floating_joint_model.cpp

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/* Author: Ioan Sucan */
 
#include <cmath>
#include <Eigen/Geometry>
#include <geometric_shapes/check_isometry.h>
#include <limits>
#include <moveit/robot_model/floating_joint_model.h>
#include <rclcpp/logger.hpp>
#include <rclcpp/logging.hpp>
 
namespace moveit
{
namespace core
{
static const rclcpp::Logger LOGGER = rclcpp::get_logger("moveit_robot_model.floating_joint_model");
namespace
{
constexpr size_t STATE_SPACE_DIMENSION = 7;
 
}  // namespace
 
FloatingJointModel::FloatingJointModel(const std::string& name, size_t joint_index, size_t first_variable_index)
  : JointModel(name, joint_index, first_variable_index), angular_distance_weight_(1.0)
{
  type_ = FLOATING;
  local_variable_names_.push_back("trans_x");
  local_variable_names_.push_back("trans_y");
  local_variable_names_.push_back("trans_z");
  local_variable_names_.push_back("rot_x");
  local_variable_names_.push_back("rot_y");
  local_variable_names_.push_back("rot_z");
  local_variable_names_.push_back("rot_w");
  for (size_t i = 0; i < STATE_SPACE_DIMENSION; ++i)
  {
    variable_names_.push_back(getName() + "/" + local_variable_names_[i]);
    variable_index_map_[variable_names_.back()] = i;
  }
 
  variable_bounds_.resize(7);
 
  variable_bounds_[0].position_bounded_ = true;
  variable_bounds_[1].position_bounded_ = true;
  variable_bounds_[2].position_bounded_ = true;
  variable_bounds_[3].position_bounded_ = true;
  variable_bounds_[4].position_bounded_ = true;
  variable_bounds_[5].position_bounded_ = true;
  variable_bounds_[6].position_bounded_ = true;
 
  variable_bounds_[0].min_position_ = -std::numeric_limits<double>::infinity();
  variable_bounds_[0].max_position_ = std::numeric_limits<double>::infinity();
  variable_bounds_[1].min_position_ = -std::numeric_limits<double>::infinity();
  variable_bounds_[1].max_position_ = std::numeric_limits<double>::infinity();
  variable_bounds_[2].min_position_ = -std::numeric_limits<double>::infinity();
  variable_bounds_[2].max_position_ = std::numeric_limits<double>::infinity();
  variable_bounds_[3].min_position_ = -1.0;
  variable_bounds_[3].max_position_ = 1.0;
  variable_bounds_[4].min_position_ = -1.0;
  variable_bounds_[4].max_position_ = 1.0;
  variable_bounds_[5].min_position_ = -1.0;
  variable_bounds_[5].max_position_ = 1.0;
  variable_bounds_[6].min_position_ = -1.0;
  variable_bounds_[6].max_position_ = 1.0;
 
  computeVariableBoundsMsg();
}
 
double FloatingJointModel::getMaximumExtent(const Bounds& other_bounds) const
{
  double dx = other_bounds[0].max_position_ - other_bounds[0].min_position_;
  double dy = other_bounds[1].max_position_ - other_bounds[1].min_position_;
  double dz = other_bounds[2].max_position_ - other_bounds[2].min_position_;
  return sqrt(dx * dx + dy * dy + dz * dz) + M_PI * 0.5 * angular_distance_weight_;
}
 
double FloatingJointModel::distance(const double* values1, const double* values2) const
{
  return distanceTranslation(values1, values2) + angular_distance_weight_ * distanceRotation(values1, values2);
}
 
double FloatingJointModel::distanceTranslation(const double* values1, const double* values2) const
{
  double dx = values1[0] - values2[0];
  double dy = values1[1] - values2[1];
  double dz = values1[2] - values2[2];
  return sqrt(dx * dx + dy * dy + dz * dz);
}
 
double FloatingJointModel::distanceRotation(const double* values1, const double* values2) const
{
  // The values are in "xyzw" order but Eigen expects "wxyz".
  const auto q1 = Eigen::Quaterniond(values1[6], values1[3], values1[4], values1[5]).normalized();
  const auto q2 = Eigen::Quaterniond(values2[6], values2[3], values2[4], values2[5]).normalized();
  return q2.angularDistance(q1);
}
 
void FloatingJointModel::interpolate(const double* from, const double* to, const double t, double* state) const
{
  // interpolate position
  state[0] = from[0] + (to[0] - from[0]) * t;
  state[1] = from[1] + (to[1] - from[1]) * t;
  state[2] = from[2] + (to[2] - from[2]) * t;
 
  // Check if the quaternions are significantly different
  if (abs(from[3] - to[3]) + abs(from[4] - to[4]) + abs(from[5] - to[5]) + abs(from[6] - to[6]) >
      std::numeric_limits<double>::epsilon())
  {
    // Note the ordering: Eigen takes w first!
    Eigen::Quaterniond q1(from[6], from[3], from[4], from[5]);
    Eigen::Quaterniond q2(to[6], to[3], to[4], to[5]);
 
    Eigen::Quaterniond q = q1.slerp(t, q2);
 
    state[3] = q.x();
    state[4] = q.y();
    state[5] = q.z();
    state[6] = q.w();
  }
  else
  {
    state[3] = from[3];
    state[4] = from[4];
    state[5] = from[5];
    state[6] = from[6];
  }
}
 
bool FloatingJointModel::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;
  if (values[1] < bounds[1].min_position_ - margin || values[1] > bounds[1].max_position_ + margin)
    return false;
  if (values[2] < bounds[2].min_position_ - margin || values[2] > bounds[2].max_position_ + margin)
    return false;
  double norm_sqr = values[3] * values[3] + values[4] * values[4] + values[5] * values[5] + values[6] * values[6];
  return fabs(norm_sqr - 1.0) <= std::numeric_limits<float>::epsilon() * 10.0;
}
 
bool FloatingJointModel::normalizeRotation(double* values) const
{
  // normalize the quaternion if we need to
  double norm_sqr = values[3] * values[3] + values[4] * values[4] + values[5] * values[5] + values[6] * values[6];
  if (fabs(norm_sqr - 1.0) > std::numeric_limits<double>::epsilon() * 100.0)
  {
    double norm = sqrt(norm_sqr);
    if (norm < std::numeric_limits<double>::epsilon() * 100.0)
    {
      RCLCPP_WARN(LOGGER, "Quaternion is zero in RobotState representation. Setting to identity");
      values[3] = 0.0;
      values[4] = 0.0;
      values[5] = 0.0;
      values[6] = 1.0;
    }
    else
    {
      values[3] /= norm;
      values[4] /= norm;
      values[5] /= norm;
      values[6] /= norm;
    }
    return true;
  }
  else
    return false;
}
 
unsigned int FloatingJointModel::getStateSpaceDimension() const
{
  return STATE_SPACE_DIMENSION;
}
 
bool FloatingJointModel::enforcePositionBounds(double* values, const Bounds& bounds) const
{
  bool result = normalizeRotation(values);
  for (unsigned int i = 0; i < 3; ++i)
  {
    if (values[i] < bounds[i].min_position_)
    {
      values[i] = bounds[i].min_position_;
      result = true;
    }
    else if (values[i] > bounds[i].max_position_)
    {
      values[i] = bounds[i].max_position_;
      result = true;
    }
  }
  return result;
}
 
void FloatingJointModel::computeTransform(const double* joint_values, Eigen::Isometry3d& transf) const
{
  transf = Eigen::Isometry3d(
      Eigen::Translation3d(joint_values[0], joint_values[1], joint_values[2]) *
      Eigen::Quaterniond(joint_values[6], joint_values[3], joint_values[4], joint_values[5]).normalized());
}
 
void FloatingJointModel::computeVariablePositions(const Eigen::Isometry3d& transf, double* joint_values) const
{
  joint_values[0] = transf.translation().x();
  joint_values[1] = transf.translation().y();
  joint_values[2] = transf.translation().z();
  ASSERT_ISOMETRY(transf)  // unsanitized input, could contain non-isometry
  Eigen::Quaterniond q(transf.linear());
  joint_values[3] = q.x();
  joint_values[4] = q.y();
  joint_values[5] = q.z();
  joint_values[6] = q.w();
}
 
void FloatingJointModel::getVariableDefaultPositions(double* values, const Bounds& bounds) const
{
  for (unsigned int i = 0; i < 3; ++i)
  {
    // if zero is a valid value
    if (bounds[i].min_position_ <= 0.0 && bounds[i].max_position_ >= 0.0)
      values[i] = 0.0;
    else
      values[i] = (bounds[i].min_position_ + bounds[i].max_position_) / 2.0;
  }
 
  values[3] = 0.0;
  values[4] = 0.0;
  values[5] = 0.0;
  values[6] = 1.0;
}
 
void FloatingJointModel::getVariableRandomPositions(random_numbers::RandomNumberGenerator& rng, double* values,
                                                    const Bounds& bounds) const
{
  if (bounds[0].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[0].min_position_ <= -std::numeric_limits<double>::infinity())
    values[0] = 0.0;
  else
    values[0] = rng.uniformReal(bounds[0].min_position_, bounds[0].max_position_);
  if (bounds[1].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[1].min_position_ <= -std::numeric_limits<double>::infinity())
    values[1] = 0.0;
  else
    values[1] = rng.uniformReal(bounds[1].min_position_, bounds[1].max_position_);
  if (bounds[2].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[2].min_position_ <= -std::numeric_limits<double>::infinity())
    values[2] = 0.0;
  else
    values[2] = rng.uniformReal(bounds[2].min_position_, bounds[2].max_position_);
 
  double q[4];
  rng.quaternion(q);
  values[3] = q[0];
  values[4] = q[1];
  values[5] = q[2];
  values[6] = q[3];
}
 
void FloatingJointModel::getVariableRandomPositionsNearBy(random_numbers::RandomNumberGenerator& rng, double* values,
                                                          const Bounds& bounds, const double* near,
                                                          const double distance) const
{
  if (bounds[0].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[0].min_position_ <= -std::numeric_limits<double>::infinity())
    values[0] = 0.0;
  else
    values[0] = rng.uniformReal(std::max(bounds[0].min_position_, near[0] - distance),
                                std::min(bounds[0].max_position_, near[0] + distance));
  if (bounds[1].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[1].min_position_ <= -std::numeric_limits<double>::infinity())
    values[1] = 0.0;
  else
    values[1] = rng.uniformReal(std::max(bounds[1].min_position_, near[1] - distance),
                                std::min(bounds[1].max_position_, near[1] + distance));
  if (bounds[2].max_position_ >= std::numeric_limits<double>::infinity() ||
      bounds[2].min_position_ <= -std::numeric_limits<double>::infinity())
    values[2] = 0.0;
  else
    values[2] = rng.uniformReal(std::max(bounds[2].min_position_, near[2] - distance),
                                std::min(bounds[2].max_position_, near[2] + distance));
 
  double da = angular_distance_weight_ * distance;
  if (da >= .25 * M_PI)
  {
    double q[4];
    rng.quaternion(q);
    values[3] = q[0];
    values[4] = q[1];
    values[5] = q[2];
    values[6] = q[3];
  }
  else
  {
    // taken from OMPL
    // sample angle & axis
    double ax = rng.gaussian01();
    double ay = rng.gaussian01();
    double az = rng.gaussian01();
    double angle = 2.0 * pow(rng.uniform01(), 1.0 / 3.0) * da;
    // convert to quaternion
    double q[4];
    double norm = sqrt(ax * ax + ay * ay + az * az);
    if (norm < 1e-6)
    {
      q[0] = q[1] = q[2] = 0.0;
      q[3] = 1.0;
    }
    else
    {
      double s = sin(angle / 2.0);
      q[0] = s * ax / norm;
      q[1] = s * ay / norm;
      q[2] = s * az / norm;
      q[3] = cos(angle / 2.0);
    }
    // multiply quaternions: near * q
    values[3] = near[6] * q[0] + near[3] * q[3] + near[4] * q[2] - near[5] * q[1];
    values[4] = near[6] * q[1] + near[4] * q[3] + near[5] * q[0] - near[3] * q[2];
    values[5] = near[6] * q[2] + near[5] * q[3] + near[3] * q[1] - near[4] * q[0];
    values[6] = near[6] * q[3] - near[3] * q[0] - near[4] * q[1] - near[5] * q[2];
  }
}
 
}  // end of namespace core
}  // end of namespace moveit