LEGO Strandbeest Optimizer
This simulator allows you to quickly check how changing Strandbeest's bar lengths affect its foot-path, but remember, just because something looks good in a simulation doesn't necessarily mean it will work well when built - at least not without some tinkering, such as managing possible dead-points (see below).
Here's a video of the simulator in action, and the embedded simulator can be found below.
This simulator allows you to quickly check how changing Strandbeest's bar lengths affect its foot-path, but remember, just because something looks good in a simulation doesn't necessarily mean it will work well when built - at least not without some tinkering, such as managing possible dead-points (see below).
Here's a video of the simulator in action, and the embedded simulator can be found below.
Below are Jansen's linkage and a LEGO approximation, scaled so that the crank=3:
Jansen's Linkage Scaled so the Crank=3, and a LEGO Approximation
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And below are Jansen's linkage measurements along with the LEGO approximation. Note: this LEGO approximation uses the 7x3 bent beam pictured on the right for Bar 8 (B8). |
Length of a LEGO 7x3 bent beam = 7.38
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Strandbeest's linkage dimensions scaled so that the crank=3, and a LEGO approximation
Strandbeest's frame coordinates, and a LEGO approximation
As you can see in the above images, the "LowFrame" variables are the distances from frame connection #2 to the center of the crank.
Below are the foot-paths of both versions, as well as the speed of the feet when in contact with the ground (assuming 8 legs, not 12).
Below are the foot-paths of both versions, as well as the speed of the feet when in contact with the ground (assuming 8 legs, not 12).
Below is the embedded simulator, which requires Flash to run on this web page. You can also run the simulator on MIT's site where you can download or modify the Scratch code. A description of the algorithms used in this Jansen linkage calculator is here.
After changing a bar's length, press the space bar to see the new foot-path, and use the left/right arrows to rotate the crank. To choose Strandbeest's bar lengths click "Jansen" then press the space bar.
Note: to more finely optimize Strandbeest, use the Strandbeest Optimizer x 100 at the bottom of this page.
Jansen Linkage Calculator
Below is another LEGO option with a higher, but shorter foot-path. Notice the X-value of the leg's lower frame connection #2 is one hole further from the crank ("LowFrameX" is increased from 8 to 9). You can see an example leg built with these dimensions in LEGO below.
A LEGO Approximation of Strandbeest
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A LEGO Approximation of Strandbeest
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Foot-Paths and Speed of Strandbeest and a LEGO Approximation with a Shorter Foot-Path
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.
Below is an example of how to build the legs of this shorter foot-path approximation of Strandbeest in LEGO. This configuration should work well as an 8-leg, steerable Strandbeest, with the long legs providing plenty of room beneath the frame to mount either LEGO's battery box or EV3 brick, as shown on this long-legged Klann walker. If you build it, please share some pictures or a video.
A LEGO Approximation of Strandbeest
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A LEGO Approximation of Strandbeest
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As shown below, Strandbeest's knee joint may tend to "flip" at its Dead Point:
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As shown below, to build straight legs that don't bind or jam, make sure leg parts connect to parts in an adjacent plane
Front View
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Top View
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Other LEGO-Friendly Possibilities for Strandbeest
Other LEGO-Friendly Possibilities for Strandbeest
Below are a few more possibilities for approximating Strandbeest in LEGO with only using straight Technic beams. You may be able to find better approximations if you include more of LEGO's bent beams in your optimization (lengths below).
Strandbeest's Linkage Dimensions Scaled so the Crank=3
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LEGO Ver 0
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LEGO Ver 1
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LEGO Ver 2
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LEGO Ver 3
This high-step version 5 to the right probably wouldn't work well with the abrupt bending of the knee, which you can better see in the below images as well as in the above video. Plus, the leg parts may collide. |
LEGO Ver 4
LEGO Ver 5?
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Knee bend of LEGO Ver 5
Of the above LEGO approximations of Strandbeest, Ver 3 has the most consistent foot-speed, but it doesn't step as high:
Of the above LEGO approximations of Strandbeest, Ver 3 has the most consistent foot-speed, but it doesn't step as high:
Jansen's Linkage Scaled so the Crank=3, and a LEGO Approximation (Ver 3)
There are likely better LEGO-friendly versions of Strandbeest that can be found with the simulator, especially if LEGO's bent bars are included in the search. Note: more odd-length beams can be created by extending the below beams with straight beams, and plugging the side lengths and angle into the Law of Cosines to calculate the new distances. Then, you can plug these odd length beams into into the optimizer with beam lengths x 100 below.
Lengths of LEGO's bent beams
Below is the Strandbeest Optimizer with the bar lengths x 100.
Jansen Linkage Calculator with Bar Lengths x 100