Type in four link lengths and see what the loop does. Does the crank turn all the way around? Where does it push badly? Which stroke is slow? This covers parts 4 to 8 of the Guidance page.
Your design is saved in this page's link. Copy link gives you a link to paste into Google Classroom or your notebook. Opening it brings everything back.
Worst cases happen when the crank lines up with the ground (0° and 180°). Check: cos μ = (b² + c² − L²) ÷ (2bc), with L = d − a or d + a.
Toggle and time ratio part 7
Rocker angle as the crank turns
The rocker's angle, measured at its fixed pivot from the ground line. A steep part of the curve is the fast stroke.
Using it on your project
Find your loop. Pick the four-bar loop in your leg that contains the crank. Measure its four lengths, pin center to pin center, in the MIT Linkage Designer or on the linkage kit.
Type them in. Ground is the distance between the two fixed pivots. The crank is the link the motor turns.
Read the checks under the drawing. Red means a real robot would have the same problem. Each one says what's wrong.
Drag the crank angle slider. Stop where μ turns red, or where the crank jams, and look at the shape the links make there.
Do the math by hand too. Your notebook has to show the three computations step by step. Use this page to check your answers, not to replace them.
Copy the link into your build log, next to the screenshot.
This page checks one loop at a time. It doesn't build linkages. Invent yours in the MIT Linkage Designer, then bring the lengths here. When your loop passes, take the same lengths to Leg and Foot Path.
