# Driving parts with velocities

Hi everyone,
My name is Alex and I am currently undertaking a PhD looking into
tailoring a bicycle chainring to a specific rider. To do this I would
like to be able to drive the model using a velocity profile of the
pedal, and also a torque profile (though this is not so important at
this stage). In an ideal world I would like to be able to get AnyBody
to alter the velocity profile itself, in effect changing the chainring
shape, so that muscle work load can be reduced and the overall
efficiency improved. I believe it is not possible to get AnyBody to
directly alter the input files themselves so will probably end up doing
this with MatLab. Does anybody have any suggestions as to how i can
successfully get the model to run from the pedal velocity profile? Any
assistance would be greatly appreciated.

best regards
Alex Purdue

p.s. I am using the full body bike model from the repository atm

Hi Alex

I think the best way to do this is to parameterize the motion using the
Fourier driver, here you can add as many terms as you like.

These parameters can be used as design variables in an optimization loop.

Alternatively it could also be done by an interpolation function where the
controls points will be your design variables.

Both approaches can be used for the motion or the load.

You are right that you can not make AnyBody directly alter the variables if
these are written in a text file used for into to a interpolation function,
but the variables could be defined in the script.

Something like this may do the jobâ€¦

AnyKinEqInterPolDriver driver = {

``````   Type =bSpline ;

BsplineOrder = 4;

T = { Main.MyStudy.tStart,Main.MyStudy.tEnd}

AnyVar v1=0; //these variables can be used as design variables...

AnyVar v2=2;
``````

``````   AnyVar v20=16;

Data = {v1,v2....v20};

AnyKinMeasure &crank = Reference to the crank joint â€¦
``````

};

So have a look at the AnyKinEqFourierDriver and the AnyKinEqInterPolDriver
objects, the bike model you are using already uses the Fourier drivers but
you could add more terms if you need more freedom in the shape, and these
terms could be design variables in you optimization.

Both of these options drive the position directly so this indirectly
controls the velocity profile, wouldnâ€™t this be ok?

Best regards

SÃ¸ren, AnyBody Support

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of alex.purdue
Sent: 05 December 2008 12:39
To: anyscript@yahoogroups.com
Subject: [AnyScript] Driving parts with velocities

Hi everyone,
My name is Alex and I am currently undertaking a PhD looking into
tailoring a bicycle chainring to a specific rider. To do this I would
like to be able to drive the model using a velocity profile of the
pedal, and also a torque profile (though this is not so important at
this stage). In an ideal world I would like to be able to get AnyBody
to alter the velocity profile itself, in effect changing the chainring
shape, so that muscle work load can be reduced and the overall
efficiency improved. I believe it is not possible to get AnyBody to
directly alter the input files themselves so will probably end up doing
this with MatLab. Does anybody have any suggestions as to how i can
successfully get the model to run from the pedal velocity profile? Any
assistance would be greatly appreciated.

best regards
Alex Purdue

p.s. I am using the full body bike model from the repository atm

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