revolute_joint_model.cpp

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/* Author: Ioan Sucan */

#include <moveit/robot_model/revolute_joint_model.h>
#include <boost/math/constants/constants.hpp>
#include <algorithm>
#include <limits>
#include <cmath>

moveit::core::RevoluteJointModel::RevoluteJointModel(const std::string& name) 
  : JointModel(name)
  , axis_(0.0, 0.0, 0.0)
  , continuous_(false)
  , x2_(0.0)
  , y2_(0.0)
  , z2_(0.0)
  , xy_(0.0)
  , xz_(0.0)
  , yz_(0.0)
{
  type_ = REVOLUTE;
  variable_names_.push_back(name_);
  variable_bounds_.resize(1);
  variable_bounds_[0].position_bounded_ = true;
  variable_bounds_[0].min_position_ = -boost::math::constants::pi<double>();
  variable_bounds_[0].max_position_ = boost::math::constants::pi<double>();
  variable_index_map_[name_] = 0;
  computeVariableBoundsMsg();
}

unsigned int moveit::core::RevoluteJointModel::getStateSpaceDimension() const
{
  return 1;
}

void moveit::core::RevoluteJointModel::setAxis(const Eigen::Vector3d &axis)
{
  axis_ = axis.normalized();
  x2_ = axis_.x() * axis_.x();
  y2_ = axis_.y() * axis_.y();
  z2_ = axis_.z() * axis_.z();
  xy_ = axis_.x() * axis_.y();
  xz_ = axis_.x() * axis_.z();
  yz_ = axis_.y() * axis_.z();
}

void moveit::core::RevoluteJointModel::setContinuous(bool flag)
{
  continuous_ = flag;
  if (flag)
  {
    variable_bounds_[0].position_bounded_ = false;
    variable_bounds_[0].min_position_ = -boost::math::constants::pi<double>();
    variable_bounds_[0].max_position_ = boost::math::constants::pi<double>();
  }
  else
    variable_bounds_[0].position_bounded_ = true;
  computeVariableBoundsMsg();
}

double moveit::core::RevoluteJointModel::getMaximumExtent(const Bounds &other_bounds) const
{
  return variable_bounds_[0].max_position_ - variable_bounds_[0].min_position_;
}

void moveit::core::RevoluteJointModel::getVariableDefaultPositions(double *values, const Bounds &bounds) const
{
  // if zero is a valid value
  if (bounds[0].min_position_ <= 0.0 && bounds[0].max_position_ >= 0.0)
    values[0] = 0.0;
  else
    values[0] = (bounds[0].min_position_ + bounds[0].max_position_) / 2.0;
}

void moveit::core::RevoluteJointModel::getVariableRandomPositions(random_numbers::RandomNumberGenerator &rng, double *values, const Bounds &bounds) const
{
  values[0] = rng.uniformReal(bounds[0].min_position_, bounds[0].max_position_);
}

void moveit::core::RevoluteJointModel::getVariableRandomPositionsNearBy(random_numbers::RandomNumberGenerator &rng, double *values, const Bounds &bounds,
                                                                        const double *near, const double distance) const
{
  if (continuous_)
  {
    values[0] = rng.uniformReal(near[0] - distance, near[0] + distance);
    enforcePositionBounds(values, bounds);
  }
  else
    values[0] = rng.uniformReal(std::max(bounds[0].min_position_, near[0] - distance),
                                std::min(bounds[0].max_position_, near[0] + distance));
}

void moveit::core::RevoluteJointModel::interpolate(const double *from, const double *to, const double t, double *state) const
{
  if (continuous_)
  {
    double diff = to[0] - from[0];
    if (fabs(diff) <= boost::math::constants::pi<double>())
      state[0] = from[0] + diff * t;
    else
    {
      if (diff > 0.0)
        diff = 2.0 * boost::math::constants::pi<double>() - diff;
      else
        diff = -2.0 * boost::math::constants::pi<double>() - diff;
      state[0] = from[0] - diff * t;
      // input states are within bounds, so the following check is sufficient
      if (state[0] > boost::math::constants::pi<double>())
        state[0] -= 2.0 * boost::math::constants::pi<double>();
      else
        if (state[0] < -boost::math::constants::pi<double>())
          state[0] += 2.0 * boost::math::constants::pi<double>();
    }
  }
  else
    state[0] = from[0] + (to[0] - from[0]) * t;
}

double moveit::core::RevoluteJointModel::distance(const double *values1, const double *values2) const
{
  if (continuous_)
  {
    double d = fmod(fabs(values1[0] - values2[0]), 2.0 * boost::math::constants::pi<double>());
    return (d > boost::math::constants::pi<double>()) ? 2.0 * boost::math::constants::pi<double>() - d : d;
  }
  else
    return fabs(values1[0] - values2[0]);
}

bool moveit::core::RevoluteJointModel::satisfiesPositionBounds(const double *values, const Bounds &bounds, double margin) const
{
  if (values[0] < bounds[0].min_position_ - margin || values[0] > bounds[0].max_position_ + margin)
    return false;
  return true;
}

bool moveit::core::RevoluteJointModel::enforcePositionBounds(double *values, const Bounds &bounds) const
{
  if (continuous_)
  {
    double &v = values[0];
    if (v <= -boost::math::constants::pi<double>() || v > boost::math::constants::pi<double>())
    {
      v = fmod(v, 2.0 * boost::math::constants::pi<double>());
      if (v <= -boost::math::constants::pi<double>())
        v += 2.0 * boost::math::constants::pi<double>();
      else
        if (v > boost::math::constants::pi<double>())
          v -= 2.0 * boost::math::constants::pi<double>();
      return true;
    }
  }
  else
  {
    if (values[0] < bounds[0].min_position_)
    {
      values[0] = bounds[0].min_position_;
      return true;
    }
    else
      if (values[0] > bounds[0].max_position_)
      {
        values[0] = bounds[0].max_position_;
        return true;
      }
  }
  return false;
}

void moveit::core::RevoluteJointModel::computeTransform(const double *joint_values, Eigen::Affine3d &transf) const
{
  const double c = cos(joint_values[0]);
  const double s = sin(joint_values[0]);
  const double t = 1.0 - c;
  const double txy = t * xy_;
  const double txz = t * xz_;
  const double tyz = t * yz_;
  
  const double zs = axis_.z() * s;
  const double ys = axis_.y() * s;
  const double xs = axis_.x() * s;

  // column major
  double *d = transf.data();

  d[0] = t * x2_ + c;
  d[1] = txy + zs;
  d[2] = txz - ys;
  d[3] = 0.0;

  d[4] = txy - zs;
  d[5] = t * y2_ + c;
  d[6] = tyz + xs;
  d[7] = 0.0;
  
  d[8] = txz + ys;
  d[9] = tyz - xs;
  d[10] = t * z2_ + c;
  d[11] = 0.0;
  
  d[12] = 0.0;
  d[13] = 0.0;
  d[14] = 0.0;
  d[15] = 1.0;

  //  transf = Eigen::Affine3d(Eigen::AngleAxisd(joint_values[0], axis_));
}

void moveit::core::RevoluteJointModel::computeVariablePositions(const Eigen::Affine3d& transf, double *joint_values) const
{
  Eigen::Quaterniond q(transf.rotation());
  q.normalize();
  joint_values[0] = acos(q.w())*2.0f;
}