Friday, June 28, 2013

Quadcopter crash due to esc failure

On Jun 27, 2013 me and "Paul the toy man" went to fly his steel tube quad at Pattaya beach but we had a problem in the first flight with Paul's quad just falling out of the sky after just a few seconds in the air as seen in this video bellow: When we took it back to the lab, this is what we found as I video'ed each prop channel controlled individually from my turnigy 9x reciever and tx. Here is the video of each channels performance in a video: This video above shows tests in the lab of how we isolated down to the channel #4 esc failure. What I didn't notice when I was making the video is that channel #1 was also much faster than all the other channels on the quad, even compared to the channel of the esc we just replaced that was still the same as the 3 other channels. This channel #1 is one that we had replaced the motor on a few days ago due to the motor windings being burned out. So I'm not sure if the problem is the kv of this motor being different than the others or maybe the esc just needs to be calibrated. I was later informed by Paul that this motor was the same spec as what was originaly on the quad. So I'm going to try recalibrate at least that channel #1 esc and see what it does. I can't find any info or procedure of how esc's are normally calibrated with a naza-m system. So I hope someone can provide me feedback of some ideas of what we might try next. When a solution is found, I will post an update to this post of what was done to correct it. The videos above were taken with a gopro hero 1 running in mode R3 for 720p 60 fps in the crash video and R2 in the lab video with the new C10 8gb transcend card that we had hoped to test that day. Update Jun 30, 2013 10:04am: I found a link with a video that shows a simple procedure used to calibrate esc when using naza. It basically uses a 4 to 1 server combiner cable to calibrate all the 4 motor esc at the same time by pluging them all at the same time directly into the receiver throttle output. I don't have this cable so I will try just calibrate each esc one at a time from the receiver used on the aircraft throttle channel #1. I later redid the calibration using the spectrum DX7 radio and receiver set. here's the video that I used for my reference: http://vimeo.com/62973278 Update July 1, 2013 6:19pm after trying every different setting in both the rc transmitter and in the naza assistant software I finally got the steel tube quadcopter to spin up again. It was stuck at the 4 yellow blinking light warm up mode ever since I did the firmware upgrade to v3.12 that I thought I had to do to get the software assistant to run at all. after tons of research I found a way to regress the firmware to the older firmware of V3.00 that ended up being what finally got it working by doing this: Phantom or NAZA Firmware Downgrade - if needed Here are the instructions to downgrade back to the original firmware... 1. Start the NAZA Assistant, go to Upgrade 2. Click on the blue text (No updates) next to Firmware e.g. 3.1 in the assistant under info. A pop-up box will appear. 3. Type the word 'door' there is no need to put your cursor anywhere, just type that word and another box will pop up. 4. Type 'test' for the user name and '125' for the password. 5. Follow the remaining instructions to 'upgrade' (in fact it's a downgrade) and the NAZA will be reverted. 6. After the progress bar is done, power cycle the Phantom. 7. Do a software compass re-calibration and when done, follow this by a manual compass calibration That I found at this link http://www.djiguys.com/Forum/viewtopic.php?f=4&t=561 after I got the version 3.00 installed I was again able to do CSC and get the motors to spin up again. That took me all day just to figure this out. So now it's ready for an outdoor field test. Wish us luck. I also made a few other changes to the "GPS quad" including: added IOC Intelligent Orientation Control enabled using gear switch with up standard flight gear switch down for homelock mode as discribed in this video: http://www.youtube.com/watch?v=-CxB3CgpboQ This change was made by moving the Aux1 channel (the gear switch) from the receiver from the naza X1 connector that does something to the gimble that we have no use for since we have no gimble, and moved it to the naza X2 connector that activates the IOC modes. This can also be disabled again with a simple switch in the naza assistant software or can also be disabled on the transmitter side if desired. I also played with the gain settings to make it more standard values as it was cranked way up to 200% for some expert pilot (that I am not). It's now set to mostly 150% the standard center start values as seen in the quick start manual for an F450 airframe. F450 DJI-2212 DJI-30A DJI-8 Inch 3S-2200 890 g 150 150 100 105 150 150 I also made some changes in the transmitter settings mostly in the throttle throw that will probably do nothing since the change was calibrated out when I did the transmitter calibration in the naza assistant. I wish I didn't do so many changes or at least I wish I had documented them as I did it since I might have done more that I forgot by the time I wrote this. Update July 2, 2013: We did a test flight today after the rework above performed. First attempted power up it failed to spin up. After a power reset we got all the props spinning. Paul gave it a try this time and was able to take off with no problem. It appeared to hover OK with no oscillation seen. he started giving very small control input pulses for forward, reverse left then right. Each input was causing normal changes in flight in the aircraft until he hit the small right maneuver. Suddenly the aircraft flipped 180 degrees and dove into the ground (lucky was soft sand). I did a quick power off and reset and did a ground test and found that channel #4 rotor was not spinning but vibrating with a jitter. All the other props were spinning normal in the standby flight mode. I powered it all down and took it to the lab for testing. At the lab it displayed the same problem as seen in the field with channel #4 just jitter and not spin. This is the same channel that we just replaced the esc on. I removed and reconnected the esc to the motor and tested it again. Now it spins up OK again. I did a full system ground test and all seems to work now. ready for flight test but I'm not totally sure this is what caused the crash. So next flight test will try to keep altitude as low as possible for a full battery to see if it will repeat the problem seen. The problem That I found may have been caused after the crash that would of put excessive current on the motor contact from the blades of the motor not being unable to spin. The reconnection would have cleaned the arced carbonized resistive path on one channel causing it to jitter. I hope this is not the case and that it does fly OK now. I also published the original contents of the exported naza parameter file before I ever made any changes to it that can be found at http://freenet.surething.biz/docs/other/dji_naza/tube_quad.nazam . Too bad I didn't also backup what is presently in the gps quad. I'll try to remember to do that next time I have the gps quad here. Paul has now taken the GPS Quad to Nicks quad lab to take a quick peak at it today. I think if the original exported file above is to be put back into the GPS quad that at least the Naza TX calibration will have to be done since the range of motion in the Spectrum DX7 TX for the gps quad setting were also changed after the export was done. Update July 3, 2013 5:36pm: Good news came back from Nick's lab today about the GPS Quad. They were able to give it a test flight and it didn't crash. Nick also looked at the gain values I had put in and said they were a bit ruff but workable. They did note in the flight test that the gps quad would drift to one side then stop. Paul was told by Nick that it maybe a propeller thing and suggested to try replace the props first. Also the props weren't a matched set with one green prop that was a slightly different design. So I have now replaced the green prop to have a full set of matched props to try another flight test some time soon. To me hearing that it at least flew without crashing within a few seconds sounds like a big plus. So sounds like we are now back on track.