Serenity

Had another chance this morning to test the navigation after correcting yesterday's mix-up with left/right rudder output. It's working as well as I could have hoped for cross-wind navigation, but the upwind tacking (aka intermediate waypoints) do not seem to be working correctly. The boat basically ends up going in circles when it should be headed towards an intermediate waypoint. At first glance, we thought maybe the gps signal had dropped out. However, log data confirms that the gps was not the culprit.

I suspect this will likely correct itself once the sails are tuned better (particularly the front sail). The range of degrees that the boat is unable to navigate without tacking is referred to as the 'no-go zone'. Since I do not adjust the tension of the sails dynamically, this zone is much wider than a typical boat would experience. I think the angle may even be wider than the angle computed for intermediate waypoints, which could definitely cause issues.

Anyone with basic sailing experience would probably notice in some of the pictures that the front sail looks let out way too much. I had done this intentionally thinking it would be nice for downwind speed, but I've decided I'd rather go slow downwind than stall on 'close hauled' headings.
Example showing front sail let out too much.. it should be much tighter/flatter here:

I still need to review the log data more carefully and try to reproduce the issue in the simulator. In any event, the good news is that I don't think there's a software/logic issue. Overall I'm quite happy with today's test run though!

More Serenity Cam Video (unfortunately I only have this version in very low quality)
Some random events in this video:

• Rowers - 0:40
• Stand-up paddler - 0:43
• Swimmers - 1:17
• Boat tracking towards waypoint - 1:55 to 2:22, 2:22 to 2:52
• Swimmer - 3:32
• Boat spinning out of control left when we expected it to sail upwind - 5:16 to5:45
• Stand-up paddler - 6:43
• Boat keel hits sand and stops - 6:55
• Lifting boat out of water - 7:07

Had my first official test run with all electronics/autopilot in place. Sailing went well, got some nice video, but auto-pilot failed. The good news is that the problem was very simple... my autopilot had left and right confused!! The result was it would navigate in the opposite direction of the current waypoint.

I realized pretty quickly that the servo was responding in reverse, but I couldn't understand why it would cause this behavior. I expected it to just take the 'long way around' to point towards the next waypoint. The trouble is, the boat constantly tries to compute the shortest angle to the next waypoint.. since I had it flipped, everytime it crossed 180 degrees away from the waypoint, it would tell itself to go the other direction (hence always stuck 180 degrees off). I was able to reproduce/confirm this in the simulator as well.

Video of 'issue':
Left vs. Right

Serenity Cam (stills and video.. back cam needs to be adjusted slightly)
Serenity Cam

With the correction now in place, another test is in order (hopefully tomorrow!) 😀

A good amount of progress has been made despite the lack of updates here. I expect to have the boat in the water as soon as next weekend (no later than the end of the month). Finally!!

In a nutshell, here's what's been accomplished:

• Finished up integration with sensors, cleaned up wiring, boxed up the main electronics in an enclosure, finished up 'control panel' with main power switches, LCD display, and display pause/resume button.
• Updated Sail Simulation software to refine navigation logic
• Ported navigation code to arduino ide project.
• Tested navigation logic by walking around the streets and parks setting waypoints, then letting the hardware tell me how to walk to each location.

What's left? Not much really, except for testing in the water now. I'm excited to see how the pictures will turn out from the cameras.. 🙂

I made a quick sweep to update each of the pages where applicable, and included a few new images and a video that might be of interest showing the updated simulator..

Sail Simulation v2 (most recent version)

'Control Panel' Basically just power switches, an LCD only used to check sensor status, etc before boat is launched, and the green button pauses/resumes the information cycling on the LCD screen.

Main electronics getting boxed up

Sail position sensor (under white silicon are 3 reed switches wired in parallel) The copper tubing you see in the picture is a rail that magnets attached to the boom (beam under the main sail) slide along. When they reach either end of the rail, they trip the reed switches indicating the sail is not stalled. (if it is stalled, that's how we know we need intermediate waypoints)