Initially, I had the intention of creating a model from the Karakuri book. After looking through it, I got inspired by the following model:
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I liked the idea of using gears to provide the rotating motion for links to move and make an object seem like its walking. Since this model had already been done, it seemed a little too simple for me. I wanted to challenge myself mode by exploring alternative designs and configurations, but still keep the same inspiration. I decided to look into link configurations in order to get a better understanding of how one could make a walking mechanism out of links and joints. I found the Klann linkage configuration and decided to learn more about its mechanics. With the Klann linkage, the leg is in contact with the ground the same amount of time that the other leg is off the ground, like a human that is walking or a horse that’s trotting. The leg pairs would look the same but have a crank angle offset of 180 degrees. Making one leg be in the opposite position as the other one. Similarly to how we walk and usually have one foot on the ground as the other foot is moving forward in the air. The way that the linkage works is by utilizing one of the links as the crank of a 4-bar mechanism. This actuating circular motion of the crank then causes a rocking motion at the opposite ends of the other grounded links. The combination of these two rocking motions allows the biggest link (the leg) to alternate its position and move back and forth in order to produce the walking motion.
Figure 2: Klann Linkage [ 2 ]
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In order to distinguish between which leg was supposed to be on the ground and in the air, I labeled them X and Y. Therefore, in this configuration, the two middle Y legs will always be synchronized and have the opposite position as that of the X legs on the outside.
References:
[ 1 ] Saka, K. (2007). Karakuri: How To Make Mechanical Paper Models That Move. New York, NY: St. Martins Griffin.
[ 2 ] Mechspdcm. (n.d.). Mechanical Spider. Retrieved from http://www.mechanicalspider.com/