Transmission intergration

XCESIV · 07-15-2007, 08:03 PM

Im about to start desigining my car pc and 1 feature we are trying to look into more is intergrating the car pc to control the changing of gears in the Auto Transmission.

What are your thoughts

guizai · 07-17-2007, 12:46 PM

you can get electronic transmissions for hot rods. lets you select gears at a push of a button. I don't think I would have the computer control this feature nor try to develop it on my own. I'd go with a proven product which has the necessary redundancies and safety settings.

Wiredwrx · 07-17-2007, 01:14 PM

And, can you imagine what would happen if the computer hung at 80 mph on the freeway, and it threw the tranny into park. OUCH.

Not nexessarily a good idea. Interesting, but not really a good idea.

Having said that, integrating such a thing could be as easy as some relays, and a relay controller (search the forum) depending on the transmission type, and how you plan to use it.

Michael

DarquePervert · 07-17-2007, 01:48 PM

Even moreso, I could see a drag racer (as an example) using inputs fromt eh engine (RPM, primarily) and shifting at a certain RPM, all PC controlled.

There's a substantial amount of risk by having a PC handle that chore, to be certain. But it's an interesting idea.

I think you're going to get more mileage from using the PC with tuning software & a modern motor/trans where you can tweak shift points and the like.

shotgunefx · 07-17-2007, 02:15 PM

Think you'd want a more dedicated solution, like an embedded processor or at least something running a real time OS and just use a PC to view status,etc.

Unless you really know your stuff, I'd probably pass.

XCESIV · 07-17-2007, 07:02 PM

Im not after the Carpc to change the actual gears and shift changes, although that would be awesome and help with times on the track. Im more thinking about just changing from park to reverse, Neutral to Drive.

There would need to be dedicated safety settings built into the system.

I discussed this with my electrical engineer and the safety precaustions we can built in seem prety easy.

A Trigger can be made to only allow changes to be made when the motors RPM are under a certain level along with only working when the driver has hsi foot on the handbrake

Wiredwrx · 07-17-2007, 07:11 PM

Quote: Originally Posted by XCESIV

Im not after the Carpc to change the actual gears and shift changes, although that would be awesome and help with times on the track. Im more thinking about just changing from park to reverse, Neutral to Drive.

There would need to be dedicated safety settings built into the system.

I discussed this with my electrical engineer and the safety precaustions we can built in seem prety easy.

A Trigger can be made to only allow changes to be made when the motors RPM are under a certain level along with only working when the driver has hsi foot on the handbrake

MOST tranmission require the movement of the lever. You will need strong servos/motors/pneumatics to move them. It won't be easy, and there is no real reason to do it, well except because it is cool.

With all your safeties, what will control them, the computer. If not, then why even use the computer to change gears. Might as well use whatever will control/be the safeties to change the gears.

Michael

XCESIV · 07-17-2007, 07:34 PM

Quote: Originally Posted by Wiredwrx

............It won't be easy, and there is no real reason to do it, well except because it is cool..........

Thats exactly it. Its cool. There is no need to do any mods to the car, but we all do it.

Quote: Originally Posted by Wiredwrx

..........With all your safeties, what will control them, the computer. If not, then why even use the computer to change gears. Might as well use whatever will control/be the safeties to change the gears......

The safeties will be triggered by relays im guessing. These will be triggered by either pressure on the brake pedal or a electronic signal from the cars computer saying the rpm are under a certain limit.

I am removing as many buttons, etc from the dash as possible. Simplifying the car as much as possible.

The leaver we see in the cabin in the car is alot more complicated than the actual leaver that changes the gears in the transmission. The leaver in the cabin is normally gated to reduce the chance of wrong gear changes. This normally requiring a button to be pushed or handle lifted.

The actual transmission has nothing like this (Well not on the transmission im using) Its basically a leaver than moves to certain points for each gear.

I have been put under the impression that merc or bmw have a carpc now that does this.

Wiredwrx · 07-17-2007, 07:50 PM

Quote: Originally Posted by XCESIV

Thats exactly it. Its cool. There is no need to do any mods to the car, but we all do it.

The safeties will be triggered by relays im guessing. These will be triggered by either pressure on the brake pedal or a electronic signal from the cars computer saying the rpm are under a certain limit.

I am removing as many buttons, etc from the dash as possible. Simplifying the car as much as possible.

The leaver we see in the cabin in the car is alot more complicated than the actual leaver that changes the gears in the transmission. The leaver in the cabin is normally gated to reduce the chance of wrong gear changes. This normally requiring a button to be pushed or handle lifted.

The actual transmission has nothing like this (Well not on the transmission im using) Its basically a leaver than moves to certain points for each gear.

I have been put under the impression that merc or bmw have a carpc now that does this.

I am aware how transmissions work.

How will relays keep the thing from shifting. How will you get over the hurdle of shifting from drive to 3-2-1 if you have to push the brake, or be under a certain rpm. What is the computer won't boot, then what. No drive, or do you then use the lever which you have removed, or are you planning on leaving the lever there anyway. If so, how does that simplify anything. And, before you can pull out of yourdriveway, you have to wait for the computer to boot. That can take like 30 seconds.

But again, like I have said, you can get a relay controller, or do a servo/linear actuator to move the lever and have them controlled by the computer.

A better choice is using a basic stamp or a PIC. They don't crash, and "boot" in less than a second.

Michael

Michael

shotgunefx · 07-17-2007, 10:24 PM

Quote: Originally Posted by Wiredwrx

...
A better choice is using a basic stamp or a PIC. They don't crash, and "boot" in less than a second.

Michael

I vote PIC (or AVR etc), I don't think a stamp would give you enough control. Do stamps let you hook into the watchdog timer? I don't recall.

XCESIV · 07-17-2007, 11:21 PM

This car is not a daily, this will be a weekend car. a 30second delay isnt a problem since for security measures i empty the air suspension to delay any possible chance of the wheels being take, or the whole car.

To completly inflate the air tanke and lif tthe car it takes 22 seconds already. Another 8 is nothing. Also with running a decently modified V8 i would wait at least 30 seconds prior to taking off to have the engine warm up, etc.

The Car PC wont be controlling each gear manually. As this isnt built for anything but cruising. its only changing which drive it is in. 1-2-3 will be controlled by the standard gearing built into the car just like a normal car. Paramaters could possibly be implemented to the system to allow different variables to change from each gear, but this is something we will not need.

The paramaters would require both the brake to be on and the RPM (and possible speed) to be under certain levels before the system will allow the function to acutally occur.

Do you have any links to information on a PIC, AVR or stamp

Blacryan · 07-17-2007, 11:39 PM

On a side note that we are talkign about trannys. Would it be at all possible for a CarPC to recognize what gear you are in on a manual tranny or a auto? like a headsup display kind of like a gauge that would just say "1" "2" "3" "4" "5" "6" "R" "N"

something like that.

XCESIV · 07-17-2007, 11:52 PM

It is possible. The newer Holdens in Australia come out with that factory on there dash. This would tapped from the cars factory computer or you could make something that sensors the point in the trans it is on and work from that.

Wiredwrx · 07-18-2007, 05:08 PM

Quote: Originally Posted by Blacryan

On a side note that we are talkign about trannys. Would it be at all possible for a CarPC to recognize what gear you are in on a manual tranny or a auto? like a headsup display kind of like a gauge that would just say "1" "2" "3" "4" "5" "6" "R" "N"

something like that.

Sure, you just need micro switches and creative use of a PIC, STAMP, or relays to display what you want.

Michael

Wiredwrx · 07-18-2007, 05:11 PM

Quote: Originally Posted by Wiredwrx

integrating such a thing could be as easy as some relays, and a relay controller (search the forum) depending on the transmission type...

You will need strong servos/motors/pneumatics to move them

But again, like I have said, you can get a relay controller, or do a servo/linear actuator to move the lever and have them controlled by the computer.

Michael