action

• ros2 action list -t

• ros2 action info /compute_path_to_pose

Action: /compute_path_to_pose
Action clients: 0
Action servers: 1
    /planner_server

• ros2 action type /compute_path_to_pose
  结果是 nav2_msgs/action/ComputePathToPose

• ros2 interface show nav2_msgs/action/ComputePathToPose

结果是 action 文件的详细信息

• ros2 action send_goal

nvidia@ubuntu:~$ ros2 interface show turtlesim/action/RotateAbsolute.action

# The desired heading in radians
float32 theta
---
# The angular displacement in radians to the starting position
float32 delta
---
# The remaining rotation in radians
float32 remaining

这三项依次是目标，结果，反馈

• 发送操作目标: ros2 action send_goal <action_name> <action_type> <values>

比如 ros2 action send_goal /turtle1/rotate_absolute turtlesim/action/RotateAbsolute "{theta: 1.57}"

nvidia@ubuntu:~$ ros2 action send_goal /turtle1/rotate_absolute turtlesim/action/RotateAbsolute "{theta: 1.57}"
Waiting for an action server to become available...
Sending goal:
theta: 1.57
Goal accepted with ID: 5cd8eb561348477abbb532fc816ce792

Result:
delta: 1.5680029392242432

Goal finished with status: SUCCEEDED

当然结果与目标有一定误差

要查看此目标的反馈，请在上次运行的命令中添加 --feedback，会看到连续的打印输出，将继续收到反馈，直到目标完成。

interface

• ros2 interface list

分类显示消息、动作、服务的所有类型

• ros2 interface package pkg_name

user@robot:~$ ros2 interface package action_msgs
action_msgs/srv/CancelGoal
action_msgs/msg/GoalInfo
action_msgs/msg/GoalStatus
action_msgs/msg/GoalStatusArray

获知某个消息类型是谁在用，可以这样查

user@robot:~$ ros2 interface packages | grep pendulum_msgs
pendulum_msgs
user@robot:~$ ros2 interface package pendulum_msgs
pendulum_msgs/msg/RttestResults
pendulum_msgs/msg/JointState
pendulum_msgs/msg/JointCommand

user@robot:~$ ros2 topic find pendulum_msgs/msg/RttestResults

• 显示消息的成员

user@robot:~$ ros2 interface proto std_msgs/msg/String
"data: ''"

service

• ros2 service type

可以看到服务的定义。

• ros2 service find

找出指定类型的所有服务

• ros2 service find std_srvs/srv/Empty

• ros2 interface show

显示服务的定义

• call命令比ROS1复杂了，需要指明service类型: ros2 service call service_name service_type