FourBar

A node.js program for a fourbar position analysis using the vector method. This library encompasses the angles of all the links and their position vectors along with the transmission angle.

FourBar Position Analysis

This library makes for quick and easy position analysis of a simple four bar linkage. Positions may be put through a simple derivative to obtain velocities and accelerations. For a better understanding of linkages and how to engineer linked mechanisms, see Robert L. Norton's Design of Machinery. Inside this text are in depth explanations of linkages and their uses.

Methods

Method call	Parameters	Description
type	N/A	'VectorMethod'
linkageType	inputLength, couplerLength, outputLength, groundLength	Returns type of linkage
couplerAngle	inputLength, couplerLength, outputLength, groundLength, inputAngle	Returns and Object with open and crossed configuration angles of coupler link from the positive x-axis based on the input link angle in Radians
outputAngle	inputLength, couplerLength, outputLength, groundLength, inputAngle	Returns and Object with open and crossed configuration angles of output link from the positive x-axis based on input link angle in Radians
couplerVector	inputLength, couplerLength, outputLength, groundLength, inputAngle, deltaAngle	Returns Objects of the real and imaginary components of both the crossed and open configurations based on the input angle in Radians + an optional delta as seen below
outputVector	inputLength, couplerLength, outputLength, groundLength, inputAngle, deltaAngle	Returns Objects of the real and imaginary components of both the crossed and open configurations based on the input angle in Radians + an optional delta as seen below
inputVector	inputLength, couplerLength, outputLength, groundLength, inputAngle, deltaAngle	Returns the real and imaginary components of the input link + an optional delta

Parameters

In the image below, input is represented by s, the coupler is p and the output is u. Driving angle is Theta 2 and the deltas are for creating ternary links.

Example

Below is a vary basic example to show how fast calculations can be made

 
const FourBar = require('fourbar');
const four = new FourBar;
 
 
let output;
let coupler;
let transmission;
 
const link1 = 20;
const link2 = 10;
const link3 = 10;
const link4 = 10;
angle = (75 * (Math.PI/180));
 
 
output = four.outputAngle(link2, link3, link4, link1, angle);
coupler = four.couplerAngle(link2, link3, link4, link1, angle);
transmission = four.transmissionAngle(link2, link3, link4, link1, angle);
 
console.log(`Crossed output angle ${(output.crossed * (180/Math.PI))} \n`);
console.log(`Open output angle ${(output.open * (180/Math.PI))} \n`);
console.log(`Crossed coupler angle ${(coupler.crossed * (180/Math.PI))} \n`);
console.log(`Open coupler angle, ${(coupler.open * (180/Math.PI))} \n`);
console.log(`TYPE: ${four.linkageType(link2, link3, link4, link1, angle)} \n`);
console.log(`Crossed transmission angle ${(transmission.crossed * (180/Math.PI))} \n`);
console.log(`Open transmission angle ${(transmission.open * (180/Math.PI))} \n`);