Chris Dugan's Course Project

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Project Overview

My robot is similar to a 4-legged spider. Its legs are built using a crank-shaft that always push extend towards the exterior of the robot. This is where the spider similarity exists.


The robot was built using Legos from the Lego Mindstorm kit. Ideas were gathered from [1] and all the photos below can be found there. Two motors are housed in a custom-built, rectangular frame. The motors operate in unison in order to balance the robot and provide more torque. In particular, the legs were built using the following design.

Chris's robot legs.gif Chris's lego legs animated.gif Chris's robot gears.jpg

The actual project involves a joint that bends at a far greater angle, again resembling spider legs. There is room for two additional legs, as this drive-train was originally designed for, however I was more curious at implementing a 4-legged creature. This presented more interesting balance and movement issues.

Weekly Updates

Week 2

This week I spent playing with the Legos and attempting to figure out how gears actually work. I also downloaded and installed Microstation. This proved to be non-trivial because the license supplied with the package is out of date. Another one exists in the Bentley directory on though, for the astute web surfer. Read the file and follow the simple directions for installation.

That being said, I've also been trying to figure out Microstation. It is a very complex program with little documentation. I found a tutorial online that is only average and only works for 2-D drawings. Check [2] for information. Additionally, it is worth noting that the default file type (.dgn) is 2-D when you create a new project within Microstation. Be sure to change the file type to .dwg when creating a new document.

Perhaps we can start up a Microstation FAQ, for instance. Maybe I will add a link to a skeleton to the main page. Help for even the smallest task would be fantastic. I cannot even make a cube!!!

Week 3

The motors work! The handyboard turned out to be a huge pain. Not having an engineering background didn't seem to help. I followed the links provided by Joe Kopena in his emails and downloaded the Windows version of Interactive C. The QuickStart was straightforward to follow. Problems arose when I discovered a faulty telephone cord (which made it impossible to connect the serial converter chip with the handyboard). This was not trivial to discover, unfortunately. Then, I discovered a faulty motor port. That is, all of the other motor ports eventually worked with the same code.

After all this initial setup was complete, I finally have a working handyboard and some motors. If anyone has similar problems, I would be glad to assist.

In other news, I have narrowed my project down to two different ideas. I am interested in getting the tw-legged creature to work, but do not know how feasible it is. I hope to narrow this down by Tuesday. My idea for balancing the two-legged creature is to use the handyboard to shift the center of gravity on the being. I plan on attempting to build a mechanism that shifts the handyboard left and right depending on which leg is on the ground. This may be idiotic, but my non-engineering self can see it working. If that doesn't work, I am going to default to a four-legged beast since balancing such should be easy and setup should be as well.

The two legged animal proved to be a failure and I have began working on a four legged animal. It has no type yet. My initial design, implemented in Legos, uses two motors. One motor powers the front legs and one motor powers the back. I will likely run into a problem because the motors do not stay in synch, but will deal with that later. My major problems are making actual legs. I think I'm going to have to get more of the shorter axles from other kits because I don't have enough and am having problems with the feet hitting the axle and each other.