Extra Simple Walking Mechanism





Introduction: Extra 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 hight because it requiered 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: Construction and Assemble

      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”.



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    Hi, I am about to start making the working model of this mechanism. Can you please provide me with the dimensions of the links and materials used.

    I will be grateful if you provide me this information. Thank You!

    Hi, you could make it of any size you want, and of any material you have. The thing is that the size will be very influenced by the material you use, and you have to keep the size relations. In my case, if I recall correctly, I used 1/4" AISI 1020 square bars, and they were 8 cm long.

    Thank you sir for your response.
    I think the sizes of links will matter. because if we fix the lengths of any two links; crank and coupler, then for obtaining the same path travelled by the legs, the positions of fixed pivot get displaced from the horizontal line. In my case, front and back leg were following the path correctly but when I placed the middle two links, the mechanism became a structural member.
    But at last, I was able to design the working mechanism.
    Thank you

    Hi, I'm learning 4 bar linkages and mechanisms right now in school, and your mechanism is awesome! (: I was just wondering what you meant by a "symmetrical mechanism" such that "one mechanism would drive the next one"?

    Symmetrical means that if you cut the figure "draw" by the leg in half in a vertical axis, one half is the mirrored image of the other one. This is accomplish by having the same length from the driver bar to the center of the leg as from the pivot of the leg to the center, and well, the leg have to be twice as long for it to work. Sorry if this part doesn't make many sense, but it's been a while since i last wrote in English and I founded hard how to explain it. You can found more about four bar mechanism in a text book from Robert Norton. Thanks for your comment .

    Nice simple mechanism. I would not want to ride a vehicle with this linkage, but it is one the simplest walking mechanism I am aware of.



    Thanks. And thank you for making thus great animation.

    Could you be more specific about the drive mechanism?

    Me encanta. Dejalo así de lento. Parece un camaleón

    Gracias!!! Aprecio mucho tu comentario :D