Visual Servoing Platform  version 3.2.0 under development (2018-12-17)
servoViper650FourPoints2DCamVelocityInteractionCurrent.cpp

Example of eye-in-hand control law. We control here a real robot, the Viper S650 robot (arm with 6 degrees of freedom). The velocity is computed in the camera frame. The inverse jacobian that converts cartesian velocities in joint velocities is implemented in the robot low level controller. Visual features are the image coordinates of 4 points. The target is made of 4 dots arranged as a 10cm by 10cm square.The device used to acquire images is a firewire camera (PointGrey Flea2)

Camera extrinsic (eMc) and intrinsic parameters are retrieved from the robot low level driver that is not public.

/****************************************************************************
*
* 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 camera frame
*
* Authors:
* Fabien Spindler
*
*****************************************************************************/
#include <fstream>
#include <iostream>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>
#include <visp3/core/vpConfig.h>
#if defined(VISP_HAVE_VIPER650) && defined(VISP_HAVE_DC1394) && defined(VISP_HAVE_X11)
#include <visp3/blob/vpDot2.h>
#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpIoTools.h>
#include <visp3/core/vpPoint.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/robot/vpRobotViper650.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(std::vector<vpPoint> &point, std::vector<vpDot2> &dot, vpCameraParameters cam,
vpHomogeneousMatrix &cMo, bool init)
{
vpHomogeneousMatrix cMo_dementhon; // computed pose with dementhon method
vpHomogeneousMatrix cMo_lagrange; // computed pose with lagrange method
vpPose pose;
for (size_t i = 0; i < point.size(); i++) {
double x = 0, y = 0;
vpImagePoint 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
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;
}
}
int main()
{
// Log file creation in /tmp/$USERNAME/log.dat
// This file contains by line:
// - the 6 computed camera 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
robot.get_eMc(eMc);
std::cout << "Camera extrinsic parameters (eMc): \n" << eMc << std::endl;
vpServo task;
bool reset = false;
vp1394TwoGrabber g(reset);
g.open(I);
g.acquire(I);
vpDisplayX display(I, 100, 100, "Current image");
std::vector<vpDot2> dot(4);
std::cout << "Click on the 4 dots clockwise starting from upper/left dot..." << std::endl;
for (size_t i = 0; i < dot.size(); i++) {
dot[i].setGraphics(true);
dot[i].initTracking(I);
vpImagePoint cog = dot[i].getCog();
}
// Update camera parameters
robot.getCameraParameters(cam, I);
std::cout << "Camera intrinsic parameters: \n" << cam << std::endl;
// Sets the current position of the visual feature
for (size_t i = 0; i < dot.size(); 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
std::vector<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);
// Compute target initial pose
compute_pose(point, dot, cam, cMo, true);
std::cout << "Initial camera pose (cMo): \n" << cMo << std::endl;
// Initialise a desired pose to compute s*, the desired 2D point features
vpHomogeneousMatrix cMo_d(vpTranslationVector(0, 0, 0.5), // tz = 0.5 meter
vpRotationMatrix()); // no rotation
// 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_d, 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 (size_t i = 0; i < dot.size(); i++)
task.addFeature(p[i], pd[i]);
// Set the proportional gain
task.setLambda(0.3);
// Define the task
// - we want an eye-in-hand control law
// - camera velocities are computed
task.print();
// Initialise the velocity control of the robot
std::cout << "\nHit CTRL-C or click in the image 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 (size_t i = 0; i < dot.size(); 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
vpImagePoint cog = dot[i].getCog();
}
} catch (...) {
std::cout << "Error detected while tracking visual features.." << std::endl;
break;
}
// During the servo, we compute the pose using a non linear method. For
// the initial pose used in the non linear minimisation we use the pose
// computed at the previous iteration.
compute_pose(point, dot, cam, cMo, false);
for (size_t i = 0; i < dot.size(); 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]);
}
// Compute the visual servoing skew vector
// 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 camera translation velocities in m/s
// v[3], v[4], v[5] correspond to camera 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() << std::endl;
vpDisplay::displayText(I, 10, 10, "Click to quit...", vpColor::red);
if (vpDisplay::getClick(I, false))
break;
// Flush the display
// std::cout << "\t\t || s - s* || = " << ( task.getError()
// ).sumSquare() << std::endl;
}
robot.stopMotion();
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 << "Catched an exception: " << e.getMessage() << std::endl;
return EXIT_FAILURE;
}
}
#else
int main()
{
std::cout << "You do not have an Viper 650 robot connected to your computer..." << std::endl;
return EXIT_SUCCESS;
}
#endif