Visual Servoing Platform  version 3.2.0 under development (2018-08-18)
servoViper850Point2DArtVelocity-jointAvoidance-basic.cpp

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

Implemented from section III.B in [4].

/****************************************************************************
*
* 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 articular
*
* Authors:
* Eric Marchand
* Fabien Spindler
*
*****************************************************************************/
#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/vpDisplayGTK.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.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()
{
try {
vpServo task;
bool reset = false;
vp1394TwoGrabber g(reset);
g.open(I);
g.acquire(I);
double Tloop = 1. / 60.f;
g.getFramerate(fps);
switch (fps) {
Tloop = 1.f / 15.f;
break;
Tloop = 1.f / 30.f;
break;
Tloop = 1.f / 60.f;
break;
Tloop = 1.f / 120.f;
break;
default:
break;
}
std::cout << "Tloop: " << Tloop << std::endl;
#ifdef VISP_HAVE_X11
vpDisplayX display(I, 800, 100, "Current image");
#elif defined(VISP_HAVE_OPENCV)
vpDisplayOpenCV display(I, 800, 100, "Current image");
#elif defined(VISP_HAVE_GTK)
vpDisplayGTK display(I, 800, 100, "Current image");
#endif
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]);
}
// 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
char legend[10];
for (unsigned int i = 0; i < 6; i++) {
sprintf(legend, "q%u", i + 1);
plot.setLegend(0, i, legend);
sprintf(legend, "q%u", i + 1);
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, 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, 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();
// Update camera parameters
robot.getCameraParameters(cam, I);
// sets the current position of the visual feature
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
pd.buildFrom(0, 0, 1);
// Define the task
// - we want an eye-in-hand control law
// - articular velocity are computed
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();
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 = (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
// 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
// Get the measured joint positions of the robot
// Update the point feature from the dot location
// 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;
}
}
}
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 (pb[j]==1) {
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++;
}
// 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;
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
{
// 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
}
// 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();
task.kill();
return EXIT_SUCCESS;
}
catch (const vpException &e) {
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