MOVEIT: Compute forward kinematics and plan in Cartesian space.

asked 2017-10-25 12:36:20 -0500

Long Smith gravatar image

I'm trying to plan trajectory which will move my arm into my "home" position. In joint space it is quite easy. However I would also like to try it in cartesian space. In order to accomplish the task firstly I compute forward kinematics for my "home" position via RobotState::getGlobalLinkTransform, turn rotational part into quaternion and then plan. However I get wrong result: the final position is not even near to the required position.

Here is my code:

#include <moveit/move_group_interface/move_group_interface.h>
#include <moveit/planning_scene_interface/planning_scene_interface.h>
#include <moveit/robot_model/robot_model.h>

#include <moveit_msgs/DisplayRobotState.h>
#include <moveit_msgs/DisplayTrajectory.h>

#include <moveit_msgs/AttachedCollisionObject.h>
#include <moveit_msgs/CollisionObject.h>

#include <moveit_visual_tools/moveit_visual_tools.h>

#include "Eigen/Geometry/Transform.h"
#include "Eigen/Geometry/Quaternion.h"

#include <map>
#include <vector>
#include <algorithm>
#include <iostream>


static const std::string PLANNING_GROUP = "arm_group";
static const std::string HOME_POSE_NAME = "home";


int main(int argc, char **argv)
{
    ros::init(argc, argv, "move_group_interface_tutorial");
    ros::NodeHandle node_handle;
    ros::AsyncSpinner spinner(1);
    spinner.start();

    /* Loading move group */
    moveit::planning_interface::MoveGroupInterface      move_group(PLANNING_GROUP);
    moveit::planning_interface::PlanningSceneInterface  planning_scene;

    ROS_INFO_NAMED("tutorial", "Reference frame: %s",
            move_group.getPlanningFrame().c_str());

    ROS_INFO_NAMED("tutorial", "End effector link: %s",
            move_group.getEndEffectorLink().c_str());

    /* Loading robot model and its' kinematic state */
    robot_model::RobotModelConstPtr robot_model  = move_group.getRobotModel();
    robot_state::RobotState *kinematic_state = new robot_state::RobotState(robot_model);

    const std::string EE_NAME = move_group.getEndEffectorLink();

    const robot_model::JointModelGroup *joint_model_group =
        move_group.getCurrentState()->getJointModelGroup(PLANNING_GROUP);


    /* Getting HOME postition and printing it */
    std::vector<double> home_joint_values;
    const std::map<std::string, double> home_joints_map =
        move_group.getNamedTargetValues(HOME_POSE_NAME);

    for(auto& x: home_joints_map) {
        home_joint_values.push_back(x.second);
        ROS_INFO_STREAM(x.first << ": " << x.second);
    }

    bool planning_succeded = false;
    moveit::planning_interface::MoveGroupInterface::Plan my_plan;

    // move_group.setJointValueTarget(home_joints_map);

    /* Planning path in Joint Space to a goal position */
    //planning_succeded = move_group.plan(my_plan);
    //ROS_INFO_NAMED("ur5-planning", "Planning succeded: %s", planning_succeded ? "yes" : "no");


    /*****************************************/
    /*      Planning in cartesian space      */
    /*****************************************/
    ROS_INFO_STREAM("Getting transformation on " << EE_NAME);

    kinematic_state->setJointGroupPositions(joint_model_group, home_joint_values);
    Eigen::Affine3d end_effector_state = kinematic_state->getGlobalLinkTransform(EE_NAME);

    Eigen::Quaterniond q_pos(end_effector_state.rotation());
    auto tr = end_effector_state.translation();

    ROS_INFO_STREAM("Translation:\r\n" << end_effector_state.translation());
    ROS_INFO_STREAM("Rotation:\r\n" << end_effector_state.rotation());
    ROS_INFO_STREAM("Qauternion rotation:\r\n" << q_pos.vec());

    geometry_msgs::Pose target_pose;
    target_pose.position.x = tr[0];
    target_pose.position.y = tr[1];
    target_pose.position.z = tr[2];
    target_pose.orientation.x = q_pos.x();
    target_pose.orientation.y = q_pos.y();
    target_pose.orientation.z = q_pos.z();
    target_pose.orientation.w = q_pos.w();

    move_group.setPoseTarget(target_pose);
    planning_succeded = move_group.plan(my_plan);
    // move_group.execute(my_plan);

    ROS_INFO_NAMED("ur5-planning", "Planning succeded: %s", planning_succeded ? "yes" : "no");

    return 0;
}
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