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Hello,

I'm currently working on a differential drive robot with ROS2 and encountering some errors with a rclcpp transform broadcaster. I hope i can get some answers as to what I am doing wrong. I'm using ROS2 dashing on ubuntu 18.04.

code:

#include <memory>
#include "rclcpp/rclcpp.hpp"
#include <tf2_ros/transform_broadcaster.h>
#include "nav_msgs/msg/odometry.hpp"
#include <geometry_msgs/msg/transform_stamped.h>
#include <tf2/LinearMath/Quaternion.h>

std::shared_ptr<rclcpp::Node> node = nullptr;

void topic_callback(const nav_msgs::msg::Odometry::SharedPtr msg){
       static tf2_ros::TransformBroadcaster br;
       geometry_msgs::msg::TransformStamped transformStamped; 
       transformStamped.header.stamp = rclcpp::Time();
       transformStamped.header.frame_id = "odom";
       transformStamped.child_frame_id = "base_link";
       transformStamped.transform.translation.x = msg->pose.pose.position.x;
       transformStamped.transform.translation.y = msg->pose.pose.position.y;
       transformStamped.transform.translation.z = 0.0;
       transformStamped.transform.rotation.x = 0.0;
       transformStamped.transform.rotation.y = 0.0;
       transformStamped.transform.rotation.z = msg->pose.pose.orientation.z;
       transformStamped.transform.rotation.w = msg->pose.pose.orientation.w;
           broadcaster.sendTransform(transformStamped);
        }
    
    int main(int argc, char * argv[])
    {
      rclcpp::init(argc, argv);
    
      auto node = std::make_shared<rclcpp::Node>("tf_broadcaster");
      auto subscriber = node->create_subscription<nav_msgs::msg::Odometry>("odom",10, &topic_callback); 
      rclcpp::spin(node);
      rclcpp::shutdown();
      return 0;
    }

error message:

/home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp: In function ‘void topic_callback(nav_msgs::msg::Odometry_<std::allocator<void> >::SharedPtr)’:
/home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp:12:45: error: no matching function for call to ‘tf2_ros::TransformBroadcaster::TransformBroadcaster()’
        static tf2_ros::TransformBroadcaster br;
                                             ^~
In file included from /home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp:4:0:
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:53:3: note: candidate: template<class NodeT, class AllocatorT> tf2_ros::TransformBroadcaster::TransformBroadcaster(NodeT&&, const rclcpp::QoS&, const rclcpp::PublisherOptionsWithAllocator<AllocatorT>&)
   TransformBroadcaster(
   ^~~~~~~~~~~~~~~~~~~~
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:53:3: note:   template argument deduction/substitution failed:
/home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp:12:45: note:   candidate expects 3 arguments, 0 provided
        static tf2_ros::TransformBroadcaster br;
                                             ^~
In file included from /home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp:4:0:
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:49:7: note: candidate: tf2_ros::TransformBroadcaster::TransformBroadcaster(const tf2_ros::TransformBroadcaster&)
 class TransformBroadcaster{
       ^~~~~~~~~~~~~~~~~~~~
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:49:7: note:   candidate expects 1 argument, 0 provided
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:49:7: note: candidate: tf2_ros::TransformBroadcaster::TransformBroadcaster(tf2_ros::TransformBroadcaster&&)
/opt/ros/eloquent/include/tf2_ros/transform_broadcaster.h:49:7: note:   candidate expects 1 argument, 0 provided
/home/frederik/ros2botpc/src/tfbroadcast/src/tfbroadcast.cpp:24:8: error: ‘broadcaster’ was not declared in this scope
        broadcaster.sendTransform(transformStamped);

Originally posted by Loekes on ROS Answers with karma: 23 on 2020-08-28

Post score: 1

Original comments

Comment by surfertas on 2020-09-06:
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2 Answers 2

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  1. Assuming that you have split declarations into a header file and definitions in the source file.

  2. You can declare the broadcaster in the header file.

     private:
    std::shared_ptr<tf2_ros::TransformBroadcaster> tf_broadcaster_;

  3. Then initialize somewhere in the constructor of the source file.

     tf_broadcaster_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);

  4. Finally, you can send a stamped transform message as so:

     tf_broadcaster_->sendTransform(transform_stamped);

A good place to check for implementations/best-practices is by reviewing the tests implemented by the maintainers of the respective package in particular when working with ROS 2 as documentation is trying to keep up. In this case review the geometry2 package, specifically test_transform_broadcaster.cpp. Finally, change the branch that you are viewing to the ROS 2 distro that you are using. (e.g. dashing in this case)

Originally posted by surfertas with karma: 265 on 2020-08-29

This answer was ACCEPTED on the original site

Post score: 3

Original comments

Comment by Loekes on 2020-09-06:
Yes this is resolved! Thanks a lot for your answer, it helped me greatly! :)

Comment by surfertas on 2020-09-07:
No problem. Please mark the answers as correct in that case.

Comment by Sourabh Misal on 2020-12-10:
@Loekes could you put the corrected code snippet of tf2? I am stuck in the implementation of tf2 in ROS2 Dashing

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My final code snippet, hope it helps!

  #include <memory>
        #include <chrono>
        #include "rclcpp/rclcpp.hpp"
        #include <tf2_ros/transform_broadcaster.h>
        #include "nav_msgs/msg/odometry.hpp"
        #include "sensor_msgs/msg/laser_scan.hpp"
        #include <geometry_msgs/msg/transform_stamped.h>
        #include <tf2/LinearMath/Quaternion.h>
        #include <tf2_ros/static_transform_broadcaster.h>
        #include "tf2_ros/buffer.h"
        #include <string.h>
        using std::placeholders::_1;
        using namespace std;
    
    class TFbroadcast : public rclcpp::Node
    {
      public:
        TFbroadcast()
        : Node("tf_broadcaster")
        {
          subscription_ = this->create_subscription<nav_msgs::msg::Odometry>(
          "odom", 20, std::bind(&TFbroadcast::topic_callback, this, _1));
          subscription2_ = this->create_subscription<sensor_msgs::msg::LaserScan>("rawscan", rclcpp::SensorDataQoS(), std::bind(&TFbroadcast::scanCallback, this, _1));
          publisher_ = this->create_publisher<sensor_msgs::msg::LaserScan>("scan", rclcpp::SensorDataQoS());
          
          tf_broadcaster_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);
        }
      private:
        rclcpp::Time now;
        void topic_callback(const nav_msgs::msg::Odometry::SharedPtr msg)
        {
           geometry_msgs::msg::TransformStamped transformStamped;
           now = rclcpp::Node::now();
           transformStamped.header.stamp = now;
           transformStamped.header.frame_id = "odom";
           transformStamped.child_frame_id = "base_link";
           transformStamped.transform.translation.x = msg->pose.pose.position.x;
           transformStamped.transform.translation.y = msg->pose.pose.position.y;
           transformStamped.transform.translation.z = 0.0;
           transformStamped.transform.rotation.x = 0.0;
           transformStamped.transform.rotation.y = 0.0;
           transformStamped.transform.rotation.z = msg->pose.pose.orientation.z;
           transformStamped.transform.rotation.w = msg->pose.pose.orientation.w; 
           tf_broadcaster_->sendTransform(transformStamped);
        }
        void scanCallback(const sensor_msgs::msg::LaserScan::SharedPtr msg)
        {
           sensor_msgs::msg::LaserScan laser;
           laser.header.frame_id = "laser_frame";
           laser.header.stamp = now;
           laser.angle_min = msg->angle_min;
           laser.angle_max = msg->angle_max;
           laser.angle_increment = msg->angle_increment;
           laser.scan_time = msg->scan_time;
           laser.time_increment = msg->time_increment;
           laser.range_min = msg->range_min;
           laser.range_max = msg->range_max;
           laser.ranges = msg->ranges;
           publisher_->publish(laser);
           laser.intensities = msg->intensities ;
        }
           rclcpp::Subscription<nav_msgs::msg::Odometry>::SharedPtr subscription_;
           rclcpp::Subscription<sensor_msgs::msg::LaserScan>::SharedPtr subscription2_;
           rclcpp::Publisher<sensor_msgs::msg::LaserScan>::SharedPtr publisher_;
           std::shared_ptr<tf2_ros::TransformBroadcaster> tf_broadcaster_;
    };
    int main(int argc, char * argv[])
    {
      rclcpp::init(argc, argv);
      rclcpp::spin(std::make_shared<TFbroadcast>());
      rclcpp::shutdown();
      return 0;
    }

Originally posted by Loekes with karma: 23 on 2020-12-10

This answer was NOT ACCEPTED on the original site

Post score: 1

Original comments

Comment by Sourabh Misal on 2020-12-11:
Thanks a lot, I understood your code and got it working

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