Synthesis of Planar Mechanism:

In the previous unit, you learned about cam-follower mechanism. For a predetermined motion of the follower you can draw profile of a cam. In this unit, you will learn the design of mechanisms to satisfy particular prescribed kinematic specifications. We will limit our discussion mostly to the planar linkages that contain only hinged joints or revolute pairs and prismatic pairs. There are three several kinds of phases in the solution of problems of synthesis: number synthesis, type synthesis, and dimensional synthesis. In type synthesis, we need to choose the type of mechanism. This decision is guided by the criteria such that space limitation & the relationship of the mechanism with other elements in the assembly. This decision is ahead of the field of kinematics in most of the cases. Thus, the first phase is not part of our discussion. Our purpose in this unit is to provide a short introduction to synthesis of linkages.

Objectives

After learning this unit, you should be able to

• recognize redundant number of links, joints & degrees of freedom,
• Find out different types of links in number synthesis,
• Synthesis of the four bar chain and slider crank chain through graphical method or analytical method, and
• synthesise a four bar chain if three location for coupler link are illustrated.