Nantucket Sound Testing, Day 5

Friday, August 21, 2009

Today we did some tests to characterize the effects of our horizontal stabilizing fins on our depth while under way. The goal was to see if we could fly the the vehicle like a plane, changing altitude by changing forward velocity. As it turns out, there isn't a huge effect, even when we pointed them down significantly.

The final recovery worked like a swiss watch.

Taking Odyssey off the boat when we got back was also a very smooth operation.

So long, Mike and Drew!

All in all, a very productive trip.

Nantucket Sound Testing, Day 4

Thursday, August 20, 2009

Today some grad students from CSAIL came out to try running some of their planning code on Odyssey.

It was a calm day, so -- combined with the fact that we are getting better at the deployment process -- everything went very smoothly.

One of the students went for a swim, so Justin gave her a tow on the vehicle.

We weren't the only ones towing thrill-seekers around the cove...

We did a lot of dive missions to test out the camera system. The vehicle makes a splash on the surface, then pops up a few minutes later (and our confidence in this process has grown considerably since the beginning of the week). Unfortunately, it looks we will have to focus the camera manually since every picture between 1.5 and 5.5 meters altitude comes out blurry.

This time, Mike Ryan picked up a recovery pole from the WHOI facility, which makes it much easier to clip the crane hook onto the lifting bail. My butt didn't get wet this time, and I was nowhere near falling off the dive ladder.

The rest of recovery is a snap.

Nantucket Sound Testing, Day 3

Wednesday, August 19, 2009

First thing this morning, we went to get our DSSI thruster fixed at their facility in Falmouth. As we had hoped, there was no damage to the thruster, so they put a new cable on it and we were good to go.

We ran almost nonstop throughout the day, setting up shop on the fly deck so we could get a better view of the vehicle.

That's it, off in the distance.

We made a lot of progress on tuning the PIDs for yaw, although the gains that produce some of our straightest trajectories also produce some of our most spectacular instabilities.

When the mechanical engineers are bored, it means the software engineers are making good progress.

Nantucket Sound Testing, Day 2

Tuesday, August 18, 2009

In the morning, the crane operator moved Odyssey onto the boat -- it was a matter of minutes. Life is easy with a giant crane truck.

The crane on the boat was also really convenient for putting Odyssey in the water.

Taking the vehicle out of the water was also fairly painless, which is good because we had to do this a few times while adjusting the trim.

Mike operates the crane, Mike and Seth fend the vehicle off of the gunwales, and Noah guides both the crane and the quick release. We're still getting the hang of this part.

Noah is about to pop the quick release.

As the vehicle pops free, we have to work to keep it off the side of the boat while Justin takes the controls.

We do a good bit of manual control to maneuver the vehicle in tight situations, and to get it set up for missions. This will get a little easier as we get the control system and behaviors set up.

While Justin and I work on some simple missions to test the control system (goal: good yaw control without vertical stabilizing fins), Seth tests whether fish are attracted to bits of hot dog.

Then something familiar happens...

The vehicle starts going in circles when it should be going straight. Have we lost a thruster again? Seaweed? Mike and Seth check it out in the zodiac... apparently the cable got wrapped around the thruster and had disconnected.

So, Seth grabbed a handful of zip ties and went to secure the cable.

Unfortunately, the thruster cable had been damaged internally... so the day was over early. Meanwhile, Mike Ryan and Noah had upgraded the refrigerator on board to a model with a freezer. We debated putting an outboard on it and having a boat race.

But the day wasn't a total loss! Seth caught a fish with the hot dog after all, which he filleted and stuck in the new refrigerator. Possibly for lunch tomorrow!

Nantucket Sound Testing, Day 1

Monday, August 17, 2009

We've arrived in Falmouth, MA at the Woods Hole pier, to meet up with Ryan Marine on the research vessel Discovery. The crane operator had left for the day, so Odyssey will spend the first night on the pier.

This vessel is a bit larger than the M/V R&R that we used previously. Our support gear fits comfortably on deck and is reasonably protected from the elements.

Night Testing: Camera Tests

Friday, August 14, 2009

At our second night at UNH, we planned ahead and bought plenty of food before the stores all closed. It helped keep us awake to take food breaks throughout the night, but we all took periodic naps when we could.

Although the camera driver and strobe system worked, the images were a little too bright (and slightly out of focus, even at long distances). We will have to adjust the focus and the aperture before doing any survey work.

At dawn, we packed up and left.

Night Testing at UNH

Thursday, August 13, 2009

To tune up our new camera and flash system, we planned to take a trip up to UNH to use the large pool at their Ocean Engineering facility.

They were already booked for the week we wanted. But because we had a fairly urgent need to get our testing done, they agreed to let us use the pool "from 7pm until dawn". Time for some all-nighters! We loaded up the truck in the afternoon instead of the evening.

The UNH facility is more than large enough for our needs. It would be great to have access to a crane like this at a pier somewhere... or in our lab, or in an MIT pool facility.

It really makes testing more productive when you can get the vehicle in and out of the water quickly!

Our major accomplishment for the day (night) was getting the PID gains tuned for depth/altitude control. They are tight to within 1cm of the target altitude!

The one nice thing about working at night is that you can turn off the lights to see how effectively the strobe system illuminates the bottom.

Field Kits

Monday, August 10, 2009

Today I organized some field kits to make deployments go more smoothly.

With the exception of those rare occasions where nothing goes wrong, bringing the right amount of stuff and having it organized -- so that you can find what you need when you need it -- is key to success.

We Need a Bigger Boat

Thursday, August 6, 2009

Pulling a 1000lb vehicle with an inflatable boat is difficult...

And in the middle of a shipping lane, it's a nail-biting experience.

Back On Track

Wednesday, August 5, 2009

With a fixed thruster arm, we are back to tuning up the control system. Testing went well, but there was an extremely tense moment when the vehicle started turning in circles when it should have been moving in a straight line...

We thought we had lost a thruster again.

Fortunately, it turned out to be some seaweed that had been floating on the surface, which got tangled in the thruster and severely reduced its efficiency.