Autonomous Blimp
Design Team 02
Jason Banaska, Hardware Manager, EE Marcus Horning, Project Leader, EE Sagar Patel, So;ware Manager, CpE Michael Wallen, Archivist, EE Faculty Advisor: Dr. Jay Adams December 2nd, 2011 Need
•  Cost effective way to achieve aerial surveillance
for informational purposes
•  Used to monitor in hard to reach places
Goal
•  To create a self stabilizing airship that can
provide useful information back to the user.
2 Design Requirements
1.  The airship should have an average flight
duration of twenty minutes.
2.  Display warning message on graphical user
interface (GUI) when battery voltage reaches a
critically low voltage level.
3.  The gondola, sensors, motors, and additional
hardware should be detachable from the blimp
envelope in less than 5 minutes.
4.  The airship must make one full rotation in the
yaw direction in under 60 seconds.
3 Design Requirements
5.  The maximum allowable drift during
autonomous flight in any direction is 1 m when
wind gusts are below 3 m/s.
6.  The user control should allow the operator to
control the pitch and yaw rotational directions,
as well as the x and z translational directions.
7.  The craft must come to a stop and warn the
user via the GUI when an obstacle is within 1m
and lies in the direction of the flight path.
4 Design Requirements
8.  The airship’s speed in the vertical direction
must be able to achieve 0.5 m/s in less than
10 seconds. Also, the airship must obtain a
speed of 1.8 m/s in the horizontal direction in
less than 6 seconds.
9.  The airship should not exceed a maximum
altitude of 122 m above ground level and
must warn the user when the craft is
approaching this position.
10. The device must transmit 800 meters line of
sight the craft’s battery voltage level,
position, altitude, aircraft speed, distance to
obstacles, and the air pressure and
temperature of the atmosphere.
5 Design Requirements
11. The accuracy of the transmitted data must be
as follows:
-Temperature within 1ºC
-Air pressure within 1kPa
-Battery voltage within 5% of actual voltage
-Speed within 5% of actual speed
-GPS position within 5 meters
6 Control System Theory of Operation
•  Multiple-Input Multiple-Output System
•  Outputs:
•  Six degrees of freedom
•  Commanded Inputs:
• 
• 
• 
• 
Velocity of Blimp in x-direction
Velocity of Blimp in z-direction
Rotational Velocity in yaw direction
Pitch Angle
7 Models of the System
8 Models of the System(continued)
9 Implementation
•  Ux, Up, Uyaw, Uz correspond to thrust/moment
necessary in respective direction.
•  These must undergo a transformation to
determine thrust produced by each motor.
10 Implementation
•  Transformations are based on orientation of motors
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𝒛↑′ &𝒅​𝒛↑′ &−𝒅​𝒙↑′ &𝒅​𝒙↑′ @𝒅​𝒚↑′ &−𝒅​𝒚↑′ &𝟎&𝟎 ][█■​𝑴↓𝟏 @​
𝑴↓𝟐 @​𝑴↓𝟑 @𝑴𝟒 ]
11 Implementation
•  We need Thrust in terms of motor rpm
12 Compensator Design
•  Each of the four compensators are designed
separately
•  Compensators were designed for minimal
overshoot, zero steady state error, and fast
response of the output
13 X-Direction Compensator
•  Simple pole at z=0.94
•  PI controller needed to reduce steady state
error
•  Gain chosen to satisfy design requirements
14 X-Direction Compensator
Step Response
Step Response
9
2
1.8
8
1.6
7
1.4
6
Amplitude
Amplitude
1.2
1
0.8
5
4
0.6
3
0.4
2
0.2
0
0
1
2
3
4
5
Time (sec)
6
7
8
9
1
0
1
2
3
4
5
6
7
8
9
10
Time (sec)
15 X-Direction Compensator
Motor rpms for Desired Step Response
10000
5000
Motor rpm
0
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
Time, in seconds
7
8
9
10
0
-5000
-10000
5000
0
5000
0
16 Hardware
Battery 1
Battery 2
Low-Dropout
Regulator
Battery
Monitor
Vin
Thrust
Motor
Controller
1
Motor 1
Motor
Controller
2
Motor 2
Motor
Controller
3
Motor 3
Motor
Controller
4
Motor 4
Desired Speed
M1
Battery
Voltage %
Desired Speed
M2
Ultrasonic
Proximity
Sensors
Desired Speed
M3
Thrust
Thrust
Barometer
MicroController
Desired Speed
M4
Accelero
-meter
Thrust
Gyroscope
Camera
Backup
GPS
Battery
Transmitter
GPS
Sensor
Xbee Pro
Camera
Receiver
Desired
x-translation
Desired Yaw
Desired Pitch
Desired
z-translation
Televison
Xbox 360
Controller
Xbee Pro
Xbee
Adaptor
PC
Monitor
17 Hardware
•  Low Dropout
Regulator
•  Battery Monitor
U1A
1
C1
10uF
2
In
Out
SHDN ADJ
3.3V
5
R2
1.2k
4
0
LT1963A
GND
0
C2
10uF
R4
100k
V3
11.1Vdc
0
1.21V
R5
81.9k
R1
2.05k
3
11.1V
0
•  Provide required
voltage to sensors
0
1
2
U9
+
3
µC
-
0
•  High Resistance, Low
Power Consumption
•  Voltage Buffer to
prevent back loading
18 Hardware
•  Gyroscope
•  Accelerometer
µC
6
VS
INT1
uC
7
C5
1uF
CS
Vin
µC
uC
3
4
SCL
Res
Res
L3G4200D
SDA
SAO
5
CS
0
2
13
NC
uC
3.3V
VDD_IO
GND
8
1
14
NC
15
9
U2A
Res
NC
Res
12
NC
11
NC
10
NC
9
NC
Res
INT2
NC
10k
8
GND
10
PLLFILT
NC
NC
470nF
INT1
GND
11
7
5
Res
74ACT109
3.0V
10nF
R3
C7
µC
Res
4
Res
12
C4
C8
100nF 10uF
µC
DRDY/INT2
3
SDO
GND
13
6
NC
SDA
16
0
2
VDD_IO
VDD
1
C6
0.1uF
SCL
3.3V
14
C3
U3A
NC
0
•  Measures Translational •  Measures Rotational
Rates
Accelerations
uC
19 Hardware
•  GPS
•  Barometer
1
3.3Vdc
2
V2
9
GND
VBACKUP
3.3V
C9
1uF
GND
GND
U4A
10
U4B
VCC
EN
8
3.3V
1uF
7
µC
0
µC
3
4
µC
TX
BS
RX
LED
6
NC
5
NC
RXM-GPS-SR
•  Coordinates of Aircraft
Positioning
VDD
SCLK
µC
CAP
DIN
µC
GND
DOUT
µC
CS
µC
C10
SHDN
MPL115A1
•  Altitude, Temperature,
Pressure
•  International
Barometric Formula
20 Hardware
•  Microcontroller
•  XBee
3.3V
µC
µC
µC
µC
µC
µC
NC
U7B
VCC
DIO0
DOUT
DIO1
DIN
DIO2
DO8
DIO3
RESET
DIO6
NC
NC
NC
NC
Associate/ DIO5
PWM1
VRef
µC
ON/Sleep
µC
DTR/Sleep-RQ/D18 DIO7
GND
0
NC
PWM0
Res
µC
NC
DIO4
NC
NC
XBEE Pro
•  Transmission Range of 300 ft
•  At least 23 IO Pins Needed
•  UART Interface
–  SPI Requires 2 Data Lines
•  Air Unit and Ground Unit To
And A Clock Signal
Communicate Between
•  Features: 3 SPI Modules, 65
Microcontroller and User
IO Pins
Remote Control
21 Hardware
•  Ultrasonic Sensor
•  Obstacle Detection
•  6.45m Maximum
Distance with 1 inch
Resolution
•  6 inch Minimum Range
•  UART Connection
22 Additional Hardware
•  Wireless Camera
–  2.4 GHz, transmission range of over 200 feet
–  RCA Ouput
•  Electric Release Valve
–  Versa Valve EZ-2140-0-243-D Electric Solenoid
Blimp
Air Valve
Hose Line
Air Release
Electric Release Valve
Motor 3
Motor 4
23 Mechanical Structure
•  Gondola
24 Software Design
blimp.fly();
25 Software Design - Overview
26 Software Design – Ground System
•  Object Oriented System – C# and .NET
Framework
•  Allows for
– 
– 
– 
– 
Creating a responsive, event driven user interface
Access to serial port (XBee wireless communication)
Interfacing with Xbox 360 controller
Modularity: program understanding, component-based
testing, extensibility, etc.
27 Xbox360 Controller Configuration
Right Trigger: Fly up
(8-bit sensitivity)
Left Trigger: Fly Down
(8-bit sensitivity)
Right Stick: Fly forwards/
backwards (16-bit sensitivity for
each plane)
Left Stick: Pitch/yaw
control (16-bit sensitivity
for each plane)
Back and Start button combination:
trigger electric release valve (Bool)
28 Ground System UML Class Diagram
29 BlimpController Execution Sequence
30 On-Board Interfacing
•  Sensor Interfacing Peripherals
–  SPI
–  UART
•  Communication
–  Data reading
•  Interrupt on available data from XBee
•  Store packet for use with control implementation
•  Hardware handshakes
–  Data sending
•  Timer-based for non-critical data
•  Hardware handshakes
31 On-Board System Control
•  Control System Implementation
–  Convert user commands to desired x-direction velocity,
z-direction velocity, yaw angular velocity
–  Calculate actual pitch angle, x-direction velocity, zdirection velocity, yaw angular velocity (from sensors)
–  Calculate error for each input (desired – actual)
–  Pass each error through difference equation
(compensator) to find Ux, Uz, Upitch, Uyaw
–  Solve system of equations for motor thrusts
–  Convert thrusts to RPM, and output PWM signals to
ESCs to control motors
32 On-Board System Control
•  Additional Logic
–  No user input
–  Ping sensors
–  FAA regulation
33 Software Design – On-Board System
•  ESC PWM for each motor
–  Single Timer
–  Output Compare for each motor
34 What’s Next?
35 Questions/Comments?
36