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Therefore linkage is Grashof
Our main goals for this linkage is to provide a smooth oscillating motion. Although our prototype was designed with no specific angle in mind, we do intend to modify and experiment with our prototype to achieve an oscillation centered with the pivot link (lower left joint) and that moves about 10 degrees from this center axis to either side. This, when having the Klann linkage mounted on it with a distance of about 8 cm from the pivot axis to the tip of the "leg", should produce a leg reach of around 3 cm.
Klann Linkage Kinematic Analysis:
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Therefore linkage is Grashof
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Timeline:
Design and Production Preparation - Nov 3-5
Production & Assembly - Nov 6
Troubleshooting - Nov 7
Reflection:
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Our 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.
Bill of Materials
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Part #
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Description
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Approx. Area (ft2)
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Quantity
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001
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Klann Linkage System
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.4
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8
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002
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Oscillating Linkage System
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.1
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8
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003
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Body Base
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1
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1
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004
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Complete Body Frame (Decorative)
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2
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1
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005
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½ in Length
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125
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006
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4mm Metal Dowel
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½ in Length
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The initial approach for the kinematic analysis was to analyze the system
The videos below show the animations for both the original Klann linkage (approximately the one used for the prototype) and our modified version with a more vertical profile.
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Design Process:
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linkage using Stephenson's six bar linkage analysis approach by creating two vector loops and using the common linkage between the two to find the missing values. Unfortunately, this method was extremely complicated and we were unable make significant progress within a long period of time and eventually moved on to simply using the displacement, velocity, and acceleration plots in motiongen. Below is a link to a google colab that was used initially to analyze the first vector loop - designated as the 4 bar loop consisting of the crank - to find the properties of the oscillating bar.
https://colab.research.google.com/drive/1coDzB8L6NwIw3rEnqCVQiPSXJW28SUmu?usp=sharing
Similar to the oscillating linkage, we did not focus on force analysis since we are primarily interested in the position profile of the end of the linkage. The goal of this linkage is to have a more vertical motion profile with still some lateral movement to account for the change in angle while moving the whole body forward.
The videos below show the animations for both the original Klann linkage (approximately the one used for the prototype) and our modified version with a more vertical profile.
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