Table 3.

States of the controller state machine.

State	Description	Entered if
IDLE	Await commands from user while the sensor is parked and secure	Sensor is parked
PIVOT	Move the sensor to either parked (horizontal) or extended (vertical). Automatically switch state upon completion.	User commands reel in/out and state is IDLE or CATCH
CATCH	Control the catch mechanism. Automatically check whether the sensor is properly secured before switching to PIVOT state if reeling in.	User commands reel in/out and state is PIVOT or REEL
REEL	Control winch motor speed based on line length and user input. Automatically detects sensor reel in complete.	User commands reel in/out and state is CATCH or DIVE
DIVE	Disengages clutch to allow sensor to fall at terminal velocity.	User commands dive and state is REEL
CUT	Cuts sensor line to prevent loss of UAV in emergency situations.	User commands cut
ERROR	Stop winch motor and broadcast error information.	Error detected by the system