广播模型
广播器
- 定义TF广播器（TransformBroadcaster）
- 创建坐标变换值
- 发布坐标变换（sendTransform）
CMakeList的find_package中增加tf
turtle_tf_broadcaster.cpp
// 订阅海龟话题，获取pose位置，之后创建tf广播其，广播world与海龟坐标系之间的tf数据#include <ros/ros.h>
#include <turtlesim/Pose.h> // 小海龟位置
#include <tf/transform_broadcaster.h> // 位置广播std::string turtle_name;void poseCallBack(const turtlesim::PoseConstPtr &msg)
{static tf::TransformBroadcaster br;tf::Transform transform;transform.setOrigin(tf::Vector3(msg->x, msg->y, 0.0));tf::Quaternion q;q.setRPY(0, 0, msg->theta);transform.setRotation(q);br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), "world", turtle_name));
}int main(int argc, char** argv)
{ros::init(argc, argv, "my_tf_broadcaster");if(argc != 2){ROS_ERROR("need turtle name as argument");return -1;}turtle_name = argv[1];ROS_INFO("turtle name is %s", turtle_name.c_str());// 构建订阅者，订阅海龟的/pose话题ros::NodeHandle n;ros::Subscriber subs = n.subscribe(turtle_name + "/pose", 10, &poseCallBack);// 循环等待回调函数ros::spin();return 0;
}
监听器
定义TF监听器（TransformListener）
查找坐标变换（waitForTransform、lookupTransform）
turtle_tf_listener.cpp
#include <ros/ros.h>
#include <geometry_msgs/Twist.h>
#include <turtlesim/Spawn.h>
#include <tf/transform_listener.h> // 位置广播int main(int argc, char** argv)
{ros::init(argc, argv, "my_tf_listener");ros::NodeHandle n;//等待服务端服务ros::service::waitForService("/spawn");// 创建客户端，连接服务为/spawn，数据类型为turtlesim::Spawnros::ServiceClient add_turtle = n.serviceClient<turtlesim::Spawn>("/spawn");// 调用服务，请求完成后生成小海龟turtlesim::Spawn srv;add_turtle.call(srv);// 构建发布者，发布话题 /turtle2/cmd_vel，话题类型为geometry_msgs::Twistros::Publisher turtle_vel = n.advertise<geometry_msgs::Twist>("/turtle2/cmd_vel", 10);// 构建监听者tf::TransformListener listener;ros::Rate rate(10.0);while (ros::ok){tf::StampedTransform transform;try{listener.waitForTransform("/turtle2", "/turtle1", ros::Time(0), ros::Duration(3.0));listener.lookupTransform("/turtle2", "/turtle1", ros::Time(0), transform);}catch(tf::TransformException &ex){ROS_ERROR("%s", ex.what());ros::Duration(1.0).sleep();continue;}geometry_msgs::Twist vel_msg;vel_msg.linear.x = 0.5 * sqrt(pow(transform.getOrigin().x(), 2) + pow(transform.getOrigin().y(), 2));vel_msg.angular.z = 4.0 * atan2(transform.getOrigin().y(), transform.getOrigin().x());turtle_vel.publish(vel_msg);rate.sleep();}return 0;
}
执行命令
roscore
rosrun turtlesim turtlesim_node
rosrun 功能包 turtle_tf_broadcaster节点名 __name:=turtle1_tf_broadcaster /turtle1
rosrun 功能包 turtle_tf_broadcaster节点名 __name:=turtle2_tf_broadcaster /turtle2
rosrun 功能包 turtle_tf_listener
rosrun turtlesim turtle_teleop_key
