ROS2与Interbotix系列机械臂教程-手眼标定

文章说明

本教程主要如何进行手眼协作中相机和臂的设置与具体操作流程
测试环境：Ubuntu 22.04 + ROS2 Humble +　wx250s机械臂 + RealSense D435i相机

环境设置

首先要搭建支架，并将RealSense摄像头固定在相机支架或三脚架顶部的 1/4 英寸螺钉上
然后将支架放在工作区域，调整摄像头位置，使摄像头指向桌面
接下来，在桌面且在摄像头的视野范围内上放置一些小的、不反光的物件，并且确保机械臂能够正常抓取
物件应该足够小，以便无论夹具从任何方向都能正常抓取起来
但它们不能太反光，因为这会干扰深度摄像头通过使用红外光定位它们的能力
同样，工作区域不应受到阳光直射，因为这也会干扰摄像头的深度感应能力
工作区域示例图：

请输入图片描述

准备一个apriltag标签，贴在机械臂上，如上图位置所示
apriltag标签保存存放在interbotix_ros_toolboxes/interbotix_perception_toolbox/interbotix_perception_modules/images/tags目录下，打印tag41_12_00005_printoff.pdf出来后再剪一个贴在机械臂上面

获取相机位姿

在测试例程前，相机必须知道臂相对于自身的位置
一种方法是手动测量从相机到机器人base_link的TF位差，并将其发布为静态变换，但此方法麻烦且有可能测出不准确的数据
相反，使用apriltag_ros的方法来查找夹具上的 AprilTag视觉基准标记相对于相机的TF变换。之后，计算从相机TF到机械臂上的变换base_link并将其发布为静态变换
假设正在现实中使用WidowX-250s机械臂，获取静态变换运行该命令

$ ros2 launch interbotix_xsarm_perception xsarm_perception.launch.py robot_model:=wx250s use_pointcloud_tuner_gui:=true use_armtag_tuner_gui:=true

RViz 应会与两个独立的 GUI 一起弹出，其中一个 GUI 将如下图所示

请输入图片描述

初始设置相机可能不能检测到AprilTag，可通过禁用扭矩方式，手动移动机械臂以便机械臂检测到AprilTag

$ ros2 service call /wx250s/torque_enable interbotix_xs_msgs/srv/TorqueEnable "{cmd_type: 'group', name: 'arm', enable: false}"

手动移动机械臂，使 AprilTag 在摄像头中清晰可见（RViz 显示屏左下方的实时视频流应该会对此有所帮助）
然后在与之前相同的终端中，按如下方式将机械臂放回原位

$ ros2 service call /wx250s/torque_enable interbotix_xs_msgs/srv/TorqueEnable "{cmd_type: 'group', name: 'arm', enable: true}"

现在，在 Armtag Tuner GUI 中，单击Snap Pose按钮
此时可以随意设置应拍摄的快照数量，确认之后将从快照计算出的位姿取平均值，以得出机械臂相对于相机的更准确位姿
检查计算姿势准确性的一种方法是切换 RViz 中的 RawPointCloud 显示
预期 AprilTag 的位置应该位于机器人模型的AR标签链接上（可能在下面几毫米）
如果不是，请继续按Snap Pose按钮，直到看起来正确为止
终端信息会显示，'static_transforms.yaml' 的文件会自动保存到系统目录中

设置目标抓取框

请输入图片描述

调整xyx，设置相机画面过滤框
默认情况下，需要抓取的物体应该在框内，比如要将物件放入前方的盒子，那么过滤框中就不应出现都到该盒子
程序只会识别框中的物件
设置完成后，点击Load Configs按钮保存配置
接下来可以进行抓取测试
更多设置信息可参阅此处
其他用于进一步定制的启动文件参数，如下所示

Argument	Description	Default	Choices
robot_model	One of: (‘px100’, ‘px150’, ‘rx150’, ‘rx200’, ‘wx200’, ‘wx250’, ‘wx250s’, ‘vx250’, ‘vx300’, ‘vx300s’, ‘mobile_px100’, ‘mobile_wx200’, ‘mobile_wx250s’)
robot_name	name of the robot (typically equal to `robot_model`, but could be anything)	LaunchConfig(`robot_model`)
base_link_frame	name of the ‘root’ link on the arm; typically `base_link`, but can be changed if attaching the arm to a mobile base that already has a `base_link` frame.	`base_link`
use_gripper	if `true`, the default gripper is included in the `robot_description` parameter; if `false`, it is left out; set to `false` if not using the default gripper.	`true`	`true`, `false`
show_ar_tag	if `true`, the AR tag mount is included in the `robot_description` parameter; if `false`, it is left out; set to `true` if using the AR tag mount in your project.	`true`	`true`, `false`
show_gripper_bar	if `true`, the gripper_bar link is included in the `robot_description` parameter; if `false`, the gripper_bar and finger links are not loaded. Set to `false` if you have a custom gripper attachment.	`true`	`true`, `false`
show_gripper_fingers	if true, the gripper fingers are included in the `robot_description` parameter; if `false`, the gripper finger links are not loaded. Set to `false` if you have custom gripper fingers.	`true`	`true`, `false`
use_world_frame	set this to `true` if you would like to load a ‘world’ frame to the `robot_description` parameter which is located exactly at the ‘base_link’ frame of the robot; if using multiple robots or if you would like to attach the ‘base_link’ frame of the robot to a different frame, set this to `false`.	`false`	`true`, `false`
external_urdf_loc	the file path to the custom urdf.xacro file that you would like to include in the Interbotix robot’s urdf.xacro file.	‘’
hardware_type	configures the `robot_description` parameter to use the actual hardware, fake hardware, or hardware simulated in Gazebo.	`actual`	`actual`, `fake`, `gz_classic`
robot_description	URDF of the robot; this is typically generated by the xacro command.	Command(FindExec(`xacro`) + ‘ ‘ + LocalVar(‘FindPackageShare(pkg= `interbotix_xsarm_descriptions`) + ‘urdf’ + LaunchConfig(`robot_model`)’) + ‘.urdf.xacro ‘ + ‘robot_name:=’ + LaunchConfig(`robot_name`) + ‘ ‘ + ‘base_link_frame:=’ + LaunchConfig(`base_link_frame`) + ‘ ‘ + ‘use_gripper:=’ + LaunchConfig(`use_gripper`) + ‘ ‘ + ‘show_ar_tag:=’ + LaunchConfig(`show_ar_tag`) + ‘ ‘ + ‘show_gripper_bar:=’ + LaunchConfig(`show_gripper_bar`) + ‘ ‘ + ‘show_gripper_fingers:=’ + LaunchConfig(`show_gripper_fingers`) + ‘ ‘ + ‘use_world_frame:=’ + LaunchConfig(`use_world_frame`) + ‘ ‘ + ‘external_urdf_loc:=’ + LaunchConfig(`external_urdf_loc`) + ‘ ‘ + ‘hardware_type:=’ + LaunchConfig(`hardware_type`) + ‘ ‘)
load_configs	a boolean that specifies whether or not the initial register values (under the ‘motors’ heading) in a Motor Config file should be written to the motors; as the values being written are stored in each motor’s EEPROM (which means the values are retained even after a power cycle), this can be set to false after the first time using the robot. Setting to false also shortens the node startup time by a few seconds and preserves the life of the EEPROM	`true`	`true`, `false`
rs_camera_pointcloud_enable	enables the RealSense camera’s pointcloud.	`true`	`true`, `false`
rbg_camera_profile	profile for the rbg camera image stream, in `<width>x<height>x<fps>`	`640x480x30`
depth_module_profile	profile for the depth module stream, in `<width>x<height>x<fps>`	`640x480x30`
rs_camera_logging_level	set the logging level for the realsense2_camera launch include	`info`	`debug`, `info`, `warn`, `error`, `fatal`
rs_camera_output_location	set the logging location for the realsense2_camera launch include	`screen`	`screen`, `log`
rs_camera_initial_reset	On occasions the RealSense camera is not closed properly and due to firmware issues needs to reset. If set to `true`, the device will reset prior to usage.	`false`	`true`, `false`
filter_ns	namespace where the pointcloud related nodes and parameters are located	`pc_filter`
filter_params	file location of the parameters used to tune the perception pipeline filters	LocalVar(‘FindPackageShare(pkg= `interbotix_xsarm_perception`) + ‘config’ + ‘filter_params.yaml’’)
use_pointcloud_tuner_gui	whether to show a GUI that a user can use to tune filter parameters	`false`	`true`, `false`
enable_pipeline	whether to enable the perception pipeline filters to run continuously; to save computer processing power, this should be set to `false` unless you are actively trying to tune the filter parameters; if `false`, the pipeline will only run if the `get_cluster_positions` ROS service is called.	LaunchConfig(`use_pointcloud_tuner_gui`)	`true`, `false`
cloud_topic	the absolute ROS topic name to subscribe to raw pointcloud data	‘/camera/depth/color/points’
tags_config	parameter file location for the AprilTag configuration	LocalVar(‘FindPackageShare(pkg= `interbotix_perception_modules`) + ‘config’ + ‘tags.yaml’’)
camera_frame	the camera frame in which the AprilTag will be detected	`camera_color_optical_frame`
apriltag_ns	namespace where the AprilTag related nodes and parameters are located	`apriltag`
camera_color_topic	the absolute ROS topic name to subscribe to color images	‘camera/color/image_raw’
camera_info_topic	the absolute ROS topic name to subscribe to the camera color info	‘camera/color/camera_info’
armtag_ns	name-space where the Armtag related nodes and parameters are located	`armtag`
ref_frame	the reference frame that the armtag node should use when publishing a static transform for where the arm is relative to the camera	LaunchConfig(`camera_frame`)
arm_base_frame	the child frame that the armtag node should use when publishing a static transform for where the arm is relative to the camera	LaunchConfig(`robot_name`) + ‘/’ + LaunchConfig(`base_link_frame`)
arm_tag_frame	name of the frame on the arm where the AprilTag is located (typically defined in the URDF)	LaunchConfig(`robot_name`) + ‘/’ + ‘ar_tag_link’
use_armtag_tuner_gui	whether to show a GUI that a user can use to publish the `ref_frame` to `arm_base_frame` transform	`false`	`true`, `false`
position_only	whether only the position component of the detected AprilTag pose should be used when calculating the `ref_frame` to `arm_base_frame` transform; this should only be set to `true` if a TF chain already exists connecting the camera and arm base_link frame, and you just want to use the AprilTag to refine the pose further	`false`	`true`, `false`
load_transforms	whether or not the static_trans_pub node should publish any poses stored in the static_transforms.yaml file at startup; this should only be set to `false` if a TF chain already exists connecting the camera and arm base_link frame (typically defined in a URDF), and you would rather use that TF chain as opposed to the one specified in the static_transforms.yaml file	`true`	`true`, `false`
transform_filepath	filepath to the static_transforms.yaml file used by the static_trans_pub node; if the file does not exist yet, this is where you wouldd like the file to be generated	LocalVar(‘FindPackageShare(pkg= `interbotix_xsarm_perception`) + ‘config’ + ‘static_transforms.yaml’’)
use_rviz	launches RViz if set to `true`	`true`	`true`, `false`
rviz_frame	desired `fixed frame` in RViz	LaunchConfig(`robot_name`) + ‘/’ + LaunchConfig(`base_link_frame`)
rvizconfig	filepath to the RViz config file	LocalVar(‘FindPackageShare(pkg= `interbotix_xsarm_perception`) + ‘rviz’ + ‘xsarm_perception.rviz’’)

演示视频

获取最新文章: 扫一扫右上角的二维码加入“创客智造”公众号