Maximum Throttle Position

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Carl
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Maximum Throttle Position

Post by Carl »

This week I'm planning to fly my Pageboy and Pulstar using a couple of my converted transmitters:

WP_20180624_14_08_16_Pro.jpg

The Waltron Mini 2 will be no problem. I'm planning to set a suitable throttle position on the left trim pot control which works perfectly, and fly just using the rudder control. I'll then just shut the throttle to end the flight (if I don't crash first :oops: ) and glide down to land.

Now with the Babcock, the throttle will be on the button. It uses Phil's PIC encoder, which offers FULL/OFF or FULL/MIDDLE/OFF control of the motor. My problem is that the Pulstar is over powered, and therefore FULL power is too much. So my question is: is there some way for me to reduce the power when Phil's encoder sends the esc the FULL throttle signal? Thought I'd check first before looking at getting a lower kv motor and/or reproping.

My next step will be to use my onboard timer for which I can set the throttle position, but before I do that I'd like to fly first with the ability to switch the motor on and off from the transmitter, hence my question above. These are steps towards me flying my Mattel pulse propo equipped Pulstar, for which I developed my timer.

Thanks in advance for any help/suggestions.

Carl
Carl

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RON
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Location: Stokesley North Yorkshire

Re: Maximum Throttle Position

Post by RON »

Carl
I’m not aware of anyway of reducing the full throttle on phil’s encoder but you can of course set the middle throttle to various percentages. So just set off on middle throttle, you can then just quickly turn the tx off and back on and your throttle will be zero. I do it all the time and because I use frsky it links back up really quick.

Ron.
G0MBV Class A Radio Amateur, North Yorkshire
Spike S
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Location: Salisbury UK

Re: Maximum Throttle Position

Post by Spike S »

Hi Carl
The South oxford Nostalgistas encountered exactly the same problem a few years ago. I assembled a small 8-leg Picaxe chip as a gizmo that goes between the Rx and the ESC. It has an onboard trimpot whereby you can limit the top value of the signal sent to the ESC.
Picaxe uses all BASIC code but the onboard device is very small and light.
I am sure that readers such as afb could code this much more elegantly than me but it performed the desired function.
Twitcher may have a spare one (still unused ??)
Throttle Tamer User Instructions.pdf
(43.77 KiB) Downloaded 154 times
inline with Rx.pdf
(1.48 MiB) Downloaded 167 times


' =======================================
' ELECTRIC MOTOR ONBOARD "VOLUME CONTROL"
' =======================================
' THROTTLE LIMITER for Rx signal to ESC
' For models using Phil G.'s Button-pushing Tx Emulator
'======================================================================================
' Last edited 27 Nov 2016 ? M. Spencer 2016
' Version 1.03(revised IC leg assignment) hardware validated 28/11/16 [91 bytes used]
'
' Previous mods:
' Version 1.02(reversed trimpot sense) 27/11/16
' Version 1.01(first hardware prototype) 11/11/16
'======================================================================================

' FUNCTION
' --------
' This module limits the output of an ESC output to emulate 'backing off' the compression screw of a
' Diesel engine. For use when trimming a 'Guided-Free-Flight' E-power model using Single Channel
' button Tx emulation where no suitable adjustment for servo 'Travel Volume' is available at the Tx
'
' The Thr servo output from receiver to ESC (Electronic Speed Controller) is intercepted and a top-limited
' demand signal is passed to the ESC
' An onboard potentiometer allows the user to top-limit the maximum motor speed anywhere between
' 50% and 100%
' The ESC responds to Transmitter demands up to that preset limit
'
' Signal integrity checking is carried out and any out of range input sets the throttle
' to zero demand (1.0mSec).
' When the signal reverts into range, ten further 'good' pulses must be received before
' resuming normal operation.

' NOTE 1: Failsafe function activates when input pulses fall out of limits
' NOTE 2: 2.4GHZ Rx or 35MHz DSM Rx may continue to output 'last good signal' if Tx input is lost

'======================================================================================
' Based on model boat "Throttle Tamer" code [version 1.01] devised by A Bond
'======================================================================================
'
' PICAXE 08M or 08M2 CONNECTIONS (some functions in this code not available in earlier 08 PIC)
' ------------------------------
' leg 01 (Vdd) +5v
' leg 02 (serial in) connect to 0v
' leg 03 (IN C.4) wiper of pot which is connected across 5v supply
' leg 04 (IN C.3) PPM input (from Rx Throttle channel)
' leg 05 (OUT C.2) PPM output to ESC
' leg 06 (OUT C.1) nc
' leg 07 (C0) nc
' leg 08 (Vss) 0v
'
'======================================================================================


'--------------------------------------------------------------------------------------
' MAIN PROGRAM LOOP STARTS HERE
'--------------------------------------------------------------------------------------

main:
pulsin C.3,1,w0 'read r/x input(looking for positive pulse, no signal inverter reqd)
'NOTE: confirmed working OK with target Rx
'(Futaba 35MHz, Futaba 2.4G, Spectrum DSM2)

if w0>225 then outtalimit 'take action if signal out of range

if w0<75 then outtalimit 'take action if signal out of range

readadc C.4,w1 'read the tamer pot
w2=w1/5 'scale the pot reading
'w2=150+w2 max 200 'generate top-limited pulselength (within range 150 to 200)
'Next line produces same w2 product from reverse direction of trimpot
w2=200-w2 min 150 'generate top-limited pulselength (within range 200 to 150)

if w0>w2 then 'if pulsin greater than potlimit, apply potlimit
pulsout C.2,w2 'and issue it
else
pulsout C.2,w0 'demand was not limited - pass through unchanged
endif

goto main
'--------------------------------------------------------------------------------------


'--------------------------------------------------------------------------------------
' DEAL WITH OUT OF LIMIT SIGNALS [A.Bond code snippet]
'--------------------------------------------------------------------------------------
outtalimit:
w3=0 'reset 'good' frames counter
servo C.2,100 'assert continuously running zero demand pulse train
skip:
pulsin C.3,1,w0 'read r/x input
if w0=<225 then 'upper range check
if w0>75 then 'lower range check
w3=w3+1 'a 'good' pulse received, increment counter
if w0>225 then outtalimit 'Zero/restart counter if bad pulse received
if w0<75 then outtalimit 'Zero/restart counter if bad pulse received

if w3>9 then 'have ten 'good pulses been received?
low C.2 'yes, switch off zero demand pulse train
goto main 'and resume normal operation

endif
endif
endif
goto skip 'less than ten 'good' pulses so far, loop back
'--------------------------------------------------------------------------------------

end

'--------------------------------------------------------------------------------------
' VOLUME CONTROL v1.03
'--------------------------------------------------------------------------------------
Spike S
(Tune for maximum smoke)
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RON
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Re: Maximum Throttle Position

Post by RON »

Why not just re-prop it so that full power is about right.

Simples..

Ron.
G0MBV Class A Radio Amateur, North Yorkshire
belli
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Joined: 19 Feb 2018, 19:19

Re: Maximum Throttle Position

Post by belli »

Can't you plug the ESC into a conventional TX/RX and reprogramme the throttle settings?
Martin
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Location: Warwickshire

Re: Maximum Throttle Position

Post by Martin »

Most ESCs ignore signals that are greater than the usual 100% throttle signal.

If you could program the ESC so that it needed a 150% signal to give full throttle, then at 100% it would only give about 67% - but like I say, you can't normally do that, even if you have a radio or servo tester or whatever that can output a 150% signal.
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Carl
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Re: Maximum Throttle Position

Post by Carl »

Martin wrote: 24 Jun 2018, 17:06 Most ESCs ignore signals that are greater than the usual 100% throttle signal.

If you could program the ESC so that it needed a 150% signal to give full throttle, then at 100% it would only give about 67% - but like I say, you can't normally do that, even if you have a radio or servo tester or whatever that can output a 150% signal.
Before posting my question I did some searching and that's exactly what I found out Martin. My first thought was could the esc be programmed so that at max the throttle will run at 75%, but it seems that's not possible.
Ron wrote: 24 Jun 2018, 15:24 So just set off on middle throttle, you can then just quickly turn the tx off and back on and your throttle will be zero. I do it all the time and because I use frsky it links back up really quick.

Ron.
Ron, I was trying to think of a way of using the 3 position throttle without having to blip past max throttle and hadn't thought of that. I'm just running 35mhz which will receive the signal as soon as the tx is switched back on. So may try that. This will give me an idea of power setting when I use my timer as I can set a % power on that like Phil's middle setting on his encoder.

Regarding re-proping, I'm just trying to see if there's a way of reducing power first as I'm happy with the setup as it is as I can control the throttle via a propo tx.

Thanks Spike S for the Throttle Tamer, I'll have a look at that for a future project as it'll be a useful little gadget to have.

Thanks for all the help,
Carl
Carl

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Carl
Posts: 267
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Re: Maximum Throttle Position

Post by Carl »

Ron wrote: 24 Jun 2018, 15:24 you can of course set the middle throttle to various percentages. So just set off on middle throttle, you can then just quickly turn the tx off and back on and your throttle will be zero. I do it all the time and because I use frsky it links back up really quick.

Ron.
Tried this on the bench and works really well. Occasionally, when switching the tx back on, the motor spins on full power for a fraction of a second and then cuts, and then everything is normal. Tried this a dozen times and happy to have a go in the week.

Thanks
Carl
Carl

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RON
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Re: Maximum Throttle Position

Post by RON »

I do it almost every flight Carl and never had a problem.
It’s just resetting your tx to defaults. It doesn’t even have enough time for your RX to go into failsafe if your quick.
G0MBV Class A Radio Amateur, North Yorkshire
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RON
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Re: Maximum Throttle Position

Post by RON »

Just thinking aloud
You could put a push to break micro momentary switch C&K type on the top of your tx which simply removes the power from the tx when you push it momentarily. This would reset your tx and throttle would be zero. It would almost be a throttle cut switch.

Ron.
G0MBV Class A Radio Amateur, North Yorkshire
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