Rover/Boat: mapping mode

[rmackay9]

It would be very convenient for users is we had a "map" control mode that would cause the rover or boat to cover all accessible areas of an indoor space or lake while also staying within the bounds of the polygon and circular fences.

The usefulness of this potential mode comes from mapping a lake as described in this Blog. The user has to be quite careful about placing the waypoints so that they are close to the shore (so that we map all of the lake) but not too close or the boat could get stuck in weeks or hit the shore. This can be difficult especially in cases where the GPS coordinates don't exactly match the GCS's map (due to GPS errors or inaccuracies in the map service the GCS is using).

DavidA made this comment:

the biggest issue I have found when survey is trying to plan the route as maps is not that accurate there can be up to a 10m map shift. How always have to survey the perimeter of the reservoir with GPS before planning a mission

DavidB says something similar:

I usually do a survey grid first then a few laps around the perimeter in steering mode using telemetry and FPV after the auto grid is complete.

Below are some thoughts on how it might work for boats which could be simpler than what is required for rovers because they typically operate in a simpler environment.

• the boat could at first travel straight forward in the direction it is facing when MAP mode is engaged.
• the shoreline (or other barrier) could be detected using an (optional) downward facing sonar (new DEPTH_MIN parameter would be required) or a forward facing or 360 degree lidar detects something. It might also just detect that it can't move forward despite motors going to full (although this could be messy).
• once the shoreline is detected the vehicle might give up on moving in that direction and instead turn back 180degrees and attempt to maintain a line X meters to the left or right of the previous line.
• the next lane might always be left of the original lane (perhaps we'd need a parameter) but eventually the board would find that it couldn't move to the next lane and would return to the original lane and then from then on lanes would be placed to the right.
• it could be tricky to consistently determine if the next lane is clear.. it might be best if the boat turns around (assuming it is a skid-steering vehicle) and continues back along the current lane but checks (with a 360 lidar or sonar?) if the next lane is clear or not.

A more advanced algorithm somehow capable of mapping behind barriers would be nice eventually.

[Avalonnw]

As an option - set a point in the middle and spiral out with pre-set distance between lines. If encounter a blocked path, keep going along the blockage until get to the required distance from previous line and continue. Something like "adaptive toolpath" in machining.

[rmackay9]

@Avalonnw, that's an interesting idea, thanks!

[Avalonnw]

Actually, that reminds me a bit too much of robot vacuum cleaners and SLAM. My LG HomBot has this Spiral mode which is essentially the same. Is SLAM implementable on current hardware without companion computers at all?

[Naterater]

From the discussions of features for other vehicles, I think this is a prime candidate for scripting instead of a built-in feature. Just my $0.02.