How-to AUV - Patch Test
General
It is important to calculate the Roll, Pitch and Heading offsets of the system before a mission starts. It is advised to do this when the system is still tethered, so that the processor can see what kind of lines are sailed.
This page will describe how to do a patch test for a dual head system, because most systems will be equipped with a dual head system. A patch test with an AUV system does not differ that much from a normal patch test.
This article will only describe how to carry out a patch test.
The processing of the patch test will be described on the following page: Patch Test Processing
Make sure that the QPD's are not too large: this can cause problems with the processing of the data in the Validator. It is advised to use a maximum QPD size of 200 Mb's.
On this page:
Patch test preparation
A couple of lines need to be sailed for the Roll, Pitch and Yaw offset calculation. If the system that is used is a dual head system, please make sure that the patch test is done individually for both heads.
Before the preparation of the patch test can start, an area needs to be chosen where the bottom is flat and has an object that can be identified (like a pipe or slope).
When this area is found, the line planning can be created in the Survey Manager of Qinsy.
The following lines are needed:
Roll
The Roll calculation needs a flat area where three runs are done when a dual head system is mounted on the AUV. A typical pattern is shown on the right. It is important to have overlap for both heads, because in Qinsy they are treated as separate systems with their own mounting angles. With the first and second run, the starboard head is covered and with the second and third run the coverage of the port side is complete.
Pitch
The Pitch calculation needs a slope or object that can be recognized. The pattern that is used most of the time for the pitch calculations is shown on the right. The line that is sailed over the slope or object needs to be sailed 2 times for each head, in opposite directions, at the same survey speed (max 9.7 knots). It is desirable that the nadirs of the heads are as close to each other as possible.
Yaw
The Yaw calculation is the hardest part of the patch test. For this test, 4 lines need to be surveyed where the object (or slope) is in the outer beams of the head. This is extra hard for a dual head system because for each head, two lines need to be sailed, in the same direction with the same survey speed with the object or slope in the outer beams but with a slightly different spacing.
