electromechanical P-R-N-D development HELP!!!

turbocad6 · 05-02-2009, 01:37 AM

OK, guys, I need some help on this one.

I need to remove my shifter from my console completely, I have things that would be better use of the space, I want to build a custom console that houses the display & control for my audio processor as well as a central command style control section with like a dial & several buttons around it for pc control like an i-drive or me/be type setup & I need to keep space for 2 cupholders so the shifter just has to go

I've always loved the mercedes electric shift, uses a stalk oposite the turn stalk thet you just push up for reverse, down for drive, push in for park, etc... when ever I want to manually shift I do that now with my paddle shifters already, so having a mechanical shifter is something I wouldn't miss one bit.

I don't necissarily need to have the stalk type setup, actually I think ideally though control would be best if there was an input for each gear selection by the push of an individual button, so any gear can be one push away, but I'm not opposed to the alternatives, which could be a potentiometer that sweeps through a range such as a servo control or worse case even a paddle type up/down setup, kinda like an electric ratchet shifter, to go from park to drive would be 3 taps down to r then n then d.

I am determined to do this but I have very little electronics knowledge as far as programming a pic or figuring out a way to do logic control, not enough to build an electronic control or something that would be able to sense position & make appropriate adjustments from different inputs or anything like that, my original idea to do this completely with just the knowledge I have was to convert my existing mechanical shifter to a real mechanical ratchet shifter, so at least I can electrically control it with just an up or down action, which could be done with a motor not too difficultly, then burry this whole ratchet shifter with motor & leavers attatched to it somewhere.

I even got as far as buying a B&M ratchet shifter & a 12v drill for it's motor & clutch, but then, I step back & look at what I'm doing & realize, I'm really kinda doing it the caveman way. I mean I'm pretty sure I could get it to work, but there are so much better ways to do this, so this is why I turn to the forum, for help & ideas as to how I could control something like this... what kind of a motor I could buy that would be appropriate for position control & how I could control it. linear actuator? great, I can hook it up, but how would I control it through the gears?

the actual gear shift movement is a shaft that rotates, there is a lever that comes off of the shaft. it needs to move an equal amount for each progression through the prnd range. fabrication is not a problem for me & I could fabricate a position sensor into this no problem but I don't even know what to do with a position sensor electrically... any help would be greatly apreciated with this project...

fixerofallthing · 05-02-2009, 07:04 AM

The hot rodders use these, and there are several, this is one example.
http://news.hspn.com/articles/836/1/...eed/Page1.html

turbocad6 · 05-02-2009, 10:20 AM

I have seen that, but $1,000 is hard to swallow, especially when it could be done for a few hundred. I wouldn't use there billet buttons... I guess I started this thread to help figure out a way to control either a linear actuator or even a stepping motor so I could build something that functions similar to that, but I do appreciate the input & the link...

Bugbyte · 05-02-2009, 04:47 PM

Right, I think a linear actuator is one of the things you need. You'll probably also need a stepper motor or a different linear actuator to move the control if it isn't a simple straight line.

I think you can use an Arduino board and some basic programming to get the thing to work, then find a way to put it on a chip as a program.

2k1Toaster · 05-02-2009, 05:39 PM

Is the shifter really mechanical in that? I thought with most new autos the shifter was all electric and it just sent signals to the gearbox to do its thing. So just send the signals without the whole shifter part...

turbocad6 · 05-02-2009, 08:54 PM

yeah nick, actual internal shifting of the gears like 1st 2nd 3rd etc is all electronically controlled on most modern cars, but P-R-N-D isstill mechanically engaged in most cars, my shifter is connected to the transmission with a rod & the gear selection is 100% mechanical, once drive is engaged then it is electronically controlled, which is where the paddles take over if it's not in auto mode...

something like this: this would be awesome to use, but I don't know how to control it...

"12 VDC 110 LB. LINEAR ACTUATOR
Brand new, SPAL part number LACT4P linear actuator. Built-in potentiometer allows for use with position-sensing circuits. Metal housing is water resistant and sealed against dust. Permanent magnet motor. Non-adjustable limit switches at end of stroke both directions."

something like this is almost good enough to control it, but it only does 3 positions & I need 4, wonder if 2 of those can be hooked up at the same time? maybe theres a way to use this for R N & D & then an override to engage park? hmmm.....

assuming the mounting & stroke are sorted & not an issue, how can I control something like that actuator? with it already having a built in potentiometer It would be very cool if I could figure out how to control it's position relative to a variable resistance even, I could then build my own mini shifter, it could translate to a variable resistance, & then build stops where I need them...

I can't see buying a kit for 1K when all I need is a $165 actuator & a way to control it. is there anyone who could build this control for me? if I had the option of adding some logic, like brake needs to be depressed to move from park or no speed input to go from nutral to reverse that would be even great, but I don't want it to be so complicated that it's unreliable, I can devise saftey lockouts external from control too I think...

turbocad6 · 05-02-2009, 08:58 PM

bugbyte, I took a peak at that Arduino board, do you know if it operates independant of a pc after it's programmed? wonder if that can be used for this, but it looks very intense to learn how to program,... I'll read more about it later... thanks for the input so far guys, I'm sure I can come up with something better than the caveman shifter I originally designed for this

quantum · 05-02-2009, 11:33 PM

Hey TurboCad!

I posted a thread on this exact same thing like 2 months ago. I wanted to do it to the DTS. Here is the thread, with a cool pic of what I was trying to imitate.

I was looking at that exact site and controller, but like you said, 3 positions is no good. I would need PRND321.

With the setup that is currently in place, I was going to cut the stalk on the floor shift below the top of the console, and make the actuator push/pull it to gear. Going further, the shift assembly could be removed and it could push or pull just the cable. Going further than that, I thought about even mounting something to te trans itself, but that was a little much.

My thought was to make it completely independant od the PC, it would suck if Windows farts and I coudn't drive. The Arduino board looked like the best option.

If you get someone to program one, maybe they would do 2 of them? I would be interested in having it done too!

Subscribed.

Which vehicle are you modding now? The FX?

GL!

Bugbyte · 05-03-2009, 12:08 AM

Quote: Originally Posted by turbocad6

bugbyte, I took a peak at that Arduino board, do you know if it operates independant of a pc after it's programmed? wonder if that can be used for this, but it looks very intense to learn how to program,... I'll read more about it later... thanks for the input so far guys, I'm sure I can come up with something better than the caveman shifter I originally designed for this

I don't think that the Arduino requires a computer except to program it. After that, I THINK that you can simply power up the board and use it as you wish.

It appears that the linear actuator you linked to has a potentiometer on it. If the arduino can measure the resistance (I think this can be done), then you should be able to program the Arduino to move the actuator to a certain position based on a button that is pushed.

turbocad6 · 05-03-2009, 01:36 AM

I like this guys line of thinking:

Quote: Originally Posted by CraziFuzzy

The other, even more reliable option, would be a pot feedback on the linear actuator, a bank of resistors a multiposition switch, and a comparator. Basically, each position of the switch would produce a 'desired' resistance (which is used in a voltage divider). This voltage is compared to a matched divider using the feedback pot on the actuator. If less than, move the actuator one way, if greater than, move it the other way. comparitors would be set up with a slight offset so there is a deadband between pos and neg differences, preventing 'hunting'.

This is basically turning the linear actuator into a servo, with preselected positions. This is done when building full-sized RC cars (a really fun, but expensive hobby)

I like that, simple & to the point, no complicated programming, I could then build a shifter instead of just buttons... 2 good leads so far

quantum, if you did do do this, you really should go to the tranny with it or at least remote mount it under the hood & attach to the tranny with a shift cable or something, doing this is worthwhile if your going to gain all that wasted space taken up by the shifter. if your going to leave it there & add an actuator to it your kinda defeating the main benefit & reason to do this conversion to begin with I think..

yeah, this is for the fx, I'm adding the dbx processor & doing a system & want to put the dbx display & controls in the console...

Tony G · 05-03-2009, 04:57 PM

might be worth taking a look at "mobility" (as they are called in the UK) solutions. Had my car handbrake replaced with a linear actuator to create space in the central console, and noticed (with interest), off the shelf solutions for auto gearboxes. Example below:

http://www.emc-digi.com/explore.cfm/smartshift/

malcom2073 · 05-03-2009, 05:05 PM

Quote: Originally Posted by Bugbyte

I don't think that the Arduino requires a computer except to program it. After that, I THINK that you can simply power up the board and use it as you wish.

It appears that the linear actuator you linked to has a potentiometer on it. If the arduino can measure the resistance (I think this can be done), then you should be able to program the Arduino to move the actuator to a certain position based on a button that is pushed.

I've gotten to play with them and they do operate entirely independently of the computer (if programed to do so). You also can measure resistance using the analog inputs and the internal pullup resistors, then it's just a matter of comparing voltages. I measure thermistors that way for temperature.

Blues · 05-05-2009, 01:19 PM

Quote: Originally Posted by Bugbyte

I don't think that the Arduino requires a computer except to program it. After that, I THINK that you can simply power up the board and use it as you wish.

Yes that's correct, the Arduino does not need a PC to run, only to program it.
It's contains an 8-bit Atmel AVR flash microcontroller.

turbocad6 · 05-05-2009, 02:41 PM

from what I'm gathering, the arduino is a good tool for this job, I'm going to order one & the actuator & see how far I can get with programming it, I'm sure with enough effort I can get this sorted & working...

I think I kinda need the actuator in place anyway just to really program it, cause I guess I'll need reference values for each of the positions anyway...

guys, thanks again for the help so far, hopefully others can take advantage of this too, how many would rather have a keyboard or a display or even something else where there ancient mechanical shifter may be?... the way it looks, an actuator & the board to control it isn't much more than $200... figuring out how to program it, guess that's the key to tie it all togeather, but once a program is written then it could be used as a template for anyone I think, just have to input there position values I guess, if I'm picturing this right...

turbocad6 · 05-05-2009, 02:44 PM

oh, & tony g thanks for that info, but from what I've seen, even with handicap options, they are extremely expensive, I've seen stuff over $1,000 but nothing really under...

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