servoViper850Point2DArtVelocity-jointAvoidance-basic.cpp

Joint limits avoidance by stopping the motion on axis near the joint limits.

Implemented from section III.B in [5].

/*
 * 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 articular
 */

 
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpDebug.h> // Debug trace
 
#include <cmath> // std::fabs
#include <fstream>
#include <iostream>
#include <limits> // numeric_limits
#include <sstream>
#include <stdio.h>
#include <stdlib.h>
 
#if (defined(VISP_HAVE_VIPER850) && defined(VISP_HAVE_DC1394) && defined(VISP_HAVE_DISPLAY))
 
#include <visp3/blob/vpDot2.h>
#include <visp3/core/vpDisplay.h>
#include <visp3/core/vpException.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/gui/vpPlot.h>
#include <visp3/robot/vpRobotViper850.h>
#include <visp3/sensor/vp1394TwoGrabber.h>
#include <visp3/visual_features/vpFeatureBuilder.h>
#include <visp3/visual_features/vpFeaturePoint.h>
#include <visp3/vs/vpServo.h>
#include <visp3/vs/vpServoDisplay.h>
 
int main()
{
#ifdef ENABLE_VISP_NAMESPACE
  using namespace VISP_NAMESPACE_NAME;
#endif
 
#if (VISP_CXX_STANDARD >= VISP_CXX_STANDARD_11)
  std::shared_ptr<vpDisplay> display;
#else
  vpDisplay *display = nullptr;
#endif
 
  try {
    vpRobotViper850 robot;
 
    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);
 
    double Tloop = 1. / 60.f;
 
    vp1394TwoGrabber::vp1394TwoFramerateType fps;
    g.getFramerate(fps);
    switch (fps) {
    case vp1394TwoGrabber::vpFRAMERATE_15:
      Tloop = 1.f / 15.f;
      break;
    case vp1394TwoGrabber::vpFRAMERATE_30:
      Tloop = 1.f / 30.f;
      break;
    case vp1394TwoGrabber::vpFRAMERATE_60:
      Tloop = 1.f / 60.f;
      break;
    case vp1394TwoGrabber::vpFRAMERATE_120:
      Tloop = 1.f / 120.f;
      break;
    default:
      break;
    }
    std::cout << "Tloop: " << Tloop << std::endl;
 
#if (VISP_CXX_STANDARD >= VISP_CXX_STANDARD_11)
    display = vpDisplayFactory::createDisplay(I, 800, 100, "Current image");
#else
    display = vpDisplayFactory::allocateDisplay(I, 800, 100, "Current image");
#endif
 
    vpDisplay::display(I);
    vpDisplay::flush(I);
 
    vpColVector jointMin(6), jointMax(6);
    jointMin = robot.getJointMin();
    jointMax = robot.getJointMax();
 
    vpColVector Qmin(6), tQmin(6);
    vpColVector Qmax(6), tQmax(6);
    vpColVector Qmiddle(6);
    vpColVector data(10);
 
    double rho = 0.25;
    for (unsigned int i = 0; i < 6; i++) {
      Qmin[i] = jointMin[i] + 0.5 * rho * (jointMax[i] - jointMin[i]);
      Qmax[i] = jointMax[i] - 0.5 * rho * (jointMax[i] - jointMin[i]);
    }
    Qmiddle = (Qmin + Qmax) / 2.;
    double rho1 = 0.1;
 
    for (unsigned int i = 0; i < 6; i++) {
      tQmin[i] = Qmin[i] + 0.5 * (rho1) * (Qmax[i] - Qmin[i]);
      tQmax[i] = Qmax[i] - 0.5 * (rho1) * (Qmax[i] - Qmin[i]);
    }
 
    vpColVector q(6);
 
    // Create a window with two graphics
    // - first graphic to plot q(t), Qmin, Qmax, tQmin and tQmax
    // - second graphic to plot the cost function h_s
    vpPlot plot(2);
 
    // The first graphic contains 10 data to plot: q(t), Qmin, Qmax, tQmin and
    // tQmax
    plot.initGraph(0, 10);
    plot.initGraph(1, 6);
 
    // For the first graphic :
    // - along the x axis the expected values are between 0 and 200 and
    //   the step is 1
    // - along the y axis the expected values are between -1.2 and 1.2 and the
    //   step is 0.1
    plot.initRange(0, 0, 200, 1, -1.2, 1.2, 0.1);
    plot.setTitle(0, "Joint behavior");
    plot.initRange(1, 0, 200, 1, -0.01, 0.01, 0.05);
    plot.setTitle(1, "Joint velocity");
 
    // For the first graphic, set the curves legend
    std::string legend;
    for (unsigned int i = 0; i < 6; i++) {
      legend = "q" + i + 1;
      plot.setLegend(0, i, legend);
      plot.setLegend(1, i, legend);
    }
    plot.setLegend(0, 6, "tQmin");
    plot.setLegend(0, 7, "tQmax");
    plot.setLegend(0, 8, "Qmin");
    plot.setLegend(0, 9, "Qmax");
 
    // Set the curves color
    plot.setColor(0, 0, vpColor::red);
    plot.setColor(0, 1, vpColor::green);
    plot.setColor(0, 2, vpColor::blue);
    plot.setColor(0, 3, vpColor::orange);
    plot.setColor(0, 4, vpColor(0, 128, 0));
    plot.setColor(0, 5, vpColor::cyan);
    for (unsigned int i = 6; i < 10; i++)
      plot.setColor(0, i, vpColor::black); // for Q and tQ [min,max]
    // Set the curves color
 
    plot.setColor(1, 0, vpColor::red);
    plot.setColor(1, 1, vpColor::green);
    plot.setColor(1, 2, vpColor::blue);
    plot.setColor(1, 3, vpColor::orange);
    plot.setColor(1, 4, vpColor(0, 128, 0));
    plot.setColor(1, 5, vpColor::cyan);
    vpDot2 dot;
 
    std::cout << "Click on a dot..." << std::endl;
    dot.initTracking(I);
    vpImagePoint cog = dot.getCog();
    vpDisplay::displayCross(I, cog, 10, vpColor::blue);
    vpDisplay::flush(I);
 
    vpCameraParameters cam;
    // Update camera parameters
    robot.getCameraParameters(cam, I);
 
    // sets the current position of the visual feature
    vpFeaturePoint p;
    vpFeatureBuilder::create(p, cam, dot); // retrieve x,y and Z of the vpPoint structure
 
    p.set_Z(1);
    // sets the desired position of the visual feature
    vpFeaturePoint pd;
    pd.buildFrom(0, 0, 1);
 
    // 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::DESIRED, vpServo::PSEUDO_INVERSE);
 
    vpVelocityTwistMatrix cVe;
    robot.get_cVe(cVe);
    std::cout << cVe << std::endl;
    task.set_cVe(cVe);
 
    // - Set the Jacobian (expressed in the end-effector frame)") ;
    vpMatrix eJe;
    robot.get_eJe(eJe);
    task.set_eJe(eJe);
 
    // - we want to see a point on a point..") ;
    std::cout << std::endl;
    task.addFeature(p, pd);
 
    // - set the gain
    double lambda = 0.8;
    // set to -1 to suppress the lambda used in the
    // vpServo::computeControlLaw()
    task.setLambda(-1);
 
    // Display task information " ) ;
    task.print();
 
    robot.setRobotState(vpRobot::STATE_VELOCITY_CONTROL);
 
    int iter = 0;
    double t_1 = vpTime::measureTimeMs();
 
    std::cout << "\nHit CTRL-C to stop the loop...\n" << std::flush;
    for (;;) {
      iter++;
 
      double t_0 = vpTime::measureTimeMs(); // t_0: current time
 
      // Update loop time in second
      double Tv = static_cast<double>(t_0 - t_1) / 1000.0;
      std::cout << "Tv: " << Tv << std::endl;
 
      // Update time for next iteration
      t_1 = t_0;
 
      // Acquire a new image from the camera
      dc1394video_frame_t *frame = g.dequeue(I);
 
      // Display this image
      vpDisplay::display(I);
 
      // Achieve the tracking of the dot in the image
      dot.track(I);
      cog = dot.getCog();
 
      // Display a green cross at the center of gravity position in the image
      vpDisplay::displayCross(I, cog, 10, vpColor::green);
 
      // Get the measured joint positions of the robot
      robot.getPosition(vpRobot::ARTICULAR_FRAME, q);
 
      // Update the point feature from the dot location
      vpFeatureBuilder::create(p, cam, dot);
 
      // 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);
 
      vpColVector prim_task;
      vpColVector e2(6);
      // Compute the visual servoing skew vector
      prim_task = task.computeControlLaw();
 
      vpColVector qpre(6);
 
      qpre = q;
      qpre += -lambda * prim_task * (4 * Tloop);
 
      // Identify the joints near the limits
      vpColVector pb(6);
      pb = 0;
      unsigned int npb = 0;
      for (unsigned int i = 0; i < 6; i++) {
        if (q[i] < tQmin[i])
          if (fabs(Qmin[i] - q[i]) > fabs(Qmin[i] - qpre[i])) {
            pb[i] = 1;
            npb++;
            std::cout << "Joint " << i << " near limit " << std::endl;
          }
        if (q[i] > tQmax[i]) {
          if (fabs(Qmax[i] - q[i]) > fabs(Qmax[i] - qpre[i])) {
            pb[i] = 1;
            npb++;
            std::cout << "Joint " << i << " near limit " << std::endl;
          }
        }
      }
 
      vpColVector a0;
      vpMatrix J1 = task.getTaskJacobian();
      vpMatrix kernelJ1;
      J1.kernel(kernelJ1);
 
      unsigned int dimKernelL = kernelJ1.getCols();
      if (npb != 0) {
        // Build linear system a0*E = S
        vpMatrix E(npb, dimKernelL);
        vpColVector S(npb);
 
        unsigned int k = 0;
 
        for (unsigned int j = 0; j < 6; j++) // j is the joint
          if (std::fabs(pb[j] - 1) <= std::numeric_limits<double>::epsilon()) {
            for (unsigned int i = 0; i < dimKernelL; i++)
              E[k][i] = kernelJ1[j][i];
 
            S[k] = -prim_task[j];
            k++;
          }
        vpMatrix Ep;
        // vpTRACE("nbp %d", npb);
        Ep = E.t() * (E * E.t()).pseudoInverse();
        a0 = Ep * S;
 
        e2 = (kernelJ1 * a0);
        // cout << "e2 " << e2.t() ;
      }
      else {
        e2 = 0;
      }
      //  std::cout << "e2: " << e2.t() << std::endl;
 
      vpColVector v;
      v = -lambda * (prim_task + e2);
 
      // 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);
 
      {
        // Add the material to plot curves
 
        // q normalized between (entre -1 et 1)
        for (unsigned int i = 0; i < 6; i++) {
          data[i] = (q[i] - Qmiddle[i]);
          data[i] /= (Qmax[i] - Qmin[i]);
          data[i] *= 2;
        }
        unsigned int joint = 2;
        data[6] = 2 * (tQmin[joint] - Qmiddle[joint]) / (Qmax[joint] - Qmin[joint]);
        data[7] = 2 * (tQmax[joint] - Qmiddle[joint]) / (Qmax[joint] - Qmin[joint]);
        data[8] = -1;
        data[9] = 1;
 
        plot.plot(0, iter, data); // plot q, Qmin, Qmax, tQmin, tQmax
        plot.plot(1, iter, v);    // plot joint velocities applied to the robot
      }
 
      vpDisplay::flush(I);
 
      // Synchronize the loop with the image frame rate
      vpTime::wait(t_0, 1000. * Tloop);
      // Release the ring buffer used for the last image to start a new acq
      g.enqueue(frame);
    }
 
    // Display task information
    task.print();
#if (VISP_CXX_STANDARD < VISP_CXX_STANDARD_11)
    if (display != nullptr) {
      delete display;
    }
#endif
    return EXIT_SUCCESS;
  }
  catch (const vpException &e) {
    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