Revision history [back]

I was able to do it following these steps:

1) Added to the manifest file the dependency: <depend package="ardrone_autonomy" />

2) Fixed the code in the following way:

#include <ros/ros.h>
#include "std_msgs/Int32.h"
#include "std_msgs/Float32.h"
#include "ardrone_autonomy/Navdata.h"

using namespace std;
ardrone_autonomy::Navdata msg_in;
float drone_altd;

void heightControl(const ardrone_autonomy::Navdata& msg_in)
{
  drone_altd=msg_in.altd;
  cout << drone_altd << endl;
}

int main(int argc, char **argv)
{
  ros::init(argc,argv,"Altitude_Control");
  ros::NodeHandle n;
  ros::Subscriber sub = n.subscribe("/ardrone/navdata", 1, heightControl);
  ros::spin();
  return 0;
}

I hope this helps.