Four Bar Mechanism

Overview

A four-bar mechanism is a mechanical system which consists of four bodies connected at four pivot points. The four bodies are called the frame, input, coupler, and follower. The frame is a fixed body that will be used as the reference-frame for any movement generated by the input link. The input link takes the input motion and transfers it to the follower, directed by the coupler link. The three moving links work in conjunction to generate the desired motion at the end-effector.

Generic Four-bar mechanism

The objective of this project was to design a four-bar mechanism for a real-life application. In this project the four-bar mechanism was designed for elderly gardeners. It seems that gardening is a leisurely activity that the elderly tend to pick up. Hours spent hunched over a garden could be strenuous to one’s back and discourage one from spending a length of time tending to a garden

Design Tasks

1. Determine 4 critical precision points of the desired motion.

   
   Precision points

   
   

2. Determine the rotation angle [radians] of the input link [beta] and the follower link [gamma] through each precision point relative to the first precision point.

   
   Beta and Gamma angles

   
   

3. Utilize the function generation algorithm with your precision points, excluding the first precision point. The first precision point is fixed to indicate starting point of the motion. The function generation algorithm solves for the distances and displacements of each consequent point that comes after the initial precision point.

   
   Function generation algorithm