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.
Replies
3.1 it was much easier but... would have the leans. 3.2 is impossible unless you turn off pre arm check for gyro. But it still acted weird and took forever to arm. I think it saw all that water and me about to let go and was thinking NO WAY!!!
Nice photos! Here's the vessel I was trying to launch from...
I think originally they had hoped to have 'boat mode' in 3.3 but ran out of time so it got bumped to 3.4
Those two photo's I posted my brother took with his Phantom. He has no problems arming on a boat or even just holding it in his hand. However...... it's my opinion they are built very cheaply. He recently just had his 4th fly away and lost it and a 4th gopro and a 4th 3 axis gimbal! So I wont be buying one of those anytime soon. I'll wait for 3.4. Just hope it comes out before winter.
That is a beautiful boat!! Do you know what year it is? Looks older but really nice lines..
Basecam gimbal firmware has an option to skip gyro calibration upon start-up. It stores the latest numbers, which you can update by unchecking the option as needed. Now i know why it has that option.
In some ways pre-3.0 APM code had the same (the good ol cold start vs warm start, hence usable on boats and ground vehicles). I figured that's gone from the onion deployment (We've been out of it since v3.1).
As for dynamic RTL, what happened to rally points? Also, LIRC MP can set a new home position in the map display much like DJI's app (needs a confirmation, etc...)?
Randy - In thinking about the solution, i'm also wondering if the following related issues are also optimal:
1) is the heading in stabilize mode taken on power-up, the armed event, or on on the throttle-up event?
2) is the RTL position taken on power-up, armed, or throttle-up?
i'm thinking that the best answer is upon the armed event for all cases in any situation.
Don't believe it makes sense to try to think about the solution from ones experience or perspective. This is so rapidly developing that the only universal solution is something like parameters and scripts.
The PX4 firmware version of the Pixhawk has simple notepad.txt application files on the SD card. There are files for startup, mixing and special parameters. As an example if you are running a servo on a channel, an update rate of 400Hz will burn many servos up. So you can set the update rated for each channel and use 400Hz for ESC motor controls and 50Hz for servos.
The PX4 is concentrated more towards autonomous solutions, like unattended launches from the top of a swaying wind turbine.
PS: On the other end of the spectrum, the $50 toys are coming out with heading hold, RTL and oh BTW ... will launch from a boat.
Interested in Randy's input, he has been sitting at the head of the table on this topic a long time.
so
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