%LINK create a new LINK object%% A LINK object holds all information related to a robot link such as% kinematics of the joint, rigid-body inertial parameters, motor and% transmission parameters.%%	L = LINK%	L = LINK(link)%% Create a default link, or a clone of the passed link.%%	A = LINK(q)%% Compute the link transform matrix for the link, given the joint% variable q.%%	L = LINK([alpha A theta D])% 	L =LINK([alpha A theta D sigma])% 	L =LINK([alpha A theta D sigma offset])% 	L =LINK([alpha A theta D], CONVENTION)% 	L =LINK([alpha A theta D sigma], CONVENTION)% 	L =LINK([alpha A theta D sigma offset], CONVENTION)%% If sigma or offset are not provided they default to zero.  Offset is a% constant amount added to the joint angle variable before forward kinematics% and is useful if you want the robot to adopt a 'sensible' pose for zero% joint angle configuration.%% The optional CONVENTION argument is 'standard' for standard D&H parameters % or 'modified' for modified D&H parameters.  If not specified the default% 'standard'.% Handling the different kinematic conventions is now hidden within the LINK% object.%% Conceivably all sorts of stuff could live in the LINK object such as% graphical models of links and so on.%% For robot models prior to Toolbox release 5 (pre Matlab objects) the% following object constructors are provided.%% 	L = LINK(DYN_ROW)		create from row of legacy DYN matrix%	L = LINK(DYN_ROW, CONVENTION)	create from row of legacy DYN matrix%% SEE ALSO: LINK/SUBSREF, LINK/SUBSASGN, SHOWLINK, ROBOT.% MOD HISTORY% 3/99 modify to use on a LINK object% 6/99 fix the number of fields inthe object, v5.3 doesn't let me change them% mod by  Francisco Javier Blanco Rodriguez <jblanco@abedul.usal.es>% $Log: link.m,v $% Revision 1.6  2002/04/14 11:02:01  pic% Updated see also line.%% Revision 1.5  2002/04/14 10:20:42  pic% Added see also line.%% Revision 1.4  2002/04/01 12:04:51  pic% General tidyup, comments, clarification, copyright, RCS keys, etc.%% $Revision: 1.6 $% Copyright (C) 1999-2002, by Peter I. Corkefunction l = link(dh, convention)	if nargin == 0,		% create an 'empty' link		l.alpha = 0;		l.A = 0;		l.theta = 0;		l.D = 0;		l.sigma = 0;		l.mdh = 0;		l.offset = 0;				% it's a legacy DYN matrix		l.m = [];		l.r = [];		v = [];		l.I = [];		l.Jm = [];		l.G = [];		l.B = 0;		l.Tc = [0 0];		l.qlim = [];		l = class(l, 'link');	elseif isa(dh, 'link')		% clone passed link		l = dh;	elseif length(dh) <= 6,		% legacy DH matrix		% link([alpha A theta D sigma])		if length(dh) < 4,				error('must provide <alpha A theta D> params');		end		l.alpha = dh(1);		l.A = dh(2);		l.theta = dh(3);		l.D = dh(4);		l.sigma = 0;		if length(dh) >= 5,			l.sigma = dh(5);		end		if nargin > 1			if strncmp(convention, 'mod', 3) == 1,				l.mdh = 1;			elseif strncmp(convention, 'sta', 3) == 1,				l.mdh = 0;			else				error('convention must be modified or standard');			end		else				l.mdh = 0;	% default to standard D&H		end		l.offset = 0;		if length(dh) >= 6,			l.offset = dh(6);		end		% we know nothing about the dynamics		l.m = [];		l.r = [];		v = [];		l.I = [];		l.Jm = [];		l.G = [];		l.B = 0;		l.Tc = [0 0];		l.qlim = [];		l = class(l, 'link');	else		% legacy DYN matrix		l.alpha = dh(1);		l.A = dh(2);		l.theta = dh(3);		l.D = dh(4);		if length(dh) == 4,			l.sigma = 0;		else			l.sigma = dh(5);		end		l.mdh = 0;	% default to standard D&H		l.offset = 0;				% it's a legacy DYN matrix		l.m = dh(6);		l.r = dh(7:9)';		% a column vector		v = dh(10:15);		l.I = [	v(1) v(4) v(6)			v(4) v(2) v(5)			v(6) v(5) v(3)];		if length(dh) > 15,			l.Jm = dh(16);		end		if length(dh) > 16,			l.G = dh(17);		else			l.G = 1;		end		if length(dh) > 17,			l.B = dh(18);		else			l.B = 0.0;		end		if length(dh) > 18,			l.Tc = dh(19:20);		else			l.Tc = [0 0];		end		l.qlim = [];		if nargin > 1			if strncmp(convention, 'mod', 3) == 1,				l.mdh = 1;			elseif strncmp(convention, 'sta', 3) == 1,				l.mdh = 0;			else				error('convention must be modified or standard');			end		else				l.mdh = 0;	% default to standard D&H		end		l = class(l, 'link');	end