KenYN's profile - activity

A number of functions expect a rclcpp::Node::SharedPtr, but when you are in an rclcpp::Node subclass it is not available, and of course something like foo(rclcpp::Node::SharedPtr(this)); is a great way to crash your program. Is there some registry of these SharedPtrs to query?

In ROS 1 my node has code like this in a subscribed message callback:

ros::Time now = ros::Time::now();
ros::Duration frameSkip = ros::Duration(m_frameSyncMs/1000.0);

// Proceed if time interval has elapsed or if clock has gone backwards
if (m_previousTimeStamp + frameSkip > now)
// etc...

Basically, when m_frameSyncMs is 100 ms with the topic being a camera feed at 30 fps, just pick out every third frame or so. This works quite happily.

Now, for ROS 2 there no longer is a Time::now(), and looking at various web pages there might be a node clock, or there might be an rcl_get_time_point_now() but shouldn't that also take the result of rcl_get_default_ros_time()?

What is the best way to do this? Furthermore, where is the best place to learn about the latest ROS 2 developments; GitHub and Discord, for instance seem a bit too light on information, and reading the source might work, but the next beta may very well invalidate everything. Finally is there a ros2bag or equivalent for recording and playing back runs?

message_filters::Synchronizer<>::registerCallback and lambdas syntax I can do: sync.registerCallback(std::bind(&a

message_filters::Synchronizer<>::registerCallback and lambdas syntax I can do: sync.registerCallback(std::bind(&a

message_filters::Synchronizer<>::registerCallback and lambdas syntax I can do: sync.registerCallback(std::bind(&a

On Noetic, I can do the following:

$ run tf2_ros static_transform_publisher 1 1 1 0 0 0 f1 f2 &
[2] 1753768
[ INFO] [1639635211.900468919]: Spinning until killed publishing f1 to f2
$ rostopic echo /tf_static 
transforms: 
  - 
    header: 
      seq: 0
      stamp: 
        secs: 1639635211
        nsecs: 900398326
      frame_id: "f1"
    child_frame_id: "f2"
    transform: 
      translation: 
        x: 1.0
        y: 1.0
        z: 1.0
      rotation: 
        x: 0.0
        y: 0.0
        z: 0.0
        w: 1.0

This is exactly what I expect to happen since the static publisher is latched.

However, on Galactic using CycloneDDS:

$ ros2 run tf2_ros static_transform_publisher --x 1 --y 1 --z 1 --frame-id f1 --child-frame-id f2 &
[1] 213102
1639635686.858624 [0] static_tra: selected interface "lo" is not multicast-capable: disabling multicast
[INFO] [1639635686.868694587] [static_transform_publisher_GjMa6BC7irM5FXBs]: Spinning until stopped - publishing transform
translation: ('1.000000', '1.000000', '1.000000')
rotation: ('0.000000', '0.000000', '0.000000', '1.000000')
from 'f1' to 'f2'
$ ros2 topic echo /tf_static 
1639635697.443620 [0]       ros2: selected interface "lo" is not multicast-capable: disabling multicast

No output is produced, but ros2 topic keeps waiting. I'm using loopback as our routers don't like multicast, but since it can find the topic /tf_static shouldn't it also be able to find the message since it uses the durability policy transient local? Or am I misunderstanding something?

I also found this GitHub bug report that suggests:

ros2 topic echo --qos-durability transient_local /tf_static

However, that fails in the same way as above for me.

I had tried: ros2 topic echo --qos-durability transient_local /tf_static But GitHub told me that I also need --qos-re

I had tried: ros2 topic echo --qos-durability transient_local /tf_static But GitHub told me that I also need --qos-re