1. Reconfigurable autonomous flight system for either commercial aircraft or UAV.
Requirements Specification
Queensland University of Technology
Science and Engineering Faculty
Australian Research Centre for Aerospace Automation
Version 1.0
December 23, 2013
Project Team:
Dr. Luis Mejias Alvarez, PhD, Principal Supervisor
Dr. Duncan Campbell, PhD, Associate Supervisor
Mr. Duncan Greer, Engineering and support
Mr. Pedro Pablo Plazas Rincon, Master Research Student
Documents Author(s):
Pedro Pablo Plazas Rincon
I. Introduction
The aim of this project is to create, develop and implement an autopilot flight system. This
autonomous flight system could be reused in a commercial aircraft or unmanned aerial vehicle
configuring some features such as user interfaces, communication and actuators modules. However,
the control algorithms which are the core of the autopilot must be the same for both types of aircraft.
This document explains in detail the requirements of this autopilot system according the standard
RTCA DO-178C.

2. II. Use cases
• Engage and disengage the autopilot
UC-001-SY Engage Autopilot System
Brief Description Initializing and engaging the autopilot.
Actors Hardware manager, pilot, UAV operator, ground station, civil aircraft, UAV.
Priority Critical
Preconditions • The autopilot master switch must be in the off position when the engine is
started to avoid damages in its electronic devices.
• The autopilot should only be engaged when the pilot selects it.
• The autopilot will refuse to engage if:
• No communications can be established with one of the servos or
sensors.
• There is a configuration problem. For instance, the type of aircraft has not
been configured.
• By default the autopilot will set in heading hold mode.
Post-conditions • The autopilot will disengage if:
• Engage/disengage switch is pressed.
• A digital servo reports that it reaches its control limit.
• Active navigation source has been lost.
• Reception or transmission faults between one of the servos, sensors,
Flight Management System(FMS).
• If the failure happens on a UAV the autopilot will continue steering.
Flow of Events Sequence
1.0 The pilot switches on the autopilot system.
2.0 The autopilot displays a message on the control panel indicating that the autopilot

3. has been engaged.
3.0 The pilot selects the type of autopilot mode.
4.0 Use Select Autopilot Mode
Scenarios • Engaging the autopilot if no navigation solution is selected.
• Engaging the autopilot if a navigation solution is active.
UC-002-SY Disengage Autopilot System
Brief Description This use case describes the situation when the autopilot is disengaged.
Actors Hardware manager, pilot, UAV operator.
Priority Critical
Preconditions • The autopilot must be engaged.
• A failure condition happens in the piloted aircraft.
Post-conditions
Flow of Events 1.0 The pilot pushes and releases the switch or bottom in a display LCD or control
wheel to disengage the autopilot in a piloted aircraft.
Alternative Events 1.1 If the system works in an UAV the operator in the ground station can disengage
the autopilot system at anytime.
2.0 The autopilot can be disengaged when a failure condition happens during a flight.
This condition does not apply for an UAV.
Scenarios • The pilot or UAV operator decides to disengage the autopilot.
• A failure happens during a flight.

4. • Guidance
• Choose an autopilot mode
UC-003-GU Select Autopilot Mode
Brief Description The autopilot offers a buttons collection that allows to pilots or UAV operators choose and
engage the autopilot modes and functions.
Actors Autopilot control, pilot, ground station.
Priority Critical
Preconditions The autopilot system must be engaged.
Post-conditions
Flow of Events Sequence
1.0 The pilot or UAV operator selects the autopilot modes in the control panel.
2.0 The system displays a menu with the autopilot modes.
3.0 If the pilot or UAV operator chooses the “Heading hold mode” then use UC-010-GU
Set Heading Mode.
4.0 If the pilot or UAV operator chooses the “Altitude hold mode” then use UC-005-GU
Set Altitude Mode.
5.0 If the pilot or UAV operator chooses the “Vertical Speed Hold Mode” then use UC-
009-GU Set Vertical Speed Hold Mode.
6.0 If the pilot or UAV operator chooses the “Vertical Speed with Altitude Capture
mode” then use UC-007-GU Set Vertical Speed With Altitude Capture Hold Mode.
Scenarios

5. • Altitude Hold Mode
UC-004-GU Set Altitude Hold Mode
Brief Description In this autopilot's control mode the piloted aircraft or UAV must maintain an
assigned altitude. When the altitude mode is engaged, the autopilot seeks to
maintain the same barometric pressure that the aircraft or UAV was flying at the
time that the altitude mode was engaged.
Actors Pilot, operator UAV.
Priority Critical
Preconditions The aircraft must be at the desired altitude and be trimmed for level flight.
Post-conditions The autopilot must maintain the same altitude during the trajectory until the pilot
or UAV operator decides to disengage this mode.
Flow of Events Sequence
1.0 The pilot presses and releases the ALT mode button on the control
panel.
2.0 The system shows on the control panel that autopilot is in altitude hold.
3.0 Use UC-005-GU Control Altitude Aircraft or UAV .

6. UC-005-GU Control Altitude Aircraft - UAV
Brief Description Height is controlled altering the pitch attitude and airspeed. This use case implements
the control algorithm to maintain the altitude and airspeed during a flight for both an
UAV or civil aircraft. Automatic control of flight is a highly complex subject, thereby this
use case only describes the main aims and does not explain in details about the
algorithm.
Actors Autopilot control, altitude sensor, elevator servo, .
Priority Critical
Preconditions • The autopilot must be switched on.
• The aircraft must be at the desired altitude.
Post-conditions • The aircraft or UAV must keep the altitude and airspeed without the human
intervention.
Flow of Events Sequence
1.0 The system reads the altitude sensor and the first height measurement must keep
while the altitude mode is engaged. Use UC-043-SE Read Sensor
2.0 The system compares and calculates the altitude error between the measured
altitude with the desired altitude from cockpit.
3.0 The system calculates the required pitch rate according the altitude error.
4.0 The system reads the actual pitch rate sensor. Use UC-043-SE Read Sensor
5.0 The system calculates the pitch rate error between the actual pitch rate with the
required pitch rate.
6.0 The acquired pitch rate error is used to adjust the elevator deflection.
7.0 If the measured altitude is lower than the desired altitude the autopilot must adjust
the elevator to climb the aircraft or UAV. Use UC-037-AC Adjust Actuator
8.0 If the measured altitude is higher than the desired altitude the autopilot must
adjust the elevator to descent the aircraft or UAV. Use UC-037-AC Adjust Actuator
9.0 The system must keep the altitude controlling the airspeed. Use UC-006-GU Case
Control Airspeed Aircraft.
Alternative events If a abnormal behaviour is detected in the altitude control algorithm, the hardware
manager thrown an system failure then Use UC-052-FA Detect Failure
Scenarios

7. • Control Airspeed Aircraft
UC-006-GU Control Airspeed Aircraft - UAV
Brief Description This use case describes how the system controls the airspeed altering the engine
power and adjusting the throttle actuator. Automatic control of flight is a highly
complex subject, thereby this use case only describes the main aims of the
requirement and does not explain the control algorithm in more details.
Actors Autopilot control, engine throttle servo, airspeed data sensor.
Priority Critical
Preconditions The maximum and minimum airspeed should be started by safety requirements.
Post-conditions
Flow of Events Sequence
1.0 The system reads the airspeed sensor. Use UC-043-SE Read Sensor
2.0 The system compares and calculates the error between the measured
airspeed with the desired airspeed. The error obtained is used to adjust the
throttle and to maintain the airspeed.
3.0 If the measured airspeed is lower than the desired airspeed, the autopilot
must adjust the throttle to increase the engine power.
4.0 If the measured airspeed is higher than the desired airspeed the autopilot
must adjust the throttle to decrease the engine power.
Alternative Events If a abnormal behaviour is detected in the airspeed control algorithm, the hardware
manager thrown an system failure, then Use UC-052-FA Detect Failure
Scenarios

8. • Vertical Speed Hold Mode
UC-007-GU Set Vertical Speed Hold Mode
Brief Description This use case describes when the pilot or UAV operator engages the autopilot's
vertical speed hold mode
Actors Pilot, UAV operator.
Priority Critical
Preconditions The autopilot must be engaged.
Post-conditions This autopilot's mode holds the climb or descent rate.
Flow of Events 1.0 The pilot or UAV operator presses and releases the VS button on the control
panel.
2.0 The pilot or UAV operator enters the desired altitude at which the aircraft or
UAV must climb or descent.
3.0 The system shows that autopilot is in vertical speed mode hold on the
control panel.
4.0 Use UC-008-GU Control Pith Angle.
5.0 When the aircraft reaches the assigned altitude the system actives an
alarm and displays a message on the control panel.

9. Alternative Events 1.1 If the autopilot is installed on a UAV the control panel is placed in the ground
station.
Scenarios
UC-008-GU Control Pitch Angle
Brief Description The purpose of this requirement is that the vertical speed can keep it during the
trajectory allowing a constant-rate climbs and descents. Automatic control of flight
is a highly complex subject, thereby this use case only describes the main aims
and does not explain in details about the algorithm.
Actors Autopilot control, elevator servo, engine throttle servo, pitch sensor, vertical speed
sensor..
Priority Critical
Preconditions The pilot sets the autopilot system in vertical speed hold mode.
Post-conditions • For safety reasons the autopilot system must limit the maximum pitch
angle.
• The aircraft or UAV must keep the vertical speed during the flight.
Flow of Events 1.0 The autopilot control system reads the vertical speed sensor. Use UC-043-
SE Read Sensor
2.0 The system calculates the error between the measured vertical speed and
the desired vertical speed from cockpit.
3.0 The vertical speed obtained error is used by the system to calculate the
required pitch rate to maintain the desired vertical speed.
4.0 The system reads the actual pitch rate measurement. Use UC-043-SE
Read Sensor.
5.0 The system calculates the pitch rate error between the actual pitch rate and
the required pitch rate. The pitch rate obtained error is used to adjust the
elevator and throttle servos.
6.0 If the measured vertical speed is lower than the desired vertical speed, the
autopilot must adjust the throttle to increase the engine power and to raise
the elevator deflection. UAV. Use UC-037-AC Adjust Actuator
7.0 If the measured vertical speed is higher than the desired vertical speed, the
autopilot must adjust the throttle to decrease the engine power and to
decrease the elevator position. Use UC-041-AC Adjust Elevator and UC-
002-AC Adjust Throttle.
Alternative Events If a abnormal behaviour is detected in the vertical speed control algorithm, the
hardware manager thrown an system failure, then use UC-052-FA Detect Failure
Scenarios
• Vertical Speed Hold Mode with Altitude Capture

10. UC-009-GU Set Vertical Speed Hold Mode with Altitude Capture
Brief Description This use case describes how the autopilot system maintains a vertical speed until
capturing the desired altitude. This mode mixes the modes vertical speed hold and
the altitude hold. When the aircraft or UAV has reached the target altitude, the
vertical speed mode is disengaged and the altitude hold mode remains engaged
keeping the achieved altitude.
Actors Pilot, UAV operator.
Priority High
Preconditions The autopilot must be engaged.
Post-conditions The system maintains the desired height.
Flow of Events 1.0 Use UC-004-GU Set Altitude Hold Mode
2.0 Use UC-007-GU Set Vertical Speed Hold Mode
Alternative Events If a abnormal behaviour is detected at the vertical speed control algorithm, the
hardware manager thrown an system failure, then Use UC-052-FA Detect Failure
Scenarios

11. • Heading Hold Mode
UC-010-GU Set Heading Mode
Brief Description This use case describes the heading mode. This mode is used to steer the
aircraft automatically along a pilot selected heading. During this mode the
ailerons are moved differentially to increase the lift on one wing and reduce it on
the other.
Actors Pilots or UAV operator.
Priority Critical
Preconditions The pilot or UAV operator maintains level flight.
Post-conditions The autopilot is disengage.
Flow of Events Sequence
1.0 The pilot or UAV operator presses and releases the HDG mode button on
the control panel.
2.0 The system shows that autopilot is on heading hold mode on the control
panel.
3.0 The pilot or UAV operator enters the desired roll angle on the control panel.
4.0 Use UC-011-GU Set Control Roll angle.
5.0 Use UC-012-GU Set Control Yaw angle.
6.0 The system maintains the roll angle until the desired heading is achieved.
Alternative Events

12. UC-011-GU Control Roll Angle
Brief Description This use case describes a brief step sequence to control the roll angle. Automatic
control of flight is a highly complex subject, thereby this use case only describes the
main aims and does not explain in details about the algorithm used to calculate the
filter coefficients.
Actors Pilot, autopilot control, right aileron servo, left aileron servo, roll sensor.
Priority Critical
Preconditions • The pilot has chosen the “Heading hold mode”.
• The pilot enters the roll angle.
• The roll reference shall be set to zero if the actual roll angle is less than 6
degrees, in either direction, at the time of heading hold engagement.
• The roll hold reference shall be set to 30 degrees in the same direction as the
actual roll angle if the actual roll angle is greater than 30 degrees at the time
of heading hold engagement.
• Steady state roll commands shall be tracked within 1 degree in calm air.
• The maximum roll angle allowed shall be 30 degrees in calm air.
• The maximum aileron command allowed shall be 15 degrees.
Post-conditions
Flow of Events Sequence
1.0 The autopilot reads the roll sensor to know its actual roll angle. Use UC-043-
SE Read Sensor.
2.0 The system calculates the roll angle error between the measured roll angle and
the desired roll angle from cockpit.
3.0 The control system uses the roll angle error to adjust the ailerons in a
coordinated way to reduce the error.
4.0 If the aircraft or UAV turns left, the left aileron goes up and the right aileron
goes down. Use UC-037-AC Adjust Actuator
5.0 If the aircraft or UAV turns right, the left aileron goes down and the right aileron
goes up at the same time. Use UC-037-AC Adjust Actuator
Alternative Events 2.1 If a problem is found with one of the sensors or the servos, the system will
display a message indicating which device presents a fault and disengage the
autopilot.
Scenarios • The autopilot cannot communicate with one of the sensors or servos.
• The aircraft can be subject to positive or negative disturbances.
UC-012-GU Control Yaw Angle
Brief Description This use case describes a brief step sequence to control the yaw angle.
Automatic control of flight is a highly complex subject, thereby this use case only
describes the main aims and does not explain in details about the algorithm used
to calculate the filter coefficients.
Actors Pilot, autopilot control, rudder servo, yaw sensor, sideslip sensor.

13. Priority Critical
Preconditions • The pilot has chosen the “Heading hold mode”.
• The pilot enters the roll angle.
• For safety reasons the autopilot system must limit the maximum yaw
angle.
Post-conditions
Flow of Events Sequence
1.0 The autopilot reads the sideslip sensor. Use UC-043-SE Read Sensor
2.0 The system calculates the sideslip angle error using the measured sideslip
angle and the desired sideslip which must be zero.
3.0 The system uses the error to move the rudder .
4.0 If the aircraft or UAV turns left, the rudder turns to the right. Use UC-037-AC
Adjust Actuator
5.0 If the aircraft or UAV turns right, the rudder turns to the left. Use UC-037-AC
Adjust Actuator
Alternative Events 2.1 The system will display a failure message indicating a fault in the control
yaw algorithm. Use UC-052-FA Detect Failure
Scenarios • The autopilot cannot communicate with one of the sensors or servos.
• The aircraft can be subject to a positive or negative disturbances.
• GPS Steering Mode

14. UC-013-GU Set GPS Steering Mode
Brief Description GPSS function follows the desired track to the active waypoint. In this mode the
autopilot guide the aircraft along the course selected.
Actors Autopilot_control, GPS, pilot
Priority High
Preconditions The autopilot must be engaged in Heading Hold Mode. Use UC-010-GU Set
Heading Mode.
Post-conditions
Flow of Events Sequence
1.0 The pilot or UAV operator selects the GPSS mode on the control panel.
2.0 The system engages the GPS mode.
3.0 The pilot or UAV operator enters the waypoint of the trajectory indicating the
latitude and longitude in degrees, minutes and seconds.
4.0 The system calculate the trajectory of the aircraft. Use UC-014 Calculate
Trajectory.
Alternative Events
Scenarios • A malfunction event of the GPS is detected. Use detect failure
UC-014-GU Calculate Trajectory
Brief Description This use case describes the trajectory calculation which is used to steer the piloted
aircraft or UAV following a flight plan. The algorithm must be able to move the aircraft
from one location to another.
Actors Autopilot control
Priority High
Preconditions The autopilot must be in heading mode
Post-conditions
Flow of Events 1.0 The system reads the initial position from GPS. The position is given by the
latitude, longitude and altitude. Use UC-043-SE Read Sensor
2.0 The system reads the aircraft attitude: roll rate and angle and pitch angle and
rate. Use Read Sensor
3.0 The system calculates the estimated position that the aircraft or UAV must have
at the moment to read a new GPS position. Use UC-043-SE Read Sensor
4.0 The system calculates the error position between the GPS actual position and
the estimated position.
5.0 The system calculates the aircraft heading attitude to correct the position error.
The parameters that the system calculates are : roll, yaw, pitch and altitude.
6.0 Use UC-010-GU Set Heading Mode.
7.0 The system emits an message in the control panel indicating that the desired
position has been reached.

15. Alternative
Events
1.1 The system will display a failure message indicating a fault in the control
trajectory algorithm. Use UC-052-FA Detect Failure
Scenarios
• Configuration
UC-015-CF Set Type of Aircraft
Brief Description This use case describes the configuration of the autopilot system to be adapted
to a piloted aircraft or an UAV. The system sets the human machine interfaces,
the communication module and actuator configuration.
Actors Technician, pilot, ground station, GPS, UAV, civil aircraft.
Priority Critical.
Preconditions
Post-conditions
Flow of Events 1.0 The technician chooses the type of aircraft where the system will be
installed.

16. 2.0 The technician selects the baud rate to GPS.
3.0 If the selected option is a piloted aircraft, the system sets the interfaces
which will be used by the pilots in the cockpit.
4.0 If the selected option is a piloted aircraft, the system sets the
CANAerospace protocol to communicate to FMS.
5.0 If the selected option is a piloted aircraft, the system chooses analog
outputs towards actuators.
Alternative Events 4.1 If the selected option is an UAV, the system sets the TCP protocol to
communicate the radio modem with the ground station.
4.2 If the selected option is an UAV, the system chooses PWM outputs
towards actuators.
Scenarios
• Communications

17. UC-026-CM Receive Data
Brief Description This use case describes the reception of packets using the CANAerospace
protocol, TCP protocol and the interface RS232. This use case is an
abstraction of each protocol and do not specific the details about each
protocol. The requirements of each protocol can be found in their
respective specifications.
Actors Autopilot comm, ground station, GPS, FMS, radio modem.
Priority Critical
Preconditions • The autopilot must be engaged.
• The autopilot and GPS must communicate using RS232.
• The autopilot and FMS must communicate using CANAerospace.
• If the autopilot works with an UAV the protocol to communicate the
aircraft and the ground station must be TCP.
Post-conditions
Flow of Events 1.0 The system receives data from the GPS or FMS.
2.0 If the autopilot does not send data to one of the systems mentioned
or one of the protocols presents an error, the autopilot will throw an
communication failure event.

18. 3.0 Use UC-053-FA Detect Failure Communications
Alternative Events If the autopilot is installed on a UAV, the system sends data to the
ground station.
Scenarios
UC-027-CM Send Data
Brief Description This use case describes the transmission of a packet using the
CANAerospace protocol, TCP protocol and the interface RS232. This
use case is an abstraction of each protocol and do not specific the
details about each protocol. The requirements of each protocol can be
found in their respective specifications.
Actors Autopilot comm, ground station, GPS, FMS, radio modem.
Priority Critical
Preconditions • The autopilot must be engaged.
• The autopilot and GPS must communicate using RS232.
• The autopilot and FMS must communicate using CANAerospace.
• If the autopilot works with an UAV the protocol to communicate
the aircraft and the ground station must be TCP.
Post-conditions
Flow of Events 1.0 The system sends data to the GPS or FMS.
Alternative Events 1.1 If the system works on an UAV, the communication is with a
ground station.
Scenarios • Autopilot transmits data to/from Flight Management System.
• Autopilot transmits data to/from Ground Station.
• Autopilot transmits data to/from GPS.
• Actuators
UC-037-AC Adjust Actuator
Brief Description This use case depicts the adjustment in any of the actuators when the civil
aircraft or UAV is controlled by the autopilot system. This use case is an
abstraction of the interaction between the autopilot system and any actuators.
Each actuator must be implemented according to its manufacturer
specifications.
Actors Autopilot control, elevator servo, rudder servo, ailerons servo, throttle servo.
Priority High
Preconditions The autopilot must be engage in any mode.
Post-conditions
Flow of Events Sequence

19. 1.0 The system verifies that the new actuator position does not exceed the
allowed maximum.
2.0 The autopilot sends analog signal to the actuator to adjust its position.
Alternative Events 1.1 If the actuator cannot adjust the new position, the system emits an
display an message in the control panel indicating the failure. Use UC-
052-FA Detect Failure
2.1 If the autopilot controls an UAV, this system sends a PWM signal to
adjust the actuator position.
Scenarios The actuator is blocked.
• Sensors
UC-043-SE Read Sensor
Brief Description This use case describes when the system reads the measurements from a
sensor. This case is an abstraction the sensor reading. Therefore, each sensor
must be implemented according to the manufacturer specifications.
Actors Roll sensor, accelerometer sensor, yaw sensor, angle incident sensor, air data
sensor, altitude sensor, pitch sensor.
Priority Critical
Preconditions The sensors should be read every certain period according to each sensor
manufacturer.
Post-conditions
Flow of Events Sequence
1.0 The system requests a data from the sensor.
2.0 The sensor sends data converting the analog signal in an digital signal.
Alternative Events 2.1 If the system does not receive data from one of the sensor. A sensor
failure will be thrown. Use UC-052-FA Detect Failure
Scenarios

20. • Failures
UC-052-FA Detect Failure
Brief Description This use case describes when an irregular performance happens during
a fly affecting the security of the aircraft or UAV. The system must be
able to detect a communication, hardware, actuator, sensor and control
failure. This use case is an abstraction and each type of failure must
implement its own logic to detect the fault.
Actors Autopilot control, autopilot communications, hardware manager, sensors,
actuators, task manager.
Priority Critical.
Preconditions • The autopilot must be engaged.
• The system has been configured to work with an piloted aircraft
or UAV.
Post-conditions • The system must distinguish the type of failure.
• The system must resolve the situation depending on the type of
aircraft.
Flow of Events
Sequence
1.0 The system cannot read a sensor, cannot change the position of
an actuator or the system presents a communication or system
failure.
2.0 The system tries to repeat the actions one more time. For

21. instance, if the system cannot read a sensor in the first time, the
autopilot will try to read a second time.
3.0 The system does not receive answer from the actuator, sensor,
FMS, ground station or GPS.
4.0 The system distinguishes the type of detected failure.
Use UC-069-TF Distinguish Type of Failure
Alternative Events 2.1 The failure is corrected and the flight continues without problems.
Scenarios • The autopilot system detects a fault in a piloted aircraft during a
flight.
• The autopilot system detects a fault in an UAV during a flight.
UC-053-FA Detect Failure Communications
Brief Description This use case describes a communication fault in the autopilot system. The
detection of communication failures is done with the three external systems
and the autopilot. The first external system is the GPS which uses the
interface RS232 to send and receive messages to/from the autopilot. The
second is the FMS which uses the CANaerospace protocol to transmit and
receive data to/from the autopilot. Finally, the third external entity is the
ground station which uses the TCP protocol to communicate to the UAV.
Actors Autopilot comm, ground station, GPS, FMS, radio modem.
Priority High
Preconditions • The system cannot to establish communication between the GPS,
Ground Station or FMS.
• Wrong data is received from the GPS, Ground Station or FMS.
Post-conditions
Flow of Events 1.0 The system detects a communication fault(Rx or TX) in the
interface RS232, the protocol CANAerospace or TCP protocol.
2.0 The system emits an alarm displaying a failure message in the
autopilot control panel in the cockpit.
3.0 Use UC-069-TF Distinguish Type of Failure
Alternative Events
Scenarios

22. • Fault tolerance
UC-069-TF Distinguish Type of Failure
Brief Description This use case identifies the type of failure in the autopilot system.
Actors Piloted aircraft, UAV, hardware manager.
Priority Normal
Preconditions The system presents a failure.
Post-conditions A message is displayed on the autopilot cockpit panel control or ground
station.
Flow of Events Sequence
1.0 The system identifies the executed task which was using the
hardware resource with failures.
2.0 Depending on the type of resource that presents a failure, the
system sends a message to autopilot control panel.
3.0 If the failure is on an actuator the system displays a message
indicating that the fault is related with an actuator.
4.0 If the failure is on a sensor the system displays a message
indicating that the fault is related with an sensor.
5.0 If the failure is on a communication protocol the system displays a
message indicating that the fault is related on a transmission or
reception data.
Alternative Events
Scenarios

23. UC-066-TF Resolve Failure
Brief Description This use case describes the process when a fault is detected and
resolved.
Actors Civil aircraft, pilot, ground station, UAV.
Priority High.
Preconditions • A failure has been detected.
Post-conditions
Sequence
Flow of Events 1.0 The autopilot system is disengaged.
Alternative Events 1.1 If the aircraft is an UAV the system sets the autopilot heading
mode.
1.2 The system configures an emergency trajectory.
Scenarios

24. • Hardware system actors

25. III. Nonfunctional Requirements
• Electrical requirements
• 6 - 32 VDC operational
• Data input and output
• Protocols: CAN aerospace, TCP.
• Interface: RS232
• Implement PWM only for UAV and analog signal for MAV.
• Standards
• DO-178B or DO-178C.
• DO-160D
•
• Environmental analysis
• Temperature and Altitude.
• Temperature variation.
• Humidity.
• Hardware and software tools to develop the project
• To be define later
• Define type of hardware and software to implement the autopilot and its interfaces.
• To be define later
• Cost to develop the project
• No specified
• Graphic User Interfaces (HMI)
• To be define later
• Physical structure
• Inside a box. No specified more details
• Testing
• To be define later
IV. Constraints
V. Document Revision History
Version 1.0
Name(s) Pedro Pablo Plazas Rincon
Date December 23, 2013
Change Description