NaviPac NaviScan. A9. Doppler Calibration

Size: px

Start display at page:

Download "NaviPac NaviScan. A9. Doppler Calibration"

Ethel McCarthy
5 years ago
Views:

1 NaviPac NaviScan A9. Doppler Calibration

2 Version History Version Who Additions 1.0 OKR 31 January 2000 Created 3.8 OKR April 2012 Upgraded to new GUI Table of contents 1. INTRODUCTION DVL CALIBRATION LOAD DATA SET THE VIEW MANIPULATING DATA CALIBRATION REPORT DATA Date:10 May 2012 Version: 3.8 Page 2 of 10

3 1. Introduction The Doppler Calibration application allow the operator to load logged files, compare raw position and Doppler track and calculate rotation and scale errors, which can be applied to data to improve quality. The application can be started from Start menu, the NaviPac Online Calibration menu or by starting the application from the browser searching for the right module: The application can load NavScan data files (SBD format) or NaviPac survey data (XYZ record format). Both file types must include: raw position gyro doppler log data Date:10 May 2012 Version: 3.8 Page 3 of 10

A standard load from dialogue pop s up: Based on the file type (SBD for NaviScan and NPD for NaviPac), you may now load the file.

4 2. DVL Calibration The program is based on the MDI technology, and it allows you to load multiple files in the same application. When started, you get the following empty look: 2.1 Load data set To load a logged file, you must activate File, New or press the new icon. A standard load from dialogue pop s up: Based on the file type (SBD for NaviScan and NPD for NaviPac), you may now load the file. If the load is OK, a new document is placed in the application display. 2.2 The view The display contains one window per loaded file. Date:10 May 2012 Version: 3.8 Page 4 of 10

The map view (as known in the NaviPac Helmsman s Display) contains two tracks: The green line shows the raw stored track, i.e. not corrected for any offsets etc.

5 The map view (as known in the NaviPac Helmsman s Display) contains two tracks: The green line shows the raw stored track, i.e. not corrected for any offsets etc. The red line shows the doppler track, as it s based on Doppler data, gyro and time. The first position is based on first recorded position. The rest is just made by adding vectors. X1 = X0 + delta-time * Speed-X. As default the view shows the middle of the data set. It s now possible to Re-centre Double click anywhere in the view and the point will be defined as new centre. Zoom in The default presentation is made in scale 1000, i.e. 1:1000. If you press the zoomin button, the scale is always reduced by a factor two, i.e > 500 -> 250, etc. Zoom out: The default presentation is made in scale 1000, i.e. 1:1000. If you press the zoomout button, the scale is always doubled. Rotate the view: The default presentation is north up. If wanted, the presentation can be rotated in steps of ten degree. This can either be done from menu (View, rotate right, View, rotate left) or by pressing the rotate buttons. If you have a nice data set, it can be printed by File, Print or by pressing the printer button. The map is now printed on any printer, and a small header is applied. The header contains the following information: Scale Centre position Number of points File name (do not use long path!) Current date/time The headers are formatted so it should fit to any printer driver, but we have observed some minor cosmetic problems. Date:10 May 2012 Version: 3.8 Page 5 of 10

2.3 Manipulating data If there is a clear difference between the raw track (green) and the Doppler track (the red), the operator may perform a manual trial-and-error calibration by scaling and

6 2.3 Manipulating data If there is a clear difference between the raw track (green) and the Doppler track (the red), the operator may perform a manual trial-and-error calibration by scaling and rotating the Doppler track. This can be done, by entering the following parameters by Edit, Scale and Rotate: Scale Y: The along ship speed is increased or decreased by a multiplication factor Scale X: The across ship speed is increased or decreased by a multiplication factor Rotate: The direction (= gyro) of the vehicle is changed by adding the angle to the logged direction. When pressing OK, the graphical display is automatically updated by the entered values. The process can be repeated several times, as the corrections are combined: Scale: Multiplied Rotate: Added By performing a stepwise refinement, the manually calibration can be performed until a satisfactory fit is obtained between raw and Doppler Track. The data report (See 2.5) will included the applied parameters. We recommend that a graphical print always will be followed by an ASCII print. View, Reset Scale and Rotate can clear the corrections. 2.4 Calibration When the Doppler data is used to improve raw Track in either Online or in NaviEdit, a Rotation and Translation matrix equation can do this. This philosophy is used in the auto calibration (Edit, Calibrate or the Calibrate icon). The data set is here merged using a Salomonsen Lite filter, which rotates and scales the Doppler track until a best fit is obtained between the two tracks. Normally the result is a smooth track, but here we pick-out the matrices instead and use them as calibration results. Date:10 May 2012 Version: 3.8 Page 6 of 10

7 We can hereby get the following parameters, which is presented in the Calibration report (See 2.5). Scale Y: How much is the speed scaled in along ships direction Scale X: How much is the speed scaled in across ships direction Rotate angle: How much is the Doppler Track rotated. Please note that it's very difficult to separate Scale-X and rotate angle. If the data set is of high quality, the system will furthermore generate recommended filter settings (for Online Salomonsen Lite Filter): Maximum acceleration: The maximum observed acceleration. Higher values will be discarded in online. Maximum position jumps: The maximum observed position jump. Higher values will be discarded in online. Gain: Doppler weight - always The calculated values can be applied to the data by activating Edit, Apply correction. We recommend that this command always is applied and that the result is printed together with the report. Please note that calibration is performed on manipulated data, i.e. any manually corrections can have influence on the result. 2.5 Report Information on the loaded data set, correction values and calculated corrections can be obtained by the View, Report menu or by pressing the report icon. The following dialogue then pops up: Date:10 May 2012 Version: 3.8 Page 7 of 10

File Name of the loaded data file Recorded: Data and time for the survey File info Number of positions Number of Doppler records Manually entered rotation angle (See 2.

8 File Name of the loaded data file Recorded: Data and time for the survey File info Number of positions Number of Doppler records Manually entered rotation angle (See 2.3 Manipulating data) Manually entered scales Calibration result Scale values Rotation angle Recommended online filter setting If the operator presses Print, an ASCII file is generated on the same location as the data file: EIVA Calibration report Date: Time: 11:59: File : S:\geofjord\J289N032.SBD Rec. : :13:16 Report: File info: Positions 929 Doppler data 5425 DL Rotated degree DL Scaled in Y and in X Calibrated: Scale Y: Date:10 May 2012 Version: 3.8 Page 8 of 10

9 Scale X: Rotate A: Recommended filter setting (if data is typical sample without noise): Maximum acceleration: Maximum position jumps: Gain: The file is printed on the default Windows printer in pure ASCII. Date:10 May 2012 Version: 3.8 Page 9 of 10

10 3. Data The DL Calibration module operates on any data set, which is in the right format and which contains both raw position and Doppler data. What kind of data gives the best calibration result? It s EIVA s experience that a good result is obtained if 1. The survey is performed as near as possible to straight lines 2. Two or more individual data sets (in different direction) is calibrated and an average result is taken Date:10 May 2012 Version: 3.8 Page 10 of 10

NAVIPAC 4 INTRODUCTION AND WORKFLOW

NAVIPAC 4 INTRODUCTION AND WORKFLOW Contents 1 Introduction to NaviPac... 3 2 Program Environment... 4 3 Hardware environment... 7 4 Workflow example... 8 4.1 Workflow: Creating a configuration... 9 4.1.1