Linkage Synthesis Theory

The mathematical synthesis of linkage movement provides a powerful tool for invention. However, the specified task may not have useful solutions, and the search for successful tasks can be discouraging.

To address this, we automate the search and evaluation process within tolerance zones specified by the designer.  These Mathematica notebooks implement our approach to finding defect-free four-bar linkage designs.

• Five-Position Synthesis of a Four-bar Linkage
• Synthesis of an RR Constraint (Function Generation)

RR Constraint Synthesis for Function Generation

Synthesis of an RR Constraint

An important technique in kinematic synthesis is the design of an RR constraint that controls the movement of two joints of an existing serial chain. For a given RR serial chain, like OA shown above, we can specify its movement through five required task positions. This provides the information needed to design an RR constraint, GW above, that ensures the system moves through the required task positions.

This technique is called function generation in the kinematics synthesis literature, because the synthesized RR constraint maintains a specified relationship between the joint angles alpha and beta at joints O and A.

Select this link to download our Mathematica notebook: RR-Constraint Synthesis. It uses a given RR chain and the associated task to determine tolerance zones, where it searches for defect-free designs.  As above, this file may download as text file so remove the .txt extension, then it should be readable by Mathematica. If you have any questions, please contact me.

Five-Position Synthesis of a Four-bar Linkage

Here we show a four-bar linkage designed to guide the coupler through five required task positions.

Please download and try our updated Mathematica notebook: Five-Position Synthesis. It searches in the vicinity of the required task for sets of positions that yield defect-free four-bar linkages.  It may download as textfile so remove the .txt extension, then it should be readable by Mathematica.

The video below shows the operation of this notebook.

If you have any problems or advice, please contact me.