revolute_joint_model.cpp

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/* Author: Ioan Sucan */
 
#include <moveit/robot_model/revolute_joint_model.h>
#include <geometric_shapes/check_isometry.h>
#include <algorithm>
#include <cmath>
 
namespace moveit
{
namespace core
{
RevoluteJointModel::RevoluteJointModel(const std::string& name, size_t joint_index, size_t first_variable_index)
  : JointModel(name, joint_index, first_variable_index)
  , 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(getName());
  variable_bounds_.resize(1);
  variable_bounds_[0].position_bounded_ = true;
  variable_bounds_[0].min_position_ = -M_PI;
  variable_bounds_[0].max_position_ = M_PI;
  variable_index_map_[getName()] = 0;
  computeVariableBoundsMsg();
}
 
unsigned int RevoluteJointModel::getStateSpaceDimension() const
{
  return 1;
}
 
void 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 RevoluteJointModel::setContinuous(bool flag)
{
  continuous_ = flag;
  if (flag)
  {
    variable_bounds_[0].position_bounded_ = false;
    variable_bounds_[0].min_position_ = -M_PI;
    variable_bounds_[0].max_position_ = M_PI;
  }
  else
    variable_bounds_[0].position_bounded_ = true;
  computeVariableBoundsMsg();
}
 
double RevoluteJointModel::getMaximumExtent(const Bounds& /*other_bounds*/) const
{
  return variable_bounds_[0].max_position_ - variable_bounds_[0].min_position_;
}
 
void 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 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 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 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) <= M_PI)
    {
      state[0] = from[0] + diff * t;
    }
    else
    {
      if (diff > 0.0)
      {
        diff = 2.0 * M_PI - diff;
      }
      else
      {
        diff = -2.0 * M_PI - diff;
      }
      state[0] = from[0] - diff * t;
      // input states are within bounds, so the following check is sufficient
      if (state[0] > M_PI)
      {
        state[0] -= 2.0 * M_PI;
      }
      else if (state[0] < -M_PI)
      {
        state[0] += 2.0 * M_PI;
      }
    }
  }
  else
    state[0] = from[0] + (to[0] - from[0]) * t;
}
 
double RevoluteJointModel::distance(const double* values1, const double* values2) const
{
  if (continuous_)
  {
    double d = fmod(fabs(values1[0] - values2[0]), 2.0 * M_PI);
    return (d > M_PI) ? 2.0 * M_PI - d : d;
  }
  else
    return fabs(values1[0] - values2[0]);
}
 
bool RevoluteJointModel::satisfiesPositionBounds(const double* values, const Bounds& bounds, double margin) const
{
  if (continuous_)
  {
    return true;
  }
  else
  {
    return values[0] >= bounds[0].min_position_ - margin && values[0] <= bounds[0].max_position_ + margin;
  }
}
 
bool RevoluteJointModel::harmonizePosition(double* values, const JointModel::Bounds& other_bounds) const
{
  bool modified = false;
  if (*values < other_bounds[0].min_position_)
  {
    while (*values + 2 * M_PI <= other_bounds[0].max_position_)
    {
      *values += 2 * M_PI;
      modified = true;
    }
  }
  else if (*values > other_bounds[0].max_position_)
  {
    while (*values - 2 * M_PI >= other_bounds[0].min_position_)
    {
      *values -= 2 * M_PI;
      modified = true;
    }
  }
  return modified;
}
 
bool RevoluteJointModel::enforcePositionBounds(double* values, const Bounds& bounds) const
{
  if (continuous_)
  {
    double& v = values[0];
    if (v <= -M_PI || v > M_PI)
    {
      v = fmod(v, 2.0 * M_PI);
      if (v <= -M_PI)
      {
        v += 2.0 * M_PI;
      }
      else if (v > M_PI)
      {
        v -= 2.0 * M_PI;
      }
    }
  }
  else
  {
    if (values[0] < bounds[0].min_position_)
    {
      values[0] = bounds[0].min_position_;
    }
    else if (values[0] > bounds[0].max_position_)
    {
      values[0] = bounds[0].max_position_;
    }
  }
  return true;
}
 
void RevoluteJointModel::computeTransform(const double* joint_values, Eigen::Isometry3d& 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::Isometry3d(Eigen::AngleAxisd(joint_values[0], axis_));
}
 
void RevoluteJointModel::computeVariablePositions(const Eigen::Isometry3d& transf, double* joint_values) const
{
  ASSERT_ISOMETRY(transf)  // unsanitized input, could contain a non-isometry
  Eigen::Quaterniond q(transf.linear());
  q.normalize();
  size_t max_idx;
  axis_.array().abs().maxCoeff(&max_idx);
  joint_values[0] = 2. * atan2(q.vec()[max_idx] / axis_[max_idx], q.w());
}
 
}  // end of namespace core
}  // end of namespace moveit