Is it possible to fly a drone from the deck of a steel ship or boat?

[sar104]

I bet the next post contains the rant about confirmation bias.

Yes, that's the pattern. It's just weird that anyone can continue to misunderstand this topic so badly.

 

[BJR981S]

Every year or so it seems that you come back and post this stuff again, and then go quiet. This year you are still wrong. What baffles me is that, quite apart from the fact that these are all established technologies that you can read about in the literature, the flight log data show all these things happening. You can see the IMU yaw being initialized by the magnetometer data, and then being corrected by the local declination when the FC gets an GNSS position lock. This is not hypothesizing.

As for the rest of your posts, I really don't even know where to start because you are just massacring basic physics and maths. You don't even understand what is meant by "initialize", apparently. It has nothing to do with calibration. And no - all three gyro axes are not the same - two of them are fixed by an absolute measurement that the IMU can make. Initial pitch and roll are measured directly by the accelerometers. Only the yaw axis is indeterminate on startup. And so, just with any gyro compass, that one has to be initialized by a compass reading.

You are a well respected member here iwho is very competent at reading and interpreting Flight Logs. However your understanding of technology and physics and the ability to think logically is lacking.

This statement is absolute rubbish "Only the yaw axis is indeterminate on startup. And so, just with any gyro compass, that one has to be initialized by a compass reading." All 3 axis are the same when power is applied. Tell me why the Yaw axis is not initialised. The IMU has a 3 axis Gyro and a 3 axis accelerometer. It does not, and never has had a Gyro Compass. Your assumption that is does had lead you down the path of error. As it has done on a number of occasions. You are good at reading Logs. Stick to that. Your understanding of other subjects is severely lacking. You invent things to justify your understanding like the "Gyro Compass".

I see that you have finally accepted my earlier information on the compass and now respect localised Magnetic Declination and have abandoned the invention "Internal world magnetic map". At least that was a positive outcome of our prior discussion.

I come back here occasional when a subject peaks my interest. I post rarely as you seem to want to pick a fight with me every time I do. I guess I am one of the few that calls it out when you are wrong.

The FC gets a compass heading from the magnetic compass, It also gets readings from the Gyro as degrees movement and it gets readings from the accelerometer as acceleration. It can compare the readings from the IMU and the compass and determine that a discrepancy has occurred. It can not modify anything on the Gyro. Again it's not a Gyro Compass. You need to learn that the Map is not the Territory. By giving something a false name it clouds the reality of what its describing. You give it behaviours that do not exist.

If this is not enough to make you rethink. Then the number of posters here in this thread that have had no issue in flying off or near large metal object as I originally described should give you some pause.

Anyhow enough time wasted here. I have a Twin Turbine SU-35S to finish building.

 

[BJR981S]

I bet the next post contains the rant about confirmation bias.

You would be wrong. Read what I post and make up your own mind.

 

[BJR981S]

Yes, that's the pattern. It's just weird that anyone can continue to misunderstand this topic so badly.

You need to understand something the misunderstanding is on you.

You are well respected here and few with point things out when you are wrong. And you will invent reasons why they are wrong. So you actually bully those that disagree with you.

As they stop doing that and you keep inventing things you get less and less feedback so as no-one is willing to tell you that you are wrong, its self fulfilling, that you believe you are correct.

 

[sar104]

You are a well respected member here iwho is very competent at reading and interpreting Flight Logs. However your understanding of technology and physics and the ability to think logically is lacking.

No - there's nothing wrong with my understanding, or @BudWalker's understanding - just yours. I'm going to reply to this post but only to ensure that the nonsense that you continue to post doesn't confuse others.

This statement is absolute rubbish "Only the yaw axis is indeterminate on startup. And so, just with any gyro compass, that one has to be initialized by a compass reading." All 3 axis are the same when power is applied. Tell me why the Yaw axis is not initialised. The IMU has a 3 axis Gyro and a 3 axis accelerometer. It does not, and never has had a Gyro Compass.

Of course the yaw axis is the indeterminate axis on startup. The IMU knows, in absolute terms from the accelerometers, which direction is down, and so pitch and roll (rotation about the y and x axes) are determined. It doesn't know which direction it is facing, and so the yaw (rotation about the z axis), is unknown. The compass supplies that information and the FC sets it as the yaw - just like when you adjust a real aircraft gyro compass to match heading before takeoff. After initialization the primary source of rotation is the rate gyro package - it is a solid state gyro compass.

Your assumption that is does had lead you down the path of error. As it has done on a number of occasions.

No. Firstly - it's not an assumption - it's how these flight control systems work. Secondly - it hasn't led to any errors - it's essential to interpreting the flight data and that's how I and others here do that.

You are good at reading Logs. Stick to that. Your understanding of other subjects is severely lacking. You invent things to justify your understanding like the "Gyro Compass".

Correct - I understand how to interpret flight logs. That's at least partly because, unlike you, I'm not entirely clueless about this subject. A gyro compass is any device tracks yaw in the earth frame of reference gyroscopically rather than magnetically. You may be imagining some kind of physical spinning device, but it can be done just the same with solid-state rate gyros provided that it has correction for drift - that's provided at low gain by the magnetometers. That's how all these IMU packages work. If you were not terminally lazy you could read the published literature on how these work, as I mentioned before. Then you too might be able to contribute something useful to these forums, rather than cluttering them up with disinformation.

I see that you have finally accepted my earlier information on the compass and now respect localised Magnetic Declination and have abandoned the invention "Internal world magnetic map". At least that was a positive outcome of our prior discussion.

No - that's not what I posted, which was:

"You can see the IMU yaw being initialized by the magnetometer data, and then being corrected by the local declination when the FC gets an GNSS position lock."​

I thought that was about as plainly stated as possible but no - apparently it was still beyond your comprehension. In even simpler terms, that means that the IMU yaw is initially set to the magnetic heading. Then, once the FC has a GNSS position lock, it uses a global magnetic declination model (you know - the ones I've given you links previously to read about but that you ignored) to determine the local declination, which it then subtracts from the IMU yaw to set to true rather than magnetic.

I come back here occasional when a subject peaks my interest. I post rarely as you seem to want to pick a fight with me every time I do. I guess I am one of the few that calls it out when you are wrong.

I find it curious that you think it's fine to wander in and post garbage, but that when I point it out I'm "picking a fight". That's definitely victim mentality. Please just stay away in future because it does bother me that I feel obliged to waste my time rebutting your posts.

The FC gets a compass heading from the magnetic compass, It also gets readings from the Gyro as degrees movement and it gets readings from the accelerometer as acceleration. It can compare the readings from the IMU and the compass and determine that a discrepancy has occurred.

Fascinating. So it's all about the readings. Lots of different readings. I never realized that.

It can not modify anything on the Gyro. Again it's not a Gyro Compass.

By "modify anything on the gyro" - you are not imagining physically rotating it are you? Oh dear - you are, aren't you?

You need to learn that the Map is not the Territory. By giving something a false name it clouds the reality of what its describing. You give it behaviours that do not exist.

The Map is not the Territory. I see. Well no - actually I have no clue what you are wittering on about.

If this is not enough to make you rethink. Then the number of posters here in this thread that have had no issue in flying off or near large metal object as I originally described should give you some pause.

Partial sentences - this is getting worrying. Ferromagnetic objects are a problem if they distort the magnetic field at takeoff or during flight. You would have seen that in the log data for multiple cases posted and discussed on this forum - if you were able to understand the logs (those things I'm good at - remember) or the discussion. Have you ever noticed that no one around here agrees with you? Any idea why that might be?

Anyhow enough time wasted here. I have a Twin Turbine SU-35S to finish building.

Sure you have¡

 

[DSGDSG]

I've taken off from steel barges and small steel decked boats before. Never directly from the deck. I've always used something to launch and land from though. No issues to date.

 

[sar104]

I've taken off from steel barges and small steel decked boats before. Never directly from the deck. I've always used something to launch and land from though. No issues to date.

As always - just check that the indicated yaw on the map agrees with the direction that the aircraft is pointing. If it does then you are good to go.

 

[Ty Barry]

Bit of a long reply but have to get this out somewhere...
I know of a few pilots who fly off steel vessels with no incidents and many flying hours, so today I did. Setup the M2E on a hatch cover, completed pre-flight, confirmed settings and parameters, calibration done, updated home point to controller as vessel is moving etc etc. The whole 9 yards. All boxes checked. Man I'm excited, Chinese crew are excited. This is going to be an awesome flight.
So after about 1min standby confirming no reference drop, link stability check.... It's lift off and depart from possible hazards and obstructions. Smooth air, slight constant breeze, sun is shining. This baby hmm she wants to fly.
So off we go, warm up with a few tracks up and down the length of the vessel, few 1/2 POIs around the bow. Awesome. Do the job, birds eye view of the open hold, amazing IR images and video, having such a nice flight. All done time to come home with 56% battery remaining. I bring the aircraft alongside, slight left bank maintaining vessel speed of 3-4knts, start descending, touch of forward input, baby's got the ball, we going to land now. That's when it all went pear shaped. Beeep beeep beeep beeep. Drone ascends to preset 60m altitude, display box warning of compass and GPS errors, rc link loss warnings, auto RTH, I'm thinking "How if your RTH location is the controller but you not linked anymore". Man everyone stopped breathing. Any spectator could see somethings not going so according to plan. The international single word for the above comes out at an excessive level of decibels. None of that, "keep your eyes on the drone and do not assume that I have control" stuff. All I had was a very angry glitchy screen full of warnings, with minimal intermittent left stick input, yaw and altitude, right stick deader than dead to which it felt like my heart decided to follow suit. In very plain english, I was starting to **** myself! Bear in mind this was not a small signal drop and recovery, it was a complete loss of everything!!
The aircraft, at that range and with our momentum, seemed like it was maintaining a hover, at which point I started legging it to the aftdeck of the vessel. Thinking it's regained its references atleast, I take my first breath that I know of. It dawns on me, the aircraft is only maintaining altitude. I tried everything from switching to atti mode, to resetting the controller, restarting the app, activating/deactivating RTH, praying. It was just getting further and further away. I could feel the nystagmus setting in, eyes flicking between visual on the drone, display screen and by then the red remaining battery percentage. Then came that little voice, "buddy...you're still up for now, but you not making it back today with the remaining battery". My eyes relaxed, as I realized it's over, at which point nausea joined the party. Override auto land 1 2 3, whether it worked to prolong the aircrafts imminent end or not, I don't know, but what I do know, is that a computers "blue screen of death" isn't a patch on the darkness that filled my display.
I can only speculate, but I think that harsh ending was a combination of magnetic interference (steel vessel), close proximity to the vessel radar and other radio systems and possibly other vessels in the high traffic area. What else could cause such a knock off? I will never know cos I'm never doing that again.
RIP Mavey ~ I fought for you till the end!

 

[Meta4]

I can only speculate, but I think that harsh ending was a combination of magnetic interference (steel vessel), close proximity to the vessel radar and other radio systems and possibly other vessels in the high traffic area. What else could cause such a knock off? I will never know cos I'm never doing that again.

Trying to land on the steel deck or hatch cover was asking for trouble.
Catching the drone is what is what you should have done.

What happened in your incident isn't clear from your description.
But the ship's radar and other electronics are unlikely to have been a factor.

If you post your flight data, that will probably go a long way to explaining the incident.

 

[Gringorio]

I agree with Meta4, radar and radio don't really mess with the drone. I both hand launch and catch when moving as well as launching from the deck or steel storage boxes on deck when stationary. In both cases I always get a compass error and magnetic interference warning. With the MP2 and Zoom, I've always ignored it with no issues since it correctly corrects itself after moving away from the ship. Here's a brief thread with links posted by others that may be of interest: Compass error when launching from ship