可视化碰撞

本节将带你逐步了解一段 C++ 示例代码，通过它你可以在 RViz 中移动和操作机械臂时，直观地查看机器人自身以及机器人与环境之间的碰撞接触点。

开始之前

如果你还没有完成，请确保你已完成 Getting Started 中的步骤。

运行代码

使用 roslaunch 直接从 moveit_tutorials 运行启动文件：

roslaunch moveit_tutorials visualizing_collisions_tutorial.launch

现在你应该能看到 Panda 机器人，以及 2 个可以四处拖动的交互标记（interactive marker）。

类

本教程的代码主要在 InteractiveRobot 类中，我们将在下面逐步讲解。InteractiveRobot 类维护一个 RobotModel、一个 RobotState，以及关于“世界”的信息（在本例中，“世界”是一个黄色立方体）。

InteractiveRobot 类使用了负责管理交互标记的 IMarker 类。本教程不涉及 IMarker 类的实现细节（imarker.cpp），但其大部分代码都是从 basic_controls 教程中复制而来。如果你感兴趣，可以在那里了解更多关于交互标记的内容。

交互

在 RViz 中，你会看到两组红/绿/蓝的交互标记箭头。用鼠标拖动它们即可。

移动右臂使其与左臂接触，你会看到品红色（magenta）球体标记出接触点。

如果你没有看到品红色球体，请确保你按照上面的说明添加了主题为 interactive_robot_marray 的 MarkerArray 显示。同时，还要确保将 RobotAlpha 设置为 0.3（或其他小于 1 的值），使机器人变为半透明，这样才能看到球体。

移动右臂使其与黄色立方体接触（你也可以移动黄色立方体），同样会看到品红色球体标记出接触点。

相关代码

完整的代码可以在 moveit_tutorials GitHub 项目中查看：此处。所使用的库可以在此处找到。为了让本教程聚焦于碰撞接触可视化，我们省略了大量理解该演示所需的背景信息。要完全理解这个演示，强烈建议你通读源代码。

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/* Author: Acorn Pooley, Michael Lautman */

// This code goes with the Collision Contact Visualization tutorial

#include <ros/ros.h>
#include "interactivity/interactive_robot.h"
#include "interactivity/pose_string.h"

// MoveIt
#include <moveit/robot_model/robot_model.h>
#include <moveit/robot_state/robot_state.h>
#include <moveit/planning_scene/planning_scene.h>
#include <moveit/collision_detection_fcl/collision_env_fcl.h>
#include <moveit/collision_detection/collision_tools.h>

planning_scene::PlanningScene* g_planning_scene = nullptr;
shapes::ShapePtr g_world_cube_shape;
ros::Publisher* g_marker_array_publisher = nullptr;
visualization_msgs::MarkerArray g_collision_points;

void help()
{
  ROS_INFO("#####################################################");
  ROS_INFO("RVIZ SETUP");
  ROS_INFO("----------");
  ROS_INFO("  Global options:");
  ROS_INFO("    FixedFrame = /panda_link0");
  ROS_INFO("  Add a RobotState display:");
  ROS_INFO("    RobotDescription = robot_description");
  ROS_INFO("    RobotStateTopic  = interactive_robot_state");
  ROS_INFO("  Add a Marker display:");
  ROS_INFO("    MarkerTopic = interactive_robot_markers");
  ROS_INFO("  Add an InteractiveMarker display:");
  ROS_INFO("    UpdateTopic = interactive_robot_imarkers/update");
  ROS_INFO("  Add a MarkerArray display:");
  ROS_INFO("    MarkerTopic = interactive_robot_marray");
  ROS_INFO("#####################################################");
}

void publishMarkers(visualization_msgs::MarkerArray& markers)
{
  // delete old markers
  if (!g_collision_points.markers.empty())
  {
    for (auto& marker : g_collision_points.markers)
      marker.action = visualization_msgs::Marker::DELETE;

    g_marker_array_publisher->publish(g_collision_points);
  }

  // move new markers into g_collision_points
  std::swap(g_collision_points.markers, markers.markers);

  // draw new markers (if there are any)
  if (!g_collision_points.markers.empty())
    g_marker_array_publisher->publish(g_collision_points);
}

void computeCollisionContactPoints(InteractiveRobot& robot)
{
  // move the world geometry in the collision world
  Eigen::Isometry3d world_cube_pose;
  double world_cube_size;
  robot.getWorldGeometry(world_cube_pose, world_cube_size);
  g_planning_scene->getWorldNonConst()->moveShapeInObject("world_cube", g_world_cube_shape, world_cube_pose);

  // BEGIN_SUB_TUTORIAL computeCollisionContactPoints
  //
  // Collision Requests
  // ^^^^^^^^^^^^^^^^^^
  // We will create a collision request for the Panda robot
  collision_detection::CollisionRequest c_req;
  collision_detection::CollisionResult c_res;
  c_req.group_name = robot.getGroupName();
  c_req.contacts = true;
  c_req.max_contacts = 100;
  c_req.max_contacts_per_pair = 5;
  c_req.verbose = false;

  // Checking for Collisions
  // ^^^^^^^^^^^^^^^^^^^^^^^
  // We check for collisions between robot and itself or the world.
  g_planning_scene->checkCollision(c_req, c_res, *robot.robotState());

  // Displaying Collision Contact Points
  // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  // If there are collisions, we get the contact points and display them as markers.
  // **getCollisionMarkersFromContacts()** is a helper function that adds the
  // collision contact points into a MarkerArray message. If you want to use
  // the contact points for something other than displaying them you can
  // iterate through **c_res.contacts** which is a std::map of contact points.
  // Look at the implementation of getCollisionMarkersFromContacts() in
  // `collision_tools.cpp
  // <https://github.com/moveit/moveit/blob/noetic-devel/moveit_core/collision_detection/src/collision_tools.cpp>`_
  // for how.
  if (c_res.collision)
  {
    ROS_INFO("COLLIDING contact_point_count=%d", (int)c_res.contact_count);
    if (c_res.contact_count > 0)
    {
      std_msgs::ColorRGBA color;
      color.r = 1.0;
      color.g = 0.0;
      color.b = 1.0;
      color.a = 0.5;
      visualization_msgs::MarkerArray markers;

      /* Get the contact points and display them as markers */
      collision_detection::getCollisionMarkersFromContacts(markers, "panda_link0", c_res.contacts, color,
                                                           ros::Duration(),  // remain until deleted
                                                           0.01);            // radius
      publishMarkers(markers);
    }
  }
  // END_SUB_TUTORIAL
  else
  {
    ROS_INFO("Not colliding");

    // delete the old collision point markers
    visualization_msgs::MarkerArray empty_marker_array;
    publishMarkers(empty_marker_array);
  }
}

int main(int argc, char** argv)
{
  ros::init(argc, argv, "visualizing_collisions_tutorial");
  ros::NodeHandle nh;

  // BEGIN_TUTORIAL
  //
  // Initializing the Planning Scene and Markers
  // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  // For this tutorial we use an :codedir:`InteractiveRobot <interactivity/src/interactive_robot.cpp>`
  // object as a wrapper that combines a robot_model with the cube and an interactive marker. We also
  // create a PlanningScene for collision checking. If you haven't already gone through the
  // :doc:`planning scene tutorial </doc/examples/planning_scene/planning_scene_tutorial>`, you go through that first.
  InteractiveRobot robot;
  g_planning_scene = new planning_scene::PlanningScene(robot.robotModel());

  // Adding geometry to the PlanningScene
  Eigen::Isometry3d world_cube_pose;
  double world_cube_size;
  robot.getWorldGeometry(world_cube_pose, world_cube_size);
  g_world_cube_shape.reset(new shapes::Box(world_cube_size, world_cube_size, world_cube_size));
  g_planning_scene->getWorldNonConst()->addToObject("world_cube", g_world_cube_shape, world_cube_pose);

  // CALL_SUB_TUTORIAL computeCollisionContactPoints
  // END_TUTORIAL

  // Create a marker array publisher for publishing contact points
  g_marker_array_publisher =
      new ros::Publisher(nh.advertise<visualization_msgs::MarkerArray>("interactive_robot_marray", 100));

  robot.setUserCallback(computeCollisionContactPoints);

  help();

  ros::spin();

  delete g_planning_scene;
  delete g_marker_array_publisher;

  ros::shutdown();
  return 0;
}

启动文件

完整的启动文件在 GitHub 上：此处。本教程中的所有代码都可以从 moveit_tutorials 包编译并运行。