Gazebo: Q&A Forum - RSS feedhttp://answers.gazebosim.org/questions/Open source question and answer forum for GazeboenCopyright Askbot, 2010-2011.Fri, 26 Aug 2016 00:03:10 -0500Symbolic jacobian of an armhttp://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/ Hi all,
I've a 7 DOF arm described in .xacro format and I would like to extrapolate its jacobian in symbolic form (not numerical angle values in the matrix ).
I tried to use KDL for this scope, and I was able to obtain the jacobian of this arm but in a numerical form. That is, during a gazebo simulation, I could read the values of each angles, insert them in the jacobian matrix with a specific kdl command, and obtain the jacobian matrix on every gazebo step time.
That's ok, but if I have another target in which I need the symbolic for of this jacobian from which extrapolate other matrix (inertial, coriolis ecc..), I'm not able to do this. (For example if I want to control my arm in a particular way in which I need the dynamic expression of the system).
Has anyone every have this problem? Is there a method with kdl or another software that I can use?
Thank you!Sun, 05 Jun 2016 05:52:15 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/Comment by abbas for <p>Hi all,</p>
<p>I've a 7 DOF arm described in .xacro format and I would like to extrapolate its jacobian in symbolic form (not numerical angle values in the matrix ).</p>
<p>I tried to use KDL for this scope, and I was able to obtain the jacobian of this arm but in a numerical form. That is, during a gazebo simulation, I could read the values of each angles, insert them in the jacobian matrix with a specific kdl command, and obtain the jacobian matrix on every gazebo step time.</p>
<p>That's ok, but if I have another target in which I need the symbolic for of this jacobian from which extrapolate other matrix (inertial, coriolis ecc..), I'm not able to do this. (For example if I want to control my arm in a particular way in which I need the dynamic expression of the system).</p>
<p>Has anyone every have this problem? Is there a method with kdl or another software that I can use? </p>
<p>Thank you!</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14039#post-id-14039Hi
Did you resolved your problem? I have almost the same problem as you I want to use Coriolis vector in my controller, do you have any suggestion for me? I have read many things in last days and I just got confused. I have tried to use DART library but till now it was not helpful, I really appreciate if you can help me.
Thanks.Sun, 31 Jul 2016 05:18:54 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14039#post-id-14039Answer by mrslvgg for <p>Hi all,</p>
<p>I've a 7 DOF arm described in .xacro format and I would like to extrapolate its jacobian in symbolic form (not numerical angle values in the matrix ).</p>
<p>I tried to use KDL for this scope, and I was able to obtain the jacobian of this arm but in a numerical form. That is, during a gazebo simulation, I could read the values of each angles, insert them in the jacobian matrix with a specific kdl command, and obtain the jacobian matrix on every gazebo step time.</p>
<p>That's ok, but if I have another target in which I need the symbolic for of this jacobian from which extrapolate other matrix (inertial, coriolis ecc..), I'm not able to do this. (For example if I want to control my arm in a particular way in which I need the dynamic expression of the system).</p>
<p>Has anyone every have this problem? Is there a method with kdl or another software that I can use? </p>
<p>Thank you!</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?answer=13570#post-id-13570 If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in [this](http://it.mathworks.com/help/symbolic/jacobian.html) page. Moreover, the Matlab [Robotic Toolbox](http://www.petercorke.com/Toolboxes.html) has a C code generator useful to directly output the calculated symbolic quantities in C format.
On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation [here](https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html).
Hope this can help.Wed, 08 Jun 2016 07:07:10 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?answer=13570#post-id-13570Comment by mrslvgg for <p>If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in <a href="http://it.mathworks.com/help/symbolic/jacobian.html">this</a> page. Moreover, the Matlab <a href="http://www.petercorke.com/Toolboxes.html">Robotic Toolbox</a> has a C code generator useful to directly output the calculated symbolic quantities in C format.</p>
<p>On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation <a href="https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html">here</a>.</p>
<p>Hope this can help.</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14263#post-id-14263Sure. My email address is:
mar.selvaggio@gmail.comFri, 26 Aug 2016 00:03:10 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14263#post-id-14263Comment by abbas for <p>If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in <a href="http://it.mathworks.com/help/symbolic/jacobian.html">this</a> page. Moreover, the Matlab <a href="http://www.petercorke.com/Toolboxes.html">Robotic Toolbox</a> has a C code generator useful to directly output the calculated symbolic quantities in C format.</p>
<p>On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation <a href="https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html">here</a>.</p>
<p>Hope this can help.</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14242#post-id-14242MarioSelvaggio, I really appreciate your intention, may I have your email, this is mine: nabafa_raiehe@yahoo.comWed, 24 Aug 2016 10:38:48 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14242#post-id-14242Comment by mrslvgg for <p>If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in <a href="http://it.mathworks.com/help/symbolic/jacobian.html">this</a> page. Moreover, the Matlab <a href="http://www.petercorke.com/Toolboxes.html">Robotic Toolbox</a> has a C code generator useful to directly output the calculated symbolic quantities in C format.</p>
<p>On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation <a href="https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html">here</a>.</p>
<p>Hope this can help.</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14136#post-id-14136I would be happy to contribute to the writing of the KDL pluginSun, 14 Aug 2016 07:09:52 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14136#post-id-14136Comment by nkoenig for <p>If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in <a href="http://it.mathworks.com/help/symbolic/jacobian.html">this</a> page. Moreover, the Matlab <a href="http://www.petercorke.com/Toolboxes.html">Robotic Toolbox</a> has a C code generator useful to directly output the calculated symbolic quantities in C format.</p>
<p>On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation <a href="https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html">here</a>.</p>
<p>Hope this can help.</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14041#post-id-14041Yes, you can write a plugin that uses KDL.Mon, 01 Aug 2016 10:17:31 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14041#post-id-14041Comment by abbas for <p>If you need the symbolic Jacobian of your robot you should calculate it in symbolic form using Matlab for example. It allows symbolic calculation as exemplified in <a href="http://it.mathworks.com/help/symbolic/jacobian.html">this</a> page. Moreover, the Matlab <a href="http://www.petercorke.com/Toolboxes.html">Robotic Toolbox</a> has a C code generator useful to directly output the calculated symbolic quantities in C format.</p>
<p>On the other hand, KDL library allows you to numerically compute the matrices of the robot dynamic model (e.g. Inertia, Coriolis, Gravity) starting from robot state (joint positions, velocities). You can find the detailed implementation <a href="https://people.mech.kuleuven.be/~eaertbel/expressiontrees/api_full/orocos_kdl/html/chaindynparam_8cpp_source.html">here</a>.</p>
<p>Hope this can help.</p>
http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14038#post-id-14038Is it possible to use KDL library in each step in gazebo for example in designing controller?Sun, 31 Jul 2016 04:58:07 -0500http://answers.gazebosim.org/question/13542/symbolic-jacobian-of-an-arm/?comment=14038#post-id-14038