edge_kinematics.h

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 *
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 *  TU Dortmund - Institute of Control Theory and Systems Engineering.
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 * Notes:
 * The following class is derived from a class defined by the
 * g2o-framework. g2o is licensed under the terms of the BSD License.
 * Refer to the base class source for detailed licensing information.
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 * Author: Christoph Rösmann
 *********************************************************************/

#ifndef _EDGE_KINEMATICS_H
#define _EDGE_KINEMATICS_H

#include <teb_local_planner/g2o_types/vertex_pose.h>
#include <teb_local_planner/g2o_types/penalties.h>
#include <teb_local_planner/g2o_types/base_teb_edges.h>
#include <teb_local_planner/teb_config.h>

#include <cmath>

namespace teb_local_planner
{

class EdgeKinematicsDiffDrive : public BaseTebBinaryEdge<2, double, VertexPose, VertexPose>
{
public:
  
  EdgeKinematicsDiffDrive()
  {
      this->setMeasurement(0.);
  }
  
  void computeError()
  {
    ROS_ASSERT_MSG(cfg_, "You must call setTebConfig on EdgeKinematicsDiffDrive()");
    const VertexPose* conf1 = static_cast<const VertexPose*>(_vertices[0]);
    const VertexPose* conf2 = static_cast<const VertexPose*>(_vertices[1]);
    
    Eigen::Vector2d deltaS = conf2->position() - conf1->position();

    // non holonomic constraint
    _error[0] = fabs( ( cos(conf1->theta())+cos(conf2->theta()) ) * deltaS[1] - ( sin(conf1->theta())+sin(conf2->theta()) ) * deltaS[0] );

    // positive-drive-direction constraint
    Eigen::Vector2d angle_vec ( cos(conf1->theta()), sin(conf1->theta()) );        
    _error[1] = penaltyBoundFromBelow(deltaS.dot(angle_vec), 0,0);
    // epsilon=0, otherwise it pushes the first bandpoints away from start

    ROS_ASSERT_MSG(std::isfinite(_error[0]) && std::isfinite(_error[1]), "EdgeKinematicsDiffDrive::computeError() _error[0]=%f _error[1]=%f\n",_error[0],_error[1]);
  }

#ifdef USE_ANALYTIC_JACOBI
#if 1

  void linearizeOplus()
  {
    ROS_ASSERT_MSG(cfg_, "You must call setTebConfig on EdgeKinematicsDiffDrive()");
    const VertexPose* conf1 = static_cast<const VertexPose*>(_vertices[0]);
    const VertexPose* conf2 = static_cast<const VertexPose*>(_vertices[1]);
    
    Eigen::Vector2d deltaS = conf2->position() - conf1->position();
            
    double cos1 = cos(conf1->theta());
    double cos2 = cos(conf2->theta());
    double sin1 = sin(conf1->theta());
    double sin2 = sin(conf2->theta());
    double aux1 = sin1 + sin2;
    double aux2 = cos1 + cos2;
    
    double dd_error_1 = deltaS[0]*cos1;
    double dd_error_2 = deltaS[1]*sin1;
    double dd_dev = penaltyBoundFromBelowDerivative(dd_error_1+dd_error_2, 0,0);
    
    double dev_nh_abs = g2o::sign( ( cos(conf1->theta())+cos(conf2->theta()) ) * deltaS[1] - 
              ( sin(conf1->theta())+sin(conf2->theta()) ) * deltaS[0] );
            
    // conf1
    _jacobianOplusXi(0,0) = aux1 * dev_nh_abs; // nh x1
    _jacobianOplusXi(0,1) = -aux2 * dev_nh_abs; // nh y1
    _jacobianOplusXi(1,0) = -cos1 * dd_dev; // drive-dir x1
    _jacobianOplusXi(1,1) = -sin1 * dd_dev; // drive-dir y1
    _jacobianOplusXi(0,2) = (-dd_error_2 - dd_error_1) * dev_nh_abs; // nh angle
    _jacobianOplusXi(1,2) = ( -sin1*deltaS[0] + cos1*deltaS[1] ) * dd_dev; // drive-dir angle1
    
    // conf2
    _jacobianOplusXj(0,0) = -aux1 * dev_nh_abs; // nh x2
    _jacobianOplusXj(0,1) = aux2 * dev_nh_abs; // nh y2
    _jacobianOplusXj(1,0) = cos1 * dd_dev; // drive-dir x2
    _jacobianOplusXj(1,1) = sin1 * dd_dev; // drive-dir y2
    _jacobianOplusXj(0,2) = (-sin2*deltaS[1] - cos2*deltaS[0]) * dev_nh_abs; // nh angle
    _jacobianOplusXj(1,2) = 0; // drive-dir angle1                                      
  }
#endif
#endif
      
public:
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW   
};




class EdgeKinematicsCarlike : public BaseTebBinaryEdge<2, double, VertexPose, VertexPose>
{
public:
  
  EdgeKinematicsCarlike()
  {
      this->setMeasurement(0.);
  }
  
  void computeError()
  {
    ROS_ASSERT_MSG(cfg_, "You must call setTebConfig on EdgeKinematicsCarlike()");
    const VertexPose* conf1 = static_cast<const VertexPose*>(_vertices[0]);
    const VertexPose* conf2 = static_cast<const VertexPose*>(_vertices[1]);
    
    Eigen::Vector2d deltaS = conf2->position() - conf1->position();

    // non holonomic constraint
    _error[0] = fabs( ( cos(conf1->theta())+cos(conf2->theta()) ) * deltaS[1] - ( sin(conf1->theta())+sin(conf2->theta()) ) * deltaS[0] );

    // limit minimum turning radius
    double angle_diff = g2o::normalize_theta( conf2->theta() - conf1->theta() );
    if (angle_diff == 0)
      _error[1] = 0; // straight line motion
    else if (cfg_->trajectory.exact_arc_length) // use exact computation of the radius
      _error[1] = penaltyBoundFromBelow(fabs(deltaS.norm()/(2*sin(angle_diff/2))), cfg_->robot.min_turning_radius, 0.0);
    else
      _error[1] = penaltyBoundFromBelow(deltaS.norm() / fabs(angle_diff), cfg_->robot.min_turning_radius, 0.0); 
    // This edge is not affected by the epsilon parameter, the user might add an exra margin to the min_turning_radius parameter.
    
    ROS_ASSERT_MSG(std::isfinite(_error[0]) && std::isfinite(_error[1]), "EdgeKinematicsCarlike::computeError() _error[0]=%f _error[1]=%f\n",_error[0],_error[1]);
  }
  
public:
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW   
};




} // end namespace

#endif