Hi All,

I am using my M210 to monitor shore lines for significant distances (several kilometres at a time).  To do so the RPA is deployed from a boat which acts as a mobile base station, transitting along the shoreline in tandem with the RPA so that when the batteries get low it is a short flight to the nearby boat for landing and battery replacement, before launching again and resuming monitoring.  When conditions are calm and the water is flat, this is no problem, the RPA is able to be restarted easily and the IMU initialises quickly to recommence flying.  However, this is not always the case, and if there is significant wind or swell the resultant waves cause the boat to move such that I have experienced significant issues with the IMU initialisation during restart after swapping batteries (i.e. not able to restart the RPA).  I was wondering if anyone had some advice as to how to overcome this issue or if there is a way to adjust the IMU initialisation "thresholds" to permit the restart of the RPA whilst experiencing some movement without compromising flight accuracy?  Or am I restricted to only being able to operate on calm days?  

Additional points:

• Landing on shore and swapping batteries and restarting from the land is not always an option.
• I am flying using TB50 batteries, which provide approx 15 min flight time, so landing on shore, getting off the boat, swapping batteries and then getting back on the boat etc. represents a significant amount of time taken out of the batteries that could be spent flying and covering more area.
• I have tried pointing the boat into the waves to minimise rocking etc., but this didn't help (wind speed approx 25 knots, waves were about 30cm high).  Perhaps slowly motoring into the waves to try and minimise the movement of the boat?
• I don't like the idea of "hot swapping" the batteries without turning the RPA off due to associated issues around voltage imbalances between batteries - ultimately leading to RPA falling out of the sky!
  

Any help or suggestions much appreciated.  Cheers.

What do think about gyro stabilzed platforms to initalize the aircraft and launching from it?
I don't know if this 2 axis (pan/tilt) product will help, but look at this link

Firstly, what RPA stands for? Secondly, I think you're asking for too much. The sole purpose of IMU system is to provide data for flight controller about the state of aircraft, and boats on rough water provide very troubled platform. Did I landed, can I put the motors on iddle? Not really, I'm still moving up and down. I'm confused ... Risky, definitely not recommended.

Keule Posted at 2018-5-14 00:42
What do think about gyro stabilzed platforms to initalize the aircraft and launching from it?
I don't know if this 2 axis (pan/tilt) product will help, but look at this link

Hi Keule,

Thanks for that, didn't know about these.  Not sure if it will compensate for the amount of movement of the boat, but I'll have a look into it.  Cheers.

Matthew Dobrski Posted at 2018-5-14 00:51
Firstly, what RPA stands for? Secondly, I think you're asking for too much. The sole purpose of IMU system is to provide data for flight controller about the state of aircraft, and boats on rough water provide very troubled platform. Did I landed, can I put the motors on iddle? Not really, I'm still moving up and down. I'm confused ... Risky, definitely not recommended.

Hi Matthew,

My apologies, RPA = Remotely Piloted Aircraft, it's the official name for drones in Australia.  My gut feeling is very similar to yours, that I'm asking too much, but thought it worth asking the forum for ideas.  Ideal weather conditions rarely align with opportunities to fly or scheduled flight times.  Thanks for the feedback.  Cheers.

FeralFlyer Posted at 2018-5-14 00:55
Hi Keule,

Thanks for that, didn't know about these.  Not sure if it will compensate for the amount of movement of the boat, but I'll have a look into it.  Cheers.

Let me know if you found something that will work for you!

Bye,
//K

Get a keel boat.

Where in the boat do you launch from? Most boats have the least amount of movement and slamming at the stern.

We are also running into this issue when operating our M210 from boats, and may look into a gyro-stabilized platform as recommended above.  We have found that our Inspire 1 V2 has no problems in the same conditions, perhaps less sensitive IMU.   I'm also wondering if there is a way to get into some advanced settings or modes that would help this issue.  

mikeLmedic04 Posted at 2018-10-17 13:25
Where in the boat do you launch from? Most boats have the least amount of movement and slamming at the stern.

Hi Mike and Gifro,

We launch from the stern of the boat, and try to use as large a boat as possible to improve stability etc.  Forward motion or drift of the boat does not seem to be an issue for the initialisation of the IMU.  I've had the IMU initialise no problems even when the boat was still moving forward (albeit slowly), so long as the water surface was calm and there was no rocking or rolling of the boat.  It seems that the physical disturbance of the gyroscopes is of most importance for initialising the IMU rather than being geospatially still.  Recently we've had good success with the IMU initialising on the boat; however, we were operating in ideal conditions (almost no wind, no swell and glass off conditions on the water).  At this stage, if the conditions are predicted to be rough and windy, I don't bother.  My only other fall back  in rough conditions would be to try and initialise the IMU whilst holding the RPA and act as my own version of a "gyro-stabilised platform".  However, i haven't tried this and am not sure how successful it would be.  Cheers.

FeralFlyer Posted at 2018-10-18 00:14
Hi Mike and Gifro,

We launch from the stern of the boat, and try to use as large a boat as possible to improve stability etc.  Forward motion or drift of the boat does not seem to be an issue for the initialisation of the IMU.  I've had the IMU initialise no problems even when the boat was still moving forward (albeit slowly), so long as the water surface was calm and there was no rocking or rolling of the boat.  It seems that the physical disturbance of the gyroscopes is of most importance for initialising the IMU rather than being geospatially still.  Recently we've had good success with the IMU initialising on the boat; however, we were operating in ideal conditions (almost no wind, no swell and glass off conditions on the water).  At this stage, if the conditions are predicted to be rough and windy, I don't bother.  My only other fall back  in rough conditions would be to try and initialise the IMU whilst holding the RPA and act as my own version of a "gyro-stabilised platform".  However, i haven't tried this and am not sure how successful it would be.  Cheers.

Thanks for the feedback.  If the IMU requires recalibration once, then it's a tough cycle because recalibrating in those conditions are tough when there's no access to shore.  Our experience seems consistent with what you are saying ... geospatial position not a big deal, but gyro action is indeed.

Hello all -- Did you try hand holding for 'stabilization' or have any of the mitigations worked consistly?  I need to do a mission in a couple weeks and are trying to determine if the M210 will work off a boat in the open seas.  Thank you, Steven