Hy-wire is the concept car from GM made of the drive-by-wire feature.For your info...
You are absolutely right. The wires carrying signals are very much
prone to noise. In fact, the vehicle fails the EMC tests so many
times during development that it becomes a pain.
But these are some development constraints in complex vehicle
networks. There is way around this issue. The signal(s) prone to
noise are made redundant. In this case for example, the signals from
throttle position sensor are fed into both PCM/ ECM as well as a
gateway module (PJB/ GEM on Fiesta and Transit) which sits on both
high speed and mid speed bus. This module monitors the signal and
helps to idenity noise. Normal checks like Checksum etc are done
anyway at all receiver nodes to check the quality of signals.
The only downside about Optical position sensors/ coders is that they
are more expensive to implement, I am not sure if any car has got
them. Do you want me to find out more info from Europe/ NA car
--- In email@example.com
, Dev Abhishek <devabhishek@...>
> Achin, Prince,
> A couple of specific questions:The cable free linkage, aka, pot,
that seems to be favoured by car manufacturers, I'm assuming this is
a resistive carbon/cermet device. Now, I'd assume this voltage is
sensed at some remote point in the ECU. Doesn't the cable length
(even assuming differential signalling (??? how?)) must make this
pretty noise prone.
> Is it practical to use optical position encoders? Does anyone
actually use them?
> Sorry, if the questions are dumb. Please help a telecom equipment
designer here. :-)
> Achin Juneja <achinjuneja@...> wrote:
> Hi Dr. Rajesh,
> DBW has been incorporated in concept cars by many auto
> manufacturers. But the concept remains a concept !! (pardon the
> pun !)
> Questions are now being asked as to (a) whether it is really
> required, (b)who does it benefit more ---the mfr. or the user, (c)
> whether it really addresses the requirements of countries like
> Now to respond to your comments :
> > The Palio D has a cable / linkage free accelerator pedal. Some
> > model also mentioned the same. Is it the new Civic?
> In diesel engines with CRDI systems, the accelerator pedal only
> operates the APS (accelerator pedal position sensor) potentiometer,
> which sends a voltage proportional to the position of the pedal, to
> the ECU, which then controls the amount of fuel injected into the
> cyls. There is no cable or mech. linkage, other than the pedal assy.
> The Hyundai Accent, Safari DICOR, Skoda TDI, Mitsubishi Lancer D,
> Ford Fiesta TDCI all have this system.
> > Long back there was a production car with a big round btton in the
> > place of the brake pedal. I thought it was the Citroen SM. I am
> > sure. Those were the days when I used to read the British Autocar
> > magazine in the British library.
> You are right --- it was the Citroen SM, manfactured from 1970 till
> 1975, that had the strange round, zero-travel, mushroom shaped
> brake 'button'. However, this was not a 'brake by wire' system. The
> round hard rubber bulb was in fact a hydraulic pressure control,
> actuated by squeezing with the foot. The harder one pressed, the
> higher the braking force.
> The Citroen SM was probably the most technologically advanced car
> its time. It had one of the first fuel injected V6 engines,
> by Maserati engineers, & a central hydraulic system powering the
> steering, brakes & suspension ! (At that time, Panhard, Berliet and
> Maserati were owned by Citroen).
> Incidentally, the 'SM' stands for 'Sports Maserati'
> It was this car that started me off on my automobiles hobby !
> A lot of original technical info on this car & its revolutionary
> systems is now available on the web. For the benefit of all members
> who don't mind an overdose of tech. stuff, here are the links :
> This gives an overview of the SM & its background.
> This link is for the tech enthusiasts. From here, if you click
> on 'Technical Guide', you can download a pdf Guide of all the SM
> Drive safe,
> Achin Juneja
> DLE BS-2, Delhi, Mar 2005, 36300 kms, 20.4 kmpl.
> Try the all-new Yahoo! Mail . "The New Version is radically easier
to use" The Wall Street Journal
> [Non-text portions of this message have been removed]
Here's a new way to find what you're looking for - Yahoo! Answers
Send FREE SMS to your friend's mobile from Yahoo! Messenger Version 8. Get it NOW
[Non-text portions of this message have been removed]