chain.hpp

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// Author: Stuart Glaser

#ifndef ROS_ETHERCAT_MODEL_CHAIN_H
#define ROS_ETHERCAT_MODEL_CHAIN_H

#include "ros_ethercat_model/robot_state.hpp"
#include <kdl/chain.hpp>
#include <kdl/jntarray.hpp>
#include <kdl/jntarrayvel.hpp>
#include <kdl/jntarrayacc.hpp>
#include <kdl/tree.hpp>
#include <kdl_parser/kdl_parser.hpp>

namespace ros_ethercat_model
{

class Chain
{
public:
  bool init(RobotState *robot_state, const std::string &root, const std::string &tip)
  {
    robot_state_ = robot_state;
    // Constructs the kdl chain
    KDL::Tree kdl_tree;
    if (!kdl_parser::treeFromUrdfModel(robot_state->robot_model_, kdl_tree))
    {
      ROS_ERROR("Could not convert urdf into kdl tree");
      return false;
    }
    bool res;
    try
    {
      res = kdl_tree.getChain(root, tip, kdl_chain_);
    }
    catch (...)
    {
      res = false;
    }
    if (!res)
    {
      ROS_ERROR("Could not extract chain between %s and %s from kdl tree",
                root.c_str(), tip.c_str());
      return false;
    }
    // Pulls out all the joint indices
    joints_.clear();
    for (size_t i = 0; i < kdl_chain_.getNrOfSegments(); i++)
    {
      if (kdl_chain_.getSegment(i).getJoint().getType() != KDL::Joint::None)
      {
        JointState* jnt = robot_state->getJointState(kdl_chain_.getSegment(i).getJoint().getName());
        if (!jnt)
        {
          ROS_ERROR("Joint '%s' is not found in joint state vector",
                    kdl_chain_.getSegment(i).getJoint().getName().c_str());
          return false;
        }
        joints_.push_back(jnt);
      }
    }
    ROS_DEBUG("Added %i joints", int(joints_.size()));
    return true;
  }
  void getPositions(std::vector<double> &positions)
  {
    positions.clear();
    for (unsigned int i = 0; i < joints_.size(); ++i)
      positions.push_back(joints_[i]->position_);
  }
  void getPositions(KDL::JntArray &a)
  {
    assert(a.rows() == joints_.size());
    for (unsigned int i = 0; i < joints_.size(); ++i)
      a(i) = joints_[i]->position_;
  }

  template <class Vec> void getPositions(Vec &v)
  {
    assert((int) v.size() == (int) joints_.size());
    for (size_t i = 0; i < joints_.size(); ++i)
      v[i] = joints_[i]->position_;
  }

  void getVelocities(std::vector<double> &velocities)
  {
    velocities.clear();
    for (unsigned int i = 0; i < joints_.size(); ++i)
      velocities.push_back(joints_[i]->velocity_);
  }
  void getVelocities(KDL::JntArrayVel &a)
  {
    assert(a.q.rows() == joints_.size());
    assert(a.qdot.rows() == joints_.size());
    for (unsigned int i = 0; i < joints_.size(); ++i)
    {
      a.q(i) = joints_[i]->position_;
      a.qdot(i) = joints_[i]->velocity_;
    }
  }

  template <class Vec> void getVelocities(Vec &v)
  {
    assert((int) v.size() == (int) joints_.size());
    for (size_t i = 0; i < joints_.size(); ++i)
      v[i] = joints_[i]->velocity_;
  }
  void getEfforts(std::vector<double> &efforts)
  {
    efforts.clear();
    for (unsigned int i = 0; i < joints_.size(); ++i)
      efforts.push_back(joints_[i]->measured_effort_);
  }

  void getEfforts(KDL::JntArray &a)
  {
    assert(a.rows() == joints_.size());
    for (unsigned int i = 0; i < joints_.size(); ++i)
      a(i) = joints_[i]->measured_effort_;
  }

  void setEfforts(KDL::JntArray &a)
  {
    assert(a.rows() == joints_.size());
    for (unsigned int i = 0; i < joints_.size(); ++i)
      joints_[i]->commanded_effort_ = a(i);
  }

  void addEfforts(KDL::JntArray &a)
  {
    assert(a.rows() == joints_.size());
    for (unsigned int i = 0; i < joints_.size(); ++i)
      joints_[i]->commanded_effort_ += a(i);
  }

  template <class Vec> void addEfforts(const Vec& v)
  {
    assert((int) v.size() == (int) joints_.size());
    for (size_t i = 0; i < joints_.size(); ++i)
      joints_[i]->commanded_effort_ += v[i];
  }

  bool allCalibrated()
  {
    for (unsigned int i = 0; i < joints_.size(); ++i)
      if (!joints_[i]->calibrated_)
        return false;
    return true;
  }

  void toKDL(KDL::Chain &chain)
  {
    chain = kdl_chain_;
  }
  JointState* getJoint(unsigned int actuated_joint_i)
  {
    if (actuated_joint_i >= joints_.size())
      return NULL;
    else
      return joints_[actuated_joint_i];
  }

  int size() const
  {
    return joints_.size();
  }

private:
  RobotState *robot_state_;
  KDL::Chain kdl_chain_;

  std::vector< JointState* > joints_; // ONLY joints that can be actuated (not fixed joints)
};

}

#endif