Visual Servoing Platform  version 3.0.1
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servoViper850FourPoints2DArtVelocityInteractionCurrent.cpp

Example of eye-in-hand control law. We control here a real robot, the Viper S850 robot (arm with 6 degrees of freedom). The velocities resulting from visual servo are here joint velocities. Visual features are the image coordinates of 4 points. The target is made of 4 dots arranged as a 10cm by 10cm square.

/****************************************************************************
*
* This file is part of the ViSP software.
* Copyright (C) 2005 - 2017 by Inria. All rights reserved.
*
* This software is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* ("GPL") version 2 as published by the Free Software Foundation.
* See the file LICENSE.txt at the root directory of this source
* distribution for additional information about the GNU GPL.
*
* For using ViSP with software that can not be combined with the GNU
* GPL, please contact Inria about acquiring a ViSP Professional
* Edition License.
*
* See http://visp.inria.fr for more information.
*
* This software was developed at:
* Inria Rennes - Bretagne Atlantique
* Campus Universitaire de Beaulieu
* 35042 Rennes Cedex
* France
*
* If you have questions regarding the use of this file, please contact
* Inria at visp@inria.fr
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Description:
* tests the control law
* eye-in-hand control
* velocity computed in the articular frame
*
* Authors:
* Fabien Spindler
*
*****************************************************************************/
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpDebug.h> // Debug trace
#include <stdio.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <stdlib.h>
#if (defined (VISP_HAVE_VIPER850) && defined (VISP_HAVE_DC1394))
#include <visp3/sensor/vp1394TwoGrabber.h>
#include <visp3/core/vpDisplay.h>
#include <visp3/gui/vpDisplayGTK.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/blob/vpDot2.h>
#include <visp3/visual_features/vpFeatureBuilder.h>
#include <visp3/visual_features/vpFeaturePoint.h>
#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpImage.h>
#include <visp3/core/vpIoTools.h>
#include <visp3/core/vpMath.h>
#include <visp3/core/vpPoint.h>
#include <visp3/vision/vpPose.h>
#include <visp3/robot/vpRobotViper850.h>
#include <visp3/vs/vpServo.h>
#include <visp3/vs/vpServoDisplay.h>
#define L 0.05 // to deal with a 10cm by 10cm square
void compute_pose(vpPoint point[], vpDot2 dot[], int ndot,
vpRxyzVector &cro, bool init)
{
vpHomogeneousMatrix cMo_dementhon; // computed pose with dementhon
vpHomogeneousMatrix cMo_lagrange; // computed pose with dementhon
vpPose pose;
for (int i=0; i < ndot; i ++) {
double x=0, y=0;
cog = dot[i].getCog();
cog,
x, y) ; //pixel to meter conversion
point[i].set_x(x) ;//projection perspective p
point[i].set_y(y) ;
pose.addPoint(point[i]) ;
}
if (init == true) {
pose.computePose(vpPose::DEMENTHON, cMo_dementhon) ;
// Compute and return the residual expressed in meter for the pose matrix
// 'cMo'
double residual_dementhon = pose.computeResidual(cMo_dementhon);
pose.computePose(vpPose::LAGRANGE, cMo_lagrange) ;
double residual_lagrange = pose.computeResidual(cMo_lagrange);
// Select the best pose to initialize the lowe pose computation
if (residual_lagrange < residual_dementhon)
cMo = cMo_lagrange;
else
cMo = cMo_dementhon;
}
else { // init = false; use of the previous pose to initialise LOWE
cRo.buildFrom(cro);
cMo.buildFrom(cto, cRo);
}
cMo.extract(cto);
cMo.extract(cRo);
cro.buildFrom(cRo);
}
int
main()
{
// Log file creation in /tmp/$USERNAME/log.dat
// This file contains by line:
// - the 6 computed joint velocities (m/s, rad/s) to achieve the task
// - the 6 mesured joint velocities (m/s, rad/s)
// - the 6 mesured joint positions (m, rad)
// - the 8 values of s - s*
std::string username;
// Get the user login name
// Create a log filename to save velocities...
std::string logdirname;
logdirname ="/tmp/" + username;
// Test if the output path exist. If no try to create it
if (vpIoTools::checkDirectory(logdirname) == false) {
try {
// Create the dirname
}
catch (...) {
std::cerr << std::endl
<< "ERROR:" << std::endl;
std::cerr << " Cannot create " << logdirname << std::endl;
return(-1);
}
}
std::string logfilename;
logfilename = logdirname + "/log.dat";
// Open the log file name
std::ofstream flog(logfilename.c_str());
try {
// Load the end-effector to camera frame transformation obtained
// using a camera intrinsic model with distortion
vpServo task ;
int i ;
bool reset = false;
vp1394TwoGrabber g(reset);
g.open(I) ;
g.acquire(I) ;
#ifdef VISP_HAVE_X11
vpDisplayX display(I,100,100,"Current image") ;
#elif defined(VISP_HAVE_OPENCV)
vpDisplayOpenCV display(I,100,100,"Current image") ;
#elif defined(VISP_HAVE_GTK)
vpDisplayGTK display(I,100,100,"Current image") ;
#endif
std::cout << std::endl ;
std::cout << "-------------------------------------------------------" << std::endl ;
std::cout << " Test program for vpServo " <<std::endl ;
std::cout << " Eye-in-hand task control, velocity computed in the joint space" << std::endl ;
std::cout << " Use of the Afma6 robot " << std::endl ;
std::cout << " task : servo 4 points on a square with dimention " << L << " meters" << std::endl ;
std::cout << "-------------------------------------------------------" << std::endl ;
std::cout << std::endl ;
vpDot2 dot[4] ;
std::cout << "Click on the 4 dots clockwise starting from upper/left dot..."
<< std::endl;
for (i=0 ; i < 4 ; i++) {
dot[i].setGraphics(true) ;
dot[i].initTracking(I) ;
cog = dot[i].getCog();
}
// Update camera parameters
robot.getCameraParameters (cam, I);
// Sets the current position of the visual feature
for (i=0 ; i < 4 ; i++)
vpFeatureBuilder::create(p[i], cam, dot[i]); //retrieve x,y of the vpFeaturePoint structure
// Set the position of the square target in a frame which origin is
// centered in the middle of the square
vpPoint point[4] ;
point[0].setWorldCoordinates(-L, -L, 0) ;
point[1].setWorldCoordinates( L, -L, 0) ;
point[2].setWorldCoordinates( L, L, 0) ;
point[3].setWorldCoordinates(-L, L, 0) ;
// Initialise a desired pose to compute s*, the desired 2D point features
vpTranslationVector cto(0, 0, 0.5); // tz = 0.5 meter
vpRotationMatrix cRo(cro); // Build the rotation matrix
cMo.buildFrom(cto, cRo); // Build the homogeneous matrix
// Sets the desired position of the 2D visual feature
// Compute the desired position of the features from the desired pose
for (int i=0; i < 4; i ++) {
vpColVector cP, p ;
point[i].changeFrame(cMo, cP) ;
point[i].projection(cP, p) ;
pd[i].set_x(p[0]) ;
pd[i].set_y(p[1]) ;
pd[i].set_Z(cP[2]);
}
// We want to see a point on a point
for (i=0 ; i < 4 ; i++)
task.addFeature(p[i],pd[i]) ;
// Set the proportional gain
task.setLambda(0.3) ;
// Display task information
task.print() ;
// Define the task
// - we want an eye-in-hand control law
// - articular velocity are computed
task.print() ;
robot.get_cVe(cVe) ;
task.set_cVe(cVe) ;
task.print() ;
// Set the Jacobian (expressed in the end-effector frame)
vpMatrix eJe ;
robot.get_eJe(eJe) ;
task.set_eJe(eJe) ;
task.print() ;
// Initialise the velocity control of the robot
std::cout << "\nHit CTRL-C to stop the loop...\n" << std::flush;
for ( ; ; ) {
// Acquire a new image from the camera
g.acquire(I) ;
// Display this image
try {
// For each point...
for (i=0 ; i < 4 ; i++) {
// Achieve the tracking of the dot in the image
dot[i].track(I) ;
// Display a green cross at the center of gravity position in the
// image
cog = dot[i].getCog();
}
}
catch(...) {
flog.close() ; // Close the log file
vpTRACE("Error detected while tracking visual features") ;
robot.stopMotion() ;
return(1) ;
}
// During the servo, we compute the pose using LOWE method. For the
// initial pose used in the non linear minimisation we use the pose
// computed at the previous iteration.
compute_pose(point, dot, 4, cam, cMo, cto, cro, false);
for (i=0 ; i < 4 ; i++) {
// Update the point feature from the dot location
vpFeatureBuilder::create(p[i], cam, dot[i]);
// Set the feature Z coordinate from the pose
point[i].changeFrame(cMo, cP) ;
p[i].set_Z(cP[2]);
}
// Get the jacobian of the robot
robot.get_eJe(eJe) ;
// Update this jacobian in the task structure. It will be used to compute
// the velocity skew (as an articular velocity)
// qdot = -lambda * L^+ * cVe * eJe * (s-s*)
task.set_eJe(eJe) ;
// Compute the visual servoing skew vector
v = task.computeControlLaw() ;
// Display the current and desired feature points in the image display
// Apply the computed joint velocities to the robot
// Save velocities applied to the robot in the log file
// v[0], v[1], v[2] correspond to joint translation velocities in m/s
// v[3], v[4], v[5] correspond to joint rotation velocities in rad/s
flog << v[0] << " " << v[1] << " " << v[2] << " "
<< v[3] << " " << v[4] << " " << v[5] << " ";
// Get the measured joint velocities of the robot
// Save measured joint velocities of the robot in the log file:
// - qvel[0], qvel[1], qvel[2] correspond to measured joint translation
// velocities in m/s
// - qvel[3], qvel[4], qvel[5] correspond to measured joint rotation
// velocities in rad/s
flog << qvel[0] << " " << qvel[1] << " " << qvel[2] << " "
<< qvel[3] << " " << qvel[4] << " " << qvel[5] << " ";
// Get the measured joint positions of the robot
// Save measured joint positions of the robot in the log file
// - q[0], q[1], q[2] correspond to measured joint translation
// positions in m
// - q[3], q[4], q[5] correspond to measured joint rotation
// positions in rad
flog << q[0] << " " << q[1] << " " << q[2] << " "
<< q[3] << " " << q[4] << " " << q[5] << " ";
// Save feature error (s-s*) for the 4 feature points. For each feature
// point, we have 2 errors (along x and y axis). This error is expressed
// in meters in the camera frame
flog << ( task.getError() ).t() << std::endl;
// Flush the display
// std::cout << "|| s - s* || = " << ( task.getError() ).sumSquare() << std::endl;
}
std::cout << "Display task information: " << std::endl;
task.print() ;
task.kill();
flog.close() ; // Close the log file
return 0;
}
catch (...)
{
flog.close() ; // Close the log file
vpERROR_TRACE(" Test failed") ;
return 0;
}
}
#else
int
main()
{
vpERROR_TRACE("You do not have an afma6 robot or a firewire framegrabber connected to your computer...");
}
#endif