الفهرس 
SUAV Equations of MotionOnly 14 pages are availabe for public view
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Abstract
The past two decades have witnessed a dramatic increase in the utilization of the
Unmanned Aerial Vehicles (UAVs). So, designing and manufacturing of UAVs are
too necessary at these days. Autonomous aircrafts represent a convenient possibility
for monitoring large areas with the addition of many military applications (military
reconnaissance, advanced attack air vehicle for hazardous missions). Autopilot is the
most important system in Small Unmanned Air Vehicle (SUAV) manufacturing. It
guides the UAV during flight with no assistance from human operators. Design of
Automatic Flight Control System (AFCS) is very challenging due to the limited
resources available onboard and the high number of constraints including weight,
space, time, energy and cost by using Commercial-Off-The-Shelf (COTS)
components. So our challenge is to design a high performance AFCS with low cost
and improving the level of autonomy.
This thesis represents a complete design of AFCS of Ultrastick-25e. Beginning
our mission with the modeling of SUAV as follows; the mathematical model of the
nonlinear equations of motion is introduced, a survey with a standard method to
obtain the full non-linear equations of motion is utilized and the linearization of the
equations according to a steady state flight condition (trimming) is derived. Linear
longitudinal and lateral models are obtained with algorithmic and a novel analytical
linearization techniques. The modeling is completed with the evaluation of the linear
model; check matching between the behavior of the states of the nonlinear model and
the resulted linear model with applying a doublet signal at the control surfaces of the
aircraft.
The autopilot design is preceded first by Model in loop stage (MIL), then
Software In loop (SIL) and at last Processor in Loop (PIL) to complete the design and
evaluate it with many circumstances.
The detailed design of autopilot and its simulation with a various flight
scenarios is introduced. The first part is the design of longitudinal motion controller.
Beginning with the inner loop pitch rate (q) (pitch damper) which is designed with the
best value of feedback gain by root locus technique and tuning it with Safety integrity
level which is defined as a relative level of risk-reduction provided by a safety
function, or to specify a target level of risk reduction. Then pitch attitude hold
controller (pitch tracker) is designed with PI-controller far away from complexity
with good performance in the time domain characteristics.
Linearization of the nonlinear equation of motion of altitude dynamics is
derived to get a linear relation between the altitude and pitch angle (θ) under
assuming of cruise speed of 17 m/s. Altitude hold controller is designed using of Pcontroller
with results better than PI-controller in the Minnesota controller. Ascending
scenario is tested in the non-linear model to check the all over behavior of the aircraft.
The design of lateral motion controller is introduced. Most inner loop is
designed with feedback gain, and then roll attitude hold controller is designed with PIcontroller
far away from complexity with good performance in the time domain
characteristics. The lateral motion controller design procedures are:
a. Roll rate feedback.
b. The roll attitude controller.
c. Linearization algorithm to get a linear relation between heading angle and roll
attitude according to coordinated turn flight.
d. The outer loop controller is a simple P-controller.
e. Yaw damper is designed with washout filter.
f. Finally, the rectangular motion command is applied in the non-linear model to
check the behavior of the aircraft.
The environment disturbances and sensors noise are considered in the design
architecture of test platform. The whole autopilot is tested under climbing turn
scenario.
After all the previous discussion, it’s the time to implement the autopilot of
SUAV. Flight computer (ArduMega 2560) is used because of its historical
successfulness in many autopilots design and its simplicity. MEMS sensors are
chosen in implementing (IMU (MPU6050), Magnetometer (HMC 5883L), GPS
(UBLOX LEA-6H)) which are smaller and lighter than the old mechanical sensor
devices, but so noisy.
With implementing the state estimator with complementary and Kalman filters;
the problem is finished and solved. All of the previous sensors are used for
implementing Attitude and Heading reference system (AHRS). The communication
link between autopilot and the ground station is achieved by using (3DR radio
telemetry module).
Processor In Loop (PIL) simulation is implemented to evaluate the pitch attitude
controller by converting the continuous system to a discrete one and implementing the
communication adaptation between MATLAB and flight computer. The results show
us that the proposed controller strategy design is very good and convenient to our
requirements.
All of these designed circuits for the most important subsystems and designing
the Autopilot for Ultrastick-25e aimed to maintain the system with small size, low
weight, low power consumption and low cost.