Drive by wire and the wish to survice the experience.

[Bruce Plecan]

-----Original Message-----
From: David-HMSE Higham <dhigh at hitachi-eu.com>
To: DIY_EFI at efi332.eng.ohio-state.edu <DIY_EFI at efi332.eng.ohio-state.edu>
Date: Tuesday, December 22, 1998 5:51 AM
Subject: Drive by wire and the wish to survice the experience.


>     Hi Gents,
<snip>
 I'm also
>     contemplating drive by wire which has the potential for some
>     interesting failure modes!
>     Does anyone have a feel for a safety strategy for such a set up?

Why not see what an oem application does, and duplicate that.
With all the law suits as of late, I'd be really confident they'd have it
dialed in.

I was thinking of using the Idle
>     Switch to validate the TPS signal which used in the control loop
>along with pedal position. Call me cautious or something, but this >does
not seem enough to me!

Sometimes simplicity is the key to design.

 Cruise footbrake switch(s) not viable due to left
>     footbraking if I'm feeling daring! Are there two pots. in the TPS, if
>     not could I install a 2nd one? Any recommendations of A/D sampling
>     freq. for the TPS?

I do beleive that gm uses a 180x a sec.
>
>     On a general point re. engine protection I've worked with Diesel FIE
>     before, (please don't black list me! I bet you would if I told it was
>     Lucas!) and these EMS's have various maps/controls to limit
>     torque/fuel, e.g. max speed, max torque curve, boost limit, coolant
>     temp protection (hot and cold). What's the score in gasoline engines
>     and how's it achieved?
>
>     One last thing for now, when you talk of MAF and MAP used for timing
>     and injection calcs, do you actually mean MAF and MAp that's
>     compensated for atmospheric pressure and intake temp?

Some earlier MAP application gm did had no IAT compensation.
Manifold Absolute Pressure, why did you go with MAp?
Cheers, and welcome
Bruce
>
>     Cheers,
>
>     Dave
>