Instructables
This instructable shows how to hack your Mechamo Inchworm to make it crawl along a suspended string. It's surprisingly easy, and should take about 10 minutes!

Here's a video of my hacked Inchworm cruising along upside down, suspended from some nylon string:



But how does the inchworm normally work? This article has a general overview, and the video below is a good example of normal operation.
http://blog.makezine.com/archive/2010/05/in_the_maker_shed_mechamo_inchworm_1.html

 
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Step 1: Parts: Rubber band, coat hanger

Picture of Parts: Rubber band, coat hanger
Get your self a nice little rubber band. Mine is one of those teal ones they wrap around your eggs when you checkout of Whole Foods.

Get a metal coathangar, and cut two pieces about 10" long. Ben them into Ws as show. Make the outside arms of the W about 2 inches long, and the inside arms ( the upside down V part) about 3 inches long. When you suspend your inchworm from the string, this will position the string right between the bottom of the inchworm's two feet.

Step 2: Attach coathanger Ws

Insert the W's into the holes closest to the bottom of your inchworm's feet (or the top, if it is upside down).

Make sure the tines of your W stick close to the inchworm's legs, so that the edges of the legs keep them trapped and stiff.

Step 3: Wrap your rubber band around the inchworm's foot

Picture of Wrap your rubber band around the inchworm's foot
W-inserted.JPG
wrap-band.JPG
Place your rubber band around one side of the foot, over the string, over the other side of the foot. This tension will be important later when you make your inchworm walk the wire. When the foot is "up", it should be loose enough to slide across the string. When it is "down," it should hold onto the string so that the inchworm can move its legs along further to get another grip. See the video or final picture for a better sense of how this works.
TheMONKEY4 years ago
Wonder How this would work as a line following robot?
lightnin9 (author)  TheMONKEY4 years ago
I don't know! Seems like it could be done with an infrared sensor... That might be cool!
Can you tell me how far the bottom foot travels with each leg movement?
lightnin9 (author)  TheMONKEY3 years ago
Uh, sorry, read that wrong. Basically, about a couple of inches. I can get a more exact measurement next time I hang it on the string if you need it.
Would like more exact measurements of it on the ground Im really thinking of makeing a line following robot from this
lightnin9 (author)  TheMONKEY3 years ago
You mean the foot that the inchworm normally rests on when it's right side up? I'll call that the main foot.

Basically, when it pulls down, it increases the tension on the rubber band and holds onto the string, so the other "feet" can get a grip farther along the string. Then, as the foot goes up, the tension on the rubber band is relaxed, allowing the main foot to slide along the string.

The video makes this process somewhat clearer. Btw, I've just managed to make a version of this that just uses coathangers bent into hooks, for the main foot and the outside feet. It makes it easier to put it directly onto a string that's tied off, rather than having to thread the string through the Ws of the current design.