subsref.html

Robot tool box - provides many functions that are useful in robotics including such things as kinem

0080             <span class="keyword">else</span>
0081                 v = <span class="string">'P'</span>;
0082             <span class="keyword">end</span>
0083         <span class="keyword">case</span> <span class="string">'mdh'</span>,
0084             v = l.mdh;
0085 
0086         <span class="comment">%%%%%%% joint limit support</span>
0087         <span class="keyword">case</span> <span class="string">'qlim'</span>,
0088             v = l.qlim;
0089         <span class="keyword">case</span> <span class="string">'islimit'</span>,
0090             <span class="keyword">if</span> isempty(l.qlim)
0091                 error(<span class="string">'no limits assigned to link'</span>)
0092             <span class="keyword">end</span>
0093             <span class="keyword">if</span> s(2).type  ~= <span class="string">'()'</span>
0094                 error(<span class="string">'expecting argument for islimit method'</span>);
0095             <span class="keyword">end</span>
0096             q = s(2).subs{1};
0097             v = (q &gt; l.qlim(2)) - (q &lt; l.qlim(1));
0098 
0099         <span class="comment">%%%%%%% dynamic parameters</span>
0100         <span class="keyword">case</span> <span class="string">'G'</span>,
0101             v = l.G;
0102         <span class="keyword">case</span> <span class="string">'I'</span>,
0103             v = l.I;
0104         <span class="keyword">case</span> <span class="string">'r'</span>,
0105             v = l.r;
0106         <span class="keyword">case</span> <span class="string">'Jm'</span>,
0107             v = l.Jm;
0108         <span class="keyword">case</span> <span class="string">'B'</span>,
0109             v = l.B;
0110         <span class="keyword">case</span> <span class="string">'Tc'</span>,
0111             v = l.Tc;
0112 
0113         <span class="keyword">case</span> <span class="string">'m'</span>,
0114             v = l.m;
0115         <span class="comment">%%%%%%% legacy parameters</span>
0116         <span class="keyword">case</span> <span class="string">'dh'</span>,
0117             v = [l.alpha l.A l.theta l.D l.sigma];
0118         <span class="keyword">case</span> <span class="string">'dyn'</span>,
0119             v = [l.alpha l.A l.theta l.D l.sigma l.m l.r(:)' diag(l.I)' l.I(2,1) l.I(2,3) l.I(1,3) l.Jm l.G l.B l.Tc(:)'];
0120         <span class="keyword">otherwise</span>, disp(<span class="string">'Unknown method'</span>)
0121         <span class="keyword">end</span>
0122     <span class="keyword">end</span>
0123 
0124 
0125 <span class="comment">%LINKTRAN    Compute the link transform from kinematic parameters</span>
0126 <span class="comment">%</span>
0127 <span class="comment">%    LINKTRAN(alpha, an, theta, dn)</span>
0128 <span class="comment">%    LINKTRAN(DH, q) is a homogeneous</span>
0129 <span class="comment">%    transformation between link coordinate frames.</span>
0130 <span class="comment">%</span>
0131 <span class="comment">%    alpha is the link twist angle</span>
0132 <span class="comment">%    an is the link length</span>
0133 <span class="comment">%    theta is the link rotation angle</span>
0134 <span class="comment">%    dn is the link offset</span>
0135 <span class="comment">%    sigma is 0 for a revolute joint, non-zero for prismatic</span>
0136 <span class="comment">%</span>
0137 <span class="comment">%    In the second case, q is substitued for theta or dn according to sigma.</span>
0138 <span class="comment">%</span>
0139 <span class="comment">%    Based on the standard Denavit and Hartenberg notation.</span>
0140 
0141 <span class="comment">%    Copyright (C) Peter Corke 1993</span>
0142 <a name="_sub1" href="#_subfunctions" class="code">function t = linktran(a, b, c, d)</a>
0143 
0144     <span class="keyword">if</span> nargin == 4,
0145         alpha = a;
0146         an = b;
0147         theta = c;
0148         dn = d;
0149     <span class="keyword">else</span>
0150         <span class="keyword">if</span> numcols(a) &lt; 4,
0151             error(<span class="string">'too few columns in DH matrix'</span>);
0152         <span class="keyword">end</span>
0153         alpha = a(1);
0154         an = a(2);
0155         <span class="keyword">if</span> numcols(a) &gt; 4,
0156             <span class="keyword">if</span> a(5) == 0,    <span class="comment">% revolute</span>
0157                 theta = b;
0158                 dn = a(4);
0159             <span class="keyword">else</span>        <span class="comment">% prismatic</span>
0160                 theta = a(3);
0161                 dn = b;
0162             <span class="keyword">end</span>
0163         <span class="keyword">else</span>
0164             theta = b;    <span class="comment">% assume revolute if sigma not given</span>
0165             dn = a(4);
0166         <span class="keyword">end</span>
0167     <span class="keyword">end</span>
0168     sa = sin(alpha); ca = cos(alpha);
0169     st = sin(theta); ct = cos(theta);
0170 
0171     t =    [    ct    -st*ca    st*sa    an*ct
0172             st    ct*ca    -ct*sa    an*st
0173             0    sa    ca    dn
0174             0    0    0    1];
0175 
0176 <span class="comment">%MLINKTRAN    Compute the link transform from kinematic parameters</span>
0177 <span class="comment">%</span>
0178 <span class="comment">%    MLINKTRAN(alpha, an, theta, dn)</span>
0179 <span class="comment">%    MLINKTRAN(DH, q) is a homogeneous</span>
0180 <span class="comment">%    transformation between link coordinate frames.</span>
0181 <span class="comment">%</span>
0182 <span class="comment">%    alpha is the link twist angle</span>
0183 <span class="comment">%    an is the link length</span>
0184 <span class="comment">%    theta is the link rotation angle</span>
0185 <span class="comment">%    dn is the link offset</span>
0186 <span class="comment">%    sigma is 0 for a revolute joint, non-zero for prismatic</span>
0187 <span class="comment">%</span>
0188 <span class="comment">%    In the second case, q is substitued for theta or dn according to sigma.</span>
0189 <span class="comment">%</span>
0190 <span class="comment">%    Based on the modified Denavit and Hartenberg notation.</span>
0191 
0192 <span class="comment">%    Copyright (C) Peter Corke 1993</span>
0193 <a name="_sub2" href="#_subfunctions" class="code">function t = mlinktran(a, b, c, d)</a>
0194 
0195     <span class="keyword">if</span> nargin == 4,
0196         alpha = a;
0197         an = b;
0198         theta = c;
0199         dn = d;
0200     <span class="keyword">else</span>
0201         <span class="keyword">if</span> numcols(a) &lt; 4,
0202             error(<span class="string">'too few columns in DH matrix'</span>);
0203         <span class="keyword">end</span>
0204         alpha = a(1);
0205         an = a(2);
0206         <span class="keyword">if</span> numcols(a) &gt; 4,
0207             <span class="keyword">if</span> a(5) == 0,    <span class="comment">% revolute</span>
0208                 theta = b;
0209                 dn = a(4);
0210             <span class="keyword">else</span>        <span class="comment">% prismatic</span>
0211                 theta = a(3);
0212                 dn = b;
0213             <span class="keyword">end</span>
0214         <span class="keyword">else</span>
0215             theta = b;    <span class="comment">% assume revolute if no sigma given</span>
0216             dn = a(4);
0217         <span class="keyword">end</span>
0218     <span class="keyword">end</span>
0219     sa = sin(alpha); ca = cos(alpha);
0220     st = sin(theta); ct = cos(theta);
0221 
0222     t =    [    ct    -st    0    an
0223             st*ca    ct*ca    -sa    -sa*dn
0224             st*sa    ct*sa    ca    ca*dn
0225             0    0    0    1];</pre></div>
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