Tarot ZYX initialisation warning

[debrooker]

My Tarot ZYX threw another paddy today, fortunately I was spooling up and hadn't left the ground and I think i've identified the issue. The unit is very sensitive to movement on initialisation, whilst this may seem obvious - its how sensitive the unit is. I had powered my unit on in mild blustery conditions (not excessively so) and the wind was hitting the side off the heli, and thinking about it this was similar conditions on the first crash I had due to this behaviour.

I had successful flights after this, by shielding the heli when powering up.

Hopefully this will save someone experiencing this...

[davew]

If it's an early unit the firmware wants updating. I have one on my 450 and it fails to initialise about 1 in 4 times! I haven't got round to doing the update but word is that it will improve the situation to a failure about 1 in 20.

If it isn't going to initialise it isn't and its not really a case of keeping it still whilst powering up.

What you have to do with this and any FBL unit is to power it up and then lift the heli and move it about and check the swash action is good. If its not then power down and re-do it.

Other than that it is an excellent unit, as good as any. I have fitted one to my 600 nitro now as well

[muscleflex]

Someone on RCGroups told me that if you hit rate mode then back to heading hold, this resets the gyro so you're fine to spool up.
if you noticed, when you hit rate mode, the tail and swash resets (twitches) and this lets you know it's reset. (it's what I've been told and what I've noticed)

i now do this everytime before I spool up.

[davew]

That's worth a try! Certainly there is a load of twitching and movement on the swash when you toggle between rate and HH.
I'll try it and let you know what I find.

[cjcj1949]

On a gyro switching to rate mode just resets the integrator. It doesn't reset the initialisation value of the sensor. It shouldn't be a problem in movement during initialisation as the sensors measure anguler rate, so its rotation rather than movement than matters. Unless you have accelerometers in there as well.

The initialisation value of the sensor is the sensor output measured during initialisation. This is the value used to define zero rate and this is why it is important to not rotate the tail during initialisation. After initialisation errors start to creep in as the sensor output changes due to temperature. This output is usually small and is misinterpreted by the gyro as a command to turn. Over time when in hold mode this turn rate adds up (or integrates) into a desired angle relative to current position and as soon as the heli is free to turn it will move rapidly to this new angle. With old cheap gyros this can be a 180 degree turn on take off, or was on my Twister Storm.

There are many ways of minimising this error. One simple way is to switch into rate mode and back into heading just before takeoff. This resets time to zero and so zeros the demanded turn relative to current position. The rate sensors are variable in performance and so one gyro and possibly one flybarless unit can behave differently from another of the same make.

[debrooker]

FYI, I'm running the latest firmware 2.5 and I always wait for the unit to move the tail and center the cyclics before moving.

Even on the latest firmware, my unit has failed to intialise (so the latest firmware doesn't cure it in my experience).

[cjcj1949]

I must get one of these to try out. I'd start by either pegging the heli to the ground to initialise or taking the unit off taping it to a bench and seeing if that fixes it. You might also have a wiring problem or a faulty unit. It could be firmware of course that hasn't been fixed yet. It could be one of your sensors that is close to the accepted limit or the initialisation data is being filtered enough. I used to work on hardware software problems like these and it was very interesting. I'll be happy to investigate this for Tarot if they supply the documentation and equipment, although I suspect they know the answer.

[debrooker]

To be honest, the unit other that 2 instances of it getting very unhappy and few more instances of it failing to initialise its been pretty good. This might seem a bit of a strange thing to say i know, but if you look at the hints the unit gives you when you power up you, you can manage it pretty well. Sort of contradicting what I said in the original post

[cjcj1949]

The Tarot stuff looks interesting. Definitely on the list. I have a lot of flybarred heads though. I expected to damage them, but it seems the more spares you have the less likely you are to need them. As I used to work in software and hardware I don't have much faith in flybarless. I do have two 450 helis though as I bought a flasher cheap for spares. I've probably got ehough bits to get it going as a flybarless.