Visual Servoing Platform  version 3.2.0 under development (2018-10-15)
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 as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* 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 <fstream>
#include <iostream>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>
#if (defined(VISP_HAVE_VIPER850) && defined(VISP_HAVE_DC1394))
#include <visp3/blob/vpDot2.h>
#include <visp3/core/vpDisplay.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/gui/vpDisplayGTK.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/robot/vpRobotViper850.h>
#include <visp3/sensor/vp1394TwoGrabber.h>
#include <visp3/vision/vpPose.h>
#include <visp3/visual_features/vpFeatureBuilder.h>
#include <visp3/visual_features/vpFeaturePoint.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, vpCameraParameters cam, vpHomogeneousMatrix &cMo,
vpTranslationVector &cto, 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();
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
vpServoDisplay::display(task, cam, I);
// 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 EXIT_SUCCESS;
}
catch (const vpException &e) {
flog.close(); // Close the log file
std::cout << "Catch an exception: " << e.getMessage() << std::endl;
return EXIT_FAILURE;
}
}
#else
int main()
{
std::cout << "You do not have an Viper 850 robot connected to your computer..." << std::endl;
return EXIT_SUCCESS;
}
#endif