This week I tested out what I made, as I’ve started to accept that what seems like it should work in the computer doesn’t always work out in real life. However, the results I got back confirmed what the computer said should happen, so that was a pleasant surprise.
According to the calculations made on the computer, I should end up with a leg that makes the same motion as Theo Jansen’s version, since it’s all in the same proportions. It’s happened to me many times before, especially during this project, where the expected results do not align with reality. This used to happen to me almost every time I used the CNC mill, so I thought there’s no better way to see if something is going to work other than to test it. That would really suck if I got through all six legs, built a frame and a drive mechanism, and just had a machine that couldn’t walk because the legs were out of proportion for some reason. With this in mind, I thought that this would be a necessary test indeed.
To do this, I put out a couple big sheets of compressed cardboard, and then drilled hole where the leg’s axis lies (bottom left corner of the top triangle), and the axis for the crank. After that, I found some scrap aluminum lying around the shop, crudely cut the pieces to the right size for the “push/pull” rods and the crank, and attached them to right points on the leg with cotter pins.
To create the path that the leg made, I made a dot of layout ink every inch or so around the leg’s cycle. The part of this that I was really interested in was the bottom of the ellipse, as this is the part where the foot is actually making contact with the ground, and driving the Grazer forward. As long as this is a straight line, parallel with the axis, I could care less about what the foot did to take a step. Turns out that the leg walks perfectly!
So what’s next? An obvious answer is to start ramping up production, churning out joint pieces and building leg components. While this will definitely start happening next week, I also need to focus on the other aspects of the Grazer’s construction, such as the frame design. Also included in this is the crankshaft design, how the frame will support bearings, and how the priorities for the project stack up. And don’t forget about getting into college!
I’ve got a pretty good sense of where I want to go — it’s looking like I’ll be applying early decision to Harvey Mudd College in Claremont, California on November 14th. It’s crunch time.