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May 03, 2014, 09:32 AM
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Cortex Gyro Setup with Jeti

I have been playing with the Cortex gyro system for about 2 weeks. I have 2 planes setup. One just the basic and the other i have started playing with the new telem feedback control features to mix airspeed back to gyro gain. I am hooked. I have a third Cortex, a 2nd MGPS and a new MSpeed sensor inbound to test.

I am going to start this thread by showing the basic DS programming for the recommended Cortex initial values. After that, i will post my telem feedback for "gain scheduling" as function of speed.

As always, there are a lot of ways to accomplish the same result with the Jeti system. So this might not be how everybody has or will do it, but i hope it can help some users get flying fast and simple with the Cortex. Enjoy!
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May 03, 2014, 09:43 AM
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Ill will only use the Normal and Hold terms from now on. I am not going to cover the physical setup or the "Quick Setup" given with the unit.

The only setting you might consider initially setting with the PC is the digital/analog servo setting. Default is analog. It will work fine if you don't
change it and you are using digital servos. I have done both. Really hard to tell the difference. I did notice a slight twitch on my servos on the analog. It seemed to go away with the digital setting. But its not a show stopper in getting going.

If you do hook it up to the PC, don't forget to power the cortex with a 2s lipo or life bat. The cortex is not powered for the firmware cable. They don't show this in the quick start!

So the recommended initial settings for the Cortex are -20%/0%/40% on the gain channel for "Normal" (Bank1), "Off", and "Hold" (Bank2) modes. They worked pretty good on both my first 2 Cortex setups. So here we go....
May 03, 2014, 09:47 AM
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Step 1:
Turn of the air plane gyro features for your model.

Goto the Basic Properties for your model (where you choose wing and tail types)
Activate Gryo 1

Activate Gyro
Last edited by cravenjw; Nov 16, 2017 at 03:27 PM.
May 03, 2014, 09:49 AM
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Step 2:
Activating the Gyro creates a Function named "Gyro Sens".

Next you need to assign a 3 pos switch to this function.
I chose the Se switch.
After flying, i strong recommend you push up for "Norma" and pull down for "Hold". With this if things get "Querky" is hold, you can quickly bump the switch up into Off or Normal. I have needed to bail out of hold! I have never need to bail out of Normal.

Note when you choose the switch direction, use reverse if need to have Hold be 100% and Normal be -100%.

Lets assign a switch:

Gyro Sens

Switch for Hold:

Switch for Hold

Switch for Normal:

Switch for Normal

Switch Complete:

Mode Switch Complete
Last edited by cravenjw; May 03, 2014 at 10:04 AM.
May 03, 2014, 10:19 AM
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Step 3:
Assign a channel to the Gyro Sens.
May 03, 2014, 10:27 AM
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Step 5:
Setup mode gains and tuning/trim knobs.

Goto the Gyro Settings

With gyro sens switch centered, Off mode, the gain is 0%, no tuning stuff.

Off Mode with Switch Cent...

With gyro sens switch in Normal Mode, the gain is -20%, the trim is 10%

Normal Mode Gain and Trim

I assign the P8 knob for trim.

Assign P8 for Normal Trim

P8 is set so full clockwise increases the Normal mode gain, from -20% base by 10% to -30%. Full ccw sets Normal gain to -10%.

Normal with P8 Full Clock...

With gyro sens switch in Hold Mode, the gain is 40%, the trim is 10%

Hold mode gain and Trim

I assign the P8 knob for trim. Note this knob is reversed.

Assign P7 for Hold Trim

P7 is set so full clockwise increases the hold gain, from 40% base by 10% to 50%. Full ccw set gain to 30%.

Hold with P7 Full Clockwi...
Last edited by cravenjw; May 03, 2014 at 10:34 AM.
May 03, 2014, 10:48 AM
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At this point the Cortex is flyable!

However, there loose recommendations that you reduce your expo when the gyro is active. I also found played with flight trims and decide to eliminate (zero them) when the gyro was active. I also wanted a sound to tell my i entered Normal or Hold modes.

Step 6: (Optional)

Given all these things, i decide to make Normal and Hold flight modes. Hold is now my highest priority flight mode. Normal the 2nd highest. I attached a custom sound to each mode.

If neither Gyro flight mode is active, then my old modes work just like they did before.
I can pull the gyro out and just disable these two modes (clear the switch) , and that's it, same plane as before!

Two new high priority modes added

Other (GyroOff) Flight Mo...

GyroNormal mode attached. Flight mode is active on same Se switch pos as gyro setting function for gains. Sound for gyro mode attached here.

GyroNormal Flight Mode

GyroHold mode attached.

GyroHold Flight Mode
May 03, 2014, 10:59 AM
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Step 7:
Full Throws. No expo! Turn it off. Gyro does it all for you.

Honestly, i switch between my high rates mode with 70% expo and either gyro mode with 0% expo. I cant really feel a difference. My advice is let this thing do its thing! But you can inch it there if you are skeptical.

My High Rates mode throws and expo.

High Rates

My GyroNormal mode throws and expo.

GyroNormal Expo

My GyroHold mode throws and expo.

GyroHold Expo
May 03, 2014, 11:10 AM
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Step 8:
After removing the expo, i tried removing all the trims. My thought was the gyro should handle anything that isn't gross mechanical setup problem. Get rid of the trims too!

I hadnt used Flight Mode Trims before. But they are great for this application. I setup all my old modes on FlightMode Trim Group A. I setup my two new Gryo modes on FlightMode Trim Group B. For B group, all trims set to 0%.

Old modes on Group A

Old Flight Mode Trims

You hit the F3 button to set global, local or group A/B

Setting FlightMode Groupe...

New gyro modes on Group B, all trims at 0%

GyroNormal Trims

GyroHold Trims
May 03, 2014, 11:27 AM
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So that is my Basic Cortex Setup.

Now you have to fly it!!!

So i would start with gyro off. Have both gain trim knobs set ccw to minimum gain.

When your ready, at mid speed, turn on the Normal mode.
Play with each axis for a bit.
If you don't see any oscillations, increase the speed, until your full speed.

No oscillations? Then dial up the Normal gain knob. repeat testing.

If you get an oscillation(s) then back the gain down.

If you didn't see one axis clearly start to oscillate before the others, then you have you Normal gain!!!

If one axis clearly starts to misbehave before the others, take note of which one. You need a PC and need to reduce the gain for that surface in the deeper settings.

On my first setup, my pitch axis went first. I reduced the elevator gain by two points. Works great now. All axises go together in Normal mode. But, i also reduced the gain of the elevator in hold mode by 2 points. This was a mistake!!! In a hold mode hover or torque roll, my elevator was weak. I ended up putting in back to the default in hold mode. Tune hold separately.
May 03, 2014, 11:31 AM
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Next we are going to apply the cool new telem feedback control features Jeti has just released to make the Cortex work better! We will feedback the speed we get from the MGPS or MSpeed sensors and reduce the Cortex gains as a function of speed. This will let us dial up the gains higher for low speeds and hold mode!

Stay tuned!!!
May 03, 2014, 11:49 AM
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I am staying tuned.

Thanks again for a great tutorial (where is the thumb up smilie?)
May 03, 2014, 12:37 PM
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Cortex Gain as a Function of Speed

So i already had the MGPS sensor in my Cortex testing airframe. So here is how i am currently using the new Telemetry Controls features of the 3.0 TX firmware to reduce my Cortex gains as a function of increasing air speed.

Please note, i know the GPS is not airspeed!I know the MSpeed airspeed sensor is theoretical better for this application. But i don't have one yet. Its shipped this morning!!! When it gets here and is installed, i will only have to change which sensor is used in the telemetry control from the MGPS 3D speed to the MSpeed speed. Until them ill be tinkering with this using my gps!

Create a proportional Telemetry Control based on speed

Create Speed Telem Contro...

Named the control "Speed" and enabled it.
Based on past flying, my extra 300 hits about 55-57m/s pretty consistently.
So i have configured the new telem control from 0 m/s to 50m/s. Setting the center at 25m/s means is simple linear function mapping to -100%, 0%, +100 at 0m/s, 25m/s, 50m/s.

I haven't had a enough flight to say this is the best range. I suspect that function that goes from 10m/s to 40m/s might be best. But there are a few issue in the jeti that might make this difficult.

We will take about better ways for Jeti to improve the control mapping later.

I have not played with the filter yet. Next time out it high on the testing list.

I set the default at 99%. This is the value when the sensor is missing. But!!! It has nothing to do with sensor quality! So if the GPS dies or unplugs it works. But it i have bad satellite reception or a bad fix, it doesn't help! It set it to 99 so i can tell its off line mainly for logging diagnostics.

In my case, ill reduce base gain with my mix. Sensor missing is mimics full speed and therefore maximum gain reduction.

I don't use the switch. I always get a value. I chose speed is used for feedback later in the mixes attached to the corresponding flight modes.

Config Speed Control Sett...
Last edited by cravenjw; May 03, 2014 at 01:00 PM.
May 03, 2014, 12:47 PM
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Step 2:
Created a GyroSpeed function

Assign GyroSpeed Function...

Assign the MX1 speed control as the switch.
Make it not Centered (0-100%) rather than (-100,100).

Assign Speed Control to G...

So now i have a function the is 0%-100% mapping of 0m/s - 50m/s
Last edited by cravenjw; May 03, 2014 at 12:52 PM.
May 03, 2014, 12:53 PM
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Step 3:
Assign GyroSpeed function to GryoSpeed servo

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