How not to land on the beach

[cosmorogers]

Went to the beach. Kind of lost orientation. Also for some reason GPS didn';t lock on so loiter didn';t work! 

Lucky the sand was quite soft! You can see it sink in after it ';lands'; which amused me 


Got that sinking feeling





Not too much damage over all, new legs, FPV transmitter aerial, and micro servo for gimbo...



It does raise a question though, what';s the best way to keep your orientation, because as you can see in the video, I am flying the completely the wrong way! 

[Hands0n]

A couple of questions:
Did you allow a full three minutes for the GPS to fully 3D lock on to the satellites and download its essential files?
What FC are you using
I';m presuming you';re flying LOS and not FPV - hence the orientation problem.

Suggestions:
Lights - fit something that you can see from a distance that indicates the front of your aircraft. There are high intensity flashing LED on HobbyKing and EBay that would do the job. Coloured light works better than white in daylight (I found).
Test all your flight modes very local to you to make sure they';re working before pushing out any distance
Get RTL working if you have it available to you - and test it as close as you can before flying distances


I';m sure others will chip in

[cosmorogers]

Did you allow a full three minutes for the GPS to fully 3D lock on to the satellites and download its essential files?

erm I might not have done this, or checked the blue fix light on the gps............ 

What FC are you using

Ardupilot 2.5 with the latest 3.1.2 firmware

I';m presuming you';re flying LOS and not FPV - hence the orientation problem.

Mainly Los, but I do have a FPV monitor on my transmitter, (you can see it briefly towards the end of the video), which I did glance at a couple of times, trouble is all of the beach looked the same!


I do have an LED at the end of each arm, which are different colours, however as I discovered today once it gets more than 10 meters away I can';t see them anymore! I shall try and invest in some ultra bright LEDs to see if they are any better.

I did try loiter closer, and wondered why it headed off south, wasn';t till I got home and looked at the logs that I realised the GPS didn';t get a lock at all!


The Ardupilot does have RTL, I just need to configure my transmitter to be able to use 6 flight modes instead of the 3 I currently have.




Was never my intention to fly that far away, and all in all, completely pilot error I feel, and currently feeling very lucky to have got away with very minimal damage!

Let that be a lesson of the day kids, don';t rush the pre flight check just because you haven';t been able to fly this year yet!  :huh

[FlyingMouse]

Glad to know there's not too much damage, otherwise it's a good video, you can even see the rain falling in the far distance, thanks for posting it.

[cosmorogers]

you can even see the rain falling in the far distance

It wasn';t so far away once I got to the downed craft, got a little wet on the trek back to the car... 




You do get some nice views down on that beach, especially when the tide is out. Its Ynyslas beach in mid Wales for those that might be interested. It';s quite nice as you can drive straight onto the beach, fly around the dunes, or around the shore line. Usually quite quiet at this time of the year.

[philf]

The sand is very soft in the Dovey estuary.....

[Hands0n]

@cosmorogers I feel your pain ::)  No, really, I do.  I jumped the gun with an APM and had a 1130pm fly away, not seen it since!  One learns the hard way I suppose ...

It is amazing how quickly these things get so small in the sky.  If you';re going to do distance and height then you need a set of strategies and settings to help you out.

Here';s a few thoughts having read and watched the video - splendid by the way, thanks for sharing. That hex of yours looks great.

GPS
So, conventional advice and ably demonstrated by Peter King (see him on YouTube) is that you should leave your GPS to lock to your current location. If you allow a full three minutes when first powering up for that session then the GPS will not only acquire all of the satellites it can see but also the Almanac and a couple of other essential files.  These allow the GPS to warm start (not requiring the three minute wait) on subsequent flights in that location.   Some of that also depends on the GPS unit itself - some of the latest units have large non-volatile memories that keep this information for longer than the older types.  Its worth hooking up your Mission planner and observing how long to "cold start" at a new location to get full 3D Lock and then how long to subsequently "warm start" at the same location.

Orientation
Even with lights, at a distance it will be difficult to work out the orientation of the aircraft using LOS.  So one way to find out is to use the Aileron to move the multi-rotor from side to side.  If it doesn';t change position in the sky then it is side on to you - in which case you can use the Pitch stick to move it forward and back which will give you a fair clue which way it is facing (right or left).  If, however, it moves in the opposite direction to your Aileron stick then it is facing you, in which case you can Pitch forward to bring it back.  If it moves in the same direction to your Aileron stick then it is pointing away from you in which cas eyou can Pitch rearwards to bring it back towards you.   Draw this out on a piece of paper and it will make sense.

Strategies
You said that you have an APM flight controller, that is a very powerful device and I reckon that you should make your initial focus to get all of the various flight modes you want/need working before you do much else.  Then go out in the field and practise using these so your muscle memory forms (stops you doing daft stuff when it all goes pear shaped).

At a bare minimum I';d suggest the following:
1) Loiter: Get this set on a switch and test it out working to make sure it does what you want it to.  Loiter is a great panic button as it will pin the aircraft in the sky to give you a bit of time to think it through.
2) Alt Hold: This will help you keep an altitude while correcting mistakes - again giving you a bit of breathing space - particularly useful to gain and altitude to save ploughing into the ground! Altitude is your friend.
3) RTL: Get this working as soon as you can. It 100% depends on GPS and your regime of letting it acquire properly.  And test it out by flying a short distance away and activating it. Put the RTL on a switch all of its own so that you don';t mix it up with other functions.
4)Stabilise+SuperSimple - This mode relies on GPS and it allows you to use the Pitch/Aileron stick to fly around relative to its launch point. So if it flies too far for your to see its orientation you just pull back on the Pitch stick and it will make a beeline directly to your launch point.

Strategies
Develop your strategies and practise them each time you go out until you';re happy with them.  I used to dedicate one of my LiPo to strategy practise at each session. I';d pretend to get into trouble and then use one of the modes to bring it back home. Then fly out and use another mode, and so on to gain confidence and plant the notion in the brain so it recalls when "fight or flight" sets in ::)

What TX are you using? There are some great YouTube videos on how to set up the various transmitters with APM and other FCs to achieve multiple modes.  I have six modes plus RTL set up on my Turnigy 9X and they';re all occupied with functions

HTH

[cosmorogers]

Some good tips there, thanks!

I think I will start to take my laptop ground station with me in future to check it has the correct lock, etc. Trouble is laptop & sand don';t tend to mix in my experience... Might have to get a solid case for it, or just leave it in the car...

Got Alt Hold working nicely (I actually switched out of that towards the end of the flight hence I hit the deck...), so that';s fine. Recently worked out I can do a nice smooth landing with it to!

I';ve had a play with loiter (when the GPS has locked!), I get about a 5 meter diameter drift circle (so it drifts out to the edge then powers back into the middle), is this normal? (I should not I haven';t fiddled with the PIDs, and not had a large windless environment to do the auto setup). Will that improve things?

Not played with RTL yet, but want to after this event!

I like your Strategies idea, seems a good plan. I just need some more LiPos! (only got one 3S 5000mAh at the moment, about 8 mins flight)

I';ve got a Devo 10 TX, which don';t seem as popular as others, but there are a few instructions out there I have found in the past, so I will try and get that setup and tested this week. Then it is just a matter of remembering what switch does what!

[Hands0n]

On my TX I have put a bit of red heatshrink on the switch dedicated to RTL - makes it a bit obvious for me in my panic moments ::)

I';d only suggest using the laptop as a GCS to get settings right.  If you have an Android phone you could use that also with the DroidPlanner app.  You';ll need to get a USB cable to the phone';s microUSB to plug the telemetry adapter in to. I';m assuming you';re using  433MHz telemetry.

With Loiter - was it a windy/breezy day? There is usually some little drift with Loiter, but 5 metres sounds a bit far. So it could just be the Loiter P value is a bit low making it a bit sluggish in response to being blown about.  Something to tweak gently perhaps.  Loiter is a good indicator of how successful RTL is likely to be.  There is a good article on Loiter Tuning here: http://copter.ardupilot.com/wiki/loiter-mode/#Tuning

On that same page it says:

The vehicle circles (aka "toiletbowls").  This is normally caused by a compass problem the most likely being magnetic interference from the power cables under the flight controller.  Running compassmot or purchasing a GPS+compass module normal resolves this.  Other possibilities include bad compass offsets set during the live calibration process or incorrect compass orientation.

If you haven';t done compassmot then you really should - and worth recalibrating the compass (do the compass dance) to make sure it that the compass is spot on.

[cosmorogers]

I assume you have a 2 way and 3 way switch to get the six channels, how does the red heat shrink fit in with that? Or you have have a separate switch just for RTL?

Yeah, don';t have a USB cable at the moment Tempted to build a bluetooth bridge, they seem quite simple, and cheap if you buy the parts (Something like this: http://www.dronetrest.com/t/bluetooth-to-telemetry-bridge/205 )

When I tested the loiter it wasn';t too windy but it was drifting in the same ish direction, rather than circling or toilet-bowling.

I want to try AutoTune (http://copter.ardupilot.com/wiki/autotune/ ) at some point, but the wind needs to die down a bit first!

I';ve done the compass dance  a couple of times, so I don';t think that is the issue

[Hands0n]

I have dedicated three switches on my Turnigy 9x to the cause.

One two-position is all by itself dedicated to RTL.
The three position switch is mixed with a two position switch to give me the six modes. Unfortunately, with how the 9x software works it requires me to sacrifice one RC channel, but thats no biggie as I don';t need all 8 anyway.

So if you';ve done the compass dance have you also done Compassmot?  That is run from Terminal mode and further compensates for any magnetic interference from the motors.  Its worth doing with the APM.

Bluetooth bridge works well at close distance - its handy to save having to keep plugging in the USB.  If I recall correctly, there are one or two things you cannot do from Mission Planner using the telemetry port - I think one is Log file download, but thats no biggie.

[cosmorogers]

Is your dedicated switch using the Channel 7 & 8 options (http://copter.ardupilot.com/wiki/channel-7-and-8-options/ )? Didn';t realise I could do that, will have to investigate further!

With the Devo 10 I';ve got more switches than channels  ::)

Don';t recall doing the Compassmot, I shall investigate further and get that done to. Thanks for pointing that out!

You probably can';t update the firmware without usb either thinking about it.

[Hands0n]

I use a Turnigy 9x at the moment - later I will move across to my Taranis that I';m still learning about.

So, I have my 3-position switch mapped to channel 5.  I then mix in the switch associated with channel 7 to act as a "shift" to gain all six modes from the combination of two switches.  This means I cannot access channel 7 at the wires interface - a worthwhile sacrifice however.

From memory: (left is the 3-pos switch, right is the 2-pos mixed in "shift" switch)
1 0 = Stabilise
1 1 = Stabilise + Super Simple
2 0 = Alt Hold
2 1 = Acro (or whatever I fancy playing around with)
3 0 = Loiter
3 1 = Land

Switch/Channel 8 is RTL all by itself.  I';ll map it to Auto Tune temporarily when required and then back to RTL when done.