jacobn.m

Robotics TOOLBOX The Toolbox provides many functions that are useful in robotics including such thi

%JACOBN Compute manipulator Jacobian in end-effector frame
%
%	JN = JACOBN(ROBOT, Q)
%
% Returns a Jacobian matrix for the robot ROBOT in pose Q.
%
% The manipulator Jacobian matrix maps differential changes in joint space
% to differential Cartesian motion of the end-effector (end-effector coords).
% 		dX = J dQ
%
% This function uses the technique of
% 	Paul, Shimano, Mayer
% 	Differential Kinematic Control Equations for Simple Manipulators
% 	IEEE SMC 11(6) 1981
% 	pp. 456-460
%
% For an n-axis manipulator the Jacobian is a 6 x n matrix.
%
% See also: JACOB0, DIFF2TR, TR2DIFF

% MOD.HISTORY
% 3/99	uses objects
% 10/01	handle Craig's conventions
% $Log: jacobn.m,v $
% Revision 1.3  2002/04/01 11:47:14  pic
% General cleanup of code: help comments, see also, copyright, remnant dh/dyn
% references, clarification of functions.
%
% $Revision: 1.3 $
% Copyright (C) 1999-2002, by Peter I. Corke

function J = jacobn(robot, q)

	n = robot.n;
	L = robot.link;		% get the links

	J = [];
	U = robot.tool;
	for j=n:-1:1,
		if robot.mdh == 0,
			% standard DH convention
			U = L{j}( q(j) ) * U;
		end
		if L{j}.RP == 'R',
			% revolute axis
			d = [	-U(1,1)*U(2,4)+U(2,1)*U(1,4)
				-U(1,2)*U(2,4)+U(2,2)*U(1,4)
				-U(1,3)*U(2,4)+U(2,3)*U(1,4)];
			delta = U(3,1:3)';	% nz oz az
		else
			% prismatic axis
			d = U(3,1:3)';		% nz oz az
			delta = zeros(3,1);	%  0  0  0
		end
		J = [[d; delta] J];

		if robot.mdh ~= 0,
			% modified DH convention
			U = L{j}( q(j) ) * U;
		end
	end