Styjun

I'm writing a package that, among other things, needs to get a transformation from the /base_laser frame to the (world) /odom frame. Both frames exist, and rosrun tf tf_echo /odom /base_laser returns the correct transformation values. The problem appears when I try to get the transformation using a TransformListener in my node; in this case, canTransform() always returns false.

The code is part of a test using the husky_simulator package to get the laser measurements and the environment.

This is the relevant part of the code:

tf2_ros::Buffer tfBuffer;
tf2_ros::TransformListener tfListener(tfBuffer);

geometry_msgs::TransformStamped transformStamped;

try

 ros::Time now = ros::Time::now();
 if (tfBuffer.canTransform("odom",
 "base_laser",
 now,
 ros::Duration(0.01)))
 
 transformStamped = tfBuffer.lookupTransform("odom",
 "base_laser",
 now);
 ROS_INFO("canTransform: TRUE");
 ROS_INFO("Transform: [%.2f, %.2f, %.2f]",
 transformStamped.transform.translation.x,
 transformStamped.transform.translation.y,
 transformStamped.transform.translation.z);
 
 else
 
 ROS_INFO("canTransform: FALSE");
 

catch (tf2::TransformException &ex)

 ROS_WARN("%s", ex.what());
 ros::Duration(1);

When launching the node, the output shows the following:

[ INFO] [1553804232.701323614, 0.176000000]: canTransform: FALSE
[ INFO] [1553804232.736923460, 0.207000000]: canTransform: FALSE
[ INFO] [1553804232.813116964, 0.275000000]: canTransform: FALSE 
[ INFO] [1553804232.856465945, 0.311000000]: canTransform: FALSE
[ INFO] [1553804232.923821528, 0.365000000]: canTransform: FALSE
[ INFO] [1553804233.977405692, 0.397000000]: canTransform: FALSE

and keeps this way, without returning a true.

This code is inside a function that is called periodically from the node main function. Everything else works as expected.

Running ROS Melodic in Ubuntu 18.04

Any help is welcome.

I finally found what was going on: the husky_simulator code uses tf while I was trying to get the transforms using tf2; once I switched to tf, the transform was found.