KDL-Examples

Some small examples for usage.

Do not hesitate to add your own small examples.

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Forward kinematic chain example

Submitted by fcauwe on Thu, 2007-11-29 11:21.

// Copyright  (C)  2007  Francois Cauwe <francois at cauwe dot org>
 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
 
#include <kdl/chain.hpp>
#include <kdl/chainfksolver.hpp>
#include <kdl/chainfksolverpos_recursive.hpp>
#include <kdl/frames_io.hpp>
#include <stdio.h>
#include <iostream>
 
using namespace KDL;
 
 
int main( int argc, char** argv )
{
    //Definition of a kinematic chain & add segments to the chain
    KDL::Chain chain;
    chain.addSegment(Segment(Joint(Joint::RotZ),Frame(Vector(0.0,0.0,1.020))));
    chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.480))));
    chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.645))));
    chain.addSegment(Segment(Joint(Joint::RotZ)));
    chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.120))));
    chain.addSegment(Segment(Joint(Joint::RotZ)));
 
    // Create solver based on kinematic chain
    ChainFkSolverPos_recursive fksolver = ChainFkSolverPos_recursive(chain);
 
    // Create joint array
    unsigned int nj = chain.getNrOfJoints();
    KDL::JntArray jointpositions = JntArray(nj);
 
    // Assign some values to the joint positions
    for(unsigned int i=0;i<nj;i++){
        float myinput;
        printf ("Enter the position of joint %i: ",i);
        scanf ("%e",&myinput);
        jointpositions(i)=(double)myinput;
    }
 
    // Create the frame that will contain the results
    KDL::Frame cartpos;    
 
    // Calculate forward position kinematics
    bool kinematics_status;
    kinematics_status = fksolver.JntToCart(jointpositions,cartpos);
    if(kinematics_status>=0){
        std::cout << cartpos <<std::endl;
        printf("%s \n","Succes, thanks KDL!");
    }else{
        printf("%s \n","Error: could not calculate forward kinematics :(");
    }
}

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Using KDL

Submitted by brenodee on Mon, 2009-09-21 16:33.

Hi, I have a basic question...how should look like my makefile in order to compile the example posted above???

Thanks,

Breno Carneiro Pinheiro Electrical Engineering

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Ruben Smits's picture

Inverse position example

Submitted by Ruben Smits on Mon, 2008-06-02 08:41.

//Creation of the chain:
KDL::Chain chain;
chain.addSegment(Segment(Joint(Joint::RotZ),Frame(Vector(0.0,0.0,1.020))));
chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.480))));
chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.645))));
chain.addSegment(Segment(Joint(Joint::RotZ)));
chain.addSegment(Segment(Joint(Joint::RotX),Frame(Vector(0.0,0.0,0.120))));
chain.addSegment(Segment(Joint(Joint::RotZ)));
 
//Creation of the solvers:
ChainFkSolverPos_recursive fksolver1(chain1);//Forward position solver
ChainIkSolverVel_pinv iksolver1v(chain1);//Inverse velocity solver
ChainIkSolverPos_NR iksolver1(chain1,fksolver1,iksolver1v,100,1e-6);//Maximum 100 iterations, stop at accuracy 1e-6
 
//Creation of jntarrays:
JntArray q(chain.getNrOfJoints());
JntArray q_init(chain.getNrOfJoints());
 
//Set destination frame
Frame F_dest=...;
 
int ret = iksolverpos.CartToJnt(q_init,F_dest,q);

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Inverse position example

Submitted by andy1982 on Mon, 2008-12-01 13:21.

Excuse me, a question is, how can we implement the Inverse Kinematics with some joint parameters, such as angle limits?

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Ruben Smits's picture

You will have to create

Submitted by Ruben Smits on Wed, 2009-02-11 09:13.

You will have to create your own solver for this. But you can start from the existing solver ;). If you need any help, don't hesitate to contact me.

Ruben

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Ruben Smits's picture

FindKDL.cmake

Submitted by Ruben Smits on Thu, 2008-07-24 08:08.

Since people want to use KDL in their own project i'm posting a FindKDL.cmake file that can find KDL and the RTT-bindings if you want to:

your CMakeLists.txt should be something like this: 


#------
PROJECT(Dummy)


INCLUDE (${PROJECT_SOURCE_DIR}/FindPkgConfig.cmake)

## Find KDL
SET( KDL_INSTALL ${CMAKE_INSTALL_PREFIX} CACHE PATH "The KDL installation directory.")
INCLUDE (${PROJECT_SOURCE_DIR}/FindKDL.cmake)
#--------

A link to the files:

http://people.mech.kuleuven.be/~rsmits/FindKDL/

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Inverse Kinematic

Submitted by oroblam on Thu, 2010-07-01 08:48.

Does anyone know where I can find a working example of Inverse Kinematic? I can't compile the example above! thank you!!

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