating a signal having a value corresponding to the acceleration of the vehicle in response to the first and second signals. In a first embodiment, the weight is a bob of a pendulum, the first parameter is a displacement angle of the bob due to acceleration and gravity and the second parameter is the force on the arm of the bob due to gravity and acceleration.

Abstract: An autonomous covert Inertial Navigation System uniquely suited for underwater applications wherein Schuler and siderial errors are bounded without external navigation aids or active instrumentation of ground speed is achieved by integrating a conventional Inertial Navigation System with a gravity gradiometer capable of measuring gravity field components independently of platform accelerations.

Abstract: A three axis attitude orientation system for a spacecraft in orbit which employs a single UV sensor. The single sensor provides roll and pitch information by locating the centroid of the earth and using this as a reference point. The system determines yaw by tracking the position of stars which appear in the field of view around the earth. Three axis attitude is determined through ultraviolet imaging of the earth's limb and adjacent stars. A non-conventional wide angle optics assembly and intensified CCD array are utilized for this purpose.

Abstract: A three axis attitude orientation system for a spacecraft in orbit which employs a single UV sensor. The single sensor provides roll and pitch information by locating the centroid of the earth and using this as a reference point. The system determines yaw by tracking the position of stars which appear in the field of view around the earth. three axis attitude is determined through ultraviolet imaging of the earth's limb and adjacent stars. A non-conventional wide angle optics assembly and intensified CCD array are utilized for this purpose.

Abstract: A sensor arrangement for detecting the influence of cross wind on the handling of a motor vehicle comprising pressure measuring points situated on opposite sides of the vehicle for the measuring of the air pressure existing in the area of the outer skin of the vehicle body. The pressure measuring points are constructed as bores in the outer skin of the vehicle body. A differential pressure sensor, which detects the differential pressure (Dp) between two vehicle sides, is arranged centrally between two pressure measuring points, and is connected with the two bores by way of hoses or lines which, if possible, should have the same length. For detecting the vehicle's entry into and emergence from a cross wind gust, the sensor filters the detected values of the wind cross force by means of a low pass filter and compares them with the filtered values that were detected immediately before.

Abstract: In a navigation system which has sensors for detecting a running distance, an azimuth, etc. of a vehicle, and a memory for storing map data; a probability density of a position of the vehicle is calculated on the basis of the sensor outputs and the map data for each of quantization units with which a probability computation determined by detection accuracies of the sensors and quantization of the map data can be executed. In addition, a final stage calculation of DP matching between trajectory data obtained from the on-board sensor data from a start point of the vehicle until a current time and a candidate route estimated from the road map data is iteratively executed, whereby a plurality of estimative vehicular positions and uncertainties (costs) corresponding to the respective estimative positions are iteratively evaluated, and a correct vehicular position is estimated by selecting at least one estimative vehicular position of low uncertainty (cost).

Abstract: The accuracy of the performance of an inertial navigation system is validated by comparing data measured by a fourth gyro and accelerometer to an analytic equivalent constructed from measurements made by a primary gyro/accelerometer orthogonal triad.

Abstract: Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Abstract: A navigation system on an automobile has a GPS receiver for producing first positional data indicating the automobile position based on radio waves from GPS satellites, and a self-operating sensor for producing second positional data indicating the automobile position based on speed and orientation sensor signals. A data processor compares previous and present first positional data to determine whether the difference therebetween is equal to or smaller than a first predetermined value, and also determines whether a PDOP value of the present first positional data is equal to or smaller than a second predetermined value. The present first positional data and the second positional data are compared to determine whether the distance between the present position of the automobile as indicated by the present first positional data and the present position of the automobile as indicated by the second positional data is equal to or greater than a third predetermined value.

Abstract: A vehicle navigation system helps locate the vehicle on a road network by overcoming, through the use of fuzzy logic, the errors of positioning sensors and routing computers. In the system, sensors continually feed position coordinates to a processing unit that traces the vehicle's path in a road database. Fuzzy logic-based reasoning is used to determine the most probable location of the vehicle, whether off- or on-road, thereby correcting errors in its raw path as sensed or computed.

Abstract: An electronic cursor (12) is movable over a digitising table (10) on which a chart (16) has been spread. The cursor can give an indication of which way it should be moved to reach a defined position on the chart. The cursor can also convert positions in terms of x, y coordinates of the table into positions in terms of latitude and longitude co-ordinates of the chart, and can display the chart positions. The cursor can also determine bearings and distances between its own position and a defined position. Several other facilities are also available. Thus, the cursor can be used to facilitate the plotting of positions and courses on the chart and in reading off positions and bearings from the chart.

Abstract: An electronic digital plotter for navigators which relieves the rigors of mechanical manual plotting of position on a chart. The plotter utilizes either a flexible or rigid board employing electromagnetic or capacitive resistance technology. It makes use of a fixed X/Y coordinate system to generate latitude and longitude coordinates from a chart overlay. The plotter employs a pencil or pen type stylus with interchangeable cartridge to locate position, derived from electronic position information on the board and hence on the chart. By comparing the location of the stylus to the input data, the plotter directs the user to the input location utilizing a visual, bullseye director display. Given ship's position, on a dead reckoning track or expected destination or waypoint, the plotter gives course, speed distance, and transit time. The plotter can also accept inputs from hand bearing compass or ship's heading compass.

Abstract: Disclosed is an apparatus for displaying a travel position, which, in carrying out steps of calculating X- and Y-coordinates of a current position of the moving body; renewably presents said current position on a road map indicated on a display screen; matches between a travel trace pattern formed by subsequent current positions and each road pattern on the road map; and puts the travel trace on the mated road pattern for correction of the current position of the moving body deviated from the road on the map, to determine what class of the road the moving body is running on, e.g. mountain road, superhighway or other ordinary road, and also changes the pattern matching condition to be adapted for the class of the road, as determined by a measured number of curves per unit of distance.

Abstract: Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Abstract: A system and process for providing systematic, updated, weather information from the ground to the pilot of an aircraft are disclosed. A ground station receives and assimilates weather data for satellite broadcast as digital weather data that is received by an aircraft (while on the ground or while airborne) within the satellite coverage area, encoded by a flight processor, and shown on a display screen to the pilot in map-type depictions and alpha-numeric format tailored to the operational needs of the pilot. The flight processor provides near real-time automatic processing and comparison of surface weather observations with the applicable forecast in both text and map depictions. The display screen information is controlled by a control panel that permits the pilot to select the departure, destination, alternate and any arbitrary airport with this selection establishing the map boundaries and with the projected flight path marked thereon.

Abstract: A detector for use on board an aircraft traveling along a path of movement to detect a power line comprises an antenna for sensing the electric field associated with the power line and producing an electric field signal, and a signal processor for receiving the electric field signal and generating a time-to-impact signal representative of the time for the aircraft to reach the power line if it continues on its path of movement. Sensors are used to determine the direction of the power line.

Abstract: A method for controlling the movement of a motor vehicle provided with tires which cooperate with the ground to define respective footprints includes monitoring the behavior of the footprints and generating at least one respective footprint signal indicative of the behavior of the footprints, using the footprint signal to control the movement of the motor vehicle and detecting at least one driving control signal generated by the driver and processing the driving control signal in dependence on the footprint signal for controlling the movement of the motor vehicle. A suitable system for carrying out the method is provided which includes extensometric transducers incorporated in the flexible structure of the tire which will deform as a result of the tire bearing on the ground so as to generate signals indicative of the behavior of the bearing region of the tread.

Abstract: A digital rebalance system for an inertial reference sensor. The rebalance system associates the error signal output with a sample value of a stored error signal and generates a rebalancing torquing pattern waveform in response to the error signal. The system includes waveform generation and error signal processing devices, precision timing devices, passive compensation circuitry and a precision switching circuit.

Abstract: A data processing device for providing data related to the categories of services available at locations along a highway in response to operator input is disclosed. The device includes a memory, a keyboard for entering input data identifying a desired service and an origin position into the memory. The input data is compressed before it is stored in the memory. The memory stores predetermined data in a compressed form related to the categories of services available at locations along the highway. The device also includes a microprocessor for retrieving from the memory the predetermined data which is a function of the input data. The microprocessor expands the retrieved compressed data into an operator readable form and provides the expanded data to a display for displaying the expanded retrieved data such as restaurants, gas stations, motels, or other services along the highway.

Abstract: Apparatus for projecting an elongated light bar representing an artificial horizon on an interior surface of an aircraft cockpit in front of a pilot of the aircraft with respect to a reference datum line on the interior surface of the cockpit. A vertical reference means, located in the cockpit or remotely therefrom maintains a vertical reference axis for all attitudes of the aircraft. A light beam source, which may be a laser beam, is aligned with a movable optical system having mirrors or lenses to convert the light beam to a plane of light. A mechanical linkage or a servomotor coupled between the vertical reference means and the optical system controls the optical system, so that the datum line appears stationary and the light bar seems to turn angularly and move vertically when the aircraft rolls and pitches.

Abstract: A vehicle-mounted navigation apparatus includes a display control unit which reads road map data from a map data storage device used for storing a plurality of road map data concerning road maps with different reduced scales in accordance with a current position of the vehicle detected by a position detecting unit. The display control unit controls the read road map to be displayed on the screen of a display unit in accordance with a control signal from a touch panel unit and further reads a scale indication pattern from an indication pattern storage device used for storing a plurality of scale indication patterns showing the respective reduced scales corresponding to the stored road maps. The display control unit superimposes the selected scale indication pattern on the selected road map.

Abstract: The invention is a method for measuring the wavelength of cross-flow vortices of air flow having streamlines of flow traveling across a swept airfoil. The method comprises providing a plurality of hot-film sensors. Each hot-film sensor provides a signal which can be processed, and each hot-film sensor is spaced in a straight-line array such that the distance between successive hot-film sensors is less than the wavelength of the cross-flow vortices being measured. The method further comprises determining the direction of travel of the streamlines across the airfoil and positioning the straight-line array of hot film sensors perpendicular to the direction of travel of the streamlines, such that each sensor has a spanwise location.

Abstract: A speed and direction indicator for ships having at least one rudder propeller, or pump jet, and preferably several such devices for determining the direction of the ship and its speed in the selected direction. An optical display is provided in the area occupied by the ship operator, on which display are shown the angle which is formed between the direction of force and a reference direction, and the strength of the thrust, independently of the operating state of the rudder propeller(s) or the pump jet(s).

Abstract: An angle of attack sensor is provided with ports for sensing flow angles in desired planes based upon differential pressure at the ports when a longitudinal or reference axis of the sensor changes relative to the flow stream. Impact pressure is also measured with the same probe, or with a separate probe, and the angle of attack is calculated by subtracting the pressures at the angle sensitive ports, and dividing by the measured impact pressure (q.sub.cm). At higher angles of attack, the denominator q.sub.cm approaches and passes through zero. When this quantity, q.sub.cm, approaches zero, the angle of attack signal becomes undefined. The problems encountered as q.sub.cm approaches zero has been a limitation of useful angle of attack range of angle of attack sensors for many years. It has been discovered that if the angle of attack ratio, where q.sub.cm is the denominator, is inverted at some point when the denominator q.sub.

Abstract: A hand-held instrument adapted selectively to provide a sportsman, such as a mountain climber, with readily-readable indications of the existing altitude or direction. The instrument includes a magnetometer which yields an analog signal as a function of direction and a pressure sensor which yields an analog signal as a function of atmospheric pressure. These analog signals are converted into corresponding digital signals and applied to a microprocessor which acts to control an LCD display having two display modes--one providing a numerical readout of altitude, the other a 360 degree readout of direction. When the microprocessor is switched to the altitude mode, it then processes the signal derived from the pressure sensor to yield a digital output for operating the display to indicate the existing altitude. When the microprocessor is switched to the direction mode, it then processes the signal derived from the magnetometer to yield a digital output for operating the display to indicate the existing direction.

Abstract: The change in capacitance of a sensor is linearly proportional to ice thickness provided that the ice thickness is significantly less than the distance between the conductive electrodes. By employing sensors with different electrodes, the sensitivity to ice may be traded off against the ability to measure greater ice thickness. A sensor with small spacing between electrodes will exhibit a large change in capacitance when covered by a thin layer of ice, however, the capacitance change will be linear only for very thin layers of ice. A sensor with greater spacing between electrodes is less sensitive to ice accretion but has a correspondingly greater ice thickness measurement range. Accordingly, sensor (55) is relatively sensitive and is employed to determine whether or not ice or water is present.

Abstract: A method that may be implemented in software, that selects tactically sound paths for vehicles from an initial position to a goal position across a piece of terrain. The method searches through possible paths before selecting a desired path. It calculates a numerical heuristic to select promising paths to explore. By exploring only a few of the most promising paths, the method maintains high computational efficiency. Specifically, a list of paths is created (12) that begins with a vehicle's initial section and moves to terrain sections surrounding the vehicle. The list of paths is sorted (13) using a minimum estimated total cost value to goal representing estimates of the relative combat values of different pieces of terrain while the vehicle is within engagement range of hostile positions. The total cost value is defined as the path's current cost value plus the estimated cost value from the current position to the goal.

Abstract: A navigation system for a vehicle which does not bewilder a driver of the vehicle with heading indication also when the driving speed of the vehicle is low. The navigation system comprises a GPS receiver, a display unit, a map memory in which a map is stored, a detecting section for detecting a driving position and a driving direction of the vehicle from information received from the GPS receiver, and a controller. The controller receives information of a driving speed of the vehicle from the vehicle and controls, when the driving speed is equal to or higher than a preset speed, the display unit to indicate on a display screen thereof the driving position and driving direction of the vehicle received from the detecting section together with the map received from the map memory, but controls, when the driving speed is lower than the preset speed, the display unit to indicate only the driving position of the vehicle received from the detecting section together with the map received from the map memory.

Abstract: Apparatus for use in a glider for indicating the rate of vertical air mass movement. The apparatus includes sensing means for detecting both glider airspeed and acceleration orthogonal to the plane of the wings. This information is used to modify the output display of a conventional variometer to eliminate the effects of drag.

Abstract: Disclosed is a travel path displaying apparatus for indicating the current position of an automobile running on a selected road in a road map appearing on an associated screen. A cumulation of errors in estimating sequential current positions will cause an incorrect indication of the automobile's position on the screen and the automobile will depart from all the roads appearing on the screen. In order to find the correct road on which the automobile is traveling it is necessary to carry out pattern matching between the travel trace and each of a number of selected roads, thereby determining which road is closest to the travel trace in shape. The apparatus permits selection of the least possible number of roads for pattern matching, thus permitting quick determination as to the road on which the automobile is traveling and as to the direction in which it is traveling.

Abstract: An on-board navigation apparatus which uses a driver having a changer function to selectively reproduce any of music- and map-containing storage media. When it becomes necessary to read map data during reproduction of a music-containing medium, the current medium is replaced with the applicable map-containing medium upon arrival of an intra-music interval. This allows one driver driving both music and map data media to read map data without interrupting the piece of music being reproduced.

Abstract: A method and apparatus for sensing wave flow across a surface wherein at least two pressure levels are sensed and combined to provide a representation of waves within the flow. In the preferred embodiment holes bored through the aircraft surface at an interval of one-half the wavelength of the flow being measured introduce pressure perturbations into a cavity so they may acoustically interfere. The interfering waveform is sensed by at least one microphone disposed in the cavity.

Abstract: A pendulum-type accelerometer for use on trucks, cranes, airplanes, and boats as a multipurpose sensor. A cylinder with a damping fluid includes four equally spaced coils in a base of the cylinder and a pendulum suspended from a top of the cylinder which swings over the coils. Coils connected to a signal processing system which provides an angular momentum and banking signal and an acceleration and deacceleration or grade indicator signal.

Abstract: A gyroscopically stabilized artificial horizon instrument used in light aircraft mounts an earth magnetic field sensitive flux sensor on its gyroscope housing to produce a signal indicative of the direction of flight. The signal is processed and produced as a digital display of direction on the face of the instrument such that the planes relation to the artificial horizon and its direction can be observed by the pilot at the same instrument location. Provision is also made for generating signals indicative of airspeed and altitude and displaying in digital form both airspeed and altitude at the same location on the artificial horizon instrument at which direction is displayed.

Abstract: A navigation apparatus for a vehicle according to the present invention is designed to compare the distance from the previous intersection or feature to a further feature with the value from an odometer (2) and then to forcibly zero the remaining distance to the further feature when the difference between the distance and the value of the odometer becomes equal to or smaller than a predetermined value and when the feature is detected by a radar (12) or a road surface sensor (13). In consequence, even if the vehicle has to travel a long distance before it reaches an intersection where it makes a turn, a correct travelled distance can be obtained by correcting the distance detection errors as each feature is detected, thereby enabling a correct present position to be detected.

Abstract: A method for determining Richardson Number, Ri, or its reciprocal, RRi, for clear air turbulence prediction using measured potential temperature profiles and determining the vertical gradient of potential temperature, d.theta./dz. Wind vector from the aircraft's instrumentation versus potential temperature dw/d.theta. is determined and multiplied by d.theta./dz to obtain dW/dz. Richardson Number or its reciprocal is then determined from the relationship ##EQU1## for use in detecting a trend toward a threshold value for the prupose of predicing clear air turbulence. Other equations for this basic relationship are disclosed together with the description of a method for combining of other atmospheric observables using multiple regression techniques to produce improved warnings of clear air turbulence.

Abstract: A calibration apparatus of an angular-velocity detection sensor for detecting a heading of a vehicle which is used in a self-contained navigational system, comprising an angular-velocity detection unit for calculating an angular velocity from an output signal of the angular-velocity detection sensor; an integration unit for calculating a current heading of the vehicle by integrating the angular velocity and by adding the integrated angular velocity to the previous heading of the vehicle; a location and heading detection unit which estimates a location of the vehicle from the current heading calculated by the integration unit, a heading obtained by a magnetic sensor and from a distance obtained by a distance sensor and which compares the estimated location with road network data obtained from a road map memory to obtain an estimated heading of the vehicle; and a heading correction unit for calculating a difference between the heading of the integration unit and the heading of the location and heading detection

Abstract: A method inputting starting and destination points into an electronic navigation system for motor vehicles in which relevant data of street system maps comprising a street identification character and reference point coordinates with assigned house numbers, are stored in a data storage. When inputting, the street identification character and house number of the starting and destination point are entered, then the data storage is first searched for the street identification character and then for the inputted house number. When there is agreement with a house number of the reference points in the data storage its coordinates are taken over for navigation. When there is a disagreement, the reference points adjacent to it in the data storage are determined and the coordinates of the starting or destination point are determined by means of interpolation and used for navigation (FIG. 20).

Abstract: A navigating apparatus which outputs information for guidance to a destination comprises an input device (1) for inputting a destination and a present position, a memory (4) in which guidance information is stored, an arithmetic unit (2) for determining optimum guidance information from the information input from the input device (1) and a display (3) for indicating the guidance information, the memory (4) having data of a plurality of parking lots at least in a destination and the arithmetic unit (2) serving to select the plurality of parking lots and guide the driver along the courses thereto in the destination. This apparatus enables the driver to go to a nearby parking lot by exploration of a course to the next parking lot at the shortest distance and guidance thereto even if a certain parking lot is full of cars in a destination.

Abstract: An aircraft banking angle indicator which includes a banking angle sensing arrangement for generating an actual banking angle signal, a maximum banking angle input device for manually entering a selected maximum banking angle, a signal processing arrangement having respective inputs connected to the banking angle sensing arrangement and to the maximum banking angle input devices for generating an excessive banking output signal indicative of a banking angle exceeding the maximum banking angle, and an indicating arrangement having a signal input connected to the banking angle output signal for indicating the excessive banking angle.

Abstract: Rate of turn indicator for a nautical vessel, aircraft and the like indicating the rate of turn or swing in units such as degrees per unit of time from a particular course of travel. The indicator includes a magnetic gyro wheel including a flexible hub rotating about an axis in the same plane as the course of travel, and electromagnetic sensing coils receiving the deviations of strength of the electromagnetic field of the magnetic gyro wheel from an axis on turning from the course of travel. The magnetic gyro wheel includes a plurality of permanent magnets of alternating poles positioned about a circumferential axis of a circular member, and a flexible hub material affixed to the interior diameter of the circular member. The hub is affixed to an axially support shaft. The rate of turn indicator includes a meter connected to the electromagnetic sensing coils through electrical circuitry and a potentiometer for zeroing the meter where the meter indicates the rate of turn.

Abstract: The present invention features a technique and system for achieving sufficiently stable, thick liquid films on an aircraft surface during a rain storm in flight, wherein such stable and thick films can be measured to determine liquid water content (LWC) in the air, and (by known correlation) rain fall rate. Rainfall impinging upon an airflow surface of an aircraft, such as a wing portion, is gathered and confined within a weir-like structure. The flow of the rain is constricted within this device to increase the film thickness and reduce shear between air and liquid boundaries, whereby a stable film surface for measurement is provided.

Abstract: A navigation apparatus in which the scale of a displayed map is automatically adjusted in dependence on parameter such as the distance between the moving object and a preselected destination.

Abstract: In the present invention the inertial measurement unit system comprises a basic strapdown inertial measurement unit and an isolated fourth gyro strapped to a rotatable platform which is commanded to rotate at a rate equal to the spin rate of the vehicle body but in an opposition direction. The rotatable platform is controlled substantially by a control signal to cause the rotatable platform to turn at a rate substantially equal to the roll of the vehicle body but in an opposite direction. A signal processing means operates on (i) the output of an inertial navigational system computer representative of the rate of rotation of the inertial measurement unit along the roll axis, (ii), the output of the isolation gyro, and (iii) an output of a counter which counts the complete revolutions of the rotatable platform. In turn, an error signal is provided which is related to the rotation measurement error of the first rotation signal.

Abstract: In an apparatus for detecting a driving azimuth of a vehicle, a gyroscopic sensor signal and a geomagnetic sensor signal are acquired. When the vehicle is driven in a disturbed geomagnetic area such as a straight road, the acquired geomagnetic sensor signal does not correctly reflect the actual driving azimuth of the vehicle. Moreover, the gyroscopic sensor signal drifts over time. When the vehicle is in such a disturbed geomagnetic area, a variation amount in the acquired geomagnetic sensor signals is subtracted from another variation amount in the acquired gyroscopic sensor signals to obtain a driving azimuth similar to the actual driving azimuth.