Abstract: A quasi tightly coupled (QTC) aided INS (AINS) process has an inertial navigator system with a loosely-coupled AINS Kalman filter that constructs INS-GNSS position measurements, a GNSS position engine that computes a position fix from observables and an externally provided a priori position and position VCV matrix. An INS position seeding process in which the externally provided a priori position to the GNSS position engine is an antenna position computed from the INS position and attitude solution. An observable subspace constraint (OSC) process computes an OCS matrix that suppress the components of the GNSS position error due to a poor geometry in the GNSS position solution in the IG position measurement constructed by the AINS Kalman filter and that multiplies the OSC matrix and the IG position measurement and measurement model matrix to suppress uncorrected component of the GNSS position error in the IG position measurement and measurement model.

Abstract: Two methods for determining a best initial heading estimate for use in an AINS system, while recording position data values and in-motion data values, assigning incremental changes to indexed heading ?k, calculating a set of time indexed present AINS position values and a corresponding set of time indexed absolute horizontal position measurement residual values, recording the absolute maximum time indexed horizontal position measurement residual and the corresponding value of ?k returning to the step of assigning an incremental increase to a next value to indexed heading ?k up to 360 degrees, identifying the maximum time indexed horizontal position measurement residual and corresponding ?k, followed by identifying the ?k having the smallest absolute maximum horizontal position measurement residual as Ak Second method uses a circular array of AINS ENGINES each with a different ?k running in parallel and finding smallest horizontal position measurement residual for Ak.

Abstract: A Land Surveyor System with Reprocessing is carried by a surveyor moving from a first known position at the start of a survey interval to a second known position at the end of the survey interval has an AINS (aided inertial navigation system) that provides a continuing sequence of time-indexed present position values. A Position Computing System uses a program that stores the sequence of time-indexed present position values in a memory. A reprocessing computer and program is activated at the second known position to access and process the continuing sequence of time-indexed present position values with a smoothing program to provide indexed and adjusted present position values for at least some of the time-indexed present position values. The system is packaged for transport and use by a surveyor. A switch permits the surveyor to signal that the unit is stationary as a reset for the AINS.

Abstract: A walking stick navigator (WSN) apparatus and process comprises an aided INS (AINS) on a staff assembly similar in operation and appearance to a GPS survey instrument. However, when GPS is available, the AINS is aided by GPS data, and the surveyor manipulates the staff assembly like a standard GPS survey instrument. When GPS is not available due to signal obstruction, the surveyor manipulates the staff assembly as a walking stick. A switch means coupled to the lower end of the staff assembly provides a stationary interval signal when the surveyor plants and holds the WSN on the ground while walking. An input process is coupled to the AINS output signals and to the stationary interval signals and provides at least one aiding input signal to the AINS for each successive stationary interval, thereby allowing the AINS to control its velocity error and position drift during a GPS outage.

Abstract: A walking stick navigator (WSN) apparatus and method comprises an aided INS (AINS) on a staff assembly with the “look and feel” of a GPS survey instrument. When GPS is available, the AINS is aided by GPS data, and the survey or manipulates the staff assembly like a standard GPS survey instrument. When GPS is not available due to signal obstruction, the surveyor manipulates the staff assembly as a walking stick. A switch means coupled to the lower end of the staff assembly provides a stationary interval signal when the surveyor plants and holds the WSN on the ground while walking. A digital computer is coupled to be responsive to AINS output signals and to the stationary interval signals and to run a program that solves a position aiding algorithm and a velocity aiding algorithm that provide at least one aiding input to the AINS for each successive stationary interval.

Abstract: A pedometer navigator system has an Euler Angle Measuring Subsystem (EAMS) coupled to a body frame provides Euler angles of a fixed coordinate system with respect to a navigational coordinate system. Left and right sensors are mounted on a surveyor's feet. An SBPMS (short baseline position measuring subsystem) provides a left vector {right arrow over (&rgr;)}leftp and a right vector {right arrow over (&rgr;)}rightp characterizing the position of the sensors with respect to the SBPMS coordinate system origin. A computer means responds to the Euler angles and left and right vector and determines an interval during which the left or right foot is stationary, and providing a transition vector referenced to the earth fixed navigational coordinate system. A navigation algorithm adds each transition vector to the previous present position of the navigation reference system to obtain a next present position of the position measuring subsystem.