electronic gurus please, servo controlled clutch

[straker]

Hi there, due to a disability I cannot operate the clutch pedal with my leg,
I want to build a set up that is like a bike clutch lever on the gearlever, that operates
a potentiometer/servo arrangement to control the clutch pedal therefore keeping the stock clutch
operation. any help appreciated please
I know there is an italian version of this but it's quite spendy, and I cannot seem to find a supplier
who doesn't also insist they fit it. I think alex zanardi uses one in the world touring cars!

anyhoo . . all input welcome thanks . . . straker

[stevieturbo]

straker said:

Hi there, due to a disability I cannot operate the clutch pedal with my leg,
I want to build a set up that is like a bike clutch lever on the gearlever, that operates
a potentiometer/servo arrangement to control the clutch pedal therefore keeping the stock clutch
operation. any help appreciated please
I know there is an italian version of this but it's quite spendy, and I cannot seem to find a supplier
who doesn't also insist they fit it. I think alex zanardi uses one in the world touring cars!

anyhoo . . all input welcome thanks . . . straker

I think you are making it out this is easier than it is. And to compare to a money no object touring car, that will use a sequential gearbox and no clutch for the most part due to the dog engagement gears....well, speaks for itself.

Demon Tweeks used to sell an automatic clutch actuator...cant seem to find it listed now though. But it wasnt cheap.

I cant see any way of remotely operating the clutch at the gear lever, that will easily allow gearchanges, and also give you the feel required to actually drive the car from standstill.
Actually devising something that will operate the clutch either via lever or button is perfectly doable though.

Pretty sure most such devices interface with engine rpm etc, so the feeding of the clutch is computer controlled so to speak.


To just make a clutch system that operates on or off, with no feel...either pneumatically or hydraulically, wouldnt be a massive task though. Still cant see it being cheap.
And then there might be insurance implications.

[VYT]

Well, the basic setup "could" be quite simple and involve no electronics.
If you could fit a small compressor, maybe electric or engine driven then you could fit an air cylinder in place of the hydaulic slave cylinder and use a hand operated 3 port valve to operate the cylinder.

One level of complication above that would be to use a hand operated air pilot valve, that will require less effort to operate and smaller piping to the gear leaver. The air pilot is used like an electrical relay would be used. It supplies a small amount of air to "switch" another valve which actually operates the cylinder.

You can of course have a switch on the gear leaver which operates a "solenoid" valve if you like.

Provided you can get a cylinder that can fit into the space and can provide enugh stroke with enough force then it should work fine.

What you will probably need is some control over the relese rate. That can be achieved with a restrictor, or say 2 separate valves on the exhaust of the cylinder. One valve to set a slow release for moving from rest and another for changes on the move where you want the clutch to engage somewhat quicker.

You could setup a system where you set a valve for "Launch" then let the lever go and the clutch will engage smoothly you then toggle the "launch" to "run" for normal driving, or jut put up with a slow engage and modulate the throttle accordingly.

A small embedded controller could be used to control all of the valves. Then your hand clutch lever would operate a switch. A second input could determine if the vehicle is moving then the controller can decide what clutch engagement method to use. Of course, playing with controllers is where the cost starts to spiral unless you want to learn how to program the embedded controller. You could buy a ready built controller to do this kind of control from RS or Farnell, you just need to learn how to program it, or know somebody that can.

[straker]

thanks for the replies, I hadnt considered pneumatic . . .

I was thinking along the lines of a wiper motor or similar under the floor with a small chain to the clutch pedal, and the lever on the gearstick works a potentiometer to control the sweep of the motor, the motor then pulls the clutch pedal down . . . the potentiometer and electronic chip programmed allowing me to hold the motor mid-sweep ( wherever I hold the lever ), ie at biting point of the clutch

certainly several alternatives to think about for me, I'm in no hurry at the moment, and I have a couple of cheap ideas that if they don't work out aren't going to hurt my pocket too much!

thanks . . .

[dilbert]

http://www.remap.org.uk/remap/links.html

A voluntary organisation that specialises in engineered solutions to virtually any medical engineering problem.

Edited by dilbert on Friday 28th May 09:37

[annodomini2]

Try these:

http://www.rse.co.uk/twinclutch.htm

[fergus91]

if you want i can put you in contact with a race team that has had quite a bit of experence makeing race cars completely hand control ( they used to have a driver that was paralised from the hips down) a clutch setup would be quite easy to do

[straker]

that would be great, as long as you dont think they would mind me pumping them for info! thanks

[Mr2Mike]

The Smart ForTwo and Roadster etc. use an electronicaly actuated but otherwise conventional clutch, as does the Fiat Seicento 'Citymatic'.

The complexity lies not with the mechanical side, but the control system. Since the bite point of a clutch moves as the friction surfaces wear, and the range of movement between just biting and fully engaged also changes, the system has to compensate for this and this is not a trivial task.

[anonymous-user]

Both Vauxhall (easytronic) and ALFA (Sillyspeed, sorry, Sellespeed) used conventional hydraulic clutch actuation methods, but bolted on an electric "power pack" that provides the hydraulic pressure to actuate the slave cylinder.

http://www.ecutesting.com/vauxhall_vectra_c_easytr...

With these systems the "power pack" contains all the necessary actuators and sensors to just "bolt on" to your clutch system. The trick bit would be hacking there command protocol, which may be easy or might be an absolute PITA !! If you picked a late model device it would almost certainly be a CAN physical layer, so a simple 8 bit micro (AVR/PIC etc) with a CAN node could easily be configured to control it, with say a position target input from a linear potentiometer mounted to a lever on the steering column etc. With this solution you will just have a "dumb" hydraulic servo or "follower" system.. You would have to still feather/ feel for the bite point which is suprisingly difficult when you havent got any pressure feedback (clutch pedal load actually falls once "over centred" giving the driver a nice positional feedback que, (even if you don't realise you are using it!)

moving to the next level and fully automating the clutch, is hard and requires a position adaption on clutch wear/temperature/ slip speed etc, bit of a 'mare (which is why things like Sillyspeed are so crap at getting it right /smooth! You also really need to control "slip" in real time during the engagement / disengagement etc

everything you ever wanted to know (and quite a lot you probably didnt!) about clutches and actuation:

http://www.schaeffler.com/remotemedien/media/_shar...



EDIT: Forgot to add: Is your car cable or hydraulic clutch ??

2nd EDIT: Also Forgot to add: Pneumatic system would be a 'mare, as the clutch's slip ratio depends upon pressure plate clamp load, which is highly non linear with displacement, and even goes down once over centred !! You need a "displacement" system, that give "positional" control of the CRB (clutch release bearing)

Edited by anonymous-user on Saturday 29th May 15:51

Edited by anonymous-user on Saturday 29th May 16:43

Edited by anonymous-user on Saturday 29th May 17:42