pr2_arm_ik.h

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/* Author: Sachin Chitta */
 
#pragma once
 
#include <urdf_model/model.h>
#include <urdf/model.h>
#include <Eigen/Geometry>
#include <Eigen/LU>  // provides LU decomposition
#include <kdl/chainiksolver.hpp>
#include <moveit_msgs/GetPositionFK.h>
#include <moveit_msgs/GetPositionIK.h>
#include <moveit_msgs/KinematicSolverInfo.h>
 
namespace pr2_arm_kinematics
{
static const int NUM_JOINTS_ARM7DOF = 7;
 
static const double IK_EPS = 1e-5;
 
inline double distance(const urdf::Pose& transform)
{
  return sqrt(transform.position.x * transform.position.x + transform.position.y * transform.position.y +
              transform.position.z * transform.position.z);
}
 
inline bool solveQuadratic(const double& a, const double& b, const double& c, double* x1, double* x2)
{
  double discriminant = b * b - 4 * a * c;
  if (fabs(a) < IK_EPS)
  {
    *x1 = -c / b;
    *x2 = *x1;
    return true;
  }
  // ROS_DEBUG("Discriminant: %f\n",discriminant);
  if (discriminant >= 0)
  {
    *x1 = (-b + sqrt(discriminant)) / (2 * a);
    *x2 = (-b - sqrt(discriminant)) / (2 * a);
    return true;
  }
  else if (fabs(discriminant) < IK_EPS)
  {
    *x1 = -b / (2 * a);
    *x2 = -b / (2 * a);
    return true;
  }
  else
  {
    *x1 = -b / (2 * a);
    *x2 = -b / (2 * a);
    return false;
  }
}
 
inline bool solveCosineEqn(const double& a, const double& b, const double& c, double& soln1, double& soln2)
{
  double theta1 = atan2(b, a);
  double denom = sqrt(a * a + b * b);
 
  if (fabs(denom) < IK_EPS)  // should never happen, wouldn't make sense but make sure it is checked nonetheless
  {
#ifdef DEBUG
    std::cout << "denom: " << denom << std::endl;
#endif
    return false;
  }
  double rhs_ratio = c / denom;
  if (rhs_ratio < -1 || rhs_ratio > 1)
  {
#ifdef DEBUG
    std::cout << "rhs_ratio: " << rhs_ratio << std::endl;
#endif
    return false;
  }
  double acos_term = acos(rhs_ratio);
  soln1 = theta1 + acos_term;
  soln2 = theta1 - acos_term;
 
  return true;
}
 
class PR2ArmIK
{
public:
  PR2ArmIK();
  ~PR2ArmIK(){};
 
  bool init(const urdf::ModelInterface& robot_model, const std::string& root_name, const std::string& tip_name);
 
  void computeIKShoulderPan(const Eigen::Isometry3f& g_in, const double& shoulder_pan_initial_guess,
                            std::vector<std::vector<double> >& solution) const;
 
  void computeIKShoulderRoll(const Eigen::Isometry3f& g_in, const double& shoulder_roll_initial_guess,
                             std::vector<std::vector<double> >& solution) const;
 
  void getSolverInfo(moveit_msgs::KinematicSolverInfo& info);
 
  moveit_msgs::KinematicSolverInfo solver_info_;
 
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW
 
private:
  void addJointToChainInfo(const urdf::JointConstSharedPtr& joint, moveit_msgs::KinematicSolverInfo& info);
 
  bool checkJointLimits(const std::vector<double>& joint_values) const;
 
  bool checkJointLimits(const double& joint_value, const int& joint_num) const;
 
  Eigen::Isometry3f grhs_, gf_, home_inv_;
 
  std::vector<double> angle_multipliers_;
 
  std::vector<double> solution_;
 
  double shoulder_upperarm_offset_, upperarm_elbow_offset_, elbow_wrist_offset_, shoulder_wrist_offset_,
      shoulder_elbow_offset_, torso_shoulder_offset_x_, torso_shoulder_offset_y_, torso_shoulder_offset_z_;
 
  std::vector<double> min_angles_;
 
  std::vector<double> max_angles_;
 
  std::vector<bool> continuous_joint_;
};
}  // namespace pr2_arm_kinematics