5.0 Flight Control System

flounderconvoyElectronics - Devices

Nov 15, 2013 (3 years and 8 months ago)

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5.0

Flight Control System


Flight Control Modes
:



Pilot Controlled Mode or Radio Controlled Mode (Stability Off / Navigation Off)



Unmanned Control Mode

(Stability On / Navigation On)



Pilot Assisted Cont
rol Mode (Stability On / Navigation Off)


Stability System Sensors
:



Yaw
, Pitch
, and Roll

Gyros (Turn
-
rate data)



X,Y, and Z Accelerometers



Pitch

and Roll

Inclinometers (2
-
axis angle data)



Speed Sensor (barometric altimeter/pitot airspeed sensor)


Navigation System Sensors
:



GPS Receiver

and Antenna



Magnetometer (Digital Compass)


Mission System Equipment:



Came
ra



Camera

Control Equipment


AFCS

Maneuvers:



Level Flight (Airspeed and Altitude given) towards waypoint



Climb



Descend



Turn (20 degree per second turn rate)



Holding Pattern



Land



Takeoff


5.1

A
FCS

System Design



The Auto Pilot

and Flight Control System (AFCS
) can be controlled by a single
processing unit or main processing unit (MPU
). This unit will receive data from several
sensors, pr
ocess that data, and command the appropriate response. Sensor data can be
obtained through an RS
-
232 serial interface, transistor
-
transistor logic, or through an
analog to digital converter.


The AFCS

will have to operate in at least two mo
des. The first mode would be the
Unmanned Control Mode
. This mode would be the fully autonomous mode giving full
control of the vehicle to the MPU
. The second mode would be the Pilot Controlled Mode
or Radio Contro
lled Mode (R/C). This mode is gives the human pilot complete control
over the vehicle through radio transmission. A third possible mode would be where the
pilot has control over the navigation of the vehicle yet the stability functions of the AFCS
is still

in operation. Input from the pilot would be recognized in this mode and when this
ceases, the AFCS would maintain the aircraft at the last attitude and heading the pilot
commanded or return to straight and level flight.


The AFCS

will have
to store defined waypoints

and make calculations to control the
vehicle towards those waypoints. The MPU

will handle all calculations related to
waypoint seeking. The GPS data received can be transformed into a local Cartesian

or
Cylindrical Coordinate system for easier processing. The MPU handling and processing
this data will then have to be capable of mathematic functions.


The AFCS

maneuvers will be sub
-
functions of a main continuous function. The data
requi
red for a 20º/second turn will be determined by the roll and pitch gyros (turn
-
rate
data), accelerometers

(linear acceleration), and inclinometers (angle data). The MPU

will
be programmed to minimize overshoot and undersh
oot of the desired heading. During a
Holding Pattern

maneuver, the AFCS waypoint data could be put into a circular list. This
list is would continuously cycle the waypoints
, creating the necessary data for the hold
ing
pattern. Bring the MPU out of the Holding Pattern maneuver mode could be done by a set
amount of time in that pattern or by a set number of completed cycles in that pattern.


Proportional
-
Plus
-
Integral
-
Plus
-
Derivative (PID
) compensators w
ill be used for each
servo. The PID values for each servo will be determined by the current maneuver. Each
servo then has several sets of PID data that will be optimized to the current maneuver
being performed. A single PID compensator for each servo will
not adequately satisfy the
stability and response requirements of several maneuvers and is therefore highly
discouraged. This data can be stored in the memory of the MPU

and accessed at the
appropriate time.








5.2

Navigation & Stability Comp
onents


Servo Controller (3
-
6 axis)

Servos (3
-
6)

GPS Receiver

GPS Antenna

IMU

(Inertial Measuring Unit)


Accelerometers (3
-
axis)


Gyros (3
-
axises)

Barometric Altimeter

Pitot Speed/Pressure Sensor

Magnetometer (Digital Compa
ss)

Inclinometers (Pitch

and Roll
)

MPU

(Main Processing Unit)


PC/104 (Embedded Computer)


PICMicro, PIC18 Micro Controller


DSP (Digital Signal Processor)

Analog/Digital Converters

TTL

Interface

RS
-
232 Co
mmunication Link (Cable, Wireless)

Radio Control Receiver/Servo Controller (Futaba, ect.)

Power Source

(3V, 5V, 12V)

















5.3

References


Applied Mathematics in Integrated Navigation Systems

Robert M. Rogers


Global Positioning

Systems, Inertial Navigation, and Integration

Mohinder S. Grewal, Angus P. Andrews, Lawrence R. Weill


Modern Inertial Technology: Navigation, Guidance, and Control

Anthony Lawrence


The Global Positioning System & Inertial Navigation

Jay A. Farrell, Matt
hew Barth


Digital Control of Dynamic Systems

Gene F. Franklin, Michael L. Workman, David Powell


Feedback Control of Dynamic Systems

Gene F. Franklin, Abbas Emami
-
Naeini, J. David Powell


Programming and Customizing PICmicro® Microcontrollers (Second Edit
ion)

Myke Predko


Modern Control System Theory and Design (Second Edition)

Stanley M. Shinners


Advanced Modern Control System Theory and Design

Stanley M. Shinners


Control Systems Engineering (Third Edition)

Norman S. Nise