servoViper850FourPoints2DCamVelocityLs_cur.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 velocity is computed in 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.

Example of eye-in-hand control law. We control here a real robot, the Viper S850 robot (arm with 6 degrees of freedom). The velocity is computed in 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.

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 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 https://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
 */
 
#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/vpDisplayFactory.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
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif

void compute_pose(vpPoint point[], vpDot2 dot[], int ndot, vpCameraParameters cam, vpHomogeneousMatrix &cMo, bool init)
{
  vpRotationMatrix cRo;
  vpPose pose;
  vpImagePoint cog;
  for (int i = 0; i < ndot; i++) {
 
    double x = 0, y = 0;
    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_LAGRANGE_VIRTUAL_VS, cMo);
  }
  else { // init = false; use of the previous pose to initialise VIRTUAL_VS
    pose.computePose(vpPose::VIRTUAL_VS, 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 measured joint velocities (m/s, rad/s)
  // - the 6 measured 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 EXIT_FAILURE;
    }
  }
  std::string logfilename;
  logfilename = logdirname + "/log.dat";
 
  // Open the log file name
  std::ofstream flog(logfilename.c_str());
 
#if (VISP_CXX_STANDARD >= VISP_CXX_STANDARD_11)
  std::shared_ptr<vpDisplay> display;
#else
  vpDisplay *display = nullptr;
#endif
 
  try {
    vpRobotViper850 robot;
    // Load the end-effector to camera frame transformation obtained
    // using a camera intrinsic model with distortion
    vpCameraParameters::vpCameraParametersProjType projModel = vpCameraParameters::perspectiveProjWithDistortion;
    robot.init(vpRobotViper850::TOOL_PTGREY_FLEA2_CAMERA, projModel);
 
    vpServo task;
 
    vpImage<unsigned char> I;
    int 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);
 
#if (VISP_CXX_STANDARD >= VISP_CXX_STANDARD_11)
    display = vpDisplayFactory::createDisplay(I, 100, 100, "Current image");
#else
    display = vpDisplayFactory::allocateDisplay(I, 100, 100, "Current image");
#endif
 
    vpDisplay::display(I);
    vpDisplay::flush(I);
 
    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 camera space" << std::endl;
    std::cout << " Use of the Viper850 robot " << std::endl;
    std::cout << " task : servo 4 points on a square with dimension " << L << " meters" << std::endl;
    std::cout << "-------------------------------------------------------" << std::endl;
    std::cout << std::endl;
 
    vpDot2 dot[4];
    vpImagePoint cog;
 
    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();
      vpDisplay::displayCross(I, cog, 10, vpColor::blue);
      vpDisplay::flush(I);
    }
 
    vpCameraParameters cam;
 
    // Update camera parameters
    robot.getCameraParameters(cam, I);
 
    cam.printParameters();
 
    // Sets the current position of the visual feature
    vpFeaturePoint p[4];
    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
    vpHomogeneousMatrix cMo;
    vpTranslationVector cto(0, 0, 0.5); // tz = 0.5 meter
    vpRxyzVector cro(vpMath::rad(10), vpMath::rad(30), vpMath::rad(20));
    vpRotationMatrix cRo(cro); // Build the rotation matrix
    cMo.buildFrom(cto, cRo);   // Build the homogeneous matrix
 
    // 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, 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.setServo(vpServo::EYEINHAND_CAMERA);
    task.setInteractionMatrixType(vpServo::CURRENT, vpServo::PSEUDO_INVERSE);
    task.print();
 
    // Initialise the velocity control of the robot
    robot.setRobotState(vpRobot::STATE_VELOCITY_CONTROL);
 
    bool init_pose_from_linear_method = true;
    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
      vpDisplay::display(I);
 
      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();
          vpDisplay::displayCross(I, cog, 10, vpColor::green);
        }
      }
      catch (...) {
        flog.close(); // Close the log file
        vpTRACE("Error detected while tracking visual features");
        robot.stopMotion();
#if (VISP_CXX_STANDARD < VISP_CXX_STANDARD_11)
        if (display != nullptr) {
          delete display;
        }
#endif
        return EXIT_FAILURE;
      }
 
      // At first iteration, we initialise non linear pose estimation with a linear approach.
      // For the other iterations, non linear pose estimation is initialized with the pose estimated at previous
      // iteration of the loop
      compute_pose(point, dot, 4, cam, cMo, init_pose_from_linear_method);
      if (init_pose_from_linear_method) {
        init_pose_from_linear_method = 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
        vpColVector cP;
        point[i].changeFrame(cMo, cP);
 
        p[i].set_Z(cP[2]);
      }
 
      vpColVector v;
      // 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
      robot.setVelocity(vpRobot::CAMERA_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() << std::endl;
 
      // Flush the display
      vpDisplay::flush(I);
 
      // std::cout << "|| s - s* || = "  << ( task.getError() ).sumSquare() <<
      // std::endl;
    }
 
    std::cout << "Display task information: " << std::endl;
    task.print();
    flog.close(); // Close the log file
#if (VISP_CXX_STANDARD < VISP_CXX_STANDARD_11)
    if (display != nullptr) {
      delete display;
    }
#endif
    return EXIT_SUCCESS;
  }
  catch (const vpException &e) {
    flog.close(); // Close the log file
    std::cout << "Catch an exception: " << e.getMessage() << std::endl;
#if (VISP_CXX_STANDARD < VISP_CXX_STANDARD_11)
    if (display != nullptr) {
      delete display;
    }
#endif
    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