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ML_79015751-Visitor
1-Visitor
Aug 11, 2022 8:02 AM UTC
Solved

Help getting this plotted correctly

I'm trying to incorporate a cycloid (standard, not epi-) into a design I'm working on. I tried to generate the appropriate curve using the equation from curve tool, but it only returned a very slight curve. I verified my equations using MATLAB. Pictures and equations are provided below:

x(t) = r(t-sin(t))

y(t) = r(1-cos(t))

where t is some angle and r is the radius of the rolling circle tracing the cycloid.

Any help would be greatly appreciated!

KenFarley
KenFarleyAnswer
21-Topaz II
Aug 11, 2022 10:51 AM UTC

The problem is that the equations as you have them are assuming the angle being evaluated is in radians.

If you are inputting the angles in degrees (0 - 360), you'll get a very large "X" result.

 

To correct this, again assuming you are setting "t" to be 0 to 360 degrees, the equations should be:

 

x = 1 * ( pi * t / 180 - sin(t) )
y = 1 * ( 1 - cos(t) )

 

This seems to give the desired curve.

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2 replies

KenFarley
KenFarley21-Topaz IIAnswer
21-Topaz II
Aug 11, 2022 10:51 AM UTC

The problem is that the equations as you have them are assuming the angle being evaluated is in radians.

If you are inputting the angles in degrees (0 - 360), you'll get a very large "X" result.

 

To correct this, again assuming you are setting "t" to be 0 to 360 degrees, the equations should be:

 

x = 1 * ( pi * t / 180 - sin(t) )
y = 1 * ( 1 - cos(t) )

 

This seems to give the desired curve.

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    MartinHanak24-Ruby III
    24-Ruby III
    Aug 11, 2022 11:01 AM UTC

    Hi,

    if you set From = 0 and To = 360 for curve from equations then use following equations.

    x=100*(t * PI() / 180 - sin(t))
    y=100*(1-cos(t))
    z=0

     

    Creo uses angle values in degrees, because of this sin(t) and cos(t) is used.

    t * PI() / 180 converts angle value to radians to satisfy cycloid definition.

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