I am working on a project to use ar-drone to check the lift rope. I help this application can be well developed and make lift technician's work safer. However, I have encountered different problems since I just learnt programming and ROS.

i am trying to public a command to the /tum_ardrone/com to make it takeoff and move and it seems I did something wrong and it never take off.

What I did: 1. roslaunch tumardrone ardronedriver and roslaunch and tumdriver.launch 2. use rostopic pub /tumardrone/com std_msgs/String 'AutoInit 500 800 4000 0.5'

I have tried different function like AutoInit, Goto and I have tried different bracket like [], "", {} and the drone never take off.

However, If i use the rostopic pub /ardrone/takeoff std_msgs/Empty {}, I can take off the drone. Can any good soul tell me what to do?