 
 // Battery Voltage Publisher
 std_msgs::Float32 voltage_msg;
-ros::Publisher battery_topic("battery_voltage", &voltage_msg);
+ros::Publisher battery_pub("battery_voltage", &voltage_msg);
 
 void publishBatteryVoltage() {
   voltage_msg.data = getBatteryVoltage();
-  battery_topic.publish( &voltage_msg );
+  battery_pub.publish( &voltage_msg );
 }
 
 

#include <ros.h>
#include <ZumoMotors.h>
#include "Timer.h"
#include <geometry_msgs/Twist.h>
#include <std_msgs/Float32.h>

// Distance between both wheels
#define WHEEL_OFFSET_M 0.1 // 10cm

// Command Velocity Subscriber
ros::Subscriber<geometry_msgs::Twist> cmd_vel_topic("cmd_vel", &cmd_vel_callback);

unsigned long last_battery_published = 0;
////////////////////////////////////////////////////////////////////////////////

void setup()
{  
  pinMode(LED_PIN, OUTPUT);
  
  // Initialize Encoders
