I think the issue comes down to the difference between (a) getting a signal from a satellite that's good enough to identify the satellite, but (b) not getting good enough data from the satellite to be able to triangulate a position -- maybe some of the data packetsji sfdgdfsg are asdfasdfg mangled sahysfg fgs bugt you adfasdfad tell Ifasf tryinadfa to commicaasdfg. EDIT: Also, remember it *had* a fix on take-off, but then lost it. So let's image that Joe Schmoe has an arc welder on the ground just below where you were flying and he starts welding something? I'm speculating....but in my experience GPS is a very weak signal coming from a satellite 25,000 miles away...and it's trying to measure the transit time with picosecond accuracy. EDIT: Or perhaps a car or truck came by with an illegal cell phone amplifier? The mindset of "it worked before" doesn't appear to apply when it comes to transit interference sources and GPS. Not my opinion, by the way, just my experience! That's a good idea for Justin to check those GPX files and look for any errors -- certainly before going out to fly again. Andy.
Michael, I was flying by myself.. I turned the MoVI on while in the air and put it in remote operator mode after take off.. The MoVI is on a spektrum DX8 and the copter a Graupner MZ-24. Care free was never setup or activated..
So I looked at the GPSSticks column, and as usual, I had to make an Excel chart to visualize the data. Big numbers hurt my little brain. But first, I made a similar chart of a “nominal” flight I made just today In my flight (which was uneventful, and where I spent a good deal of time in AH/PH, as you did), it resulted in this GPSSticks chart: Nick and roll were working hard at times to compensate for a good wind that was blowing in from the ocean. But as you see, there’s very little rhythmic oscillation in this chart. When I use a similar function for your doomed flight, here’s what I see: The rhythmic oscillations are quite obvious, and it seems something has caused the flight control and/or nav control to swing way farther than it was when it was flying properly in the first part of the flight. What caused this? Not sure, but interference could be the culprit. I still believe that something could have physically broke on the copter, but clearly this data indicates that the GPS system was in bad shape. Now the $64,000 question is...why?
OK, that eliminates a couple other things from the possibility list. Are you getting the audible telemetry data through your MZ-24 - either its speaker of earphones?
Great charts Steve. Hopefully Justin will have a chance to look through or post the 2 prior flights to see if there was any of this acting up in a less obvious way.
I have had a similar event where the copter has lost its marbles, and what I found at the time was that it was a loose connection between the NC and the MK WI232, this sent the copter into violent circling pattern, however when I switched GPS off the copter went back to normal. Now, I hot glue all the ribbon cables on, as per Andy's suggestion when I use them. I don't suppose you had a WI232 or Xbee connected at the time?? Cheers Chris
If you hard yaw left or right it will cause motor restarts. You can reduce this by bumping up the minimum to gas to about 15. Go through your motor connections and just make sure everything is good. I have seen GPS and PH flake out before. It just happens. I know its terrifying but if you can keep your composure just remember to turn PH off and you will fly normally. Are you running 2.06A and the latest Nav software? If not, please do because its very solid. PH is better in 2.06A. Also another good thing to do is make sure all your GPS connections are hot glued.
Justin does not have the new small external compass board do guys think that with that board on board it would have avoided this GPS fix faliure?
Jose It wouldn't help a GPS fix issue because that's more of a function of satellite reception. There are 2 added benefits of the external compass. The first one is that it allows you to be able to install the NAV and GPS boards back over the flight control board. This helps with a better center of gravity and in my opinion is a better cleaner install. The external compass allows you to put the compass far away from all your lipo wires to prevent lipo interference. Lipo interference is the number one issue of weird GPS quirks like toilet bowl. Its also very important to make sure there are no gaps in space on your lipo wires. This includes all the way from the battery tip to the power board.
Hey guys! Wow! Amazing how many responses in such a short period.. Thanks for embarking on this crazy ride of figuring out why!?? Andy, you mentioned the copter lost its “gps fix” where do you see this is this different from the number of satellites? Look guys, we trust GPS to fly 747s, I don’t think an outside source should interfere so severely. We always have a pilot on board to be there incase of a malfunction, but I would say there is something wrong with the technology of this device specifically. This SHOULD NOT HAPPEN. One difference is most jets are flying higher most of the time, but still, they LAND themselves! Also, does the GPS Antenna receive GPS signal from the ground? Why would or should anything from below effect what its getting from the SKY? ALSO- I fly my PHANTOM 2 in this area ALL OF THE TIME and have NEVER EVER EVER had a single problem. Not just here, but Ive never had a problem with the Phantom ANYWHERE! If you guys open the GPX reader and look at the MAP, you will see a definite circle/spiral. Also, if you watch the video again, you can start to see circles almost at the start of the video. Steve! OMG that is a great chart! I think that’s what my heart rate was doing as well! Nice to see it laid out like that.. Can you give me some more info as to what were looking at? Series 1?2?3? +400 – 400? Thank you! Michael, I have the audible on the remote, no ear piece yet.. If you look at the GPX data, you can see exactly when she says something, and it’s not until later in the chaos.. So no help from her. I will post the GPX Files from the previous flights now. Chris! I like the idea of hot gluing or some sort of way to secure the cables! Great idea! Honestly these copters are like flying with an open heart.. NOT too smart…. I did have the X-bee connected, and actually that cable flew off during the crash.. There was no one watching the DATA during the flight though. DAVE, Thanks for clearing up the motor restarts.. I was definitely pushing the sticks quite HARD!! (Surprised they didn’t break) So without a “solve” right now to WHY, I think the best things to do: 1- If this happens to you, you should (if possible) get higher in the sky away from any obstructions, turn off you GPS/Position Hold and fly manual. Most likely unless there is physical damage this should get things less sucky. 2- Hot glue ribbon Cables or secure them some how.. GPX FILES ATTACHED - - - 801 is first flight, 802 is the second.
Justin, It’s a gross oversimplification to say that “we use GPS to fly 747s”. The consumer-grade GPS systems that are in our copters can’t hold a candle to the military-grade GPS systems in commercial aircraft. I’m no expert, but there are numerous systems integrated with GPS in those birds that make for a considerably more reliable system than the little ones we use. There have been numerous well-documented instances of the GPS flaking out in MK copters (and others, of course, too), and not all of them are pilot error. I’ve been concerned for quite some time that self-appointed vigilantes could be determined to “take out” UAVs with a variety of really simple tools, so don’t ignore the possibility that somebody on the ground, after hearing your copter go overhead several times, decided to fire up their little Radio Shack creation (parabolic dish, RF modulator, etc...) and try to knock you out of the air. But maybe that’s all very silly. IMHO your only “error” was not disabling GPS sooner. As for me, despite the obvious attraction to dPH and the ability to fly around with GPS enabled, I only ever use it to hold position in a hover. I don’t like the feeling of how dPH performs, and if I’m moving around, I always turn it off. AH is another matter, as it’s not prone to interference in the same way PH is, so I do sometimes rely on it. An example is a low pass over surfers in the water, as I might be a fair distance away, and want to ensure that I maintain a constant altitude. I would encourage you to think of Position Hold as the same thing as putting a car’s transmission in ‘PARK’. But that’s just my opinion.
Steve, this will derail this conversation, but the fact is the PH is put on this craft to be used in anyway the operator feels is needed. Its supposed to work, period. Some people like using CRUISE control on a car, some don't, its a personal preference.. As far as comparing it to a commercial jetliner, yes, maybe it over simplifying it, but the point is that pilots put passengers lives in the hands of GPS. Yes I'm sure its a million times better, but why put a feature on copter that has such a fatal flaw. EDIT: I live in Florida where we have wind and gusts on a regular basis, and fighting that without PH will be difficult. Back on topic.. Are we sure its GPS?
Another thing.. I hate to keep bringing up the PHANTOM, but they sell about 1000 of them a day from a rumor I heard.. That copter stays in the air with VERY few problems. Yes I'm sure you can google a few things here and there, but there are probably a million of them out there compared to maybe 10,000 CS8/MKs with many documented incidents like this..
Not really derailed at all. Your assertion that this should all be bulletproof is going to result in disaster, IMHO. At some point as these machines mature, I hope that we’ll see commercial-grade, redundant systems. But that is absolutely not the case right now. There are such UAS available, but they are literally 10x the cost of a Cinestar (or more), and for good reason. If anybody told you otherwise, I’m sorry to say you were misled. But back to the task at hand, to answer your question, what is pretty clear from the data is that the GPS was steering the copter, and was doing a very poor job of it. The thing that isn’t clear is why that was the case. Have you made any changes to the GPS gain in the MK Tools? I do see something that’s interesting, and that’s that once the copter started meandering, it was experiencing some very severe angles. Depending on how your copter is configured, it’s possible that pitching the nose down at a severe angle (which was clearly happening in the video as boom 1 came into camera view repeatedly) could cause the GPS antenna to become partially obstructed by the LiPos and/or their wires (or something else), causing it to momentarily fritz out and overcorrect. I could see how this could result in the kind of oscillation you experienced. In other words, what could have changed from your previous flights to this one (and from early in the same flight) is that the wind or something could have picked up to the point where the copter was operationally compromised. All this is conjecture on my part, but is based on my own experience. For example, I have placed my own GPS antenna at the top center of my copter (as Holger does on his MK builds), as I believe that the boom 1 placement can have issues like what you saw.
Hi All, My $0.02: On line 26 it throws out a Speak low voltage error when the voltage is above the 22 mark (23.6). I'm leaning towards a ribbon cable gradually coming loose/intermittent to start the ball rolling downhill. Typically a loss of connection results in a "Navi board error", but I have experienced this after aggressive flying and the wind speed blowing the cable completely off the pins while flying in manual mode. You can pinch a couple of the pins outward to make the connection snug, but each preflight should be ribbon cable snug and secure if you plan on using GPS. Side note - don't you love GPX files Back in the day you would have a glitch and all you could do is shrug your shoulders and say WTF??? Cheers, Jeff
Andy (and others), I’ve attached the actual Excel document that I used to create this graph. Would like to hear whether you have any comments or refinements.
Justin I understand your point but you need to know how to fly the copter if the auto functions don't work. This is not a commercial grade GPS system. This is a consumer grade at best GPS system. To my knowledge none of the leading copter electronic manufacturers offer commercial grade GPS yet. You can't rely on it working because if it doesn't you have to know how to fly and what to do in case it fails. If GPS reception goes bad you need to know what to do and know when you shouldn't even try to use it. I'm sure MK will upgrade GPS as technology becomes better but its no where near where it really needs to be. Even in jet liners things happen. Look at the state of the art technology that went into the 777. Not only did it not prevent Flight 370 from going off course, they have no idea why it happened and can't find the plane. When I fly I try to fly with minimal technology needed and not to rely on Position hold. When I film golf courses there's holes that have the T box completely covered by trees and I need to fly manually. Or if I have to fly indoors there's no possible way to use GPS. Just my 2 cents to derail the thread even more.