Rob Lass's Course Project
The current robot is a six legged walker inspired by the composition of ants. I got all the pieces I needed today (10/10), and put it together only to learn that one motor was not enough to power the legs once I put it on the ground. I tried using two motors, but it took me a while to find two sets of ports that did not seem dead. Wow, it moves!
The biggest problem with the robot is that the legs come off very easily. Every time I kick it, or knock it off my dresser, the legs fall off. It is important to put the legs on so that one of the front legs is always on the ground, as well as one of the back legs. Otherwise, the robot will fall over when it tries to walk.
I'm hoping to use an open source software system to do the modelling and simulation. I found a program called Blender that seems to let me import the lego models. It has a physics engine built in, and based on examples I've found online I think it is of suitable quality.
The Blender interface is certainly... different. Fortunately, there is a pretty good tutorial available on Wikibooks that walks you through the different features of the program, gradually making you more comfortable with it. The tutorial says about the interface: "eventually, you will wish all your programs worked this way." I don't know if I agree with this statement.
I've got a large portion of the model in Blender. I finally figured out that you can select a model and press "n" to enter a rotation relative to the base. (Yes, it really did take me a while to find this feature.) All of the lego models that I imported were 45 degrees off on the z-axis for some reason, so I used 0, 0, -45 for x, y, and z respectively.
Chris Dugan gave me the gear that I was missing, but for some reason it is not scaled properly in blender (it was WAY too small). I scaled it by hand, and I'm hoping it will work with the other gears properly.
Old Inchworm Robot
I found out wheels were not allowed. So, I took it apart to make the six-legged walker instead.
The robot is in the correct shape, and the motors have been added. They both work, but I only have one cable for connecting a motor to a Handyboard, so I can't power them both until I find another one. I also need to add the sensors to toggle the motors when the robot's "hump" is fully up, or fully down.
The motors are strong enough to pull the robot in its current form, so I assume that means it is feasible.
The robot will not work on the carpet in my room; there is not enough traction. It works on the tile floor in my kitchen, and I assume that is good enough.
I tried out a number of different animals before I found one that seems feasible. My first idea, a hopping robot, turned out to be too hard to implement with the materials available. I played around with the lego kit one night while going through a biology textbook, and decided to go with an inchworm-like robot.