unmanned aerial vehicle (uav) flight control system...
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Unmanned Aerial Vehicle (UAV) Flight Control
System Design for Pipeline Following Operation Amina Ibrahim Khaleel*, Dr. Euan McGookin#
*MSc Student at Mechanical Engineering Department, University of Glasgow, Glasgow G12 8QQ, UK ([email protected]) #Department of Aerospace Engineering, University of Glasgow, Glasgow G12 8QQ, UK ([email protected])
The focus of this dissertation is to develop a simulation model that describes the dynamics of a fixed-wing UAV, design a flight control
system using a suitable control method as well as designing an automated navigation system to make the UAV follow the pipeline path.
Introduction UAVs are robotic aircraft systems that function autonomously or
are remotely piloted. There are various applications of UAVs in
different fields, a simple example is in civil security work. In most
of the applications their main role is monitoring and close
observation of the object and terrain they fly over. One of which
is; monitoring above ground oil and gas pipelines for
maintenance purposes.
Flight control System A Proportional-Integral-Derivative (PID) controller was used to
design the flight control system using Ziegler-Nichol’s tuning
method. The PID was used to control the heading manoeuver of
the UAV. Fig 2 below illustrates the feedback flight control
system.
The feedback calculates the heading error as the difference
between the UAV’s desired heading angle,ψd and the measured
angle, ψ. This error was fed into the controller and minimised by
the use of the PID gains. Table 1 shows the gains used to obtain
a robust heading controller.
Navigation System A navigation system was developed using Line-Of-Sight (LOS)
autopilot to provide autonomous flight and guide the UAV to follow
the pipeline path. Fig 4 depicts the navigation system.
This was accomplished by a heading command to the UAV’s
heading system to approach the line of sight between its current
position (x,y) and the waypoint of the pipeline to be reached (xd,yd).
The LOS angle is given by:
The waypoint switching was designed on the basis whether the UAV
lies within the circle of acceptance defined around the particular
pipeline waypoint with R as its radius.
If
is satisfied, then the selection of next waypoint is triggered else the
waypoint is not reached[1]. With this mechanism the UAV was able
to follow the pipeline as shown in Fig 5 below.
In Fig 5, the UAV is seen to follow the pipeline path and is able to
manoeuver to acquire all meandering turns. This depicts an effective
autopilot. With a larger acceptance radius, the UAV is seen to follow
the pipeline more closely.
For a closer tracking, the UAV was designed to follow the pipeline
within a corridor of ±50m. The wider the corridor the more flexible
the UAV turns without saturating the rudder.
Conclusion In conclusion, the use of PID control method has been shown to
provide robust flight performance of the UAV. Waypoint acquisition
using LOS guidance shows that the scheme is robust.
Reference [1] Anthony J. Healey, D. L. (1993). Multivariable sliding-mode
control for autonomous diving and steering of unmanned underwater
vehicle. IEEE journal of oceanic engineering , 18 (3), 327.
University of Glasgow, charity number SC004401
Fig 1: Fixed-wing UAV following a Pipeline
PID Controller
UAV + -
ψ Δψ ψd u
Fig 2: Flight Control System
Table 1: Table of gains
Fig 3 shows a stable and
robust heading controller
response, with no overshoot,
zero steady state error for a
45° change in heading and
approximately 10s response
time. With this heading
manoeuver, the rudder
response is still within ±45°
i.e not saturated.
Ψd = arctan2 (yd – y , xd - x) (1)
Position feedback (x,y)
PID
Controller UAV LOS
Autopilot
Δψ ψd u
Heading Feedback, ψ
(xd,yd)
waypoints
+ -
Fig 4: Navigation System
R2 ≥ [ (yd-y)2 + (xd+x)2 ] (2)
Fig 5: UAV Following Pipeline Path
Kp Kd Ki
5 12 0.0012
Fig 3: Closed-loop Heading
and Rudder response