Design ProcessBrainstorm:
The process for designing and producing our prototype focused on refining the proportional lengths of the two most important linkage systems. For our leg linkage, based on the known Klann Linkage, we aimed to minimize lateral movement but not completely get rid of it. The small amount of lateral movement is meant to compensate for the slight lateral movement caused by the arc of the oscillating linkage. With these two movements opposing and timed oppositely we want to create as close to a straight line path of motion as possible. First step was to prepare our linkage designs for production. We first brainstormed on finding a way to combine the 4-bar and Klann linkages at two different planes of axis'. We wanted to make sure that the 4-bar oscillating mechanism would smoothly move in the x axis with no interference while the Klann linkage would move vertically at following that to make a synchronized motion with all legs. We decided that creating a gear train that would synchronize all of the legs in one motion was the best course of action. One large transmission gear would drive all the smaller gears connected to the 4-bar oscillating linkages surrounding it and would also translate that motion vertically with using a bevel gear assembly.
Manufacturing methods:
We decided on using the laser cutter and plywood to produce all our links as it would be the easier, quickest, and most effective method. Our prototype links were purposely left without bearing slots and produced at a smaller scale than we expect our final product to be in order to minimize material usage and time. Rather than connect every link via bearing and dowel we simply drilled small holes in our linkage pivot points and created pin joints using a bit of steel wire. We were able to create working linkages for both systems. And experiment with different length links to alter the path our systems.
Design Process:
The process for designing and producing our prototype focused on refining the proportional lengths of the two most important linkage systems. For our leg linkage, based on the known Klann Linkage, we aimed to minimize lateral movement but not completely get rid of it. The small amount of lateral movement is meant to compensate for the slight lateral movement caused by the arc of the oscillating linkage. With these two movements opposing and timed oppositely we want to create as close to a straight line path of motion as possible.
Working Prototype:
We used a bevel gear to simultaneously drive the oscillating and Klann linkages at a 1:1 gear ratio. We refined our link measurements to achieve the most optimal position profiles and then planned out the orientation and mounting of the linkage systems on a base. The images and video below shows the gear assembly and combined motion profile of the walking mechanism.
View file name IMG_1462.MOV height 250
Bill of Materials
Part # | Description | Approx. Area (ft2) | Quantity |
001 | Klann Linkage System | .4 | 8 |
002 | Oscillating Linkage System | .1 | 8 |
003 | Body Base | 1 | 1 |
004 | Complete Body Frame (Decorative) | 2 | 1 |
005 | 1/8 in Nut & Bolt | ½ in Length | 125 |
006 | 4mm Metal Dowel | ½ in Length | 24 |
Timeline:
Design and Production Preparation - Nov 3-5
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Lastly, we realized that this project would require large amounts of ball bearings and dowels and using them is likely to increase the size of our project. Thus, we are considering using a different method of joining our links, likely some form of pin or nut and bolt.Next StepsOur next steps are going to be to start finalizing our plans for the connection between the two linkage systems. We currently intend to use a bevel gear to simultaneously drive the oscillating and Klann linkages at a 1:1 gear ratio. With that figured out we will refine our link measurements to achieve the most optimal position profiles and then plan out the orientation and mounting of the linkage systems on a base. This base needs to look like the silhouette of a spider's body so we have to work around this shape. Once the mounting of the linkage systems, motor, and power source are determined and properly integrated into the intended spider shape we can start fabricating the links and assembling them, being sure to test them and ensure they run smoothly and with no collisions or jams. At this point the hardest part is over and we can start the full assembly of our project, designing and producing an aesthetically pleasing 3D body for the spider. We intend to do this my using spaced out layers of laser cut wood slotted perpendicular to the base to form the framework of a 3D body around all our components.