How to Launch Arducopter, IRIS, or SOLO from a Boat

Recently, I was asked to shoot some stills and footage of a sportfishing yacht for a client. We went out on a beautiful morning with no wind and an almost perfectly calm ocean. If you wanted optimal conditions, its wasn't going to get much better than that morning.

I connected the battery to my custom built quadcopter running APM 2.6. It would not arm. We were sitting about 4 miles off shore, not moving, gently rocking on an ocean about as calm as I've seen it. I was trying to launch from the middle of the lowest platform of the boat, at the stern. I had good GPS. Everything else checked out. It would not arm.

As soon as I got back to dry land, I tried it again. It armed without hesitation. Apparently Arducopter needs to be on solid ground to initialize. So what next?

Arducopter 3.3

In doing my research, I found this thread:
http://diydrones.com/forum/topics/launch-and-recovery-from-boat

Chris Anderson says, "Starting with 3.3, calibration on a moving surface will be easier. As far as the gimbal goes, it depends on the make. The 3DR Solo gimbal will calibrate on a boat, but not all will"

I have two points here. First, the gimbal is not an issue for me. Simple BGC lets you turn off the startup accelerometer calibration. It still works fine if you don't let it calibrate every time. Second, I'm using APM 2.6 so I'll have to upgrade to Pixhawk if I want to use Arducopter 3.3.

Arm on Shore first

Next, I found this thread:
http://diydrones.com/forum/topics/launching-from-a-moving-boat-can-it-be-done

The first person to comment boots his quad on shore, then takes it powered up, in his kayak. I see where that could work but that only gives me the use of one battery.

Bring a Laptop?

Considering the idea of calibrating on shore, what if I brought my laptop on the boat with me? I could power up on shore then launch from the boat and fly the first battery. After I return to the boat, I could connect APM to the laptop with USB, then disconnect and swap the flight battery for a fresh one. Would this work? I will do some experiments and post the results on this thread.

Dynamic RTL is a Separate Issue

I've already posted the desire for Dynamic RTL, where the copter returns to YOU instead of the original launch location. Obviously this is desirable for any mission launched from a boat. It seems like a much easier feature to add. The Tower app already knows your GPS location in order to do "follow me" mode. The DJI Inspire already has this feature. My thread is here:
http://diydrones.com/group/arducopterusergroup/forum/topics/dynamic-rtl-can-apm-or-pixhawk-do-it-can-tower-do-it-dji-inspire

I will post more information as I find it. Hopefully this thread will be a resource for those wanting this feature.

2 points.

1. Is that when you can RTL from a boat, I would fly the copter as close as possible before hitting RTL, so that the boat hasnt had a chance to moved much since it acuired its GPS fix. (Now I am making the assumption that the newer RTL Chris was talking about takes the GPS position of the ground (or water, he he) once you it RTL. Now if it updates every 5 seconds or so that would be another matter)

2. I didnt want to believe it first...But the Pixhawk is FAR superior then the APM for multi Copters. All of Inertial guidance software is huge and has to run fast just to keep the copter level (or at least where it should be) on top of the code for flying. Now for a plane or the like you dont need that high level of Inertial guidance. So the speed and memory size of the APM should be fine for awhile (plus those Pixhawk Pitot tubes are Bloody expensive!)

Now if youve already got a newer GPS you sholdnt have much to buy that works with the Pix. I had to re-pin my older telemetry...But there are cables avalibe, and all the new one come with 2. Now whether you spend $90 for a knockoff or $199 for the real deal is your call. Personally I have had about the same luck with bad modules from 3DR as I have had for knockoffs. SO your call on that one.

But If you think about what youve put into your copter, and what you stand to lose......Would you really want to run and outdated module? Now I was first to the party with the APM and Ive owned every version theyve had. With the pixhawk I held off. And for a long time the 2 were so close that it wasnt a big deal...My point is I am not a jump on the bandwagon and digg my heels in kinda guy. But this ones worth it....and there is really nothing new you have to learn about it. my biggest deal was PPM Sum....But I just Frsky X8R with new long range ends on it for $35 to solve that problem. I could have flashed my existing module....But I could use an extra so....

Replies

- OwlPic > Randy September 12, 2015 at 6:56am
  
  Randy ... You are right this is very important. It is actually more important than a just boat. In grass, wet ground or very rocky area it is not possible or maybe desirable to put on a "flat" stable surface.
  
  It would be nice to be able to arm while holding over your head. (I know ... only for professionals)
  
  What more is required than to offer a parameter that sets the amount of motion allowed inorder to arm?
  
  The PX4 version for example is far less fussy to arm if slightly tilted or moving.
  
  Thank You
Robert Giordano September 11, 2015 at 10:04pm

"Boat Mode" on MikroKopter

On http://mikrokopter.altigator.com/boat-mode-take-off-from-a-boat-n-3... it says:

Since the version 2.08, MikroKopter has a "boat" mode which has been especially developed in order to solve the takeoff problem on a platform that is in motion (like a boat, or every other moving landing surface).

This method uses as reference the last values of the gyros that were saved during the most recent initialization made on the mainland. It is therefore important to have completed this process (initialization) during the last 1 or 2 days before, because these sensors are quite sensitive and unstable in medium term.

The article continues by showing a special stick configuration that arms the copter in "Boat Mode". It seems like it wouldn't be too difficult to implement this feature. The code might include "safety rules":

- The timestamp of the last saved values must be within the last n hours. (n defaults to 3? (i.e. a "3 hour tour")

- Loiter cannot be used for launch unless the speed of the boat/platform is close to zero (less than 1m/s?)

- In "Boat Mode", RTL would automatically change to "Dynamic RTL" if the telemetry radio is connected.

Boat mode: take off from a boat

Sometimes drone users wish to be able taking off from a boat. Even for very large ships, a boat is somehow always moving. Before starting to fly…
- MR60
  
  Forrest Frantz > Robert Giordano September 12, 2015 at 7:19am
  
  Tall grass? If using a multi-copter to photo waterfalls in the mountains, how is one supposed to take off in tall grass on a knoll?
- Will Snodgrass > Robert Giordano September 11, 2015 at 10:31pm
  
  2 points.
  
  1. Is that when you can RTL from a boat, I would fly the copter as close as possible before hitting RTL, so that the boat hasnt had a chance to moved much since it acuired its GPS fix. (Now I am making the assumption that the newer RTL Chris was talking about takes the GPS position of the ground (or water, he he) once you it RTL. Now if it updates every 5 seconds or so that would be another matter)
  
  2. I didnt want to believe it first...But the Pixhawk is FAR superior then the APM for multi Copters. All of Inertial guidance software is huge and has to run fast just to keep the copter level (or at least where it should be) on top of the code for flying. Now for a plane or the like you dont need that high level of Inertial guidance. So the speed and memory size of the APM should be fine for awhile (plus those Pixhawk Pitot tubes are Bloody expensive!)
  
  Now if youve already got a newer GPS you sholdnt have much to buy that works with the Pix. I had to re-pin my older telemetry...But there are cables avalibe, and all the new one come with 2. Now whether you spend $90 for a knockoff or $199 for the real deal is your call. Personally I have had about the same luck with bad modules from 3DR as I have had for knockoffs. SO your call on that one.
  
  But If you think about what youve put into your copter, and what you stand to lose......Would you really want to run and outdated module? Now I was first to the party with the APM and Ive owned every version theyve had. With the pixhawk I held off. And for a long time the 2 were so close that it wasnt a big deal...My point is I am not a jump on the bandwagon and digg my heels in kinda guy. But this ones worth it....and there is really nothing new you have to learn about it. my biggest deal was PPM Sum....But I just Frsky X8R with new long range ends on it for $35 to solve that problem. I could have flashed my existing module....But I could use an extra so....
Robert Giordano September 11, 2015 at 9:49pm

Discussion on 3DRpilots.com

http://www.3drpilots.com/threads/boat-mode.1179/

This is an interesting discussion. Someone raised the point that if you're moving and you take off in Loiter mode, the quad could slam back into you or the boat. Well, this just confirms my previous post. I want to take off from a STATIONARY vessel and I certainly want to be LANDING on one as well. =)
Robert Giordano September 11, 2015 at 9:47pm

Ardupilot on GitHub

On https://github.com/diydrones/ardupilot/issues/1361 it says:

There are two risks for arming and taking off on boats. The first one is that the gyro calibration will likely fail. It'll go with it's best guess which is likely ok most of the time but at least one case has been reported where the vehicle got a case of "the leans". I.e. the pilot had to keep pulling further and further back on the pitch stick to keep it level... eventually there wasn't enough stick left and it flipped over. This is because the gyro calibration didn't work very well. Plane has a parameter that allows skipping the gyro cal, we don't have it in copter although it's easy to add.

The 2nd less risky issue is the pre-arm checks will fail if it thinks the vehicle is moving over 50m/s (i.e. 1.5feet / second). This can be disabled by setting the ARMING_CHECK to Skip INS.

For Landing there may be an issue with the landing check's 30deg/sec rotation rate not being passed meaning the vehicle cannot be disarmed in AltHold or Loiter.

Looks like more reasons to arm on shore, then keep it powered while on the boat. Also, I think it would ALWAYS be best to take off from a stationary boat, rather than a moving boat. I can imagine situations where you don't have control over the boat coming to a stop for you, but then I question whether you should be trying to fly in those situations.
- Federico Boldori > Robert Giordano September 19, 2015 at 5:09am
  
  Hi, you dont need a laptop. Buy some cellphone usb battery charger. I use them to power my iris+ for ten minutes before every flight to warm up the board. Then i connect the battery and unplug usb.
  
  You could power it on the shore with usb. Wait some minutes to get it warmed up and reboot it for better sensor calibration. Then with the usb plugged go on the boat. When you are ready plug the battery, disconnect usb and fly.
- Robert Giordano > Federico Boldori September 21, 2015 at 7:10am
  
  Hey Federico! I just did a number of successful flight tests using my "boat simulator" and my laptop. Please see this post!
  
  Also, I thought about using a USB phone charging battery and I have several of them. Its a good idea. The problem is, I don't want to take a chance plugging an untested power source into my flight controller. I would rather have an engineer who knows the actual specifications of the board, tell me if that's a safe option.
  
  Also, we're talking about APM and Pixhawk boards. One may work while the other could fry.

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