While good for visualizing the motion of rigid components, the animation packages available today aren’t much help when it comes to elastic components. To get around this shortcoming, you can use “regemination”—my term for creating an animation by successive regenerations of a model file.
Once your model is set up properly, it is just a matter of clicking a few buttons and typing a name to generate the JPEG files. Amazingly, it doesn’t take many JPEG files to create a nice-looking outcome. I’ve written a small Java application to give me more control over my animations, but any free animator off the web will also do the job.
1. Create an extra-large surface feature.
Pro/ENGINEER has a tendency to position the center-of-mass after a model has been regenerated. As a result, regenerating a model will move and/or zoom the model inside the Pro/E window—a problem for animating. To counter this, you can stabilize the display by creating an extra-large (on the order of 10x or so) surface feature, such as a box around the geometry. Be sure to turn off surface feature shading in the Model Display dialog box (Fig. 1).
2. Add a few simple Pro/PROGRAM statements, if desired.
First, change the names of model dimensions that vary to logical terms. For example, use DEPTH instead of d32. You can either edit each variable dimension for your animation manually or use Pro/PROGRAM to ask you to enter new values.
Using Pro/PROGRAM is extremely easy:
To open up the Pro/PROGRAM editor, pick Edit Design under the Tools menu.
In the INPUT/END INPUT section, insert a line after INPUT and type the dimension name and variable type. In the following example, WIDTH is the dimension name and it has a variable type of NUMBER (Fig. 2).
Save and Exit.
Answer Yes to “Do you want to incorporate your changes into the model?” and pick Enter to enter values.
Pick the dimension you want to change, Done Sel, and enter the values. The model will regenerate. From this point on, Pro/ENGINEER will ask how you want to change the varying dimensions every time the model is regenerated.
To create the JPEG files, simply Regenerate, change the varying dimension values, and Save a copy as JPEG, choosing your page size and dpi. Without any scrubbing, 300dpi works well. Of course, this step is tedious so you may want to create one or more mapkeys to make things go more quickly. Anywhere from 10 to 20 images will create a decent animation.
Remember to save all the JPEG files into a single folder and sequentially append a two-digit number to indicate the animation order. For example, for a part called “chassis.prt,” generate JPEG files labeled “chassis01.jpg,” “chassis02.jpg,” and so on.
4. Clean up the JPEG files as necessary.
This is an optional step. I use a 600dpi setting and reduce the image size to create a smoother, less blocky image. This higher setting creates a 6600 by 5100 image, which Microsoft Photo Editor won’t even open. I could resize the image to around 640 by 480 using Microsoft Paint, but I instead resize all the JPEG files at once using a custom Java application. (A freeware program that works well is called JPEG Resizer, available www.virtualzone.de).
5. Animate the JPEG files.
This is the fun step. You can use any JPEG file animator you can find free on the internet (for example, ImageToAVI, available at www.aswsoftware.com). I reduce the frames-per-second rate from 29 to 15 when using ImageToAVI since the animation would otherwise run too fast. My Java application allows me to start, stop, speed up, speed down, zoom in, zoom out, loop, repeat, and step forwards and backwards.
Figure 3. JPEG Animator Controls
Voila!
Although this is a very crude way to create animations, it’s the only method I know to animate non-rigid Pro/ENGINEER parts. In fact, many of the steps are necessary just to work around some of Pro/ENGINEER’s quirks. The ability to animate non-rigid parts would be a nice addition to Pro/ENGINEER.
Toua Vang is a mechanical designer at Guidant Corporation in Saint Paul, Minnesota.
