# Scenario: Returning to a Series of Known Positions

Sometimes you need to return to a series of known waypoints. You could imagine a requirement to visit a series of buoy anchors or pipeline supports once a week. You could do a series of waypoint navigation segments as described in the autonomous waypoint navigation scenario. However, as the distance traveled increased, the position fix will accumulate errors. Let’s say the anchors are 100m apart, by the time you get to the fifth or six anchor you could have a position error of 20 or 30 meters.

Since the positions of the anchors are all known in this scenario, as you arrive at each anchor you could send a position update to the DVL, to reset the accumulated error.

**What this requires in addition to the DVL**: In addition to what is needed for manual or autonomous waypoint navigation, you will want a simple way to send the true waypoint positions to the DVL when the ROV is at the waypoint. You will also want a simple way to select the next waypoint. You could type the coordinates in as needed, but that is tedious and error-prone, and having a software assist would be helpful.


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