Remote Control Car Dyno

[Michael Carruthers]

Hi all,
I am trying to build a dyno for my remote control car using labview. I have
programmed a 8051 microcontroller to calculate the current speed of the car
and send this value (in ascii) to the SERIAL port of my computer.

I need Labview to be able to calculate the TORQUE and POWER and display these
graphs on the computer screen (in realtime). Is there anyone that has done
something similar or can help me get started. Any advise / examples would
be very much appreciated.

Thankyou
Michael

Please respond via my e-mail below
kero_c@yahoo.com.au

[B & C Duffey]

Hi,

one crude way compute the power would be to use your velocity input from the
microcontroller to calculate the acceleration (rate of change of velocity)
and use good old F=ma to compute F (force) this would require that you know
the mass of the vehicle.
You could also use an accelerometer to directly measure acceleration instead
of having to compute it from the velocity. Torque is a little more
complicated, one way that a friend of mine and I devised was to use a pickup
on either end of the drive shaft and to measure the amount of twist imparted
to the driveshaft under load. Under no load the time difference between the
pulses from each end of the driveshaft maintain a constant relationship,
under load one pulse will lag (or lead depending on your point of view)
the
other (you also need the rotational speed of the driveshaft) from all this
you compute the displacement. Using the mechanical properties of the
driveshaft one can compute the amount of torque required to produce the
measured displacement. The above technique was never tried and may be
difficult to do in the real world. The method of measuring power detailed
above would give you actual road horsepower (not the horspower generated by
the engine).

Hope this helped

Chris



Michael Carruthers wrote in message
news:391ce011@newsgroups.ni.com...
>
> Hi all,
> I am trying to build a dyno for my remote control car using labview. I
have
> programmed a 8051 microcontroller to calculate the current speed of the
car
> and send this value (in ascii) to the SERIAL port of my computer.
>
> I need Labview to be able to calculate the TORQUE and POWER and display
these
> graphs on the computer screen (in realtime). Is there anyone that has done
> something similar or can h
elp me get started. Any advise / examples would
> be very much appreciated.
>
> Thankyou
> Michael
>
> Please respond via my e-mail below
> kero_c@yahoo.com.au
>

[Spencer]

I developed a small DC motor Dyno for my senior project. You need to
be able to sense the torque of your motor. We used a force transducer,
then it was just a matter of simple calculations. Power =
Torque*Rotational Velocity. Since you've got the speed, you need the
power. I don't know what your budget is like (fortunately, ours was
large), but you should be able to come up with something.

I believe the webpage is still up at the following address
http://cc.usu.edu/~sljxf/index.html it doesn't have all the complete
information, but there are a couple of pictures of what we did.

If you let me know what your budget is for purchasing additional
components, I could probably help you come up with a solution.

Spencer Anderson
spencerwa@hotmail.com



In article <391ce
011@newsgroups.ni.com>,
"Michael Carruthers" wrote:
>
> Hi all,
> I am trying to build a dyno for my remote control car using labview.
I have
> programmed a 8051 microcontroller to calculate the current speed of
the car
> and send this value (in ascii) to the SERIAL port of my computer.
>
> I need Labview to be able to calculate the TORQUE and POWER and
display these
> graphs on the computer screen (in realtime). Is there anyone that has
done
> something similar or can help me get started. Any advise / examples
would
> be very much appreciated.
>
> Thankyou
> Michael
>
> Please respond via my e-mail below
> kero_c@yahoo.com.au
>
>


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