ESC and/or Motor set failure and troubleshooting - Quanum Nova

As I mentioned in my previous post ... it took two Nova's and 2 years of flights, but it appears I have finally experienced my first (stock) ESC or Motor failure. The post will update as I fumble-through the troubleshooting for the first time :-)

Here are the symptoms the Quanum Nova is displaying with a failed ESC or motor:

• On power-up, the Nova's power-up sequence of Motor & ESC twitching/ beeping is different and abnormal. It lasts a few seconds longer than normal, but finally stops.
    
• It still allows you to Arm the aircraft. If you remember to bump the throttle on/off a few times (to make sure all props/motors spin on command) you will likely find one prop not responding properly. If you forget to test and attempt to take-off anyway, the multi-rotor will likely flip and crash.

So I start with the trouble-shooting. The is the newer Nova with the stock v1.6 ESCs. The bad esc/motor set is the Green-LED back-left (aft-port) one.

Here is something I noticed and might further help in troubleshooting.

If you disconnect only the PWM signal cable (the Dupont connector at the FC) of a "suspected bad" esc/motor-set (but leave power going to the ESC), and then power-up the Nova ...

• The known-BAD set continues to twitch/beep constantly.
   
• A known-GOOD set does not twitch/beep constantly. It does for it's initial test, then goes quiet like normal.

So, an indication of something. Obviously, the ESC is complaining about something. Only catch with his test is that a motor must be connected to hear the twitch/beeps but you don't actually have to power-up the motor manually (beyond what the ESC does during self-test). I also now see how shorted motors can fry and good ESC on simple power-up-and-test.

The ESC soldering, wiring, and PCB look fine. I see no blown chips or bad soldering.

I opened the motor, and the windings look good. My new LC/LCR meter (a gift) is not working properly for motor coil measurements in uH/mH, so I have another one on order. I will update this post later.

Update 1:
Ok, I got a working LC-Meter. This motor appears to be good because I am getting the following between the 3 motor pairs: 35.8, 35.6, 36.2 uH (aka mH). I took the readings with the magnet-bell removed and they were as they should be (within 10% of each other). Also, windings and magnets physically look good (nothing melted, burnt, or out-of-place).

I installed a used/working Nova v2.4 green-led-ESC. Seems motor solder-pads are in a different orientation than old v1.6 ESCs. I say that because after soldering to match the bad ESC, I still had to swap a motor wire-pair to get this motor to spin in the proper direction. It was no big-deal, but note worthy. It behaves like a good ESC/Motor set now (see above ... both tests ... connected and disconnected). I needed to program the ESCs (all-at-once) and re-do all calibrations.

Toward the end of ESC-Calibration, I observed that all motors now spin properly and turn in the proper directions. There is also a Motor Test in MissionPlanner. I like to do it from Terminal.

More repairs and updates documented here.

Edit: Just wanted to mention that it was indeed just a blown ESC (almost brand-new and blew without cause). This one v2.4 ESC works and flies fine with the other three v1.6 ESCs.

Flight Session 51 - Flying my Novas

My last few flight sessions have been with the new DT-180 drone. Some general LoS flying, but also trying to practice my FPV. Today, I thought I would take my Novas over to the school-field for some flights. Partly cloudy, 90f, and 5mph winds.

Super-Nova (newer Nova #2):

As I get to the field and get everything setup and ready for take-off ... I feel a few sprinkles. I look off in the distance, and a new dark thunder-cloud is approaching. I decide to go for it.

On power-up, I noticed that the Nova's power-up sequence of motor/esc twitch/beeping was different and abnormal. I tried again and got the same. I didn't think much more of it since it Armed ok. I likely bumped the throttle a couple of times to test motor spin, (as I usual do) but not sure. I felt a few more sprinkles so it's now or never. On take-off, it flipped over. Compass puck got cracked. Nova will still Arm, but back/left (aft-port) motor/esc set will not spin prop. Super-Nova definitely not living-up to its name. It never rained.

It took two Nova's and 2 years of flights, but it appears I have finally experienced a stock ESC or Motor failure. Caught me totally off-guard. The Nova was trying to tell me something (a few extended seconds of twitching/beeping of the ultimately non-functioning esc/motor-set on power-up) ... but I didn't understand.

Strange thing about it ... this is the newer Nova (with the v1.6 ESCs), and it 's never been crashed (well, unless you count just now when it flipped on take-off due to a non-spinning motor). Whatever component went bad here, it appears to have happened while Nova was sitting on garage shelf. Either that or it happened on initial take-off/throttle-up/amp-up.

In light of this event, I'm gonna have to add a couple of steps to my main pre-flight checklist.

- Listen for extra (abnormal) beeps/twitching from ESC/Motor sets during initial lipo connection and aircraft power-up (even if it stops after a few seconds).

- After Arming, bump the throttle on/off a few times and make sure all props/motors spin on command.

Because apparently, you can have a failure in a ESC/Motor set and it will still pass pre-arm tests and allow Arming ( basically goes un-detected). Without the pilot performing the above pre-flight observations ... there is no way to prevent a flip/crash/damage when you punch the throttle to take-off.

Current known issues:
1. Repair or replace bad motor and/or ESC in bad set
2. Repair cracked puck and do epoxy mod to reinforce.
3. Check GPS-module cable. I lost GPS for 5 mins during field testing (and it didn't appear to be an GPS-Almanac update).

Nova #1:

Only thing here is that both of my Turnigy-2700 Lipos have now puffed-up again and are apparently too large to fit into the old Nova any more (even with PDB raised-up 2mm). I used the Vant-3000 (that I usually run in the Super-Nova) instead.

The Nova flew great. All modes and Loiter. Quanum Retracts are still working fine. Flew around fast and stable. Fun flying and seems more casual than FPV. Just had the one battery that fit, but got over 12 minutes flight-time on it. GPS working OK for a 6-series. Barometer altitude reporting acceptably today on this quad.

Two uBlox GPS & Compass combo-modules for Pixhawk compared

Both of these are advertised as being "GPS combo-modules" with uBlox NEO-M8N GPS and a HMC5883L compass. They are both pinned with Molex PicoBlade for easy PixHawk use. The content of this post started as a rant/complaint, but I've decided to present it as a Comparison, so I can offer a suggested alternative. Ok, so first the bad ...

Beitian GPS & Compass combo-module (white):

Looks pretty on the outside right? Well, looks can be deceiving.

For starters, it only works intermittently. Initial testing revealed it gets more erratic as it warms-up. Inside, we first find a conventional uBlox chipset missing. However, if you look through the hole, you see a chip with uBlox printed on it ... so who knows if it's all real. Not sure if that is a battery or super-capacitor, but it's spot-welded in. Also interesting that the magnetometer is apparently under the metal shield ? (the other side is just the ceramic GPS antenna).

Then I noticed that instead of using the available (dependable and industry-standard) Molex PicoBlade connector, they have instead decided to hard-wire solder the tiny cable wires directly to the module's PCB. Seems this miss-step allowed the real problem (below) to even manifest itself in the first place. It might not have been so bad if the assembly technician knew how to solder.

Yes, the real surprise inside is the soldering (zoom in or "open in new tab/window"). The wires are frayed and barely attached. Not only that, but all the connections are poor, dull, and obvious "cold solder" connections that aren't always making good contact. Everyone knows what happens if your GPS or compass becomes disconnected or glitched in flight ... right, the aircraft flies-away or crashes. I think this poor soldering is why the module works intermittently, worse as it warms-up, clearly un-reliably, and completely unfit for its purpose.

Finally, there is no obvious indication or arrow pointing forward. Neither on the module's outer case or inner PCB. The compass chip is not visible either.

EDIT 11-2017
I needed a GPS (and external compass) for a new PixRacer quad I'm putting together. So, instead of wasting $20 on this, I decided to try to fix it (it's a challenge right ? :) and good micro-soldering practice). I think the main problem was the poor solder job.

The cable itself has a nice molded strain-relief.  I was temped to just splice-in a Pico-Blade 6-pinner, but that's more hacky-work and the designer went the other way for some reason. Instead, I removed the wires, cleaned the holes, and carefully re-stripped and tinned the thin wires. I think the wires should go through the holes, and then solder (like a normal hole-thru part).

Here is what it looks like now. It looks "rough" but it's functionally solid. Seems to work fine so far. Wow, GPS on uBlox 8-series is so much better than 6-series (even in poor conditions). And yes, the compass/magnetometer works fine (even under the metal shield). The "S" points to the front, and the "B" is to the back of quad.

GR-BD uBlox GPS & Compass combo-module (black):

 

I had this NEO-M8N unit, out on porch getting "warmed-up" for a recent test flight. I was getting SATS:15 & HDOP:0.8 . So, good performance and as expected ... much better than my uBlox 6-series units in same environment.

  

This GR-BD GPS module is much better built. Inside you find a more standard looking uBlox chipset. They also use a properly crimped cable connector to match the one provided on the PCB. This provides a much better connection to vital sensors like these (compared to the white Beitian unit) . In hours of testing, I have never seen this GR-BD module fail. While the proper direction is already clearly marked, the compass chip is also visible. I like the visible blue status led also. I'm in the USA, so not sure about performance when using alternate GLONASS (GNSS).

In summary, I guess the real advantage of this black GR-BD one, over the white Beitian one ... is that it actually worked without first being opened and repaired :)

Pixhawk v2.4.8 bench-testing & barometer accuracy with drift

I finally got around to firing-up the new PixHawk v2.4.8 on the workbench. It came with ArduCopter v3.2.1. I had to flash to v3.3.3 to cure some external Compass detection issues. I then had to flash to AC_v3.4rc2 to fix "compass variance" errors. It's now working except for this altitude drifting issue. 

So, it turns-out that ESCs and motors do not have to be installed for Pixhawk to Arm and run a simulated “test-flight”. I was able to now better compare the new Pixhawk-v248 altitude behavior against my other FCs.  

Test conditions:

- FC and sensors are powered-up and “warmed-up” for 5 minutes before Arming

- Only the FC is connected. No GPS for now.
- Using on-board compass only. Calibrated and not throwing “Compass Variance” errors
- FCs are completely calibrated (gyros, etc.)
- FCs are sitting on the actual flat level ground outside
- During mock “test flights”, FC were occasionally picked-up to 2 meters, held for Tower chic's announcement (about 30 secs), and then set back down.

Initial Observations (for all tested FCs unless noted):

- Daylight, temperature, and weather not large factors (example pic below from a night run)

- All FCs drift a bit after cold power-up. This appears to be normal. I allow 5 minutes to warm-up.
- On Arming, altitude is reset to 0.0 meters. After a cold-boot, works nice to reset barometer after power-up but before take-off.
- Neither the APM_252 nor PixRacer ever exhibited a deviation any different or worse than about 1.0 meters in any test.

The below chart shows results from actual sim-flights in my backyard. While it only shows a few, I would say I have run about 10 tests so far. Multiple tests of same FC showed similar results (so no big problem they aren't all logged).

 

Altitude of ground (as determined by FC)	APM_252	PixRacer	Pix248_F01	Pix248_F02
Power-up	0.0	0.0	0.0	0.0
After 5 minutes warm-up	0.3	0.1	-3.0	-3.0
After Arming (resets altitude once)	0.0	0.0	0.0	0.0
During simulated flight. 1 minute	0.1	0.0	-0.1	0.2
During simulated flight. 2 minutes	0.2	0.0	-3.0	-1.0
During simulated flight. 10 minutes	0.7	0.1	-7.0	1.0
During simulated flight. 30 minutes	1.0	0.8	-10.0	-2.0
After landing	1.0	0.8	-10.0	-2.0
Max in-flight barometer units deviation	1.0	0.8	10.0	2.0

Like the popular PixHawk 2.4.6 before it ... the PixHawk 2.4.8 and PixRacer all still use the same Measurement Specialties MS5611 barometer sensor. Even my old APM_252 FCs uses the same. When looking at Flight-Example-01, I don't see how the PixHawk_v248 can be determined good and trusted on a $1000 aircraft if it can't even determine it's own altitude closer than this. I had hoped to use this aircraft for precise auto-missions. From this example simulated-flight (F01), you can see it clearly performs worse than the others.

Sometimes this PixHawk_v248 drifts into positive altitudes instead of negative. Originally, I had thought that Arming (and it's reset) was required to net a good result. However, (at least in this case) I'm seeing that is not the case, and a drifting barometer will continue to drift, no matter how many times you reset or Arm-Reset it. I'm thinking it must be a bad barometer on the board. Hopefully just a rare random bad unit.

Update 08-29-2016
I have continued to run tests (up to about 15 iterations now) and example test-flight scenarios with similar results. They have been run on both 90f hot-days and cool 70f nights. Weather is active (like always) but is generally mild (no storms).

Most results are similar. However, it seems I ran enough tests (about 6 now) on PixHawk_248 to get a rare result. I have updated the above chart with that flight (in column PixHawk v248 - Example Flight #02). It shows that this exact PixHawk_v248 (that has been performing so poorly) finally showed a result more in-line with similarly equipped FCs (it finally performed properly once). It seems to say that this MS5611 barometer sensor can work under ideal conditions or maybe just randomly. However, since it's not reliably correct or dependable, I will likely never fly this particular FC on a nice aircraft as originally intended.

You can also start to see how some pilots might not notice a 1-2 meter barometer drift during a flight. Conceivably, you could take off at 0.0 meters. During the flight, the barometer might drift around 2.0 meters. But if it happens to drift back near true altitude (around the time you land), the pilot might not even notice.

I'm thinking the Measurement Specialties MS5611 barometer sensor is a fairly delicate and sensitive sensor. It might be that some work better than others. Maybe I just got a "boarder-line sensor" that tends to drift too much over a short period of time. Hard to say how many FCs that might end-up affecting over the years. I just visually confirmed that my PixHawk v2.4.8 from BG does have the proper sensor soldered onto the PCB.

MEAS - 561101BA03

Grey foam is there and lightly pressing against sensor. In my case, it appears to be a bad $3 barometer sensor .

Update 09-28-2016

I contacted vendor. They sent me a new one after seeing these test results. This new one works properly. I holds a 1-meter or better accuracy while on flight-line or during mock flights.

DT-180 Racing Drone - Diatone 180mm Full Setup & Mods

Ok, so the DT-180 flies. Now, let's see what I can do with it. This post will update for a while.

I did a partial de-Pinning of FrSky_X4R-SB so that it will fit behind camera (and partially under Naze32-FC).

Cut last 2 pins down flush like the others. I will never need CH-2/CH-3 anyway. Leave the 6-pins for SBus & CH-1.

Needs one more thin coat of Liquid-Tape, for 2 total.

Install between beeper and PWM-cable.

PWM cable is just barely long enough.

Not really needed, but how about a small piece of black-tape for one more piece of insurance. I didn't know, but it turns-out that 99% of the bottom of this Naze32 PCB is smooth and void of components. That really helps make this mod possible. If you loose the threads on a stand-off, try some Teflon-tape.

X4R-SB got to keep its protective outer case. Its still a bit loose in space and not crushed. Wire and antenna management is key due to close props.

Naze32 is still level and securely hard-mounted with black nylon screws like before.

Nothing shorting-out.
Arms, spins-motors, RSSI is good.
Test flight successful. (Updated 7-15-2016)
- Battery got a bit hot.

CleanFlight Steps edited for this simple flight of this version of Naze32 FC and FrSky X4R-SB (via SBus):

Setup with CleanFlight Configurator v1.2.2
Identified Board:AFNA Version:2
Using NAZE firmware CLFL v1.12.1 (4-10-2016) Stable

• Calibrate Accelerometer
• Let sit still on level surface
• Save your config if you want (I do this often as I make changes and progress)

Ports

• UART-1
• Data = MSP/11520 (never change this)
• UART-2
• RX = Serial RX

Configuration

• Mixer = Quad-X
• Receiver Mode = RX_Serial (SBus)
• Serial Receiver Provider = SBus
• ESC & Motor Features
• Motor_Stop & Dis-Arm Motors (5 secs)
• Throttle numbers are Min=1150, Middle=1500, Max=1850, Min_Cmd=1000
• Some of these might need adjustment, but theses do work/fly.
• System Configuration
• Loop Time = 2000
• Other Features

Receiver

• Select Option for JR/Spektrum
• That will give you TAER1234 (Throttle, Aileron, Elevator, Rudder, Aux1-4)
• By now your radio TX/RX set should be Bound and working. Turn on Taranis, and see it respond in CleanFlight. If paired TX/RX radio-set are both on and bound together, the Naze32-FC should not be beeping. X4R-SB green-led should also be lit.

Modes

• Setup some modes ... like Angle flight-mode (Auto-Level) on your main switch. (video)

Sensors

• Move and manipulate the Blade quad and watch sensors respond.

Diatone Tyrant 180 (DT-180) & FrSky X4R-SB (SBus) - Quick Build & maiden-flight

Nice carbon frame & PDB. Pretty tight in there, and props are close. I easily installed FrSky X4R-SB receiver on top of Diatone DT-180 for now. I used the supplied 10-pin RC-Pig-Tail cable. Carefully apply pressure when inserting the 10-pin header connector because its only soldered to the top of the PCB. The black-DuPont RC-plugs stick-out of X4R-SB a bit and increases its required mounting space.

Must have Velcro-strap on main battery. Now trying another around back wires and antenna. Props are installed in normal CW/CCW Naze32 order. The supplied nyloc prop-nuts are two black/silver colored pairs, they all screw-on in the normal direction. Using wire-ties and heat-shrink for whisker antennas. Only difference with mine is the tubing-middle is tied-down.

• First, I like to Bind receiver (a FrSky X4R-SB with it's own battery) to new Model #05 on Taranis. Don't forget to power-cycle X4R-SB at the end. Look for green-led on successful bind and even currently-bound status.
• With volt-meter, be sure BEC on quad is outputting about 5.0 volts. If so, you can use this for power now.
• First, turn on Taranis. Then, power-up drone (Naze32_FC & X4R-SB_TX) with it's lipo. Always follow this order and vice-versa for power-down.

CleanFlight Configurator v1.2.2

• Set CleanFlight Ports & Config for SBUS. Save and reboot.
• See the bottom of this page for basic CF settings.
• Calibrate accelerometer/gyro (easy ... just let rest and be motionless). 
• Check for radio coms
• Main 4 control channels
• Setup one main Flight-Mode switch (AUX-1) and check Modes
• Backup Settings

• Those settings, radio is responding, easy calibrate gyro, and I am good to fly.

 

Maiden Test-Flight
- Location & weather: Outside backyard in medium winds.
Results: Two successful take-offs, hovers, light-flying, and landings. Flew battery until low-voltage alarm sounded. No damage for today. Will try with a fresh lipo and goggles later.

Radio installs easily in the DT-180 PnF drone. Intermediate pilots and builders with only basic skills should be able to get this quad into the air fast. Now that the DT-180 is a proven flier, I went ahead and partially de-pinned this X4R-SB ... allowing it to fit behind the camera.

Still ToDo:
- Tune PIDs

Blade-185 Drone take-off crash-landing up into tree with no-damage.

It started as a simple take-off under a tree. I got stuck on a vine at first, but the required throttle to break-free catapulted quad up into the lower tree branches. It came-to-rest and perched itself on this large branch ... with no damage.

Tough little quad. Had 5 minor crashes flying thru 2-batteries in my back-yard "obstacle-course" :) No damage to racing-drone, and the new skid-plate/antenna-guard seems to be doing its job.