THE PAGE OF JIM

Jim is a double-frame walking machine built by the Carnegie Mellon Robotics Club. There were five of us working on it. Jim was our entry in the SAE walking machine contest.

This is the design for the main body, which houses all of the motors and batteries and computers. This is how I learned to use Pro/Engineer. I will explain Jim further after the next picture.



This is a rendering of Jim, done in 3D studio by Charlie Reverte. There are two independent frames attached to the box in the center. The box is the part shown above. The top frame can move up and down or tilt due to the two arms attached to cogs, and translate back and forth due to the chain and motor on top. There is a shaft through the center of the body, attached to the lower frame; this allows it to rotate. The lower frame can also translate back and forth, with a rack and pinion. The purpose of having two separate moving frames, rather than one, is that the center box, which contains most of the mass, will move continuously. The center box contains all the motors, batteries, and computer. The top frame will be moving forward as the lower frame translates the entire robot forward, then lifts the robot and moves the robot forward as the lower frame moves forward. Throughout this motion, the center box does not stop, and there is much less inertia to overcome with each step.




Below is a picture of Jim, our frame walker, half built. The five motors are not yet mounted. Two will be in the holes near the bottom of the blue frame, with a chain going up to cogs on the arms mounted on shafts in the bearings. These arms will move approximately 60 degrees both directions from horizontal. The other end of the arms is attached to the upper frame of the robot, which is not yet assmbled. This allows the upper frame to move vertically, and tilt either direction if the arms do not move together. This is how Jim lifts himself. One motor will be mounted on the top frame, and another on the bottom frame (the one Jim's sitting on). The rack of the rack-and-pinion for the lower frame is visible on the bottom of the tubes. Both frames can translate horizontally under power of these motors, and this is how Jim moves. Because he has two translating frames, the main mass of the batteries and motors can move in a continuous moton, rather than the start-and-stop of many frame walkers. The final motor will be attached to the top of the blue frame, with a cog and chain connecting it to the shaft in the center. This will rotate the lower frame, and allow Jim to turn. He will have a lot of onboard computing, including a vision system running on a Pentium laptop.



Here is a picture of Jim, basically finished. This picture was taken on the driveway of the repair shop in a small town in Indiana where we broke down on the way to competition. Jim had been finished about half an hour before this picture.



At the end of the year, we planned on finishing up Jim and making him walk. We also planned on beginning another walking machine with the same locomotion concept, but with some basic design changes. At the beginning of this year, we decided there were enough difficulties in making Jim walk, and very little benefit to be gained, so we decided to scrap Jim and focus on Jim2. Becuase Jim didn't walk, and we didn't compete in the contest, it may seem like a failure, but it is far from that. Five undergraduates built Jim. Two of us are continuing with the robotics club, working on several new projects with interested first-year students. Another benefit derived from Jim is the fact that, since we worked on it so much, people noticed. All members of the robotics club have been offered technical jobs in the robotics institute. In addition, the robotics club recieved a $20,000 grant from the Heinz foundation to continue building robots and training students. This grant allows us to focus on designing and building robots rather than calling companies, asking for donations, and designing a robot around the parts we could obtain.


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