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VERTIGO2 Preliminary Design Review
ECE Project Team Members
Calvin Turzillo
Duro Taylor
Kevin Boyce
Jeff Laub
Prateek Mohan
Ryan Strauss
Tebo Leburu
Mimi Phan
ECE Coordinator: Mimi Phan
AE Project Team Members
Nikhil Nair
Luke Alexander
CS Project Team Member
Chris Fernando
Project Leader: Luke Alexander
Prepared By: Mimi Phan
Received By: Dr. Ken Ports
On this 1th November 2004
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Table of Contents
_________________________
I. Product Technical Description
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II. Detailed Product Specifications
5
III. Gantt Chart
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IV. Three Design Options
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V. Conceptual Sketches
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VI. Design Selection and Rationale
15
VII. Preliminary Bill of Materials
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VIII. Financial Status
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Product Technical Description
Prateek Mohan
“The first phase of the VERTIGO project saw the analysis and design of the aircraft’s
geometry, its aerodynamics, and its structural integrity. Problems with the initial design
included a poorly designed tilting mechanism, center of mass location, and most
importantly an undeveloped control system. The later design problem was simply due
to time constraints as the original project was very ambitious in its design objectives.
The emphasis of VERTIGO2 is to design the electrical and control systems that will
render the aircraft functional as stated in its original design objectives.”
-
Luke Alexander
(VERTIGO2 Team Leader)
As stated by the previous VERTIGO (Versatile Robotic Tilt-rotor for Information
Gathering Operations) team, the main objective of the project was to develop a plane that
could take-off vertically, make a smooth transition to horizontal flight in mid-air, and
then finally land on the ground in vertical mode. This project is marketable and is
intended for both personal and private use. However, the US military would benefit the
most from this endeavor. VERTIGO could be used for high altitude reconnaissance, and
would be very useful in combat as a deadly intruder for stealthy missions.
The VERTIGO concept was based of Boeing’s V-22 Ospery tilt-rotor vertical take-off
aircraft. Aircrafts were built to fly fast and helicopters were developed for vertical as well
as horizontal flight. VERTIGO incorporates these two concepts in a versatile way. This
plane was conceptualized, keeping in mind the need for a craft that would require very
little runway space or none at all, that could land on any hard terrain, and could fly fast
like a plane. The primary takers for this product would most likely be the US military,
Earth atmospheric research teams, geological research teams, and the like.
Our primary objective is carried over from the previous years VERTIGO team, which is
to successfully take-off the ground, make a smooth transition from vertical to horizontal
flight mode, transition back to vertical flight mode, and then finally land on the ground.
The secondary objectives are minor and involve using the on-board camera for live aerial
feed and sending live flight status of the plane using the sensors on-board. If time willing,
we intend on implementing a GPS system on-board plane, however this is not important.
VERTIGO has two main systems for control and communication purposes: the ground
station and the on-board system. The on-board control and communication system is
complex when compared to the ground station, as it involves receiving critical flight data
from the ground station for flight control and then forwarding these control signals to: the
main DC motors for controlling the speed of the motor and synchronizing the motors to
the same speed and blade position in vertical flight mode, to the flaps on the plane to
control the motion of the plane in horizontal mode. Also, the on-board flight system is
responsible for sending back to the ground station continuous real time flight data, and
live video feed from the on-board camera.
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The preliminary design for the control and communication system for the on-board flight
system was developed by the circuitry team. The on-board system would need to be top
of the line and unique in order to process huge amounts of data with great accuracy. For
this purpose we will be using a PIC with a large memory, large bus speed and a large
amount of I/O pins. The PIC microprocessor would receive data from the primary onboard flight receiver. This data would then be forwarded to a specific sub-system
depending on the input. There are three main sub-systems: the horizontal flight mode, the
vertical flight mode, and the DC motor control. Depending on the assembly language
programming, the input signals for each sub-system will be divided by giving each set of
signals a unique address. The horizontal flight mode system would have a unique address
for its signals, similarly for the other two systems. The live video feed will be provided
by a separate system which will have its own transmitting station on-board. If we decide
to add the GPS system, its data will also be transmitted back to the ground station using
the main PIC microprocessor.
The primary purpose of the ground station is to control the VERTIGO plane, provide
support to process the data received from the plane such as real time flight status, and the
live aerial video feed. An RC controller with at least 16 channels will be used to control
the plane. Reason being so the plane can be controlled by a single user instead of multiple
users. A single computer will be used to receive the live video feed from the plane and
also to view the status of the plane such as altitude, speed, pressure, heading, etc. This
information will be viewed on the computer using either a GUI (Graphical User
Interface) method or a simple display program which will display the live feed separately
and the flight status separately.
Stated below is a recap of the main objectives of this project:
Primary Objectives:
1.
Design and integrate a proper electrical system to ensure functionality
a. Design, build, and program a base station control mechanism.
b. Design, build, and program an on board computer to carry out commands
from the ground station.
2.
3.
4.
5.
Design a simple, sufficient tilting mechanism for the rotor assemblies
Perform laboratory testing to verify aerodynamics and functionality
Achieve vertical flight and vertical maneuverability
Land
Secondary Objectives:
1.
2.
Getting a GUI interface for the ground system computer.
Stage 2 – Perfecting the design once primary objectives have been
accomplished successfully.
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Detailed Product Specifications
Kevin Boyce
The Circuitry:
The ECE team members of project VERTIGO² have decided to undertake an existing
project from 2003-2004. It has been determined that VERTIGO’s goals were very
ambitious given the time constrains of the project. By eliminating the “feature creep”,
our main objective is to create a fully functional control system for the aircraft. We
found that GPS tracking devices and various sensors (altimeter, air speed, and the like)
are not only unnecessary, but also managed to overcomplicate the design. Our plans also
incorporate the idea of a non-modularized design. Such design allows us to make the
entire control system much smaller than before mostly be eliminating 3 unnecessary
microprocessors, and by hardwiring all mechanical devices rather than using bulky
sockets and plugs which allow for easy device replacement.
At one point our system design incorporated the use of an RC controller for the ground
based control mechanism. We have decided to eliminate the RC controller by redesign,
thereby reducing the complexity of the system. This minimizes the time needed to study
the controller and its functions. Instead of an RC controller, we will be using a laptop
computer equipped with a joystick or game pad along with an RF transmitter to signal the
onboard computer in the craft. The serial transmitter operates on a frequency of
433 MHz, has a transfer rate of 9600 baud, using TTL logic as illustrated in Tables 1 and
2.
Inside the aircraft, a PIC 18F, will receive commands via the RF serial receiver. As seen
in Table 3, the 18F has a maximum frequency of 40MHz and a supply voltage of 0 to 5
volts. Utilizing an enhanced flash memory system, total memory capabilities are 9,216
bytes (memory types are broken down as seen in table 3). Communications to external
devices are provided by the 34 input/output pins available, easily connected because to
the dual inline package of the microprocessor. One of the more useful features of this
microprocessor is the built in analog to digital conversion. Analog to digital conversion
allows for the implementation of analog sensors to check the states of various devices
being controlled by the microprocessor, yielding a more accurate control of the overall
system, thereby eliminating errors. As a completely individual system, the onboard
camera will transmit a live video feed directly to a receiver on the ground connected to a
monitor (more in-depth details can be obtained from the table (4) below.
The Programming:
Ryan Strauss
The software level of this project consists of two parts. The first part is the Graphical
User Interface (GUI), which is the program(s) that the pilot will use to control the
aircraft. The second part is the programming of the interrupt controller (PIC), which will
control the movements of the aircraft based upon the pilot’s instructions.
The GUI will be created by implementing a C++ serial and joystick library. More
specifically, each library has a basic, important function. The serial library is used to
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facilitate the transfer of information read from the joystick device and output the
necessary signals to the PIC via the serial transmitter. The joystick library is
correspondingly used to poll the joystick device for its current position, which is used as
a reference to adjust the aircraft's position appropriately.
The PIC microcontroller will be programmed using PIC Basic, which is a programming
language that is specifically designed to manipulate the PIC. The PIC will act as an
intermediary between the pilot and the motors/flaps of the aircraft. It will accomplish
this by receiving signals from the laptop controller and sending out the correct signals to
the motors and flaps on the plane. To implement this, the PIC will have to continuously
poll each input port for a signal from the laptop (via the serial port). Once the PIC
receives a signal or signals from the laptop, it will then send a signal to the corresponding
motor or flap to move.
To help differentiate distinct signals and to ease flight operations, the PIC will operate in
two modes. The first mode is the vertical mode, which is used mainly for take-off and
landing. The second mode is the horizontal mode, which directs the travel of the aircraft.
Besides polling different input ports, each mode will also control the position of the
propellers on the aircraft. The use of two separate modes will also allow for a more
dynamic joystick control because one movement of the joystick can now do two separate
aircraft maneuvers.
Product Device
Wireless Serial Transmitter
Specification
Frequency
I/O Transfer Rates
Range
Supply Voltage
Approx board size
Connection
Serial Data Interface
Details
433 MHz
9600 baud
75m (250 ft)
+5 v
~3.25 in x 1.25 in
Single Pin serial connection
RS-232 (Max 232A)
Table 1: Serial Communications
Product Device
Wireless Serial Receiver
Specification
Frequency
I/O Transfer Rates
Supply Voltage
Approx board size
Range
Connection
Serial Data Interface TTL
Details
433 MHz
9600 baud
+5 v
~3.25 in x 1.25 in
75m (250 ft)
Single pin to microcontroller
RS-232 (Max 232A)
Table 2: Serial Communications
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Product Device
PIC18F4431
Specification
Maximum Frequency
Memory Type
Program Memory Size
EEPROM Size
RAM Size
I/O Pins
Package Style
PWM Signals
A/D Conversion
Details
40MHz
Enhanced Flash Memory
8,192 bytes
256 bytes
768 bytes
34
Dual Inline Package
8
10-bit
Table 3: The Microprocessor
Product Device
Wireless Camera w/ receiver
Specification
Frequency
I/O Transfer Rates
Supply Voltage
Approx board size
Weight
Connection
Serial Data Interface
Details
2.4 GHz
Table 4: Other Devices
Gantt Chart
Mimi Phan and Luke Alexander
Please refer to Appendix 1 for the overall team Gantt chart, and Appendix 2 for the
internal ECE schedule sheet.
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3 Design Options
Mimi Phan
Each and every component plays a vital role in the overall product whether it is
associated with the functionality of the aircraft or the control system. The previous
VERTIGO team made decisions on various design options, and found out whether or not
they were good choices in the end. VERTIGO² has studied the previous team’s design.
We found what design choices worked well along with the ones that did not. With that,
we have decided to incorporate some aspects of the previous year’s design with our new
ones. These new ideas are design ideas that may solve the problems encountered by the
previous project team.
Design Option 1:
Chip Selection
Mimi Phan
Deciding on what kind of PIC to use plays a major role in the production of the
VERTIGO² control system. The PIC is the basis of the control system. We will wire the
PIC to the necessary components of the plane and etc. The brain will be programmed
with all the necessary control operations using PICBASIC programming language.
The PIC should have the capability to operate ten different servos that are located in
various parts of the aircraft, the stepper motor with gear mechanism, and two motor
controllers.
16F vs. 18F
PIC 16F Family
The team has the option of choosing from two different PIC families. The first of these is
the 16F PIC. A PIC from the 16F family has been taken in consideration mainly for its
ease in programming. Anyone who is a beginner to programming or working with PICs
is usually recommended a 16F PIC. Even with the ease of programming, there’s always
a catch. In this case, a 16F PIC can only be programmed using 35 RISC instructions.
With the instruction limitation, one may have to do a little bit more research before
choosing to use a 16F PIC. The max frequency that a 16F PIC can handle is 20 MHz
which could potentially cause a problem with delays. With the PIC, an EEPROM would
be required if more memory is used. A 16F family PIC also only has 2 PWMs as well as
standard Flash memory design.
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Material Quantity Price
16F PIC 1
$9.58
Total
$9.58
Table 5: Cost of 16F PIC
Pros: Since the majority of the programmers on the team don’t have much experience in
programming a PIC, a 16F PIC would be an ideal chip to work with due to its ease of
programming.
Cons: The previous VERTIGO ECE team encountered various problems with using the
16F PICs due to their limitations. The 16F PIC only has 2 PWMs. The team stated that it
would have been more beneficial to have more PWMs per chip than the 16F was
restricted to. The complexity of the aircraft controls, more PWMs were required which
in turn required the team to use more PICs. Also, the 16F PIC could not handle
frequencies more than 20 MHz, which might cause delay issues with the control system.
PIC 18F Family
The second PIC family has a lot more to offer than the 16F. While the 16F family is
easier to code, an 18F PIC is more complex when it comes to programming. Even
though the programming may be a little more complex, there isn’t any limitation to it as
the 16F PIC. One can program 18F PIC using software such as PICBASIC. There is
also second or third party software in C or Java that can be used to program the chip. If
our programmers aren’t proficient in Basic, they can always program in one of the other
languages. An 18F PIC has an edge over the 16F in many ways. It can withstand a max
frequency of 40 MHz, and manages to consume less power (using nano-watt technology).
Plus, it has more memory and doesn’t require the use of an EEPROM. In addition, an
18F PIC has the capability of performing serial and I²C communication.
Material
Quantity Price
18F PIC (PIC18F4431) 1
$9.58
Total
$9.58
Table 6: Cost of 18F PIC
Pros: An 18F PIC has many advantages over the 16F PIC. Due to the complexity of the
control system, it is ideal to have more PWMs on a single chip. The previous VERTIGO
team suggested that a PIC with at least 8 PWMs to be used for the control system. In this
case, an 18F PIC has 8 PWMs built on. It also has an advantage of having more overall
memory. With more memory, an EEPROM will not have to be used. This definitely
saves the trouble of having to incorporate the EEPROM with the PIC.
Cons: The only disadvantage to using the 18F PIC is the complexity of programming.
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1 PIC vs. 2 PICs
The team has been weighing the benefits of running the entire system off of one PIC or
two PICs. Again, the PIC will need to control a total of ten servos located at different
parts of the plane, a stepper motor, and two motor controllers.
Pros: The advantage in using one PIC instead of two of them is weight reduction. The
previous team was plagued with weight issues. A PIC requires a number of battery cells
to power up. This means that the more PICs you use, the more batteries are needed.
With all the weight of the batteries inside of the aircraft, other problems (issues with lift
and etc) arise.
Cons: The only disadvantage to using one PIC is not having enough resources to control
every aspect of the aircraft. With two PICs, it may be difficult in having the PICs
communicate with one another.
Jeff Laub
1 PIC (All Servo’s controlled by 1
PIC)
Servo
Servo
Servo
Servo
Servo
Servo
Servo
Servo
Servo
PIC
Servo
Servo
Servo
Figure 1: Block Diagram of Single PIC Configuration
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PIC
Figure 2: Block Diagram of Dual PIC Configuration
Design Option 2:
Control Input Device
Tebo Leburu
RC Controller
The controller takes input from the user through the gimbals, encodes it, and then sends it
to the onboard aircraft controls through a receiver. By adjusting the gimbals, the user
provides information to how the aircraft should move. The information is transmitted as
signals through an antenna utilizing either AM or FM radio frequencies to a receiver on
the aircraft. Then onboard computer takes over, and controls the aircraft using the input
signals
Controller
To aircraft controls
Onboard
Receiver
Figure 3: Block Diagram of RC controller
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Material
Quantity Price
R/C aircraft Controller 1
$200.00
Total
$200.00
Table 7: Cost of R/C Controller
Pros: The RC aircraft controller would be easy for the pilot to use without any further
research.
Cons: The team would run into difficulties programming the RC controller along with
the interface of the on-board flight system. Also, the RC controller would have to be
taken apart to determine capability. With the use of the RC controller alone, the team
would not get live, visual feedback from the aircraft.
Game Console Controller (Joystick)
The system works by sending analog control signals to the computer. These signals are
translated digitally before being sent to the aircraft controls to generate required motion.
The computer picks up the signals by monitoring the control signals wires of the joystick.
Wires then open and close according to the motion that is being applied to the joystick.
In turn, the computer reads the information and interprets it. Then it forwards that
information to the onboard computer.
To the aircraft
Joystick
Laptop
Figure 4: Block Diagram of Laptop w/Joystick
Material
Quantity Price
Game Console Controller 1
$80.00
Laptop
1
$1500.00
Total
$1580.00
Table 8: Cost of Laptop w/Joystick
Pros: The laptop is running function code to the PIC. The joystick nor the computer
need to be programmed. The joystick is going to be function calls to the PIC through the
computer.
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Cons: The pilot of the aircraft may have trouble using the laptop with joystick
configuration.
Stepper Motor vs. Linear Actuator (Tilt Mechanism)
Luke Alexander
One major task of importance that will ensure success is to design a sufficient means of
transition between flight modes. Preliminary design alternatives to this task include
using one linear actuator to perform work on the transition shaft instead of four giant
servos that had to be linked and precisely matched to function properly. The introduction
of the linear actuator would lessen the complexity of the previous configuration by
replacing two radial displacements, one motion for each pair of linked servos, with one
simple linear motion without the clutter of extra linkages and electric interfacing. The
problem with the linear actuator is that a horizontal motion must be translated into a
radial motion. This can only be achieved by designing the actuator anchor point to rotate
in order to keep the actuator arm equidistant from the axis of rotation. Also, the linear
actuator arm requires a significant distance to ensure its maximum displacement. This
presents a problem when the fixed geometry of the aircraft is considered.
Another design alternative, and the most feasible, is to use a stepper motor and a worm
gear system to drive the transition shaft. A Worm gear can be attached to a connecting
collar that will be attached to each transition shaft—one for each rotor. The drive gear,
called the worm, would be attached to the stepper motor which would be permanently
mounted inside the aircraft. This type of setup would eliminate the mess of the original
VERTIGO design and would also allow for radial position referencing. The use of the
worm gear will allow a mechanical advantage since now the output torque can be
adjusted by tuning the gear ratios accordingly. A simple sketch of this idea is illustrated
in the figure above. This design will allow a simple means of transitioning while
providing adequate torque with a low weight impact.
Figure 5: Stepper Motor Design
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Material
Quantity Price
Stepper Motor 1
$169.95
Total
$169.95
Table 8: Cost of Stepper Motor
Conceptual Sketches
Calvin Turzillo and Luke Alexander
Figure 6: Conceptual Drawing of the VERTIGO aircraft
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Figure 7: Conceptual Sketch of VERTIGO Aircraft in Air
Design Selection and Rationale
Ryan Strauss and Duro Taylor
Our main goal is to create a system that will allow the VERTIGO aircraft to fly. To do
this, it is important to make the control systems as simple and error free as possible. The
team has researched the previous year’s design. We have decided to incorporate some
aspects of their design with ours. Last year’s VERTIGO team had a great vision for the
project. In the end, this vision proved to be too overwhelming. This year we want to
stress a simpler design in order to make the aircraft successful.
We chose an 18F PIC over the 16F family because of two main reasons. The first reason
is that the 18F uses PICBASIC, which would make it easier to program than by using the
35 PIC assembly instructions. The second reason is that the 18F has more overall
memory than the 16F. The 18F also has a maximum frequency of 40MHz while the 16F
has a maximum frequency of 20MHz. This means that it will process commands quicker,
which will enable the pilot to better maneuver the aircraft. We chose to use one PIC
microprocessor instead of two because of the difficulty in making multiple PICs
communicate with each other. In addition, it makes the overall system smaller. Even
though it would be easier to program the two flight modes (one on each PIC), it is still
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easier to program the two flight modes on a single chip. One chip also requires less
power than two chips, which means that we do not need to load the plane with the weight
of extra batteries.
We chose to use the laptop with joystick instead of the wireless remote control. Due to
our time constraints, it would be impossible to take apart the radio controller and
reprogram it to fit our needs. By using the laptop with joystick, it becomes easier to
program the interface between the pilot and the aircraft.
Preliminary Bill of Materials
Item
PIC Microcontrollers
Serial Reciever
Pilot Interface
Laptop
Joystick
Software
ECE Materials
Wires
Nuts/Bolts
Solder
Prototype Boards
Servos
Motor Controls
Serial Transmitter
Printed Circuit Boards
Stepper Motor
Total
Mimi Phan and Luke Alexander
Quantity
5
1
Price
$9.58
$200.00
Cost
$47.90
$200.00
1
1
1
1
$1500.00
$70.00
$100.00
$250.00
$1500.00
$70.00
$100.00
$250.00
Vendor
Microchip
CompUSA or Best Buy
RadioShack
RadioShack
RadioShack
4
2
1
2
1
$40.00
$240.00
$200.00
$80.00
$169.95
$160.00
$480.00
$200.00
$160.00
$169.95
$3337.85
$1837.85
without
laptop
Table 9: Bill of Materials
Financial Status
Mimi Phan
Funding plays a major role in the success of the VERTIGO² project. Without proper
funding, the team will not have to monetary resources to purchase the materials to
complete the project. Luke Alexander, the project lead, is currently working on gaining
funds and sponsors for the project. We are hoping to have the same sponsors from the
pervious project as well as some new ones. As of right now, the team has a guaranteed
amount of $250 each from the ECE and AE/ME departments. We still have to acquire
more funds in order to make this project work.
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Another factor that plays a major role in the success of the project is teamwork. Without
the support and effort of each individual team member, the project would fail. From the
numbers shown below, the hours performed by each team member seems very low. It
was indeed lower than expected. The low numbers are due to many reasons. The
VERTIGO team did not become official until a couple of weeks after the semester
started. The hurricanes that our area encountered also contributed to the low work hours.
Most members did not have electricity or Internet during this time. One or two members
were out of town during the hurricanes. Also, there were some occasions where some
team members didn’t send activity reports. That also played a role in the low work
turnout.
The budgeted hours are based on 8 hours per week. As of right now, the total for
budgeted hours is 32. This is based off of four weeks.
Name
Mimi Phan
Kevin Boyce
Jeff Laub
Tebo Leburu
Prateek Mohan
Ryan Strauss
Duroseme Taylor
Calvin Turzillo
Total
Hours Worked
30.5
6
4
9
15
12.75
11
12
99.5
Hours Budgeted
32
32
32
32
32
32
32
32
256
Table 10: Hours Worked Vs. Hours Budgeted
Percentage Worked
95.32%
18.75%
12.5%
28.12%
46.86%
39.84%
34.38%
37.5%
39.16%