Furuno Electric Company Limited

Masaru Fukuda

Hiroyuki Toda

Sadao Sato

Naomi Fujisawa

Koji Hayashi

Kaoru Nakayama

A GPS-Based ADS for determining attitude and heading of a moving body comprises a GPS receiver, an inertial sensor unit, a blockage area calculator, a sensor anomaly detector and a monitor. The GPS-Based ADS provides information useful for making a judgment on appropriateness of installation sites and mounting conditions of a GPS antenna and inertial sensors based on blockage area information concerning each satellite signal blockage area obtained by the blockage area calculator and sensor signal anomaly information concerning each inertial sensor anomaly obtained by the sensor anomaly detector.

GPS-based attitude determination system with self-diagnosis function

A carrier phase-based relative positioning apparatus includes a plurality of antennas fixedly mounted on a moving body for receiving positioning signals from satellites, an inertial measurement unit (IMU) for measuring accelerations and angular velocities of the moving body, a reference attitude calculator for calculating attitude information about the attitude of the moving body from observables of the IMU at least before an integer ambiguity candidate is initially determined, an integer ambiguity estimator for estimating integer ambiguity candidates from the positioning signals received by the antennas, and an integer ambiguity validator for evaluating correctness of the integer ambiguity candidates estimated by the integer ambiguity estimator.

Apparatus and method for carrier phase-based relative positioning

An attitude sensing apparatus for determining the attitude of a mobile unit is provided that can reliably estimate an alignment angle between a GPS antenna coordinate system and an IMU coordinate system with good accuracy regardless of the magnitude of the alignment angle. Based on observation of the difference between a GPS angular velocity and an IMU angular velocity, an alignment angle estimating section estimates an alignment angle and sensor errors. An alignment angle adder and a sensor error adder cumulatively add and update the estimated alignment angle and sensor errors, respectively. The estimated alignment angle is fed back to an inertia data converter while the estimated sensor errors are fed back to an inertia data correcting section. The apparatus repeatedly performs estimation until the estimated alignment angle gradually approaches a true alignment angle by successively feeding back estimated values to a flow of alignment angle estimation process.

Attitude sensing apparatus for determining the attitude of a mobile unit

A carrier-phase-based relative positioning device employs a signal processing method which makes it possible to continue estimation of integer ambiguity values even when the number of positioning satellites has changed, determine an integer ambiguity value by efficiently verifying the integer ambiguities in a short time, and calculate a baseline vector. The positioning device includes an integer ambiguity resolving section which determines integer ambiguities of single or double phase differences using a Kalman filter and lambda notation. The Kalman filter is used to calculate estimated values of floating ambiguities and the lambda notation is used to calculate estimated values of the integer ambiguities based on the floating ambiguities. A candidate of a potentially true integer ambiguity that is considered most reliable is determined through various verification processes. When the number of positioning satellites has increased or decreased, or when a reference satellite has been switched, a floating ambiguity after the change in satellite information is estimated from a baseline vector estimated before the change.

Carrier-phase-based relative positioning device

A carrier phase-based relative positioning apparatus comprises a plurality of antennas of which at least one is installed on a mobile unit. The apparatus determines the position of each antenna other than one antenna used as a reference antenna relative to the reference antenna by receiving radio signals transmitted from a plurality of position-fixing satellites with the multiple antennas, observing a single difference phase or a double difference phase, and calculating an integer ambiguity of the single difference phase or the double difference phase. The apparatus judges that the integer ambiguity has been incorrectly determined if the position of any of the antennas relative to the reference antenna (or the angle of a flat plane formed by those two antennas) falls out of a preset range in which the relative position (the angle of the flat plane) falls under normal conditions.

Carrier phase-based relative positioning apparatus

A system for determining the heading and/or attitude of a body receives radio waves from a plurality of position-fixing satellites using at least three antennas fixedly mounted at different positions of the body. To reliably obtain integer ambiguity solutions of carrier phases of the radio waves in a shorter time, the system directly determines integer ambiguities from attitude angle data obtained by an IMU attitude processing section when the integer ambiguities are to be redetermined in the event of an interruption of the received radio waves or a change in the combination of satellites to be used. This system provides a user with highly accurate uninterrupted heading and/or attitude angle information.

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Nishinomiya, Japan

Masaru Fukuda