trac_ik.cpp

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#include <trac_ik/trac_ik.hpp>
#include <boost/date_time.hpp>
#include <boost/make_shared.hpp>
#include <Eigen/Geometry>
#include <ros/ros.h>
#include <limits>
#include <kdl_parser/kdl_parser.hpp>
#include <urdf/model.h>

namespace TRAC_IK {

  TRAC_IK::TRAC_IK(const std::string& base_link, const std::string& tip_link, const std::string& URDF_param, double _maxtime, double _eps, SolveType _type ) :
    initialized(false),
    eps(_eps),
    maxtime(_maxtime),
    solvetype(_type),
    work(io_service)
  {

    ros::NodeHandle node_handle("~");

    urdf::Model robot_model;
    std::string xml_string;

    std::string urdf_xml,full_urdf_xml;
    node_handle.param("urdf_xml",urdf_xml,URDF_param);
    node_handle.searchParam(urdf_xml,full_urdf_xml);
    
    ROS_DEBUG_NAMED("trac_ik","Reading xml file from parameter server");
    if (!node_handle.getParam(full_urdf_xml, xml_string))
      {
        ROS_FATAL_NAMED("trac_ik","Could not load the xml from parameter server: %s", urdf_xml.c_str());
        return;
      }
    
    node_handle.param(full_urdf_xml,xml_string,std::string());
    robot_model.initString(xml_string);
    
    ROS_DEBUG_STREAM_NAMED("trac_ik","Reading joints and links from URDF");

    KDL::Tree tree;
    
    if (!kdl_parser::treeFromUrdfModel(robot_model, tree))
      ROS_FATAL("Failed to extract kdl tree from xml robot description");

    if(!tree.getChain(base_link, tip_link, chain))
      ROS_FATAL("Couldn't find chain %s to %s",base_link.c_str(),tip_link.c_str());

    std::vector<KDL::Segment> chain_segs = chain.segments;

    boost::shared_ptr<const urdf::Joint> joint;

    std::vector<double> l_bounds, u_bounds;

    lb.resize(chain.getNrOfJoints());
    ub.resize(chain.getNrOfJoints());

    uint joint_num=0;
    for(unsigned int i = 0; i < chain_segs.size(); ++i) {
      joint = robot_model.getJoint(chain_segs[i].getJoint().getName());
      if (joint->type != urdf::Joint::UNKNOWN && joint->type != urdf::Joint::FIXED) {
        joint_num++;
        float lower, upper;
        int hasLimits;
        if ( joint->type != urdf::Joint::CONTINUOUS ) {
          if(joint->safety) {
            lower = std::max(joint->limits->lower, joint->safety->soft_lower_limit);
            upper = std::min(joint->limits->upper, joint->safety->soft_upper_limit);
          } else {
            lower = joint->limits->lower;
            upper = joint->limits->upper;
          }
          hasLimits = 1;
        }
        else {
          hasLimits = 0;
        }
        if(hasLimits) {
          lb(joint_num-1)=lower;
          ub(joint_num-1)=upper;
        }
        else {
          lb(joint_num-1)=std::numeric_limits<float>::lowest();
          ub(joint_num-1)=std::numeric_limits<float>::max();
        }
        ROS_INFO_STREAM("IK Using joint "<<joint->name<<" "<<lb(joint_num-1)<<" "<<ub(joint_num-1));
      }
    }
    
    initialize();
  }


  TRAC_IK::TRAC_IK(const KDL::Chain& _chain, const KDL::JntArray& _q_min, const KDL::JntArray& _q_max, double _maxtime, double _eps, SolveType _type):
    initialized(false),
    chain(_chain),
    lb(_q_min),
    ub(_q_max),
    eps(_eps),
    maxtime(_maxtime),
    solvetype(_type),
    work(io_service)
  {

    initialize();
  }

  void TRAC_IK::initialize() {

    assert(chain.getNrOfJoints()==lb.data.size());
    assert(chain.getNrOfJoints()==ub.data.size());

    jacsolver.reset(new KDL::ChainJntToJacSolver(chain));
    nl_solver.reset(new NLOPT_IK::NLOPT_IK(chain,lb,ub,maxtime,eps,NLOPT_IK::SumSq));
    iksolver.reset(new KDL::ChainIkSolverPos_TL(chain,lb,ub,maxtime,eps,true,true));

    for (uint i=0; i<chain.segments.size(); i++) {
      std::string type = chain.segments[i].getJoint().getTypeName();
      if (type.find("Rot")!=std::string::npos) {
        if (ub(types.size())>=std::numeric_limits<float>::max() && 
            lb(types.size())<=std::numeric_limits<float>::lowest())
          types.push_back(KDL::BasicJointType::Continuous);
        else
          types.push_back(KDL::BasicJointType::RotJoint);
      }
      else if (type.find("Trans")!=std::string::npos)
        types.push_back(KDL::BasicJointType::TransJoint);
    }
    
    assert(types.size()==lb.data.size());


    threads.create_thread(boost::bind(&boost::asio::io_service::run,
                                      &io_service));
    threads.create_thread(boost::bind(&boost::asio::io_service::run,
                                      &io_service));

    initialized = true;
  }

  bool TRAC_IK::unique_solution(const KDL::JntArray& sol) {

    for (uint i=0; i< solutions.size(); i++)
      if (myEqual(sol,solutions[i]))
        return false;
    return true;

  }

  inline void normalizeAngle(double& val, const double& min, const double& max)
  {
      if (val > max) {
        //Find actual angle offset
        double diffangle = fmod(val-max,2*M_PI);
        // Add that to upper bound and go back a full rotation
        val = max + diffangle - 2*M_PI;
      }

      if (val < min) {
        //Find actual angle offset
        double diffangle = fmod(min-val,2*M_PI);
        // Add that to upper bound and go back a full rotation
        val = min - diffangle + 2*M_PI;
      }
  }

  inline void normalizeAngle(double& val, const double& target)
  {
      if (val > target+M_PI) {
        //Find actual angle offset
        double diffangle = fmod(val-target,2*M_PI);
        // Add that to upper bound and go back a full rotation
        val = target + diffangle - 2*M_PI;
      }

      if (val < target-M_PI) {
        //Find actual angle offset
        double diffangle = fmod(target-val,2*M_PI);
        // Add that to upper bound and go back a full rotation
        val = target - diffangle + 2*M_PI;
      }
  }


  bool TRAC_IK::runKDL(const KDL::JntArray &q_init, const KDL::Frame &p_in)
  {
    KDL::JntArray q_out;

    double fulltime = maxtime;
    KDL::JntArray seed = q_init;

    boost::posix_time::time_duration timediff;
    double time_left;

    while (true) {
      timediff=boost::posix_time::microsec_clock::local_time()-start_time;
      time_left = fulltime - timediff.total_nanoseconds()/1000000000.0;

      if (time_left <= 0)
        break;

      iksolver->setMaxtime(time_left);

      int kdlRC = iksolver->CartToJnt(seed,p_in,q_out,bounds);
      if (kdlRC >=0) {
        switch (solvetype) {
        case Manip1:
        case Manip2:
          normalize_limits(q_init, q_out);
          break;
        default:
          normalize_seed(q_init, q_out);
          break;
        }
        mtx_.lock();
        if (unique_solution(q_out)) {
          solutions.push_back(q_out);
          uint curr_size=solutions.size();
          errors.resize(curr_size);
          mtx_.unlock();
          double err, penalty;
          switch (solvetype) {
          case Manip1:
            penalty = manipPenalty(q_out);
            err = penalty*TRAC_IK::ManipValue1(q_out);
            break;
          case Manip2:
            penalty = manipPenalty(q_out);
            err = penalty*TRAC_IK::ManipValue2(q_out);
            break;
          default:
            err = TRAC_IK::JointErr(q_init,q_out);
            break;
          }
          mtx_.lock();
          errors[curr_size-1] = std::make_pair(err,curr_size-1);
        }
        mtx_.unlock();
      }
      
      if (!solutions.empty() && solvetype == Speed)
        break;
      
      for (unsigned int j=0; j<seed.data.size(); j++)
        if (types[j]==KDL::BasicJointType::Continuous)
          seed(j)=fRand(q_init(j)-2*M_PI, q_init(j)+2*M_PI);
        else
          seed(j)=fRand(lb(j), ub(j));
    }
    nl_solver->abort();

    iksolver->setMaxtime(fulltime);

    return true;
  }

  bool TRAC_IK::runNLOPT(const KDL::JntArray &q_init, const KDL::Frame &p_in)
  {
    KDL::JntArray q_out;

    double fulltime = maxtime;
    KDL::JntArray seed = q_init;

    boost::posix_time::time_duration timediff;
    double time_left;

    while (true) {
      timediff=boost::posix_time::microsec_clock::local_time()-start_time;
      time_left = fulltime - timediff.total_nanoseconds()/1000000000.0;

      if (time_left <= 0)
        break;

      nl_solver->setMaxtime(time_left);

      int nloptRC = nl_solver->CartToJnt(seed,p_in,q_out,bounds);
      if (nloptRC >=0) {
        switch (solvetype) {
        case Manip1:
        case Manip2:
          normalize_limits(q_init, q_out);
          break;
        default:
          normalize_seed(q_init, q_out);
          break;
        }
        mtx_.lock();
        if (unique_solution(q_out)) {
          solutions.push_back(q_out);
          uint curr_size=solutions.size();
          errors.resize(curr_size);
          mtx_.unlock();
          double err, penalty;
          switch (solvetype) {
          case Manip1:
            penalty = manipPenalty(q_out);
            err = penalty*TRAC_IK::ManipValue1(q_out);
            break;
          case Manip2:
            penalty = manipPenalty(q_out);
            err = penalty*TRAC_IK::ManipValue2(q_out);
            break;
          default:
            err = TRAC_IK::JointErr(q_init,q_out);
            break;
          }
          mtx_.lock();
          errors[curr_size-1] = std::make_pair(err,curr_size-1);
        }
        mtx_.unlock();
      }
      
      if (!solutions.empty() && solvetype == Speed)
        break;
      
      for (unsigned int j=0; j<seed.data.size(); j++)
        if (types[j]==KDL::BasicJointType::Continuous)
          seed(j)=fRand(q_init(j)-2*M_PI, q_init(j)+2*M_PI);
        else
          seed(j)=fRand(lb(j), ub(j));
    }

    iksolver->abort();

    nl_solver->setMaxtime(fulltime);

    return true;
  }

  void TRAC_IK::normalize_seed(const KDL::JntArray& seed, KDL::JntArray& solution) {
    // Make sure rotational joint values are within 1 revolution of seed; then
    // ensure joint limits are met.

    bool improved = false;

    for (uint i=0; i<lb.data.size(); i++) {

      if (types[i]==KDL::BasicJointType::TransJoint)
        continue;

      double target = seed(i);
      double val = solution(i);

      normalizeAngle( val, target );

      if (types[i]==KDL::BasicJointType::Continuous) {
        solution(i) = val;
        continue;
      }

      normalizeAngle( val, lb(i), ub(i) );

      solution(i) = val;
    }
  }

  void TRAC_IK::normalize_limits(const KDL::JntArray& seed, KDL::JntArray& solution) {
    // Make sure rotational joint values are within 1 revolution of middle of
    // limits; then ensure joint limits are met.

    bool improved = false;

    for (uint i=0; i<lb.data.size(); i++) {

      if (types[i] == KDL::BasicJointType::TransJoint)
        continue;

      double target = seed(i);

      if (types[i] == KDL::BasicJointType::RotJoint && types[i]!=KDL::BasicJointType::Continuous)
        target = (ub(i)+lb(i))/2.0;

      double val = solution(i);

      normalizeAngle( val, target );

      if (types[i]==KDL::BasicJointType::Continuous) {
        solution(i) = val;
        continue;
      }

      normalizeAngle( val, lb(i), ub(i) );

      solution(i) = val;
    }

  }


  double TRAC_IK::manipPenalty(const KDL::JntArray& arr) {
    double penalty = 1.0;
    for (uint i=0; i< arr.data.size(); i++) {
      if (types[i] == KDL::BasicJointType::Continuous)
        continue;
      double range = ub(i)-lb(i);
      penalty *= ((arr(i)-lb(i))*(ub(i)-arr(i))/(range*range));
    }
    return std::max(0.0,1.0 - exp(-1*penalty));
  }


  double TRAC_IK::ManipValue1(const KDL::JntArray& arr) {
    KDL::Jacobian jac(arr.data.size());

    jacsolver->JntToJac(arr,jac);

    Eigen::JacobiSVD<Eigen::MatrixXd> svdsolver(jac.data);
    Eigen::MatrixXd singular_values = svdsolver.singularValues();

    double error = 1.0;
    for(unsigned int i=0; i < singular_values.rows(); ++i)
      error *= singular_values(i,0);
    return error;
  }

  double TRAC_IK::ManipValue2(const KDL::JntArray& arr) {
    KDL::Jacobian jac(arr.data.size());

    jacsolver->JntToJac(arr,jac);

    Eigen::JacobiSVD<Eigen::MatrixXd> svdsolver(jac.data);
    Eigen::MatrixXd singular_values = svdsolver.singularValues();

    return singular_values.minCoeff()/singular_values.maxCoeff();
  }


  int TRAC_IK::CartToJnt(const KDL::JntArray &q_init, const KDL::Frame &p_in, KDL::JntArray &q_out, const KDL::Twist& _bounds) {

    if (!initialized) {
      ROS_ERROR("TRAC-IK was not properly initialized with a valid chain or limits.  IK cannot proceed");
      return -1;
    }


    start_time = boost::posix_time::microsec_clock::local_time();

    nl_solver->reset();
    iksolver->reset();

    solutions.clear();
    errors.clear();


    bounds=_bounds;

    std::vector<boost::shared_future<bool> > pending_data;

    typedef boost::packaged_task<bool> task_t;
    boost::shared_ptr<task_t> task1 = boost::make_shared<task_t>(boost::bind(&TRAC_IK::runKDL, this, boost::cref(q_init), boost::cref(p_in)));

    boost::shared_ptr<task_t> task2 = boost::make_shared<task_t>(boost::bind(&TRAC_IK::runNLOPT, this, boost::cref(q_init), boost::cref(p_in)));

    boost::shared_future<bool> fut1(task1->get_future());
    boost::shared_future<bool> fut2(task2->get_future());

    /*
    // this was for pre-c++11
    pending_data.push_back(boost::move(fut1));
    pending_data.push_back(boost::move(fut2));
    */
    pending_data.push_back(fut1);
    pending_data.push_back(fut2);

    io_service.post(boost::bind(&task_t::operator(), task1));
    io_service.post(boost::bind(&task_t::operator(), task2));

    boost::wait_for_all(pending_data.begin(), pending_data.end());

    if (solutions.empty()) {
      q_out=q_init;
      return -3;
    }

    switch (solvetype) {
    case Manip1:
    case Manip2:
      std::sort(errors.rbegin(),errors.rend()); // rbegin/rend to sort by max
      break;
    default:
      std::sort(errors.begin(),errors.end());
      break;
    }

    q_out = solutions[errors[0].second];

    return solutions.size();
  }


  TRAC_IK::~TRAC_IK(){
    // Force all threads to return from io_service::run().
    io_service.stop();

    // Suppress all exceptions.
    try
      {
        threads.join_all();
      }
    catch ( ... ) {}

  }

}