Aspects of the disclosure are directed to acquiring aligned geographic coordinates of a vertical position. In one aspect, a vertical navigation system includes a light source to generate a source beam; a beam splitter to generate a first and a second source references derived from the source beam; a hollow retroreflector to produce a first and a second vertical references derived from the first and the second source references; an attitude sensor to capture a plurality of reference stars and to measure a first set of angles for the first vertical reference and a second set of angles for the second vertical reference, the first set of angles and the second set of angles are relative to the plurality of reference stars; and a processor to produce the aligned geographical coordinates using the first set of angles, the second set of angles, a gravity vector measurement and a time signal.

Aspects of the disclosure are directed to acquiring aligned geographic coordinates of a vertical position. In one aspect, a vertical navigation system includes a light source to generate a source beam; a beam splitter to generate a first and a second source references derived from the source beam; a hollow retroreflector to produce a first and a second vertical references derived from the first and the second source references; an attitude sensor to capture a plurality of reference stars and to measure a first set of angles for the first vertical reference and a second set of angles for the second vertical reference, the first set of angles and the second set of angles are relative to the plurality of reference stars; and a processor to produce the aligned geographical coordinates using the first set of angles, the second set of angles, a gravity vector measurement and a time signal.

A system and a method which determines the mass of a ship moving in water, comprising at least two gravitational field strength sensor units that are stationary relative to the ship at a known distance from each other, and an analytical unit which determines the mass of the ship based of measurement signals acquired by the at least two GFS sensor units.

A system and a method which determines the mass of a ship moving in water, comprising at least two gravitational field strength sensor units that are stationary relative to the ship at a known distance from each other, and an analytical unit which determines the mass of the ship based of measurement signals acquired by the at least two GFS sensor units.

A change in geoid height is measured easily. A geoid measurement method of the present invention executes an inertial measurement data acquiring step, a comparison data acquiring step, a state variable estimating step, and a geoid calculating step. In the inertial measurement data acquiring step, data related to velocity, position, and attitude angle is acquired as inertially-derived data based on the output of an inertial measurement part having a three-axis gyro and a three-axis accelerometer attached to a moving body. In the comparison data acquiring step, data related to velocity is acquired as comparison data from a source other than the inertial measurement part. In the state variable estimating step, state variables including a plumb line deviation are estimated by using the inertially-derived data and the comparison data to apply a Kalman filter in which the plumb line deviation is included in the state variables.

The present disclosure discloses a submarine position detection method based on extreme points of gravity gradients. A space rectangular coordinate system is established by taking a centroid of the middle cylindrical portion as a coordinate origin, a direction pointing to a bow is taken as a forward direction of the X axis, a direction pointing to a port is taken as a forward direction of the Y direction, and a vertical upward direction is taken as a forward direction of the Z axis. The detection method includes steps of: determining a horizontal position of a submarine, i.e., coordinates (X, Y), according to a position of a central extreme point and a central position between extreme points of non-diagonal components of a gradient tensor; and determining a functional relation between a depth and the extreme points of gravity gradients by using the submarine model.

The present disclosure discloses a submarine position detection method based on extreme points of gravity gradients. A space rectangular coordinate system is established by taking a centroid of the middle cylindrical portion as a coordinate origin, a direction pointing to a bow is taken as a forward direction of the X axis, a direction pointing to a port is taken as a forward direction of the Y direction, and a vertical upward direction is taken as a forward direction of the Z axis. The detection method includes steps of: determining a horizontal position of a submarine, i.e., coordinates (X, Y), according to a position of a central extreme point and a central position between extreme points of non-diagonal components of a gradient tensor; and determining a functional relation between a depth and the extreme points of gravity gradients by using the submarine model.

An attitude control device is provided and includes a control unit that determines a gravity direction in a flying object on a basis of static acceleration components computed on a basis of a first acceleration detection signal obtained by detecting dynamic acceleration components acting on the flying object and a second acceleration detection signal obtained by detecting the dynamic acceleration components and the static acceleration components acting on the flying object, and controls an attitude of the flying object on a basis of the gravity direction.

A system implementing a method for generating a navigation output is provided. The method includes determining a gravitational anomaly estimate based at least in part on inertial sensor data and navigation output; generating navigation and sensor corrections that are due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter corrections from at least a navigation output estimate, the gravitational anomaly estimate, and the gravity map data; and generating the navigation output based on the inertial sensor data, gravity map data and the navigation and sensor corrections.

A system implementing a method for generating a navigation output is provided. The method includes determining a gravitational anomaly estimate based at least in part on inertial sensor data and navigation output; generating navigation and sensor corrections that are due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter corrections from at least a navigation output estimate, the gravitational anomaly estimate, and the gravity map data; and generating the navigation output based on the inertial sensor data, gravity map data and the navigation and sensor corrections.