This is a series of four videos that show how to: Specify three positions for the foot of a leg consisting of a hip and knee joint; Use three position synthesis to design a four-bar function generator to guide the hip joint; Then use three position synthesis to design a second four-bar function generator to […]
About Prof. McCarthy
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Entries by Prof. McCarthy
The graphical construction of a four-bar function generator that coordinates three input and three output angles is presented in the video below. It is possible to coordinate as many as five input-output angles, but this requires numerical calculations using software like our MechGen FG iOS application. More notes on Kinematic Synthesis Also see my book Kinematic […]
Our MechGen FG iOS application provides five position synthesis for four-bar linkages. A Demo of the iPad version is provided below. It is also available on the iPhone.
The graphical construction of a four-bar linkage that coordinates two positions of an input crank with two positions of an output crank is presented in this video using Geogebra. A linkage that coordinates the values of input and output angles is called a function generator. It is possible to design a four-bar linkage to coordinate […]
This video adds a skew pantograph to a four-bar linkage in order to reorient and change the size of the coupler curve. The result is a six-bar leg mechanism with a foot trajectory that is a scaled version of the original coupler curve.
In this video, we start with a four-bar linkage and coupler curve and construct an additional crank with a floating link connected to the coupler point. This floating link becomes the leg of the Klann-style leg mechanism. Adjustment of the dimensions of the added links shapes the foot trajectory.
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 […]
This video shows the construction of the cubic of stationary curvature. The intersection of the cubic of stationary curvature with the inflection circle, iw Ball’s point which is a coupler point that traces a locally straight line trajectory. This video also shows how to vary the coupler point and the dimensions of the reference polygon […]
This tutorial constructs the inflection circle for a particular configuration of a four-bar linkage. This construction was recommended by my colleague Gordon Pennock because it is simpler than the one I provide in my book Kinematic Synthesis of Mechanisms.
This tutorial shows how to use Geogebra to construct the canonical coordinate system for a particular configuration of a four-bar linkage. It starts with a quadrilateral which is to be the configuration of the linkage at a particular instant. Then constructs the velocity pole and the instant center of the positions of the input and […]