Quick Tip #11 – Repositioning the Vehicle

In this quick tip, we’re going to talk about repositioning your vehicle in Workspace. Primarily, when you’re looking at the Mission Panel in Workspace, you want where you are. When your vehicle is on the surface, the GPS provides accurate positioning data.

Things change when you get below the surface, as there is no single sensor, and no analog to GPS, that can provide your position. Instead, your vehicle is probably using a dead-reckoning system to estimate your position based on its available sensor data.

In a dead-reckoning system, there are three things you need to know in order to estimate your position underwater: your starting point, your velocity, and your attitude in three dimensions. Based on this you need a minimum of three sensors: a GPS, a velocity sensor (Doppler Velocity Log), and a compass.

However, no matter how good your sensors are, it’s important to remember that they’re only providing estimates of your position. The thing about estimates is that they accumulate error over time. This means that the longer your mission goes on, your vehicle’s positional error is accumulating.

So How do you Fix your Position?

The first thing you should do, regardless of how you reposition the vehicle, is to disable positioning mode. If you have an active waypoint, and change your vehicle’s position, it may try and return to the Waypoint.

If you’re on the surface, and your version of Workspace has Reset to GPS; you can use that to set the vehicle position to the GPS location. You can find the Reset to GPS in the Setup Tab in the Mission Panel Tools.

To manually set your position to a location on the Mission Panel, you can right click the spot on the Mission Panel where you want to position your vehicle and select Set Position. This is really useful if use a combination of the sonar fan and a chart to line up on a distinct landmark.

Thanks for taking the time to check out our quick tips. Hopefully this will help your vehicle in the right place relative to the map. As always, if you’d like more information, you can contact us at blog@greensea.com. We’re here to help you to get the information you need.

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