4-Bar Walking Linkage Optimizer
The below interactive simulator allows you to quickly check how changing the linkage's bar lengths affect the path it draws as the crank is rotated.
Here is the a video of the simulator in action:
Jeep2003's awesome mechanical ostrich uses a similar 4-bar linkage:
And here's a great LEGO implementation by Hiro Labo:
Below is the interactive simulator. It allows you to simulate between 1 and 4 legs to make it easier to gauge the amount of foot contact at each corner of the robot. The sim is started by clicking the green flag. You can also run it on MIT's site where you can modify the Scratch code.
After changing a bar's length, click somewhere other than a slider bar and then press the space bar to see the new linkage, and use your keyboard's left/right arrows to rotate the crank.
Below is the interactive simulator. It allows you to simulate between 1 and 4 legs to make it easier to gauge the amount of foot contact at each corner of the robot. The sim is started by clicking the green flag. You can also run it on MIT's site where you can modify the Scratch code.
After changing a bar's length, click somewhere other than a slider bar and then press the space bar to see the new linkage, and use your keyboard's left/right arrows to rotate the crank.
A description of the algorithms, and how we used them to simulate linkages, is here.
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.