拾取和放置
注意：本教程中使用的功能已弃用。要执行拾取和放置操作，应使用 MoveIt 任务构造器 (MTC)（使用 MoveIt 任务构造器拾取和放置）。
在 MoveIt 中，抓取是使用 MoveGroup 接口完成的。为了抓取一个物体，我们需要创建moveit_msgs::Graspmsg，以便定义抓取操作中涉及的各种姿势和姿态。观看此视频以查看本教程的输出：
https://youtu.be/QBJPxx_63Bs
入门
如果您还没有这样做，请确保您已经完成入门指南中的步骤。
运行演示
打开两个终端。在第一个终端中启动 RViz 并等待所有内容完成加载：
roslaunch panda_moveit_config demo.launch
在第二个终端中运行拾取和放置教程：
rosrun moveit_tutorials pick_place_tutorial
您应该会看到与本教程开头的视频类似的内容。
理解moveit_msgs::Grasp
有关完整文档，请参阅moveit_msgs/Grasp.msg。
该消息的相关字段是：-
-
trajectory_msgs/JointTrajectory pre_grasp_posture- 这定义了我们进行抓取之前末端执行器组中关节的轨迹位置。 -
trajectory_msgs/JointTrajectory grasp_posture- 定义了末端执行器组中关节抓取物体的轨迹位置。 -
geometry_msgs/PoseStamped grasp_pose- 末端执行器应尝试抓取的姿势。 -
moveit_msgs/GripperTranslation pre_grasp_approach- 这用于定义接近物体的方向和行进的距离。 -
moveit_msgs/GripperTranslation post_grasp_retreat- 这用于定义抓住物体后移动的方向和行进的距离。 -
moveit_msgs/GripperTranslation post_place_retreat- 这用于定义物体放置在某个位置后移动的方向和行进的距离。
完整代码
整个代码可以在moveit_tutorials GitHub 项目中看到。
创建环境
创建向量来容纳 3 个碰撞对象。
std::vector<moveit_msgs::CollisionObject> collision_objects; collision_objects.resize(3);
添加最初保存多维数据集的第一个表。
collision_objects[0].id = "table1"; collision_objects[0].header.frame_id = "panda_link0";/* Define the primitive and its dimensions. */ collision_objects[0].primitives.resize(1); collision_objects[0].primitives[0].type = collision_objects[0].primitives[0].BOX; collision_objects[0].primitives[0].dimensions.resize(3); collision_objects[0].primitives[0].dimensions[0] = 0.2; collision_objects[0].primitives[0].dimensions[1] = 0.4; collision_objects[0].primitives[0].dimensions[2] = 0.4;/* Define the pose of the table. */ collision_objects[0].primitive_poses.resize(1); collision_objects[0].primitive_poses[0].position.x = 0.5; collision_objects[0].primitive_poses[0].position.y = 0; collision_objects[0].primitive_poses[0].position.z = 0.2; collision_objects[0].primitive_poses[0].orientation.w = 1.0;
添加第二张表，我们将在其中放置立方体。
collision_objects[1].id = "table2"; collision_objects[1].header.frame_id = "panda_link0";/* Define the primitive and its dimensions. */ collision_objects[1].primitives.resize(1); collision_objects[1].primitives[0].type = collision_objects[1].primitives[0].BOX; collision_objects[1].primitives[0].dimensions.resize(3); collision_objects[1].primitives[0].dimensions[0] = 0.4; collision_objects[1].primitives[0].dimensions[1] = 0.2; collision_objects[1].primitives[0].dimensions[2] = 0.4;/* Define the pose of the table. */ collision_objects[1].primitive_poses.resize(1); collision_objects[1].primitive_poses[0].position.x = 0; collision_objects[1].primitive_poses[0].position.y = 0.5; collision_objects[1].primitive_poses[0].position.z = 0.2; collision_objects[1].primitive_poses[0].orientation.w = 1.0;
定义我们将要操作的对象
collision_objects[2].header.frame_id = "panda_link0"; collision_objects[2].id = "object";/* Define the primitive and its dimensions. */ collision_objects[2].primitives.resize(1); collision_objects[2].primitives[0].type = collision_objects[1].primitives[0].BOX; collision_objects[2].primitives[0].dimensions.resize(3); collision_objects[2].primitives[0].dimensions[0] = 0.02; collision_objects[2].primitives[0].dimensions[1] = 0.02; collision_objects[2].primitives[0].dimensions[2] = 0.2;/* Define the pose of the object. */ collision_objects[2].primitive_poses.resize(1); collision_objects[2].primitive_poses[0].position.x = 0.5; collision_objects[2].primitive_poses[0].position.y = 0; collision_objects[2].primitive_poses[0].position.z = 0.5; collision_objects[2].primitive_poses[0].orientation.w = 1.0;
选择管道
创建要尝试的抓握向量，目前仅创建单个抓握。这在使用抓握生成器生成和测试多个抓握时非常有用。
std::vector<moveit_msgs::Grasp> grasps; grasps.resize(1);
设置抓握姿势
这是 panda_link8 的姿势。
确保在设置 grasp_pose 时，将其设置为操纵器中最后一个链接的姿势，在本例中为panda_link8。您必须补偿从panda_link8到末端执行器手掌的变换。
grasps[0].grasp_pose.header.frame_id = "panda_link0"; tf2::Quaternion orientation; orientation.setRPY(-M_PI / 2, -M_PI / 4, -M_PI / 2); grasps[0].grasp_pose.pose.orientation = tf2::toMsg(orientation); grasps[0].grasp_pose.pose.position.x = 0.415; grasps[0].grasp_pose.pose.position.y = 0; grasps[0].grasp_pose.pose.position.z = 0.5;
设置预抓取方法
/* Defined with respect to frame_id */ grasps[0].pre_grasp_approach.direction.header.frame_id = "panda_link0"; /* Direction is set as positive x axis */ grasps[0].pre_grasp_approach.direction.vector.x = 1.0; grasps[0].pre_grasp_approach.min_distance = 0.095; grasps[0].pre_grasp_approach.desired_distance = 0.115;
设置抓捕后撤退
/* Defined with respect to frame_id */ grasps[0].post_grasp_retreat.direction.header.frame_id = "panda_link0"; /* Direction is set as positive z axis */ grasps[0].post_grasp_retreat.direction.vector.z = 1.0; grasps[0].post_grasp_retreat.min_distance = 0.1; grasps[0].post_grasp_retreat.desired_distance = 0.25;
抓握前设置 eef 姿势
openGripper(grasps[0].pre_grasp_posture);
openGripper 函数
/* Add both finger joints of panda robot. */ posture.joint_names.resize(2); posture.joint_names[0] = "panda_finger_joint1"; posture.joint_names[1] = "panda_finger_joint2";/* Set them as open, wide enough for the object to fit. */ posture.points.resize(1); posture.points[0].positions.resize(2); posture.points[0].positions[0] = 0.04; posture.points[0].positions[1] = 0.04; posture.points[0].time_from_start = ros::Duration(0.5);
抓握时 eef 的姿势设定
closedGripper(grasps[0].grasp_posture);
closedGripper 功能
/* Add both finger joints of panda robot. */ posture.joint_names.resize(2); posture.joint_names[0] = "panda_finger_joint1"; posture.joint_names[1] = "panda_finger_joint2";/* Set them as closed. */ posture.points.resize(1); posture.points[0].positions.resize(2); posture.points[0].positions[0] = 0.00; posture.points[0].positions[1] = 0.00; posture.points[0].time_from_start = ros::Duration(0.5);
设置支撑面为表1。
move_group.setSupportSurfaceName("table1");
调用 pick 来使用给定的抓握方式拾取物体
move_group.pick("object", grasps);
放置管道
TODO(@ridhwanluthra) - 调用 place 函数可能会导致“所有提供的 place 位置都失败。正在以详细模式重试最后一个位置。”这是一个已知问题。
理想情况下，您会创建一个要尝试的 place 位置向量，尽管在此示例中，我们仅创建了一个 place 位置。
std::vector<moveit_msgs::PlaceLocation> place_location; place_location.resize(1);
设定地点 位置 姿势
place_location[0].place_pose.header.frame_id = "panda_link0"; tf2::Quaternion orientation; orientation.setRPY(0, 0, M_PI / 2); place_location[0].place_pose.pose.orientation = tf2::toMsg(orientation);/* For place location, we set the value to the exact location of the center of the object. */ place_location[0].place_pose.pose.position.x = 0; place_location[0].place_pose.pose.position.y = 0.5; place_location[0].place_pose.pose.position.z = 0.5;
设置预定位方法
/* Defined with respect to frame_id */ place_location[0].pre_place_approach.direction.header.frame_id = "panda_link0"; /* Direction is set as negative z axis */ place_location[0].pre_place_approach.direction.vector.z = -1.0; place_location[0].pre_place_approach.min_distance = 0.095; place_location[0].pre_place_approach.desired_distance = 0.115;
设置放置后撤退
/* Defined with respect to frame_id */ place_location[0].post_place_retreat.direction.header.frame_id = "panda_link0"; /* Direction is set as negative y axis */ place_location[0].post_place_retreat.direction.vector.y = -1.0; place_location[0].post_place_retreat.min_distance = 0.1; place_location[0].post_place_retreat.desired_distance = 0.25;
放置物体后设置eef的姿势
/* Similar to the pick case */ openGripper(place_location[0].post_place_posture);
设置支撑面如Table2。
group.setSupportSurfaceName("table2");
调用 place 来使用给定的位置放置物体。
group.place("object", place_location);
