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

**Chester** · 05-06-2009, 09:22 PM

Originally Posted by turbocad6

I ordered everything from http://www.trossenrobotics.com/

I ordered a 4" stroke actuator with built in pot. 4" is more than enough for prnd but if you want to go through 3-2-1 also then get the 6"...

The only downfall that I can see with that actuator is the speed of it, at 0.5 inches / second.

That means that from park to drive, you are looking at up to 8 seconds to make the change.

Definately not knocking the parts, thats some good quality kit at a good price, but just think about how long you would normally take to shift between gears, I know I would only take about 1 second max to shift from park all the way through to drive.

Just something to think about, I hope I'm not sinking a ship here, because I would LOVE to do this mod (I have a tribute with a column shift, which I would kill to get rid of the column shifter!).

But let us know how it all goes, I'm following this thread keenly.

**turbocad6** · 05-07-2009, 01:40 AM

that's at max load if it was lifting 110lb's, it'll take me around 1.5 seconds from park to drive I think & with a stronger actuator I can decrease the pivot point leverage to use even less stroke. I did look at high speed one at the other site I linked but that's better for longer stroke applications & only 35lbs force instead of the 110... I think it'll be fine & I'll be able to fine tune the shift time to a certain extent through altering the pivot points...

**Crinos** · 05-07-2009, 03:28 AM

Do you have any options for quicly putting the car in neutral?
Say you drive on snow, and suddenly the car skids and you need to put it in neutral for easing the torque on the drive wheels.

Love the idea of moving the shifter completely, but I see some drawbacks as well... Lack of quick neutral beeing the biggest one...

**2k1Toaster** · 05-07-2009, 03:34 AM

What about a flappy-paddle system as a backup for those "just in case" moments?

**Chester** · 05-07-2009, 04:49 AM

I guess that would be my worry too, how reliable the unit is...

I would think that would be part of the added cost of the EMC systems, the fact that its pretty much failsafe.

How reliable would it be if used with something like an ardiuno board? Last thing I would want is to be stuck out in the country 250km from anywhere, with no shift abilities!

And good point on the shift speed turbocad, I missed the bit that it was at full load. Would be interesting to see how much pressure is actually required to shift the transmission in real world use.

**Tony G** · 05-07-2009, 06:00 AM

Saw the reference to the firgelli linear actuators - thought I would share my experiences with them.

Use a high-speed (2"/s) 18" travel firgelli for my sliding drawer fridge/freezer - again in my project VW T5 Caravelle exec. Although its the high-speed gearing, it has suprising torque to it - certainly overkill for a 30L fridge drawer. The fridge idea was the reason why I had to lose the handbrake (down an otherwise vacant space between the seats), hence the mobility actuator previously mentioned.

The new SPAL 3 button controller looks excellent - it would of been perfect for my fridge 1) open full 2) open half (just for your drinks) 3) and close. Given the in-built limit switches - I did the 3 modes using good old 555 timers! and relay - simple but effective. Wouldn't dream of using them for gears though!

So far, no issues with either linear actuator - in fact love the electric handbrake.. Linear actuators are friendly beasts, and will find their way into more carputer (MP3car) project cars I'm sure.

For me, a failsafe would be essential on a gearshift, and could come from an simple overide bi-directional switch to supplant the PIC control.
Good luck Turbocad!!

**turbocad6** · 05-07-2009, 11:41 AM

for those that don't know me,I am a nut, totally anal & an obsessive compulsive person in general, so yeah, I did already consider each & every safety concern & each & everything I can think of that "could" go wrong. you can be sure that I will address each the best way I know how.

first concern is a brake lock out. don't want the car to be running & something accidentally hitting a drive gear & the car taking off on you. this is the reason for the brake lock out on most cars & this is very easy to achieve. no gear can be selected unless the brake is depressed.

second largest concern is a reverse lockout. most cars with shifters use a button on the shifter that would need to be pressed in order the engage reverse. this is so if you're driving down the road, it is harder to acidentally engage reverse or park... this can be done with a speed sensor to be even safer than most OEMS though with an electric shift, as with most OEM's it's still not very difficult to accidentally engage a reverse or park gear even when moving, but on a fully electric setup it's not to difficult to make these engagements totally locked out... ideal situation there is that drive & neutral can be engaged at any speed, but reverse & park can only be engaged with no vehicle movement... ultra ideal would be a threshold lockout at say 4-5 mph, as I usually don't like to wait for a full stop to engage reverse to drive & back... you won't hurt anything engaging an opposite gear at these low speeds & I do it all the time, allows for much more fluid driving & maneuvering in general.

a failsafe manual override for the actuator is easy to pull off in case of logic failure.

I've done work with actuators before & they are super reliable, chance of actual actuator failure is very slim, & in a case like that worse case, I'd have to crawl under the truck, pop a clevis pin & select a gear manually in an emergency. not like I have never had to do that even with manual shifter cars in the past anyway, the option is there but I can't see ever having to use it with the exception of a completely dead battery & a need to engage neutral to roll the dead vehicle. again, this can be accomplished in an emergency situation by crawling under the truck.

I have never ever come across a time that I would need to engage neutral when driving, ever... with the exception of a vehicle stall. then, you'd want to be able to shift to neutral to restart while still rolling, again, not impossible to accommodate though, & in my ideal setup I would be able to go back forth drive to neutral & drive at any speed anyway, so this should be accounted for...

the first day I install this, since I may not have any or all of the safety lockouts in place from the get go, my idea would be to initially at least have a second button that also needs to be depressed for any shift movement, so I will need to press a button on the left of my column with one hand while selecting a gear with the other... crude but safe initially. unless I'm holding the left button in the actuator can do nothing...

if I can get the ardino figured out & under control that would go a long way toward implementing these safety's, as it can be fed a speed reference & a brake input & then programming with AND or NOR... if I can't deal with the ardino then these same safety's could be implemented with separate electronics like relays & stuff...

**Tony G** · 05-10-2009, 04:48 PM

I can see your project is well researched. Has led me to do some of my own, and can see the technology is well known as "shift by wire", with many google returns. Dura have a system which can be adapted to standard auto boxes. Might be worth looking at this for more info...

"Dura Automotive Systems have released a 'shift-by-wire' system for adaption to standard automatic transmissions. It will be used by Citroen in the C4 Picasso Auto. The system utilises an Electronic Control Unit (ECU) coupled with a 'Mechatronic Actuator' which shifts all positions (P-N-D-R). it can shift from Park to drive in 250 milli-seconds"

The product page here: http://www.duratronics.net
Sadly lacking detail...

**Jitters333** · 05-19-2009, 07:13 AM

Originally Posted by Tony G

Saw the reference to the firgelli linear actuators - thought I would share my experiences with them.

Use a high-speed (2"/s) 18" travel firgelli for my sliding drawer fridge/freezer - again in my project VW T5 Caravelle exec. Although its the high-speed gearing, it has suprising torque to it - certainly overkill for a 30L fridge drawer. The fridge idea was the reason why I had to lose the handbrake (down an otherwise vacant space between the seats), hence the mobility actuator previously mentioned.

The new SPAL 3 button controller looks excellent - it would of been perfect for my fridge 1) open full 2) open half (just for your drinks) 3) and close. Given the in-built limit switches - I did the 3 modes using good old 555 timers! and relay - simple but effective. Wouldn't dream of using them for gears though!

So far, no issues with either linear actuator - in fact love the electric handbrake.. Linear actuators are friendly beasts, and will find their way into more carputer (MP3car) project cars I'm sure.

For me, a failsafe would be essential on a gearshift, and could come from an simple overide bi-directional switch to supplant the PIC control.
Good luck Turbocad!!

So you put a freezer/fridge in your car? Am I mistaken

Edit: and my contributions to the thread lol

I found both those items on ebay, from the same dealer ~150$
http://cgi.ebay.com/Linear-Actuator-...QQcmdZViewItem

Edit2: And i still don't get how you will get N/D into one button? How is that going to work? and man you would think there would be more controllers like this one out there... I couldn't really find one

**turbocad6** · 06-02-2009, 01:22 PM

I have recieved all the parts, have done a quick test & everything looks fine so far... actuator is plenty powerful for this task & I can reduce the throw for fast enough shifting no problem... there is no room to mount this actuator directly to the shift arm at the tranny so I will have to remote mount it & have it cable actuated... haven't had time to do it yet but should pretty soon... I'll update when I do...