ompl_constraints.h

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/* Author: Jeroen De Maeyer, Boston Cleek */
 
#pragma once
 
#include <ostream>
 
#include <ompl/base/Constraint.h>
 
#include <moveit/ompl_interface/detail/threadsafe_state_storage.h>
#include <moveit/robot_model/robot_model.h>
#include <moveit/macros/class_forward.h>
#include <moveit_msgs/msg/constraints.hpp>
 
namespace ompl_interface
{
MOVEIT_CLASS_FORWARD(BaseConstraint);
MOVEIT_CLASS_FORWARD(BoxConstraint);
MOVEIT_CLASS_FORWARD(OrientationConstraint);
 
class Bounds
{
public:
  Bounds();
  Bounds(const std::vector<double>& lower, const std::vector<double>& upper);
  Eigen::VectorXd penalty(const Eigen::Ref<const Eigen::VectorXd>& x) const;
 
  Eigen::VectorXd derivative(const Eigen::Ref<const Eigen::VectorXd>& x) const;
 
  std::size_t size() const;
 
private:
  std::vector<double> lower_, upper_;
  std::size_t size_;
 
  friend std::ostream& operator<<(std::ostream& os, const ompl_interface::Bounds& bounds);
};
 
std::ostream& operator<<(std::ostream& os, const ompl_interface::Bounds& bounds);
 
/****************************
 * Base class for constraints
 * **************************/
class BaseConstraint : public ompl::base::Constraint
{
public:
  BaseConstraint(const moveit::core::RobotModelConstPtr& robot_model, const std::string& group,
                 const unsigned int num_dofs, const unsigned int num_cons = 3);
 
  void init(const moveit_msgs::msg::Constraints& constraints);
 
  void function(const Eigen::Ref<const Eigen::VectorXd>& joint_values, Eigen::Ref<Eigen::VectorXd> out) const override;
 
  void jacobian(const Eigen::Ref<const Eigen::VectorXd>& joint_values, Eigen::Ref<Eigen::MatrixXd> out) const override;
 
  Eigen::Isometry3d forwardKinematics(const Eigen::Ref<const Eigen::VectorXd>& joint_values) const;
 
  Eigen::MatrixXd robotGeometricJacobian(const Eigen::Ref<const Eigen::VectorXd>& joint_values) const;
 
  virtual void parseConstraintMsg(const moveit_msgs::msg::Constraints& constraints) = 0;
 
  virtual Eigen::VectorXd calcError(const Eigen::Ref<const Eigen::VectorXd>& /*x*/) const;
 
  virtual Eigen::MatrixXd calcErrorJacobian(const Eigen::Ref<const Eigen::VectorXd>& /*x*/) const;
 
  // the methods below are specifically for debugging and testing
 
  const std::string& getLinkName()
  {
    return link_name_;
  }
 
  const Eigen::Vector3d getTargetPosition()
  {
    return target_position_;
  }
 
  const Eigen::Quaterniond getTargetOrientation()
  {
    return target_orientation_;
  }
 
protected:
  TSStateStorage state_storage_;
  const moveit::core::JointModelGroup* joint_model_group_;
 
  // all attributes below can be considered const as soon as the constraint message is parsed
  // but I (jeroendm) do not know how to elegantly express this in C++
  // parsing the constraints message and passing all this data members separately to the constructor
  // is a solution, but it adds complexity outside this class, which is also not ideal.
 
  std::string link_name_;
 
  Bounds bounds_;
 
  Eigen::Vector3d target_position_;
 
  Eigen::Quaterniond target_orientation_;
 
public:
  // Macro for classes containing fixed size eigen vectors that are dynamically allocated when used.
  // https://eigen.tuxfamily.org/dox/group__TopicStructHavingEigenMembers.html
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW
};
 
/******************************************
 * Box constraint
 * ****************************************/
class BoxConstraint : public BaseConstraint
{
public:
  BoxConstraint(const moveit::core::RobotModelConstPtr& robot_model, const std::string& group,
                const unsigned int num_dofs);
 
  void parseConstraintMsg(const moveit_msgs::msg::Constraints& constraints) override;
 
  Eigen::VectorXd calcError(const Eigen::Ref<const Eigen::VectorXd>& x) const override;
 
  Eigen::MatrixXd calcErrorJacobian(const Eigen::Ref<const Eigen::VectorXd>& x) const override;
};
 
/******************************************
 * Equality Position Constraints
 * ****************************************/
class EqualityPositionConstraint : public BaseConstraint
{
public:
  EqualityPositionConstraint(const moveit::core::RobotModelConstPtr& robot_model, const std::string& group,
                             const unsigned int num_dofs);
 
  void parseConstraintMsg(const moveit_msgs::msg::Constraints& constraints) override;
 
  void function(const Eigen::Ref<const Eigen::VectorXd>& joint_values, Eigen::Ref<Eigen::VectorXd> out) const override;
 
  void jacobian(const Eigen::Ref<const Eigen::VectorXd>& joint_values, Eigen::Ref<Eigen::MatrixXd> out) const override;
 
private:
  static constexpr double EQUALITY_CONSTRAINT_THRESHOLD{ 0.001 };
 
  std::vector<bool> is_dim_constrained_;
};
 
/******************************************
 * Orientation constraints
 * ****************************************/
class OrientationConstraint : public BaseConstraint
{
public:
  OrientationConstraint(const moveit::core::RobotModelConstPtr& robot_model, const std::string& group,
                        const unsigned int num_dofs)
    : BaseConstraint(robot_model, group, num_dofs)
  {
  }
 
  void parseConstraintMsg(const moveit_msgs::msg::Constraints& constraints) override;
 
  Eigen::VectorXd calcError(const Eigen::Ref<const Eigen::VectorXd>& x) const override;
 
  Eigen::MatrixXd calcErrorJacobian(const Eigen::Ref<const Eigen::VectorXd>& x) const override;
};
 
Bounds positionConstraintMsgToBoundVector(const moveit_msgs::msg::PositionConstraint& pos_con);
 
Bounds orientationConstraintMsgToBoundVector(const moveit_msgs::msg::OrientationConstraint& ori_con);
 
ompl::base::ConstraintPtr createOMPLConstraints(const moveit::core::RobotModelConstPtr& robot_model,
                                                const std::string& group,
                                                const moveit_msgs::msg::Constraints& constraints);
 
inline Eigen::Matrix3d angularVelocityToAngleAxis(const double& angle, const Eigen::Ref<const Eigen::Vector3d>& axis)
{
  double t{ std::abs(angle) };
  Eigen::Matrix3d r_skew;
  r_skew << 0, -axis[2], axis[1], axis[2], 0, -axis[0], -axis[1], axis[0], 0;
  r_skew *= angle;
 
  double c;
  c = (1 - 0.5 * t * std::sin(t) / (1 - std::cos(t)));
 
  return Eigen::Matrix3d::Identity() - 0.5 * r_skew + (r_skew * r_skew / (t * t)) * c;
}
 
}  // namespace ompl_interface