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Feb 26, 2017, 04:41 PM
3D? I only got two thumbs!
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Mini-HowTo

Latching Throttle Cut


guys234 asked if it was possible to make a latching throttle cut switch (https://www.rcgroups.com/forums/show...ostcount=27394). I took that as a challenge, and here's how I did it.

The goal:
When the throttle cut switch is flipped to the cut position, the throttle channel is disabled, regardless of throttle setting. That's standard behavior so far. But when throttle cut switch is flipped back, if the throttle is not off, the throttle stays cut until you lower the throttle back down. So the throttle cut "latches" even after you flip the switch, until you lower the throttle. The goal is to make sure you don't have an accidental runaway plane if you flip the throttle cut switch after having accidentally bumped the throttle up.

Latching behavior reminded me of flip flops in the hardware logic world. A flip flop can be made with two NAND or two NOR gates. And those gates are analogous to a logic switch in the jeti tx, so that's the direction I choose to go.

I use Sb for throttle cut. I've swapped it out for a jeti 2 pos locking toggle switch, because I don't want to accidentally bump it on or off. In my DS-16, when the switch is in the position I want the throttle to be cut in, it's displayed as a check in the user interface. If the switch you choose to use is the other way around, just reverse any usage of Sb I show here - if my pic shows not reversed, reverse it, and if my pic shows reversed, un-reverse it.

We need 3 logical switches. The first is to select when to reset throttle cut. The second and third construct the flip flop to get the latching behavior. And the throttle cut function is setup to use L3's output. The throttle cut is set straight from Sb, no logic switch needed there.

The details;

L1, reset throttle cut. Sb reversed AND P4 proportional, not centered, x<10%.
L2, flip flop set. Sb OR L3 reversed
L3, flip flop reset. L1 OR L2 reversed.
Throttle Cut switch: L3 reversed.

L1 screen pics:
L1 SetupL1 SbL1 P4

L2 screen pics:
L2 SetupL2 SbL2 L3 rev

L3 screen pics:
L3 SetupL3 L1L3 L2 rev

Throttle cut screen pics:
Other Options TC SetupTC L3 rev

The whole thing set up in an otherwise generic model file attached - 0007Thr.txt (rename .txt to .jsn to use).
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Feb 26, 2017, 06:31 PM
Registered User
JOddino's Avatar
Quote:
Originally Posted by AeroKen
guys234 asked if it was possible to make a latching throttle cut switch (https://www.rcgroups.com/forums/show...ostcount=27394). I took that as a challenge, and here's how I did it.

The goal:
When the throttle cut switch is flipped to the cut position, the throttle channel is disabled, regardless of throttle setting. That's standard behavior so far. But when throttle cut switch is flipped back, if the throttle is not off, the throttle stays cut until you lower the throttle back down. So the throttle cut "latches" even after you flip the switch, until you lower the throttle. The goal is to make sure you don't have an accidental runaway plane if you flip the throttle cut switch after having accidentally bumped the throttle up.

Latching behavior reminded me of flip flops in the hardware logic world. A flip flop can be made with two NAND or two NOR gates. And those gates are analogous to a logic switch in the jeti tx, so that's the direction I choose to go.

I use Sb for throttle cut. I've swapped it out for a jeti 2 pos locking toggle switch, because I don't want to accidentally bump it on or off. In my DS-16, when the switch is in the position I want the throttle to be cut in, it's displayed as a check in the user interface. If the switch you choose to use is the other way around, just reverse any usage of Sb I show here - if my pic shows not reversed, reverse it, and if my pic shows reversed, un-reverse it.

We need 3 logical switches. The first is to select when to reset throttle cut. The second and third construct the flip flop to get the latching behavior. And the throttle cut function is setup to use L3's output. The throttle cut is set straight from Sb, no logic switch needed there.

The details;

L1, reset throttle cut. Sb reversed AND P4 proportional, not centered, x<10%.
L2, flip flop set. Sb OR L3 reversed
L3, flip flop reset. L1 OR L2 reversed.
Throttle Cut switch: L3 reversed.

L1 screen pics:
Attachment 9820832Attachment 9820831Attachment 9820830

L2 screen pics:
Attachment 9820836Attachment 9820835Attachment 9820834

L3 screen pics:
Attachment 9820839Attachment 9820837Attachment 9820838

Throttle cut screen pics:
Attachment 9820852Attachment 9820853

The whole thing set up in an otherwise generic model file attached - 0007Thr.txt (rename .txt to .jsn to use).
Excellent work and a great idea. We should all use it from now on.

Jim O
Feb 27, 2017, 04:27 AM
Registered User
Very Elegant AeroKen, thanks - a must safety feature for Electric aircraft.
Mar 01, 2017, 02:29 PM
Registered User
Puttputtmaru's Avatar
There might be an easier way but applying this to helicopters, where you want the stick to be centered, I added an extra logical switch with a throttle stick condition:

X>47% AND x<53% and use it as an extra condition for the latching to work with stick centered.
Mar 01, 2017, 02:56 PM
Registered User
Please explain the stick centered bit? Haven't flown helicopters for a while but never spooled up with. Throttle stick centered.. I could understand adding a test for normal flight mode in addition to low throttle stick but dont understand why you would want to release throttle cut at half stick??? Maybe I'm just out of touch??

Wayne
Mar 01, 2017, 05:36 PM
Registered User
Puttputtmaru's Avatar
First off I am talking electric helicopters.

The trend now, and I have followed it because of some mishaps, is not to have the first throttle curve starting at 0 (zero) and then increase.

With the slow spool up that ESC allow now, you start at zero pitch with a flat curve already at a level that will give you the first headspeed that you want, usually in the 1600 to 1700 range for a 700 helicopter unless you like slow headspeed.

So in fact you start your helicopter by flipping a switch, that for Jeti is the throttle cut, with the stick already centered and with your pitch at zero. The pitch range will be usually -2 to +11 more or less.

The point is to avoid, once you go 3D, to get into the habit to cut your throttle, as with an airplane, by pulling the throttle stick all the way down. If you are in 3D mode this will give you full throttle and full negative to disastrous results.

Helicopter pilots are even going now with centered spring loaded throttle stick for an easier time to find neutral.

I have not done that since I am flying airplanes too, but probably will when I get a DC-24, my DC-16 will become my helicopter only Tx then.

Hope that clears it for you Wayne.
Mar 01, 2017, 06:05 PM
Registered User
Quote:
Originally Posted by Puttputtmaru
First off I am talking electric helicopters.

The trend now, and I have followed it because of some mishaps, is not to have the first throttle curve starting at 0 (zero) and then increase.

With the slow spool up that ESC allow now, you start at zero pitch with a flat curve already at a level that will give you the first headspeed that you want, usually in the 1600 to 1700 range for a 700 helicopter unless you like slow headspeed.

So in fact you start your helicopter by flipping a switch, that for Jeti is the throttle cut, with the stick already centered and with your pitch at zero. The pitch range will be usually -2 to +11 more or less.

The point is to avoid, once you go 3D, to get into the habit to cut your throttle, as with an airplane, by pulling the throttle stick all the way down. If you are in 3D mode this will give you full throttle and full negative to disastrous results.

Helicopter pilots are even going now with centered spring loaded throttle stick for an easier time to find neutral.

I have not done that since I am flying airplanes too, but probably will when I get a DC-24, my DC-16 will become my helicopter only Tx then.

Hope that clears it for you Wayne.
Thanks for the explanation.. I alway just used the traditional setup of the throttle curve going to 0 in normal mode even though I typically had +\- 10 degrees of pitch in all modes. Since you still need to return to a specific flight mode to have a throttle curve that's off at center I'm not sure I see a significant advantage but I can see where others may...

Still seems the throttle cut function should be also based on the "off" throttle curve selected because if it isn't you may still goo to full throttle at any throttle position...

Wayne
Apr 08, 2017, 08:12 PM
Registered User
cansfan's Avatar
Quote:
Originally Posted by AeroKen
guys234 asked if it was possible to make a latching throttle cut switch (https://www.rcgroups.com/forums/show...ostcount=27394). I took that as a challenge, and here's how I did it.

The goal:
When the throttle cut switch is flipped to the cut position, the throttle channel is disabled, regardless of throttle setting. That's standard behavior so far. But when throttle cut switch is flipped back, if the throttle is not off, the throttle stays cut until you lower the throttle back down. So the throttle cut "latches" even after you flip the switch, until you lower the throttle. The goal is to make sure you don't have an accidental runaway plane if you flip the throttle cut switch after having accidentally bumped the throttle up.

Latching behavior reminded me of flip flops in the hardware logic world. A flip flop can be made with two NAND or two NOR gates. And those gates are analogous to a logic switch in the jeti tx, so that's the direction I choose to go.

I use Sb for throttle cut. I've swapped it out for a jeti 2 pos locking toggle switch, because I don't want to accidentally bump it on or off. In my DS-16, when the switch is in the position I want the throttle to be cut in, it's displayed as a check in the user interface. If the switch you choose to use is the other way around, just reverse any usage of Sb I show here - if my pic shows not reversed, reverse it, and if my pic shows reversed, un-reverse it.

We need 3 logical switches. The first is to select when to reset throttle cut. The second and third construct the flip flop to get the latching behavior. And the throttle cut function is setup to use L3's output. The throttle cut is set straight from Sb, no logic switch needed there.

The details;

L1, reset throttle cut. Sb reversed AND P4 proportional, not centered, x<10%.
L2, flip flop set. Sb OR L3 reversed
L3, flip flop reset. L1 OR L2 reversed.
Throttle Cut switch: L3 reversed.

L1 screen pics:
Attachment 9820832Attachment 9820831Attachment 9820830

L2 screen pics:
Attachment 9820836Attachment 9820835Attachment 9820834

L3 screen pics:
Attachment 9820839Attachment 9820837Attachment 9820838

Throttle cut screen pics:
Attachment 9820852Attachment 9820853

The whole thing set up in an otherwise generic model file attached - 0007Thr.txt (rename .txt to .jsn to use).
Excellent, Thank You very much!! This will be standard operating procedure on all models moving forward.


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