kinematics-js

Kinematics.js

A forward and inverse kinematics package for a basic 6 axis robotic arm.

Inverse

import { inverse } from 'kinematics-js';

inverse(5, 0, 11, 0, 0, 0, {
  base: 1,
  v1: 2.5,
  v2: 3,
  v3: 2.5,
  v4: 2.5,
  v5: 2.5,
  v6: 2,
});

Parameter	Description
x	x cartesian coordinate in the three dimensional space relative to the base frame
y	y cartesian coordinate in the three dimensional space relative to the base frame
z	z cartesian coordinate in the three dimensional space relative to the base frame
r1	euler angle 1, the rotation around the z1 axis of the end effector
r2	euler angle 2, the rotation around the x axis of the end effector
r3	euler angle 3, the rotation around the z2 axis of the end effector
config	robot configuration see table below

Key	required	Description
base	no	height of the base
v1	yes	length between joint 1 and 2
v2	yes	length between joint 2 and 3
v3	yes	length between joint 3 and 4
v4	yes	length between joint 4 and 5
v5	yes	length between joint 5 and 6
v6	yes	length between joint 6 and the end effector

Examples:

// First define a config for the robot
const config == {
  v1: 2.5,
  v2: 3,
  v3: 2.5,
  v4: 2.5,
  v5: 2.5,
  v6: 2,
};

/**
 *     |
 *    [ ]
 *     |
 *    ( )
 *     |
 *    [ ]
 *     |
 *    ( )
 *     |
 *    ( )
 *     |
 *    [ ]
 */
inverse(0, 0, 15, 0, 0, 0, config)
// ==> [0, 0, 0, 0, 0, 0]

/**
 *                  [ ]
 *                   |
 *    ( ) -- [ ] -- ( )
 *     |
 *    ( )
 *     |
 *    [ ]
 */
inverse(5, 0, 10, 0, 0, 0, config)
// ==> [0, 0, -Math.PI / 2, 0, Math.PI / 2, 0 ]

/**
 *                  [ ]
 *                   |
 *    ( ) -- [ ] -- ( )
 *     |
 *    ( )
 *     |
 *    [ ]
 */
inverse(5, 0, 11, 0, 0, 0, { ...config, base: 1 })
// ==> [0, 0, -Math.PI / 2, 0, Math.PI / 2, 0 ]

Forward

import { forward } from 'kinematics-js';

forward(0, 0, -Math.PI / 2, Math.PI, -Math.PI / 2, 0, {
  v1: 2.5,
  v2: 3,
  v3: 2.5,
  v4: 2.5,
  v5: 2.5,
  v6: 2,
});
// ==>
// [-1, 0, 0, 5],
// [0, -1, 0, 0],
// [0, 0, 1, 10],
// [0, 0, 0, 1],
//
// The return value gives you the rotation matrix and also the cartesian location which you can get below
// const x = res[0][3];
// const y = res[1][3];
// const z = res[2][3];

Parameter	Description
theta1	angle of joint j1 in radians
theta2	angle of joint j2 in radians
theta3	angle of joint j3 in radians
theta4	angle of joint j4 in radians
theta5	angle of joint j5 in radians
theta6	angle of joint j6 in radians
config	robot configuration see table below

Key	required	Description
base	no	height of the base
v1	yes	length between joint 1 and 2
v2	yes	length between joint 2 and 3
v3	yes	length between joint 3 and 4
v4	yes	length between joint 4 and 5
v5	yes	length between joint 5 and 6
v6	yes	length between joint 6 and the end effector

Live Demo

See the kinematics in action here

Kinematics Diagram