Devices, program products and computer implemented methods for touchless metrology having virtual zero-velocity and position update

Abstract

Embodiments of a metrology device and a computer-implemented method generate survey data without touching the subsea objects being surveyed. The metrology device can include an inertial navigation system (INS) outputting position and orientation data of the metrology device; an aiding device positioned at a known distance and orientation with respect to the INS for collecting image data of the subsea objects; and a computer having one or more computer programs that use the image data to calculate measured velocity of the metrology device at first and second subsea objects to perform virtual zero velocity updates, and uses an apparent difference in the position of the first subsea object measured prior and subsequent to measuring the second subsea object to perform virtual position update.

That claimed is: 
     
         1 . A computer-implemented method of surveying a plurality of subsea objects with a metrology device including an inertial navigation system (INS) operable to output INS data including accelerometer and gyroscope data associated with a position and orientation of the metrology device and an aiding device operable to output distance and orientation data of the plurality of subsea objects with respect to the metrology device, the computer-implemented method comprising:
 navigating the metrology device to a first measurement point, and collecting, at a first time, first subsea object data from the first measurement point including a relative position of the first subsea object with respect to the first measurement point;   navigating the metrology device to a second measurement point, and collecting, at a second time, first subsea object data from the second measurement point including a relative position of the first subsea object with respect to the second measurement point;   navigating the metrology device to a third measurement point and collecting, at a third time, second subsea object data from the third measurement point including a relative position of a second subsea object with respect to the third measurement point;   navigating the metrology device to a fourth measurement point and collecting, at a fourth time, second subsea object data from the fourth measurement point including a relative position of a second subsea object with respect to the fourth measurement point;   calculating a measured velocity of the metrology device between at least one of the first and second measurement points and the third and fourth measurement points using the collected relative positions of the first and second subsea objects with respect to respective measurement points and a difference between respective times;   correcting the INS data with the measured velocity such that a drift of the INS data grows generally linearly with time;   subsequent to the fourth time, navigating the metrology device to a navigated measurement point in which data output from the INS and data from the aiding device can be collected from the first subsea object, and collecting, at a fifth time, first subsea object data including a relative position of the first subsea object with respect to the navigated measurement point;   calculating a drift correction for the INS data using the difference between the collected relative positions of the first subsea object position with respect to the first and navigated measurement points;   determining a proportion of the drift correction corresponding to a proportion of time elapsed between the first and third times and time elapsed between the first and fifth times; and   correcting the collected relative position of the second subsea object using the determined proportion of the drift correction.