AMT - Automated Manual Transmission

Pyrthian · Post by **Pyrthian** » Fri Jun 10, 2005 3:18 pm

was sitting at the park drinking beers, and started to ponder....
Computer controlled manual transmission. Did a minor internet search, and find this has been done. By Getrag no less. So I started thinking how to make this work for me & my 4-spd. the computers inputs would be RPM, TPS, hydraulic pressure & gear selection (which will include a "D" position). not having any experience in hydraulics, the only feedback I could think of for clutch position is by monitoring hydraulic pressure for the slave cyl. this also lets me keep the eixsting manual clutch for safety, because being of my design, it will fail at the most inoppertune time. I think I wanna go with solenoids for the shifting, for speed. hydraulic would be "softer" and would probably last longer, but I want the instant snap shifts. now onto the actual software/programming. basic instruction set would be wrapped around "if the RPMs drop, increase clutch hydraulic pressure". the "clutch hydraulic pressure drop" rate will be determined by engine RPM's & TPS. I also thought of the other end, "if the RPM climb over XXX rate, increase clutch hydraulic pressure", which would control wheel spin. got this idea from NASCAR. notice how they all have their igntion boxes in full view? because they had cheater bozes, where if the RPMs climbed at XXX rate, the box would cut back the timing. cheater traction control.
I think this will work, and work great, but am looking for comments & suggestions. and if this is already done, where I can go buy it?
and what to use for the SCM (shifting control module )? dont want to use a PC. thinking more an analog computer, than a digital computer, being the instructions are VERY simple, and the inputs & outputs are minimal.

if this sounds to stupid - let me know - I can take the flamin'

stimpy · Post by **stimpy** » Fri Jun 10, 2005 3:34 pm

I'll be following this thread.

So would this be a system whereby you could select shift modes for strip vs street? Would this be like a manu-matic type of arrangement? I may not be following your plan, so forgive me if I'm not. What would the benefit be for a daily driven vehicle, if any?

Pyrthian · Post by **Pyrthian** » Fri Jun 10, 2005 3:55 pm

well, being its reading the TPS also, the "clutching" should get more aggresive as the throttle goes down, so the "street/strip" setting will be the throttle. and, I'm not really got a plan yet, just ideas. the benifit I'm going for is FAST shifting. it started out with just using solenoids instead of those DAMN shift cables for gear selection, then I figured I could add a hydraulic pump, to run the clutch, for a quick clutch in - neutral - next gear - clutch out sequence. this part is very easy. its the daily driving, comfortable clutch slip takeoff thats the hard part.

Pyrthian · Post by **Pyrthian** » Fri Jun 10, 2005 4:53 pm

well, just thought of a big problem with my idea......
letting the throttle off during the shift. as it is right now, when the clutch goes in, the motor will rev out. ug.
nevermind....

emod19 · Post by **emod19** » Sat Jun 11, 2005 11:09 am

Why not use a rev limiter or interupt the ignition signal during the shift process? Clutch disengaged- power is cut, clutch engaged-power comes back on. This would also let the transmission shift easier from the drop in engine speed.

Steve

Kohburn · Post by **Kohburn** » Sat Jun 11, 2005 7:10 pm

pneumatics will give you the speed and be more reliable than solenoids in a hot engine bay

p8ntman442 · Post by **p8ntman442** » Sat Jun 11, 2005 8:02 pm

why not just buy a good auto and use that? Ryan.hess is building the paddle shifted 4t60e units (for 200 bucks). A better Idea, and much more practical as you can control shifting by the padles and also go full auto mode. No doubt your idea can be done, I just dont see any bennefit in doing so.

Pyrthian · Post by **Pyrthian** » Mon Jun 13, 2005 10:05 am

I dont want to power a torque convertor. thats roughly 5-10 HP, running the torque convertor/trans pump.

yes, rev limiter/ignition cut-out is a great idea - things are looking good again.

and, I'm more familear with electronics than with hydraulics, thats why I started with solenoids. but the hydraulics will probably be a better way to go, being they are slightly softer - not hammering into postion. and, since I'm already going hydraulic with the clutch....

anyways, now onto the fun stuff - still need to work out the brain of this thing. again, I think an analog computer would be a better final unit, but that would be harder to develop.

Kohburn · Post by **Kohburn** » Mon Jun 13, 2005 10:08 am

are you aiming for a fully auto or a manually controlled tiptronic sequential shifting manual that you don't have to press the clutch on?

Pyrthian · Post by **Pyrthian** » Mon Jun 13, 2005 10:40 am

ideally, a fully automated manual transmission. My drunken park daydream had a shifter laid out like:

1 D 3

N

2 R 4

and I can just push the shifter into "1", no pedals at all, and the clutch would slip away and I roll away. Then do it again, except holding 3000 RPM, and I push it into "1" again, and it tears off, with little, but no real tire spin.

The Dark Side of Will · Mon Jun 13, 2005 1:24 pm

Pyrthian wrote:I dont want to power a torque convertor. thats roughly 5-10 HP, running the torque convertor/trans pump.

yes, rev limiter/ignition cut-out is a great idea - things are looking good again.

and, I'm more familear with electronics than with hydraulics, thats why I started with solenoids. but the hydraulics will probably be a better way to go, being they are slightly softer - not hammering into postion. and, since I'm already going hydraulic with the clutch....

You're turned around... solenoids would be more gentle than hydraulics. I'd much prefer them when working a trans with a shift linkage designed to be actuated by human hands. Remember, the shift finger is held to the shift shaft in a 282 but a roll pin and nothing else...

A hydraulic clutch wouldn't be too hard. You could use a power steering pump to provide pressure, one on/off solenoid to disengage, and a PWM solenoid to apply.
The on/off solenoid would be between the slave cylinder and the pump and would be normally closed.
When you command a shift, the on/off solenoid would open, applying full pressure to the slave and disengaging the clutch instantly. A microswitch on the slave would de-energize the solenoid when the clutch was fully released, trapping pressure in the slave. The shift solenoids would make the shift, then the PWM solenoid would activate to bleed off the pressure in the slave cylinder and thus apply the clutch at a rate determined by either a shift firmness map or the length of time you pulled the paddle to initiate the shift in the first place.

If you wanted a fully electric system, you could use a fast stepper motor worm driving a ball screw to actuate the throw out mechanism. Feedback to the control system would be through a linear position sensor on the screw.

The Dark Side of Will · Mon Jun 13, 2005 1:26 pm

p8ntman442 wrote:why not just buy a good auto and use that? Ryan.hess is building the paddle shifted 4t60e units (for 200 bucks). A better Idea, and much more practical as you can control shifting by the padles and also go full auto mode. No doubt your idea can be done, I just dont see any bennefit in doing so.

Ryan's device can not go full auto. Part of the reason that it's available for $200 is that there's not provision for automatic operation. The going rate for a stand alone trans controller that can handle fully automatic operation seems to be about $700.

I haven't fully researched this yet, but I believe there are some issues with engine braking in some transmissions when the gear selected by the shift solenoids is not the same as the gear indicated by the position of the shift quadrant.

Pyrthian · Post by **Pyrthian** » Mon Jun 13, 2005 1:52 pm

The Dark Side of Will wrote: ...A hydraulic clutch wouldn't be too hard. You could use a power steering pump to provide pressure, one on/off solenoid to disengage, and a PWM solenoid to apply.
The on/off solenoid would be between the slave cylinder and the pump and would be normally closed.
When you command a shift, the on/off solenoid would open, applying full pressure to the slave and disengaging the clutch instantly. A microswitch on the slave would de-energize the solenoid when the clutch was fully released, trapping pressure in the slave. The shift solenoids would make the shift, then the PWM solenoid would activate to bleed off the pressure in the slave cylinder and thus apply the clutch at a rate determined by either a shift firmness map or the length of time you pulled the paddle to initiate the shift in the first place.

If you wanted a fully electric system, you could use a fast stepper motor worm driving a ball screw to actuate the throw out mechanism. Feedback to the control system would be through a linear position sensor on the screw.

good stuff - sounds like your on my page. I was thinking worm gear also, but I wanted to be able to have my existing clutch still functional for when something stupid happens. In yer next post, your making me think these systems are available somewhere? but, from the sounds of it, I think I'll just go the easy way, and just let it do raw shifting, and not worry about full-on automatic functions.

Kohburn · Post by **Kohburn** » Mon Jun 13, 2005 3:10 pm

The Dark Side of Will wrote:
You're turned around... solenoids would be more gentle than hydraulics. I'd much prefer them when working a trans with a shift linkage designed to be actuated by human hands. Remember, the shift finger is held to the shift shaft in a 282 but a roll pin and nothing else...

A hydraulic clutch wouldn't be too hard. You could use a power steering pump to provide pressure, one on/off solenoid to disengage, and a PWM solenoid to apply.

i still think pneumatics are the best route - fast, strong, self cusioning, and you can just wire up the electronic control solenoid valves..

The Dark Side of Will · Mon Jun 13, 2005 4:34 pm

I like electric power myself. Can control the force used by actuators by controlling voltage, can measure load by monitoring current draw. Electron pump is already installed on pretty much all engines.

The big thing that steers me away from hydraulics and pneumatics is complexity. They are extra systems that are controlled by extra systems... keep it all electric and keep it simple.

IMO, hydraulic is a bit simpler than pneumatic. Most engines have provisions or equipment available to mount power steering pump & reservoir. Mounting air compressor & tank for pneumatic drive is slightly more difficult. However, you don't have to worry very much about leaks in a pneumatic system...

Formula69 · Post by **Formula69** » Mon Jun 13, 2005 10:46 pm

RPM jump shouldn't be an issue if the shift is fast. It's called power shifting is it's common for muscle car drivers (i.e. beefy transmissions, etc.) to keep their foot planted on the floor when they shift. If your electronic controlled shift is faster, the rev increase won't be the issue.

I think the shifting speed is going to be limited to the synchros. That is unless you also program your controller to match rpms for the shift. That's how Ferrari's system works.

Better get to coding...

Kohburn · Post by **Kohburn** » Tue Jun 14, 2005 7:39 am

Formula69 wrote:RPM jump shouldn't be an issue if the shift is fast. It's called power shifting is it's common for muscle car drivers (i.e. beefy transmissions, etc.) to keep their foot planted on the floor when they shift. If your electronic controlled shift is faster, the rev increase won't be the issue.

I think the shifting speed is going to be limited to the synchros. That is unless you also program your controller to match rpms for the shift. That's how Ferrari's system works.

Better get to coding...

use the 4speed and swap in the dogbox gears.. no synchros to slow your shifts - can shift at any speed - but it'll whine like a rally car with the straight gears

Pyrthian · Post by **Pyrthian** » Tue Jun 14, 2005 9:36 am

well, I'm gonna stick with hydraulic clutch & solenoid shifting. gonna scavange some auto door locks, see if they got the throw for the shifting. I guess step one will be eliminating the shift cables, and making "push button" shifting. each push will need to activate a 2-step shift, step one being shift to netutral, step two being shifting into selected gear. or maybe, making it somewhat smart, being from 1 to 2, you dont need to goto neutral, and from 3 to 4 you dont need it either. ok: "if (new gear is on same selector set as current gear) then (go straight to new gear) else (go neutral first : then go to new gear)"....so much for simple push button.....well, off to the pile of never done ideas this goes....looking forward to my next drunken day at the park.....

Kohburn · Post by **Kohburn** » Tue Jun 14, 2005 11:18 am

a 4 or 5 poll rotary switch with enough throws to have one for each gear should be able to control it

that way you could sequentially click through the gears

Pyrthian · Post by **Pyrthian** » Tue Jun 14, 2005 12:08 pm

won't that be cute - dail-a-gear....yup - 5 position - 4 forward, 1 reverse - oops, make that 6 - need neutral.