How to Make AR.Drone Take-Off or Land

  By Anna Sandler

Make sure you are familiar with "How to program AR.Drone remotely over WIFI" chapter before you continue to this tutorial.

AT*REF command

This command is used to control the basic behavior of the drone such as take-off, landing, emergency stop and reset.

Make sure the command AT*FTRIM has been called before taking-off for horizontal calibration; otherwise Ar.Drone won’t be able to stabilize itself when flying.

Syntax

AT*REF=[Sequence number ],[Input]<LF>

Explanation:

• Sequence number- 1 if it is a first command, or sequence number value of previous command + 1.
• Input- AR.Drone control a 32 bit-field integer. See explanation for AR.Drone control bit field below.

Example:

The following UDP packet sends 3 AT*REF commands for emergency stop.
First command-Make the drone to land;
Second command- Changes AR.Drone mode from normal to emergency mode to stop its engines;
Last command- This command is sent to stop sending the emergency signal.

The UDP packet that is sent to AR.Drone is:
AT*REF=1,290717696<LF>AT*REF=2,290717952<LF>AT*REF=3,290717696<LF>

AR.Drone control bit-field values

This input field is used to start the takeoff or lending operation or to change the mode for emergency procedures.
Bits order is from right to left MSB first.

The following are AR.Drone modes:

• Normal mode- flying or waiting on the ground;
• Emergency mode- AR.Drone engines are cut off;

The control input contains from the following bits:

• Bit 0-7: are not used. Set to 0;
• Bit 8: Change emergency mode bit.
  Set the value to 1 to change the mode.
  If the drone is at normal mode, its mode will be changed to emergency mode in order to stop the engines immediately.
  If the drone is at emergency mode, its mode will be changed to normal mode to allow the drone to take off again.
  Set the value to 0 to stay at the same mode or after sending the emergency signals that have been verified and executed by the AR.Drone.
• Bit 9: take off or land.
  Set the value to 1 to start the take-off operations to the 1-meter-hight-hovering state.
  Keep sending this command until the state of AR.Drone will show that it actually took off.
  Set the value to 0 to make the drone land.
  This command should be repeated until the drone state in the navdata shows that drone actually landed.
• Bit 10-17: are not used. Set to 0;
• Bit 18: not used. Set to 1;
• Bit 19: not used. Set to 0;
• Bit 20: not used. Set to 1;
• Bit 21: not used. set to 0;
• Bit 22: not used. set to 1;
• Bit 23: not used. set to 0;
• Bit 24: not used. set to 1;
• Bit 25-27: not used. set to 0;
• Bit 28: not used. set to 1;
• Bit 29-31: not used. set to 0;