Modern_Robotics/code/MATLAB/JacobianBody.m

%*** CHAPTER 5: VELOCITY KINEMATICS AND STATICS ***

function Jb = JacobianBody(Blist, thetalist)
% Takes Blist: The joint screw axes in the end-effector frame when the
%              manipulator is at the home position, in the format of a 
%              matrix with the screw axes as the columns,
%       thetalist: A list of joint coordinates.
% Returns the corresponding body Jacobian (6xn real numbers).
% Example Input:
%{
  clear; clc;
  Blist = [[0; 0; 1;   0; 0.2; 0.2], ...
           [1; 0; 0;   2;   0;   3], ...
           [0; 1; 0;   0;   2;   1], ...
           [1; 0; 0; 0.2; 0.3; 0.4]];
  thetalist = [0.2; 1.1; 0.1; 1.2];
  Jb = JacobianBody(Blist, thetalist)
%} 
% Output:
% Jb =
%   -0.0453    0.9950         0    1.0000
%    0.7436    0.0930    0.3624         0
%   -0.6671    0.0362   -0.9320         0
%    2.3259    1.6681    0.5641    0.2000
%   -1.4432    2.9456    1.4331    0.3000
%   -2.0664    1.8288   -1.5887    0.4000

Jb = Blist;
T = eye(4);
for i = length(thetalist) - 1: -1: 1   
    T = T * MatrixExp6(VecTose3(-1 * Blist(:, i + 1) * thetalist(i + 1)));
	Jb(:, i) = Adjoint(T) * Blist(:, i);
end
end