simple walking mechanism

For a college course I was required to build and analyze a mechanism, so I decided to make a walking mechanism, because since I had a LEGO Technics I always wanted to make a walking robot but I was never successful. Now with a lot more of knowledge I made it happen.

Step 1: Designing

     When you investigate a little bit about walking mechanisms the first thing you might find is the “Strandbeest” from Theo Jansen. It is a great design but is more complicated that what I was looking for.

     I then found a cartoon sequence that shows how to draw a character walking. Observing this cartoon I notice that the walking action follows kind of a drop form, and I remembered that some 4 bars mechanisms did this shape, so using a program named “4 Bars” I searched for the best option for my purposes.

     Wanting to make my walking “bug” very stable I decided that the best way to accomplish this was with a tripod, so I need to make a six legged “bug” so at all times there will be at least three legs on the floor. I also didn’t wanted to use chains or belts to drive all the mechanisms, so I try what is called a symmetrical mechanism and make that one mechanism drive the next one and so on. So I ended with four identical mechanisms in each side that needed just one axel to drive one mechanism in each side.

     Later I draw it on Inventor to solve some constructions issues, like how to connect everything together in a way it wouldn’t be so bulky and didn’t interfere with each other. Then I built it with LEGOs and notice that the step couldn't be very high because it required more power from the motor.(For a more detailed way of how I design it you can send me a message or post a comment)

STEP 2; Assembly

      The construction was really easy because all the parts were almost the same. I print out the blue prints for the design I made in Inventor, and make all the parts using a press drill, a file and a welding machine. For the connection between the motor and mechanism I used a combination of endless screw and straight teeth gear. I had the gear from an old remote control car, the endless screw I made it on the lathe, and the motor I took it off a can opener because I wanted a slow and powerful electric motor.
     I feel more comfortable working with steel because of my background in precision mechanics, that’s why I used a square steel bar to make all the parts.
     The easier way I thought of making the connections between all the bars was with rivets. I just put a piece of tin in between the pieces I wanted to assemble, so when I removed the piece of tin there will be a gap that allows the movement of the parts.

     Here is a video of the mechanism working. It goes pretty slow but it gives you time to appreciate the complex of the movement and the beauty (that’s how I feel about it) it has.

Step 3: Finishing touches

    I add on top of it half of a water bottle to make it look like a beetle, and give it more of a bug feeling. Later I paint it green, and this is the final result.
    Hope you enjoyed this Instructable, and if you have any question about anything feel free to send me a message or post a comment. And thanks for “watching”.