4 Bar Linkage Optimizer
This Scratch simulator allows you to quickly check how changing the linkage's bar lengths affect the path it draws as the crank is rotated.
The bar map below shows 5 bars, b0 thru b4, but since the angle between b2 and b4 is fixed, j1 thru j4 is considered a single bar. Also, the frame functions as a bar of the linkage, with frame connections j0 and j3 creating bar b0.
To run the embedded Scratch simulator below requires that Flash be enabled. You can also run the simulator on MIT's site where you can download or modify the Scratch code.
After changing a bar's length in the simulator, press the space bar to see the how the path changes. Use the left/right arrows to rotate the crank.
The bar map below shows 5 bars, b0 thru b4, but since the angle between b2 and b4 is fixed, j1 thru j4 is considered a single bar. Also, the frame functions as a bar of the linkage, with frame connections j0 and j3 creating bar b0.
To run the embedded Scratch simulator below requires that Flash be enabled. You can also run the simulator on MIT's site where you can download or modify the Scratch code.
After changing a bar's length in the simulator, press the space bar to see the how the path changes. Use the left/right arrows to rotate the crank.
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For more ideas and analysis of four bar linkages, download the Hrones and Nelson Atlas here.
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When building a simulated linkage in LEGO, remember to use beams with one more hole than the bar's length. For example, a bar of length 8 requires a LEGO beam with 9 holes, because when determining the length of LEGO beams, the first hole is always counted as zero.
A description of the algorithms, and how we used them to simulate linkages, is here.
A description of the algorithms, and how we used them to simulate linkages, is here.