Skip to main content

graphics - Animating a rotating disk


I have a system with 3 degrees of freedom that I want to know if it is possible to visualise with Mathematica in the two-dimensional $X-Y$ plane. I have a plane circular object rotating at its set speed say $10$ deg/s. This object is not rotating at the $(0, 0)$ origin point but is displaced from the origin $(0, 0)$ coordinates and its motion path is described by


$x=x_0 + a \times \cos(\omega \: t)$ and $y=a \times \sin(\omega \: t)$


Some values: $x_0 = 1$ mm; $a=0.25$ mm, $\omega=10$ deg/s (same as the rotating speed of the circular object). The radius of the circular object can be taken to be a couple of cm say $2$ cm.


The time parameter $t$ in the parametric equations can be discretised in $20$ steps as follows:


$\mathrm{step}= \frac{360 \; \mathrm{deg}}{\omega \times 20} = \frac{360}{10 \times 20}=1.8$ s


so that $\mathrm{step}$ will take values $0$, $1.8$, $3.6$, $\ldots$, $34.2$ s.


Thus the product $\omega \: t$ as the cosine and sine arguments of the parametric path can be written as



$\omega \: t = \omega \times \frac{\mathrm{step \times \pi}}{180}$


which in units gives $\frac{\mathrm{deg}}{\mathrm{seconds}} \times \frac{\mathrm{seconds} \times \mathrm{radians}}{\mathrm{deg}} = \mathrm{radians}$.


Any help will be appreciated to this Mathematica newbie on how to go about to simulate this kind of motion. Desired animation fatures:




  1. Perhaps the circular object can have hatched shading so that its rotating motion can be seen on top of its following the parametric circular path;




  2. The $x-$ and $y-$axes should be visible;





  3. The parametric path given by the parametric equations in $x$ and $y$ should be visible as a circle.





Answer



Lets start with some parameters (note that I've chosen larger values for a and x0 here to actually see the movement of the centre)


radius = 20;
x0 = 10;
a = 5;
om1 = 10 Degree;

om2 = 10 Degree;

The centre of the rotating object at time t is given by


centre[t_] := {x0 + a Cos[om1 t], a Sin[om1 t]};

I'm using RegionPlot to create an image of the disk centred at the origin


circ = RegionPlot[x^2 + y^2 <= radius^2, {x, -radius, radius}, 
{y, -radius, radius},
Mesh -> 20, MeshStyle -> {{Red}, {Blue}}, BoundaryStyle -> Black,
PlotStyle -> None]


Mathematica graphics


Next, we're defining a function for creating the plot at time t. I'm using Rotate and Translate to get the orientation and position of the disk. The path of the centre is plotted using ParametricPlot


plot[t_] := Show[Graphics[
Translate[Rotate[{circ[[1]], Point[{0, 0}]}, om2 t], centre[t]]],
If[Abs[t] <= $MachineEpsilon, {},
ParametricPlot[centre[s], {s, 0, t}, PlotStyle -> {Black}]],
PlotRange -> {{-2 radius, 2 radius}, {-2 radius, 2 radius}},
Axes -> True]


Plugging this function into Animate will create an animation of this function:


Animate[plot[t], {t, 0, 36}]

Mathematica graphics


Comments

Popular posts from this blog

plotting - How to draw lines between specified dots on ListPlot?

I would like to create a plot where I have unconnected dots and some connected. So far, I have figured out how to draw the dots. My code is the following: ListPlot[{{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4,13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full] I have thought using ListLinePlot command, but I don't know how to specify to the command to draw only selected lines between the dots. Do have any suggestions/hints on how to do that? Thank you. Answer One possibility would be to use Epilog with Line : ListPlot[ {{1, 1}, {2, 2}, {3, 3}, {4, 4}, {1, 4}, {2, 5}, {3, 6}, {4, 7}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, {1, 10}, {2, 11}, {3, 12}, {4, 13}, {2.5, 7}}, Ticks -> {{1, 2, 3, 4}, None}, AxesStyle -> Thin, TicksStyle -> Directive[Black, Bold, 12], Mesh -> Full, Epilog -> { Line[ ...

dynamic - How can I make a clickable ArrayPlot that returns input?

I would like to create a dynamic ArrayPlot so that the rectangles, when clicked, provide the input. Can I use ArrayPlot for this? Or is there something else I should have to use? Answer ArrayPlot is much more than just a simple array like Grid : it represents a ranged 2D dataset, and its visualization can be finetuned by options like DataReversed and DataRange . These features make it quite complicated to reproduce the same layout and order with Grid . Here I offer AnnotatedArrayPlot which comes in handy when your dataset is more than just a flat 2D array. The dynamic interface allows highlighting individual cells and possibly interacting with them. AnnotatedArrayPlot works the same way as ArrayPlot and accepts the same options plus Enabled , HighlightCoordinates , HighlightStyle and HighlightElementFunction . data = {{Missing["HasSomeMoreData"], GrayLevel[ 1], {RGBColor[0, 1, 1], RGBColor[0, 0, 1], GrayLevel[1]}, RGBColor[0, 1, 0]}, {GrayLevel[0], GrayLevel...

list manipulation - Selecting multiple columns from a matrix?

Sample data: data = { {{2013, 1, 1}, 24.13, 167.67, 231.82}, {{2013, 1, 2}, 32.15, 170.92, 225.99}, {{2013, 1, 3}, 35.43, 172.68, 221.67}, {{2013, 1, 4}, 36.73, 173.05, 218.32}, {{2013, 1, 5}, 58.19, 165.96, 197.05}, {{2013, 1, 6}, 69.99, 163.50, 187.52}, {{2013, 1, 7}, 71.37, 154.21, 175.58}, {{2013, 1, 8}, 72.51, 149.66, 163.25}}; I want a DateListPlot with three graphs, so for a matrix formed by columns 1 and 2, one for columns 1 and 3, and 1 for columns 1 and 4. At the moment I'm using this code: data2 = Transpose[{data[[All, 1]], data[[All, 2]]}]; data3 = Transpose[{data[[All, 1]], data[[All, 3]]}]; data4 = Transpose[{data[[All, 1]], data[[All, 4]]}]; DateListPlot[{data2, data3, data4}, Joined -> True, Filling -> {3 -> {1}}] but I have a hunch that this can be done more efficiently. I don't like the Transpose s in particular. Any ideas? edit (for extra credit) What if I need to multiply the second column by 2, which in my solution is simp...