servoViper650FourPoints2DArtVelocityInteractionCurrent.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 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.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.

/****************************************************************************
 *
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2019 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 <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();
    vpPixelMeterConversion::convertPoint(cam, 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
    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;
  }

  pose.computePose(vpPose::LOWE, cMo);
}

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
  vpIoTools::getUserName(username);

  // 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
      vpIoTools::makeDirectory(logdirname);
    } 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 {
    vpRobotViper650 robot;
    // Load the end-effector to camera frame transformation obtained
    // using a camera intrinsic model with distortion
    vpCameraParameters::vpCameraParametersProjType projModel = vpCameraParameters::perspectiveProjWithDistortion;
    robot.init(vpRobotViper650::TOOL_PTGREY_FLEA2_CAMERA, projModel);
    vpHomogeneousMatrix eMc;
    robot.get_eMc(eMc);
    std::cout << "Camera extrinsic parameters (eMc): \n" << eMc << std::endl;

    vpServo task;

    vpImage<unsigned char> I;

    bool reset = false;
    vp1394TwoGrabber g(reset);
    g.setVideoMode(vp1394TwoGrabber::vpVIDEO_MODE_640x480_MONO8);
    g.setFramerate(vp1394TwoGrabber::vpFRAMERATE_60);
    g.open(I);

    g.acquire(I);

    vpDisplayX display(I, 100, 100, "Current image");
    vpDisplay::display(I);
    vpDisplay::flush(I);

    std::vector<vpDot2> dot(4);

    vpImagePoint cog;

    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();
      vpDisplay::displayCross(I, cog, 10, vpColor::blue);
      vpDisplay::flush(I);
    }

    vpCameraParameters cam;

    // Update camera parameters
    robot.getCameraParameters(cam, I);
    std::cout << "Camera intrinsic parameters: \n" << cam << std::endl;

    // Sets the current position of the visual feature
    vpFeaturePoint p[4];
    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
    vpHomogeneousMatrix cMo;
    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
    vpFeaturePoint pd[4];
    // 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
    // - articular velocity are computed
    task.setServo(vpServo::EYEINHAND_L_cVe_eJe);
    task.setInteractionMatrixType(vpServo::CURRENT, vpServo::PSEUDO_INVERSE);

    vpVelocityTwistMatrix cVe;
    robot.get_cVe(cVe);
    task.set_cVe(cVe);

    // 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
    robot.setRobotState(vpRobot::STATE_VELOCITY_CONTROL);

    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
      vpDisplay::display(I);

      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();
          vpDisplay::displayCross(I, cog, 10, vpColor::green);
        }
      } catch (...) {
        std::cout << "Error detected while tracking visual features.." << std::endl;
        break;
      }

      // 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, 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
        vpColVector cP;
        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
      vpColVector 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
      robot.setVelocity(vpRobot::ARTICULAR_FRAME, v);

      // 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
      vpColVector qvel;
      robot.getVelocity(vpRobot::ARTICULAR_FRAME, qvel);
      // 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
      vpColVector q;
      robot.getPosition(vpRobot::ARTICULAR_FRAME, q);
      // 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;

      vpDisplay::displayText(I, 10, 10, "Click to quit...", vpColor::red);
      if (vpDisplay::getClick(I, false))
        break;

      // Flush the display
      vpDisplay::flush(I);

      // std::cout << "\t\t || 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 << "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