此博文主要是用来记录ROS-Kinetic 中，用于机器人轨迹规划的MoveIt功能包的学习记录。
引： MoveGroup PlanningScene ROS API 的主要功能是，定义一个将要添加到RVIZ环境中的物品，并在RVIZ中显示。
同时，在使用RVIZ进行抓取，放下的仿真时，也需要用这个教程，在抓取完成时，将物品与机器人夹爪链接在一起，在机器人夹爪放开物品后，再将物品与机器人夹爪解除绑定。
官方教程主要以代码实例为主，所以，在下边的代码中，主要通过注释的方式，解释代码含义，通过代码实例，学习MoveIt内部内容。
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/* Author: Sachin Chitta, Michael Lautman */
#include <ros/ros.h>
#include <geometry_msgs/Pose.h>
// MoveIt!
#include <moveit_msgs/PlanningScene.h>
#include <moveit_msgs/AttachedCollisionObject.h>
#include <moveit_msgs/GetStateValidity.h>
#include <moveit_msgs/DisplayRobotState.h>
#include <moveit_msgs/ApplyPlanningScene.h>
#include <moveit/robot_model_loader/robot_model_loader.h>
#include <moveit/robot_state/robot_state.h>
#include <moveit/robot_state/conversions.h>
#include <moveit_visual_tools/moveit_visual_tools.h>
int main(int argc, char** argv)
{
ros::init(argc, argv, "planning_scene_ros_api_tutorial");
ros::AsyncSpinner spinner(1);
spinner.start();
ros::NodeHandle node_handle;
//PlanningSceneRosAPI这个功能包在本教程中，主要功能是在RVIZ中显示一个box，将这个box链接在ROBOT上，解除链接，然后再移除这个box
//Part0： 注意！！重要， 这个moveit_visual_tools工具箱，主要功能是在RVIZ界面中显示信息/轨迹等内容
moveit_visual_tools::MoveItVisualTools visual_tools("panda_link0");
visual_tools.deleteAllMarkers();
// ROS API
// ^^^^^^^
// ROS API的功能是：规划一个不同于当前显示环境的一个场景
//
//Part1：创建一个Publisher，用于发送planning_scene(规划场景)
// 并且等待有Subscriber订阅这个topic后，再进行下一步操作
// Advertise the required topic
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// We create a publisher and wait for subscribers
// Note that this topic may need to be remapped in the launch file
ros::Publisher planning_scene_diff_publisher = node_handle.advertise<moveit_msgs::PlanningScene>("planning_scene", 1);
ros::WallDuration sleep_t(0.5);
while (planning_scene_diff_publisher.getNumSubscribers() < 1)
{
sleep_t.sleep();
}
//等待操作人员按按钮，或者输入
visual_tools.prompt("Press 'next' in the RvizVisualToolsGui window to start the demo");
//Part2：定义一个将被链接到Robot并显示在RVIZ中的物品对象
//Step2.1 创建被连接的对象，确定链接的link，确定连接后，被连接物体的位姿
moveit_msgs::AttachedCollisionObject attached_object; //声明连接对象
attached_object.link_name = "panda_leftfinger"; //确定物品将要连接到的link名
/* The header must contain a valid TF frame*/
attached_object.object.header.frame_id = "panda_leftfinger";
/* The id of the object */
attached_object.object.id = "box";
/* A default pose */
geometry_msgs::Pose pose;
pose.orientation.w = 1.0;
//Step2.2 创建一个Box对象，并将前边设置的位置，名称，位姿等参数进行输入
/* Define a box to be attached */
shape_msgs::SolidPrimitive primitive; //定义一个box
primitive.type = primitive.BOX;
primitive.dimensions.resize(3);
primitive.dimensions[0] = 0.1;
primitive.dimensions[1] = 0.1;
primitive.dimensions[2] = 0.1;
attached_object.object.primitives.push_back(primitive);
attached_object.object.primitive_poses.push_back(pose);
// step2.3 创建一个向RVIZ中添加物品的对象
attached_object.object.operation = attached_object.object.ADD;
//step2.4由于要进行抓取和放置的仿真，因此需要禁用碰撞检测
attached_object.touch_links = std::vector<std::string>{ "panda_hand", "panda_leftfinger", "panda_rightfinger" };
// Part3： 创建一个planningScene场景对象，并将box添加进来
ROS_INFO("Adding the object into the world at the location of the hand.");
moveit_msgs::PlanningScene planning_scene;
planning_scene.world.collision_objects.push_back(attached_object.object);
planning_scene.is_diff = true;
planning_scene_diff_publisher.publish(planning_scene); //使用的是publisher
visual_tools.prompt("Press 'next' in the RvizVisualToolsGui window to continue the demo");
// Interlude: Synchronous vs Asynchronous updates
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// There are two separate mechanisms available to interact
// with the move_group node using diffs:
//
// * Send a diff via a rosservice call and block until
// the diff is applied (synchronous update)
// * Send a diff via a topic, continue even though the diff
// might not be applied yet (asynchronous update)
//
// While most of this tutorial uses the latter mechanism (given the long sleeps
// inserted for visualization purposes asynchronous updates do not pose a problem),
// it would is perfectly justified to replace the planning_scene_diff_publisher
// by the following service client:
ros::ServiceClient planning_scene_diff_client =
node_handle.serviceClient<moveit_msgs::ApplyPlanningScene>("apply_planning_scene");
planning_scene_diff_client.waitForExistence();
// and send the diffs to the planning scene via a service call:
moveit_msgs::ApplyPlanningScene srv;
srv.request.scene = planning_scene;
planning_scene_diff_client.call(srv);
// Note that this does not continue until we are sure the diff has been applied.
//
// Part4： 将添加到RVIZ的box，连接到机器人本体上
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// 当我们需要使用RVIZ进行机器人抓取仿真时，在抓取发生时，我们所做的实际上就是将物品attach到机器人上;
// 当release之后，我们再将物品detach下来即可
// 为了不出差错， 链接操作需要分两步进行
//* Step4.1 首先将RVIZ环境中已经存在的object移除
moveit_msgs::CollisionObject remove_object;
remove_object.id = "box";
remove_object.header.frame_id = "panda_link0";
remove_object.operation = remove_object.REMOVE;
//* Step4.2 在添加物品之前，首先要求人，这个diff message是否已经被清空？否则将报错
/* Carry out the REMOVE + ATTACH operation */
ROS_INFO("Attaching the object to the hand and removing it from the world.");
planning_scene.world.collision_objects.clear();
planning_scene.world.collision_objects.push_back(remove_object);
planning_scene.robot_state.attached_collision_objects.push_back(attached_object);
planning_scene_diff_publisher.publish(planning_scene);
visual_tools.prompt("Press 'next' in the RvizVisualToolsGui window to continue the demo");
// Part5： 将物品从robot上，解除绑定
//* Step5.1 ：将已经添加的object移除
moveit_msgs::AttachedCollisionObject detach_object;
detach_object.object.id = "box";
detach_object.link_name = "panda_link8";
detach_object.object.operation = attached_object.object.REMOVE;
//* Step5.2 ：将添加box时，所用的对象清空
ROS_INFO("Detaching the object from the robot and returning it to the world.");
planning_scene.robot_state.attached_collision_objects.clear();
planning_scene.robot_state.attached_collision_objects.push_back(detach_object);
planning_scene.robot_state.is_diff = true;
planning_scene.world.collision_objects.clear();
planning_scene.world.collision_objects.push_back(attached_object.object);
planning_scene.is_diff = true;
planning_scene_diff_publisher.publish(planning_scene);
visual_tools.prompt("Press 'next' in the RvizVisualToolsGui window to continue the demo");
// Part6： 将物品从rviz环境中清除
ROS_INFO("Removing the object from the world.");
planning_scene.robot_state.attached_collision_objects.clear();
planning_scene.world.collision_objects.clear();
planning_scene.world.collision_objects.push_back(remove_object);
planning_scene_diff_publisher.publish(planning_scene);
// END_TUTORIAL
visual_tools.prompt("Press 'next' in the RvizVisualToolsGui window to end the demo");
ros::shutdown();
return 0;
}