15-394 Assignment 2: Build an Automaton

Design

  • Design an automaton in SolidWorks. It should be a cam-driven automaton like the ones we saw in the videos, with at least four moving figures. It must be three-dimensional, not planar, meaning that the segments of your automaton cannot all move in the same plane the way the LittleMan automaton did. A hand crank should power the mechanism. Nothing other than the crank should be hand-driven.

  • To start, download FrameParts.zip, and LinearBushingPatterns.zip, and inspect their contents. You can use these as a starting point for your design. The example frame should be modified to provide for four figures and any other changes you need to support your specific automaton design. There are two choices for linear bushing with subtly different shapes: LinearBushingPattern_10_6_50 and LinearBushingPattern_10_6_65. They both have 10 cutouts, but the cutouts are a tiny bit wider in the former design.

  • At least one of the four figures in your automaton must implement rotational motion, and at least one must use a cam with linear bushing. The rest is up to you. Please see the example automaton in IDeATe for an idea of what you should do.

  • Materials provided: 12x24 inch hardboard (3/16 inch thickness); 1/2 inch diameter wooden dowel; 1/4 inch diameter delrin rods (6 inches long; you can cut them shorter) to serve as cam followers.

  • Designing your automaton involves making the cam parts, gears, and crank handle, and designing the figures and any background scenery required. Attach the stabilizing rings to the camshaft, located outside of the side panels, to help prevent the camshaft from slipping left or right, which could cause the dowels to fall off the cams.

Simulate

  • Simulate your automaton in SolidWorks. Remember to turn on SolidWorks Motion in the SolidWorks Add-Ins tab, and then change the animation type from "Animation" to "Motion Study".
  • Save an animation file from your simulation. To do this, click on the Save Animation button which is in the same row as the Motor, Damper, and Solid Body Contact buttons, but further to the left. Use the AVI file format. Be careful not to make the file size too big; keep it below 40 MB.

  • Some tips: You can use cam mates to simulate cam motion in your mode, but cam mates don’t work well in motion analysis. Instead of relying on these for the analysis, make solid body contacts and add gravity. Also, use a solid body contact between the gears; otherwise the top gear will slip through or slide down the camshaft.

  • Don't make the cams too pointy or they will get stuck on the dowels during the motion analysis, and the physical device might bind.

  • Use "lock" mates to attach the cams to the camshaft instead of checking the "lock" checkbox in the coincident mate. The latter won't work in motion analysis, but lock mates do work.

Fabricate and Assemble

  • Laser cut your parts using some combination of Masonite/hardboard, wood, cardboard, and acrylic. It might be a good idea to cut each cam twice and double them up; thicker cams make it easier for the delrin cam followers to stay in place.

  • Use 4-40 hardware to assemble the frame. use either brass round-headed fasteners or 4-40 screws to assemble the other parts of your mechanism.

  • Use a glue gun (available at IDeATe) to attach the cams and crank handle to the camshaft. You can also use it to glue two cams together to make a thicker one. We also have wood glue and other kinds of glue at the Glue Station in room A5, just outside the laser cutter room.

  • For the artistically inclined: color your components by painting them, drawing on them, applying stickers or decals, etc.

Document

  • Generate a realistic rendering of your mechanism in SolidWorks. Follow the same procedure you used in the Mechanism assignment.

  • Take a photograph of your actual automaton.

  • Post the rendering and the picture to Piazza in the thread provided for this purpose.

    Hand-In

    Hand in a zip file handin.zip containing the following:
    1. Your SolidWorks part and assembly files, and your DXF files.
    2. Your animation file.
    3. Your rendering image.
    Due date: check the class schedule.

    Grading (20 pts)

    • 10 pts - Design: at least four cams (or equivalent) in your automaton; different/custom character; motion in more than one plane
    • 6 pts - Fabrication: laser cut and assembled automaton.
    • 4 pt - Files: Source files, images, and animation.
    • 2 pts - BONUS: possible extra points for extraordinary creativity (multiple characters, interesting links, colorful, etc.)

    Gallery of Past Projects

    • Dave Touretzky