Reason given for shutdown: [new node registered with same name]

edit

Hello Here is what I'm trying to : I'm using an rplidar, arduino connected to Raspberry with ROS kinetic, to do autonomous mapping and navigation.

First, i run the rplidar with

roslaunch rplidar_ros view_rplidar.launch

then , slam mapping with

roslaunch rplidar_ros view_slam.launch

then I used hector_exploration with

roslaunch hector_exploration_node exploration_planner.launch

Final, to publish the cmd_vel topic I run

rosrun hector_exploration_controller simple_exploration_controller

My question, when I try to send cmd_vel values to Arduino through this code below

#include <ArduinoHardware.h>
#include <ros.h>
#include <geometry_msgs/Twist.h>

ros::NodeHandle nh;

geometry_msgs::Twist msg;

ros::Publisher pub("cmd_vel", &msg);

void setup()
{
 nh.initNode();
 nh.advertise(pub);
} void loop()
{

pub.publish(&msg);
nh.spinOnce();
}

Once I run this code on arduino, my rplidar stop spinning and give me this error message

[ WARN] [1532545086.000125786]: Shutdown request received.
[ WARN] [1532545086.000656149]: Reason given for shutdown: [new node registered with same name]