Back in early January I was tasked with the duty of delivering my recently quadrupley bypassed father to my aunty's house down on the south coast of New South Wales for some much needed rest and relaxation. As it happens, the quiet sleepy town of Moruya, in which my aunty resides, is also home to Hobby King's Australia based warehouse. Not being one to pass on an opportunity to double task efficiency, I decided after depositing my father into my aunt's capable hands that I might as well make use of the ample cargo space offered by my humble little hatchback. So I dropped in to grace to the good people at HK Aus with some good old first person custom.
To cut a long tangent short, this is what I brought home with me:
The 1500x300x400mm shipping box of the UAV-3000 was a tight fit, but no problem for the jack of all trades GTi.
Anyway, while I was there in the showroom, I noticed a few warranty return/clearance items on the bench at heavily discounted rates. Among these items was a folding multirotor platform. The IdealFly IFLY-4, with which a former customer had apparently had little success, appeared to be a nice and entirely complete airframe which simply needed a new FC. Keen for a new build, I swapping it for a single John Flynn, bid the HK team a good day and headed north.
Once at home I did a bit of research on the IFLY-4 and was surprised to find out that, due to the fact the IFLY-4 ESCs communicate via I2C, I would need to replace these as well as the FC. So, I set about ordering the following items:
* APM
* GPS/MAG
* Afro Slim ESCs
* I also ordered a motor to replace one with a bit of play in it.
When these items finally arrived last week I set about assembling my new craft along with a few extra items from the parts bin including camera, RCRX, power meter, BEC, cables, fasteners, and batteries.
Introducing the IdeaFly IFLY-4 Reloaded - APM Edition.
You know how with some builds nothing seems to go right? When holes don't line up, you can't seem to find the right sized fasteners, you are forced to think and rethink, mount and remount, route and reroute and repeatedly forced to retrieve tools that are out of immediate reach? Well this build was nothing like that. It just seemed to come together beautifully.
I had originally modified the factory distribution board with the intention to recycle it for it's former purpose however, after damaging some of the PCB traces I realised it really didn't have the current carrying capacity I would like, so I just used it as a mounting platform for the APM, which was attached using soft double sided adhesive foam, choosing instead to deal with power distribution at the Power Module.
I was really pleased with my work on the Power Module. It is very very strong (much stronger than I expected, and it has been tested with great force), super compact, neat and convenient for maintenance. A Turnigy 3A BEC powers all 5VDC needs with the exception of the camera, which is left to rely on it's own on board battery (no chance of nasty noise entering camera).
Amazingly, after removing the factory I2C ESCs, I found that the Afros slotted very neatly in to the arms. Having read about others having issues with Simon K ESCs and AutoTune, I was a little worried about having problems with the Afro Slims, but I simply had to persevere due to their convenient size, affordable price and strong performance credentials. I am not exactly using them in a low kv pancake applcation either, so the "she's be right, mate" attitude prevailed. Just a dab of hot glue was required to firmly hold them in place. I was worried about using hot glue on such a heat generating component, but they don't seem to warm up much at all, as the chipset is 30A rated and they are running at less than 50% duty at max.
The GPS/Mag was purchased on ebay for about $18. It is mounted on a re-purposed FPV camera bracket which I flattened and fastened to the front of the frame using hard double sided adhesive foam and two zip ties giving a solid but nicely dampened mount for the GPS/Mag. Mounting holes were a perfect match, and I had all the right nylon M2.5 fasteners and spacers in the tool box to suit. TIP - Invest in an assortment of M2.5 and M4 nylon and SS fasteners, as it will save you so much build time.
A 433Mhz Telemetry Radio from RCTimer is mounted on a short 2-inch boom at the back of the centreplate in the same way outlined above, but with two M2.5 bolts added to ensure it remains firm and alignment stays true.
For battery duties I decided to use the 3S 2200mAh Turnigy, of which I have several. It is about 25mm too short to span the top centreplate and corresponding anchor points, so I fabricated a hold down plate to solve the problem. Keeping weight to an absolute minimum, the hold down bracket is made from Balsa wood, painted black with a texta and enclosed in clear heatshrink. The bracket is plenty strong and weight is less than 10 grams.
At this point, I had the basic hardware sorted and moved onto setting up the firmware and configuring all relevant settings in Mission Planner. This is not my first APM setup, so navigation was pretty straight forward. I did use Mission Planner instead of APMPlanner2 due to familiarity though, and I did go through some fiddling getting the right hex and character set for MinimOSD Extra (hence why I didn't tune better position for the telemetry info in the 4:3 frame - I just wanted to move on once it was working effectively). I was also surprised to learn that the only firmware setting on the Afro Slims able to be set by the user without the USB programming tool is the max and min throttle points. With the USB programming tool riced at just $6.65 this would seem an easy up sell if only mentioned in the ad.
Ready to fly, I grabbed my Nexus 7 ground station and a battery and headed out to the backyard to burn through a charge on the standard settings. As usual, the APM's default PIDs worked fine out of the box. Super pleased with myself, I headed back inside and proceeded to invest several hours sanding the props into perfect equilibrium.
Next I wanted to try AutoTune for the first time, having witnessed Ian Lions perform this operation with his TBS disco earlier this year. So I grabbed another battery and headed for the park. Ardupilot performed it's dance with effortless finesse, delivering an exciting but otherwise unremarkable result on the first attempt (only ~800mAh consumed). The improvement in flight performance was immediately recognisable and I was just overwhelmed by how precisely it could be maneuvered and positioned. What a fantastic afternoon!
That evening I headed home and began adding the requisite parts to enable FPV and aerial video capture.
For imaging duties, I chose the little Mobius Action Cam. It is a great little camera, offering 4/5ths of a gopros performance and convenience at just 1/5th of the price. Plus, it is a significant upgrade on the #26 808 I was using previously. The file format it generates is much easier to work with too, as it imports into iMovie for iPad/iPhone for fast easy editing and convenient upload to youtube.
For mechanical isolation I created two small plates from balsa wood roughly the size of two moon gel rectangles placed side by side. The top plate was cut to tightly tessellate with the exposed bolts on the underside of the GPS mount and the bottom plate was left flat. The two balsa plates were sanded and coloured with texta, moongel was placed between these two layers and the sandwich loosely wrapped in cling wrap. This gave a really nice surface to mount against and the whole thing is held in place by a relatively loose fitting velcro strap with an extra piece of moongel added below the camera for good measure. The results offered by this isolation method have proved very pleasing. First Person View of telemetry overlayed video is transmitted back to my DIY Ground Station via a DIY 5.8Ghz VTX.
The next day I jumped in the car and headed up to my sister's place in the mountains in order to give the newly updated rig a run. The whether was overcast, but relatively mild. I ran down two batteries and got some nice test shots. Unfortunately, I also lost the canopy during a particularly fast decent. The great news is that I was traveling backwards at a rate of knots when it fell so I was able to capture the descent of the canopy via the onboard camera. Using the below images the canopy was found the next day.
Smitten with my new craft, the next morning I set out at sparrow's fart for more flights. Overly eager, I was up and ready too early and cursing Siri for making me wait.
30 minutes before sun up I was parked down at Old Government House in UNESCO world heritage listed Parramatta Park. The second I saw the first few photons shoot in my direction I was away. I was starting to gain real confidence in the reliability of the craft at this point. All features and functions, like loiter precision, just spot on.
Reviewing the video from these early morning flights exposed the low light and exposure balancing limitations of the little Mobius. But there are only so many photons a tiny lens and sensor can collect in 33.3-millisecond.
I continued with more flights, moving from place to place. I drove between locations and carted my little integrated ground station so to record both telemetry (via DroidPlanner) and live video stream (via SD DVR installed into DIY ground station).
By mid morning I had been to several locations and had put about half a dozen charges through the craft.
I went home to download and review the media from the Mobius. Most flights were conducted twice, once recording 1080HD@30fps and then again recording stills at 250-millisecond intervals. It seems logical I should have realised this earlier, but the Mobius is not able to deliver live video out while simultaneously capturing and recording 3MP images 4 times a second. Mobius prioritises live output over still image capture, so I didn't pick up on this issue until getting home. Sadly, all the airtime spent capturing stills gave just gave me hundreds of images like this (the panoramas above were recovered from these corrupt files):
Then I set out again, revisiting many of the locations I had shot at earlier in the day. After getting another half a dozen or so more flights under my belt, I returned home at about noon. I put the Mobius and the installed 2200mAh Lipo on charge and grabbed a quick bite to eat for lunch. Before downloading the media from my second morning outing, and (for the first time in 2 days) without bothering to link DroidPlanner and operate the flight recorder in my ground station, I set out into the backyard to get a nice panorama of nearby Lake Parramatta and the surrounding woodland.
While performing the same pirouette maneuver (at about ~40-metres AGL), just as I had done so many time before, I noticed the craft drift noticeably beyond previously experienced limits. I immediately aborted the maneuver, and attempted to recover but failed.
What happened next is not entirely clear. I think I switched to stabilise mode, but this did not help. I then went for loiter mode, but the craft continued moving away from me at an accelerated rate. So I think I went for loiter again, but that didn't arrest the craft either. Next I remembered that RTL was associated with channel 8 so I flicked that, but this didn't help. I then remembered the the RTL failsafe I had set in the event of loss of RCTX link so I switched the transmitter off in the hope this would return it to me. Unfortunately the craft was ~300-metres away from me by this time, and it was not coming back.
In a state of fright, I jumped in the car and scanned the streets for about an hour. Nothing. It was gone. What the hell did I just do I wondered? How could the craft be so predictable and so obedient, just to go and do it's own thing all of a sudden?
Upon reflection I realised that my perception of what happened and what I was doing was probably not as accurate as I would have liked it to be.
First of all, how sure was I that I was pirouetting in loiter? Could I have been in alt hold instead? That would have explained why the craft went off alignment. I am really not sure about this, but my assumption is to blame myself and not the hardware. Also, were the mode commands I sent the craft following loss of control correct? Probably not, no, not at all actually. My channel 8 switch which has always previously been used for RTL failsafe was, at the time of the incident, still associated with AutoTune. So, when I flicked the channel 8 switch (the moment it went out of sight) I had shot myself in the foot. Next, turning off the controller would have been a good idea, but only if I had returned FTL to channel 8. In actual fact, by turning off the RCTX I had totally doomed the craft. Air Craft Investigation seems to reveal that I am completely to blame.
Ashamed, embarrassed and disappointed, not knowing what else to do and having no idea where my craft had ended up, I headed down to my local area command to file an incident report.
What a weekend!
Comments
mP1 - Thanks mate.
I am not convinced my VTX is an issue for my RCRX. The sea of 2.4Ghz wifi networks in my immediate area is another thing though. I base this on the fact that a little while back I did a quick hack job on a little 250mm mini. The configuration had a V8R4-II (with tiny 1-inch antenna) buried in a carbon fibre frame. It's range was terrible here at home, but great up in the radio pollution free air up above the Colo River.
Yeah, tree and even just leaves are an issue for the higher frequencies, but I am not yet doing anything beyond line of sight. Nor have I attempted FPV navigation. I am still earning my wings (or should I say my rotors). I plan to move down to 433Mhz IRC RCTX/RX, as well as invest in some serious FPV gear from Video Aerial Systems, before doing anything BLOS. Needless to say though, none of this has anything to do with my lack of talent.
The reason that the Telemetry info was not positioned optimally was touched on above. This is the screen I normally use, which makes much better use of the available area. I also have second screen option on channel 6 which drops out the horizon and other obstructing datapoints, for when a clear view is required.
Craig - I read about that. You may well be right. When she asked me the question I felt it necessary to disclose the fact that, while I was simply doing basic panoramas of the heritage rich government lands of Parramatta and North Parramatta (Parramatta Park, Cumberland Hospital, Norma Parker Centre, Wisteria Gardens, Parramatta Gaol), I had technically flown above land currently administered by the Department of Corrections (Norma Parker Centre and land adjacent to Parramatta Gaol). I was quick to add that both these sites have been decommissioned, and that I had cleared my flight with the security staff on site.
The Norma Parker Centre was my take off location for the first panorama in the set above. You can just make out the burnt remains of the Old Industrial School for Girls on the right hand side of this shot. You can also see Paramatta Gaol on the left side of the third panorama down, which was shot above the playing fields behind the Gaol (which is administered by the Western Area Health Service).
I posted a video with info about this little known place a while back. If period architecture, big old trees and a bit of history is your thing, then it might be worth a look.
Oliver - I guess each frequency combo has it's strengths and weaknesses. This setup has served me well so far, but I have not expected to much from it either (still very much LOS).
My mode switch setup was pretty failsafe - (3-way + 2-way with POS 1-STAB 2-LOIT 3-ALTHOLD 4-STAB 5-DRIFT 6-RTL). All down = STAB. All up = RTL. Very simple, it was me that failed. As you say, I lack practice and need to know my gear better. It sucks to loose a craft but hey, at least you know where yours ended up. I hate not knowing the fate of mine!
Leonard - All great advice. Reading your list of points, it is clearly evident that I need to spend more time pre-flight. As well as practice evasive manuveures (like your stabilise+full throttle option - I would need plenty of practice for that to become my natural reaction).
Through fear of an unscheduled RTL event (something that caught me off gaurd previously), I chose not to set a perimeter initially. Stupid. This is another example of where I hamstrung the APMs ability to help itself in these types of situations. It I had set a wall for it to hit, it probably would have been able to bring itself back (notwithstanding the fact that I ran out of talent at the critical moment, and did all the wrong things).
Euan - Yeah, the time and effort is the killer. Like penning a great story, then loosing it to a freeze, crash or error... I find it hard to do things over, as it is never as enjoyable the second time. I did do some very simple (basic hovering) maidens, with tlogs from the first 2 flights following AutoTune downloaded via APMPlanner2. VIB and MAG were well within allowable limits, and she could loiter on a needlepoint (as you can see in the vid above).
DroidPlanner was connected for all but the last flight, so I assume that I can pull some more detailed data from any logs it stores. I will be looking into that shortly.
Doug - My contact details and a reward note, as described by Michael, will be an essential inclusion on all future craft. Regarding switch settings. I had a pretty simple setup, just ran out of talent really.Ground Station was not connected during my last flight. After the fact, I did think about grabbing the Nexus 7 Ground Station and driving around looking for a connection, but by the time this thought occurred to me hours had passed.
Joe - That's what I was thinkin'.
@leonardthall - i like the tips, but for #6, did you mean 'loiter'? I feel like zero/full throttle in stabilize is a... bad idea
Three things comes to mind on this incident.
1. Might be a good idea to put your contact information on the copter in case a honest soul finds it and decides to return it to you.
2. Too many options programmed into copter/radio makes it very easy to make these mistakes. Suggest dumbing down flight modes and set fail safes. I know I've gotten myself into plenty of trouble by panicking and selecting the wrong switch.
3. Industry show make a radio beacon type device that can be detected by any number of means to locate downed aircraft from a nominal distance from aircraft.
Lastly, Maybe a good idea to use your tablet to map aircrafts position at time signal was lost and then track down range from that position.
Sorry for your loss and I hope you will be able to locate it.
Damn, that's gutting. Especially after all the time and effort! I find that's what hurts more than the cash.
Did you do any maiden testing? Looking for vibes, compass interference etc. I always like to do a very simple shakedown flight and log analysis before getting adventurous.
Hi mate,
Heart breaking story!!!
If you are in Adelaide let me know and I will buy you a beer!!!
I have had a similar loss of a copter with a very similar setup. I watched it float away on the wind in AltHold. I have since implemented a few changes. At this time I had RTL on channel 7 and switched to it in the case of reciever failsafe. Problem is when you get two mode changes, one on the mode switch and another on ch7, the last one is the one that happens. In my case, the ch7 was slightly earlier than the mode switch leaving me in Alt Hold.
So since then I:
1. Implemented low throttle failsafe and make sure it is working before my first flight.
2. Went to 2.4 GHz (I was on 36 MHz and dammaged my RX antenna on a landing reducing my range to 10m)
3. Always have my fence enabled and set to about 500m or 100m outside the distance I intend to fly.
4. I have RTL always set on my channel 7 switch and Stabilise is always achieved by pushing another stick up making the two very easy to access without any mistake.
5. My normal take off procedure is to take off and switch to loiter, I then move away 10 m and switch RTL. Only then do I fly the rest of the battery out.
6. My "Oh Crap" reaction is always to switch to Stabilize and apply full throttle (or zero throttle) with zero roll, pitch, yaw input. I then work the problem from a safe height or it is obvious the copter has entered an automatic mode.
7. I always do a quick cell check before I plug the battery in every time.
8. If flying in any sort of stressful on unusual situation I make sure I have telemetry running so I have a backup control method.
9. At least once on every outing I practise my manual recovering in stabilise from a distance. Basicly it I switch to stabilise and push the stick forward and apply left yaw. If the copter goes left I know it is moving away from me and I continue the turn until I can't see it move left any more. I then stop the yaw knowing it is coming back to me. If it goes right I know it is already coming towards me and I react accordingly. Using this technique I have flown the copter back manually from 300m in the middle of the night with only the status led visible on the copter.
Hope that helps you in some small way.
Again very sorry to see you lose such a nice build!!! And I have got to say I admire your level headed reaction!!!!
@Oliver
My only dislike for 5.8 is its limited range with a basic setup and troubles penetrating trees. I am relatively familiar with the Parramatta area where Quadzi was flying and theres certainly a lot of trees with lots of leaves in some areas. Im just suggesting that possibly these got in the way when it disappeared and did its own thing.
I prefer lower frequencies they give you more range and penetration thru objects. 5.8 only does well in very open spaces.
Do you have any specific reason for the that 2.4 - 5.8 suspicion? I am under the impression that this is one of the better combinations...
@ Quazi
Sorry for your loss, been there, about three years ago crashed a Multiplex Merlin w.Ruby FC into the Pacific due to switch/mode confusion. Ever since, I preflight my Tx as well as the aircraft and think about and run through the modes before powering up. I especially make a point of practicing switching into stabilize instantly, without looking at the Tx, from any other configuration (being that I am comfortable flying manually). It's saved me more than once.
@Quazi
Sorry to hijack this thread, but why do you place the osd overlay on the bottom. Your blocking the view of the ground which is more vital than the clear sky. I m also wondering why you dont place the distance from home, horiz & vertical speed and possibly rssi ?
I personally put most of my osd data along the top and at 9 and 3 oclock.
Quazi, they might have asked you about footage in regards to the Dept of Corrections due to the recent busting of a quadflyer trying to deliver drugs into a prison. And that any aerial footage of prisons might be useful for some escape artists. Nice writeup about your experience, thanks for sharing.
@Quadzimodo
Sorry for your loss, but i think 2.4 & 5.8 are asking for trouble. Go for UHF for the tx & 1.3 for vid. A few trees like those around Parra will result in tx loss and panics which cause you to hit the wrong button.
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