This video starts with a four-bar linkage with a coupler curve that is to be used as the foot trajectory for a leg mechanism. It presents a Geogebra construction of two additional bars, one of which is connected to the coupler point and moves without rotating. This means the bar can be expanded into a leg that places the desired coupler curve where the designer specifies. This is described in Chapter 4 of Kinematic Synthesis of Mechanism.
https://i2.wp.com/mechanicaldesign101.com/wp-content/uploads/2019/04/Figure-4.6.png?fit=1528%2C1452&ssl=1 1452 1528 Prof. McCarthy http://mechanicaldesign101.com/wp-content/uploads/2016/07/mechanical-design-101LOGOf.png Prof. McCarthy2019-04-26 13:51:302019-05-25 12:04:39Construction of a Translating Link for a Leg Mechanism