Three Position Synthesis 2

Construction for Three-Position Synthesis of a Four-Bar Linkage

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.

MechGen on iPhone

Five Position Synthesis of Four-bar Function Generators

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.

Construction for Two-Position Synthesis of a Four-Bar Linkage

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 as many as five input and output angles. However, this requires numerical calculations using software such as our MechGen FG iOS application.

Graphical Two Position Synthesis of a Four-bar linkage Function Generator.

Construction of a Skew Pantograph Leg Mechanism

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.

Construction of Klann-style Leg Mechanism

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.

Construction of a Translating Link for a Leg Mechanism

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.

Walking Robot Student Project

Walking Machine Class Projects: Ohio State ME 5751

Prof Haijun Su at Ohio State University had his students design walking machines for their final project in ME 5751. Here are videos of four project teams from that event.

Team A:

Team B:

Team C:

Team D:

Sphinx and Sphere VR and the History of Kinematic Synthesis

Our Sphinx software was the first computer-aided design system for spherical linkages. It used IRIS system by Silicon Graphics. Collaboration with Judy Vance lead to a Virtual Reality version of this design system.

This is a link to the description of this research at Iowa State University.

This video shows the operation of these two design systems;


LINCAGES and the History of Kinematic Synthesis

The linkage design software developed by Art Erdman and his students at the University of Minnesota, called LINCAGES: Linkage INteractive Computer Analysis and Graphically Enhanced Synthesis Package, was developed in 1977 through 2000. This is a link to his information site. His guide map that evaluates all of the linkages formed from points on the circle-point and counter-point curves was a nice innovation.

This link connects to a YouTube video shows the linkage design process using LINCAGES:


KinSyn and the History of Kinematic Synthesis

My first experience with computer based kinematic synthesis was a 1982 presentation by Roger Kaufman of his KinSyn linkage design software on an Apple II microcomputer. This is a link to his description of his experience in those early days of computer-aided design of linkages.

His paper that describes this software can be found here. The photos are a terrific look into the computer technology in the 1970’s.

Here is a video that describes the operation of KinSyn, which I find to be an impressive integration of kinematics calculations in the background with a useful graphical presentation of information to the designer. I have to say that the graphical display was impressive in its day.