The Boeing Company

Melville D McIntyre

Leonard R Anderson

Timothy Allen Murphy

Steven Barry Krogh

Andrew William Houck

Ward H Zimmerman

Guy R Olbrechts

David L Sebring

John F Gilbert

Jack C Shaw

Steven B Krogh

The present method and apparatus consists of storing past values of estimated IRU error and using these past values to update the coasting filter when switching from GPS to inertial mode. Through the storage of past IRU error estimates, it is possible to avoid misdirected guidance from an erroneous GPS signal. The MMR and ground station can require up to 6 seconds to identify a failed GLS signal.

Skipping filter for inertially augmented landing system

An airplane precision approach guidance system and method. The airplane precision approach guidance system includes: (i) GPS landing system (GLS) components (,) for receiving and processing signals from GPS satellites (,) and a GPS ground station (,) and generating a first set of velocities; (ii) an inertial reference system (IRS)(,) for generating a second set of velocities; and (iii) guidance software (,) for generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the generated first and second set of velocities. The airplane precision approach guidance system also includes flight instruments (,) and an autopilot system (,) for receiving and processing the information produced by the guidance software. The guidance software may be executed by a conventional airplane processor, such as the GLS processor, the IRS processor or the airplane's autopilot processor, or by a separate stand-alone processor. The runway centerline information may be stored at the ground station or in local memory. The ground station can also provide differential GPS information. In airplanes that include redundant systems, voting is used to determine which IRS supplies the second set of velocities.

Inertially augmented GPS landing system

An air data computer outputs a data stream indicative of measured airspeed of an aircraft, for use in generating a display of airspeed to a pilot. To correct for the inherent processing delay, a correction factor is added to the data stream, so that the display is more closely related to the actual airspeed of the aircraft at the time of the display. The correction factor can be calculated by determining the average rate of change of airspeed during a preceding time interval and multiplying the average rate of change by the processing delay.

Airspeed prediction filter

A fault-tolerant air data and inertial navigation reference system utilizes skewed axis inertial sensors and fault-tolerant redundant electronics to provide higher redundancy with fewer parts. Parallelly operating processor circuits each receive the individual outputs of six skewed-axis gyros and six skewed-axis accelerometers. Each processor independently processes parity equations using the outputs to identify malfunctioning sensors. Further, the output of each processor is transmitted to three parallelly operating voter circuits. The voters are operable to discard a processor if its output does not agree with the majority. The voter outputs are similarly fed back to the processor circuits, which compare these outputs, and discard any voter whose output disagrees with the majority, thus providing a completely integrated system.

Integrated fault-tolerant air data inertial reference system

An integrated air data system for use on an aircraft. Airframe air data units (18) are connected to receive a plurality of redundant total pressure sensor inputs (20,22,24), a plurality of redundant static pressure sensor inputs (26,28,30), and a total temperature sensor input (32). Similar redundant sensor inputs are provided a first and second channel in each of two electronic engine controls (34,36). Bidirectional data buses (16) connect the airframe air data system to the electronic engine control system, so that the same sensor signals are available for each of the systems. The airframe air data unit and the primary electronic engine control channel having priority to control each engine are independently operative to select a preferred total pressure, static pressure, and total temperature value according to a common programmed logic scheme. The selection logic gives priority to the use of the same value for common parameters in each of the systems, where possible. The logic also minimizes the risk that failure of a single sensor may result in use of an incorrect value for a parameter, and that any combination of failures of different sensors, except for similar failures occurring independently on each engine, might result in an undesired effect on more than one engine.

Integrated aircraft air data system

A plurality of inertial measuring unit (IMU) modules (41A, B, C and D) each comprising gyros and accelerometers (61, 65 and 67) for sensing inertial information along two orthogonal axes, are strapdown mounted in an aircraft, preferably such that the sense axes of the IMUs are skewed with respect to one another. Inertial and temperature signals produced by the IMU modules, plus pressure signals produced by a plurality of pressure transducer modules (43A, B and C) and air temperature signals produced by total air temperature sensors (45A and B) are applied to redundant signal processors (47A, B and C). The signal processors convert the raw analog information signals into digital form, error compensate the incoming raw digital data and, then, manipulate the compensated digital data to produce signals suitable for use by the automatic flight control, pilot display and navigation systems of the aircraft. The signal processors include: an interface system comprising a gyro subsystem (47), an accelerometer and air calibration data subsystem (50) and an air data and temperature subsystem (52); a computer (54); an instruction decoder ( 56); and, a clock (58). During computer interrupt intervals raw digital data is fed to the computer (54) by the interface subsystems under the control of the instruction decoder (56). The computer includes a central processing unit that compensates raw digital gyro and accelerometer data to eliminate bias, scale factor, dynamic and temperature errors, as necessary. The central processing unit also modifies the gyro and accelerometer data to compensate for relative misalignment between the sense axes of the gyros and accelerometers and for the skewed orientation of these sense axes relative to the yaw, roll and pitch axes of the aircraft. Further, accelerometer data is transformed from body coordinate form to navigational coordinate form and the result used to determine the velocity and position of the aircraft. Finally, the central processing unit develops initializing alignment signals and develops altitude, speed and corrected temperature and pressure signals.

Integrated-strapdown-air-data sensor system

A closed-loop controller for controlling the frequency of the power applied to a gyroscope synchronous motor to rotate the seismic mass (wheel) of the gyro so as to compensate for movement of the gyro case about the spin axis of the gyro is disclosed. The controller includes a sensor for sensing fluctuations in the current drawn by the gyro, said fluctuations being directly related to the fluctuations in the load angle of the gyro caused by movement of the gyro case about the spin axis. The current fluctuations create an analog voltage, which is amplified by several orders of magnitude. The result is used to modulate the frequency of the applied power so as to compensate for the load angle fluctuations caused by case movement about the spin axis. In essence, the controller reduces the frequency of the hunting mode of the gyro to a level below which movement of the gyro case about its spin axis has substantially no undesirable effect. In addition, the controller phase shifts the feedback modulation signal so as to damp hunting excursions at the lower hunting mode frequency. Finally, noise signals, particularly noise signals at the motor excitation frequency, are filtered out to prevent such signals from saturating the feedback electronics.

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Bellevue, WA, United States of America

Melville D McIntyre