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5-Regular Member

## 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!

1 ACCEPTED SOLUTION

Accepted Solutions
21-Topaz I
(To:ML_7901575)

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.

2 REPLIES 2
21-Topaz I
(To:ML_7901575)

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.

24-Ruby II
(To:ML_7901575)

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.

Martin Hanák
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