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Author Topic: Steering options  (Read 1864 times)

Colin Bishop

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Steering options
« on: March 09, 2009, 09:14:15 PM »

If the idea of a dedicated mixer doesn't appeal then there are some more basic options which might offer an alternative.

The idea is to switch between one stick steering and "tank" steering by using a third channel to "group up" or "group down" your speed controllers using  a RX switch.

The "dots" on the TX indicate whether the motors are slaved to one TX or are operating independently in "tank" steering mode. The "retract" switch is used to toggle between the two.

Colin
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John W E

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Re: Steering options
« Reply #1 on: March 09, 2009, 09:20:53 PM »

Hi ya there Colin

Have you tried this method out on modern-day Speed Controllers - especially the PIC ones? - due to the fact that some PIC Speed Controllers do not like to have their signal from the RX to the Speed Controller tampered with - by switching it on and off.

That is if I have understood your circuit diagram correctly?  :-)

aye
John
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Colin Bishop

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Re: Steering options
« Reply #2 on: March 09, 2009, 09:45:03 PM »

Fair point John but no problems with the ASTEC ESCs fitted to the model.

Colin
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Peter Fitness

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Re: Steering options
« Reply #3 on: March 09, 2009, 09:49:07 PM »

Very interesting, Colin, but in light of John's reply, would it work with Mtroniks ESCs?

Peter.
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Colin Bishop

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Re: Steering options
« Reply #4 on: March 09, 2009, 10:02:13 PM »

No idea! I suppose it depends on the individual ESC setup sequence. Suck it and see I suppose....

Colin
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malcolmfrary

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Re: Steering options
« Reply #5 on: March 11, 2009, 10:24:45 PM »

Most ESCs should be tolerant of the occasional momentary loss of signal.  If the switch is a microswitch, it should hop from one state to the other before the PIC gets stroppy, as a side effect of the PIC programming needing more than one frame to fully settle on a new value.  Each data frame is about 20mS long, each channel uses about 2mS, the microswitch will change state in about 1 mS - the PIC will at worse get one mangled frame, a frame a couple of mS early or late, of a missed frame.  If the ESC is programmed for the real world, it must tolerate these conditions, or gather a lot of complaints.
MicroSwitches got the name not from the size, because most are big for the current handling, but from the shortness of the switching time.
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Colin Bishop

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Re: Steering options
« Reply #6 on: March 11, 2009, 10:39:09 PM »

The switch in my setup is a relay (see pic). I would imagine the changeover is pretty instantaneous.

Colin

P.S. Where is FLJ when we need him?
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malcolmfrary

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Re: Steering options
« Reply #7 on: March 11, 2009, 11:01:17 PM »

At best, probably about 3 to 5 milliseconds, but with a shorter contact bounce time.  Still shorter than the frame time.  There are solid state ways of doing the job without messing up the data stream, they just need one of the gentlemen on here who are up to date with this new fangled stuff.  Of course, it would probably actually cost the same as a mixer........
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Colin Bishop

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Re: Steering options
« Reply #8 on: March 11, 2009, 11:24:48 PM »

Quote
Of course, it would probably actually cost the same as a mixer........

And there's the rub!

Mind you, there is a difference. Using a mixer is a bit like driving an automatic car whereas this method is analogous to a manual one. Whatever takes your fancy I suppose.

Colin
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FullLeatherJacket

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Re: Steering options
« Reply #9 on: March 12, 2009, 07:50:46 AM »

Use of a mixer requires only two channels to effect steering via differential motor speeds; this requires four. Nice if you have them to spare; most don't.
ACTion Condor speed controllers are Autoset, so you would need to wait two seconds after changing over to be sure that the ESC microprocessors have re-set properly. During this interval any movement of either stick will move the neutral position for one or both of the speed controllers.
For this reason I don't advocate using Mr Bishop's system in conjunction with our speed controllers, so any damage caused by doing so would be outside the terms of the warranty.
I wouldn't like to comment on its suitability when using other speed controllers.
FLJ
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Colin Bishop

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Re: Steering options
« Reply #10 on: March 12, 2009, 09:09:45 AM »

I'm only using three FLJ but the points made by yourself and others about using this method with modern ESCs is a very valid one.

Colin
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FullLeatherJacket

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Re: Steering options
« Reply #11 on: March 12, 2009, 11:06:04 AM »

I'm only using three FLJ but the points made by yourself and others about using this method with modern ESCs is a very valid one.

Colin

Really?
Mixer = One channel for rudder (e.g. RH Stick side-to-side), and the other for motors forward/reverse (e.g. LH Stick Up/Down)

Now.... let me try to count the number on your sketch again:
1. Rudder (RH Stick side-to-side)
2. ESC #1 (RH Stick Up/Down)
3. ESC #2 (LH Stick Up/Down)
?  Mode Changeover (2-way switch)

Bother! I must have lost a finger somewhere............

FLJ
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Colin Bishop

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Re: Steering options
« Reply #12 on: March 12, 2009, 01:12:08 PM »

I assumed you meant the speed control function only FLJ. Sorry about your finger, I can guess where it is.... :o

Colin
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