P09233 Master File
Michael Skube - Mechanical Engineer (ME)
James Hunt - Mechanical Engineer (ME)
Joseph Peters - Electrical Engineer (EE)
Kevin Li - Electrical Engineer (EE)
John Isely - Mechanical Engineer (ME)
William Atkinson - Mechanical Engineer (ME)
Heidi Morgan - Electrical Engineer (EE)
1
Table of Contents
Section A
A.1
P09233 Introduction
A.2
One Page project Summary
Section B – Sensor Documentation
B.1
Airspeed Sensor
B.1.1 Device description
B.1.2 Design Specification
B.1.3 Pugh Analysis
B.1.4 Components Specification
B.1.5 Test Plan
B.1.6 Test Results
B.2
Altitude Sensor
B.2.1 Device description
B.2.2 Design Specification
B.2.3 Pugh Analysis
B.2.4 Components Specification
B.2.5 Test Plan
B.2.6 Test Results
B.3
GPS Sensor
B.3.1 Device description
B.3.2 Design Specification
B.3.3 Pugh Analysis
B.3.4 Components Specification
B.3.5 Test Plan
B.3.6 Test Results
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B.4
IMU Sensor
B.4.1 Device description
B.4.2 Design Specification
B.4.3 Pugh Analysis
B.4.4 Components Specification
B.4.5 Test Plan
B.4.6 Test Results
B.4.7 Final Design
B.5
Microprocessor
B.6.1 Device description
B.6.2 Design Specification
B.6.3 Pugh Analysis
B.6.4 Components Specification
B.6.5 Test Plan
B.6.6 Test Results
B.6
Components Box
Appendix
Section 1
Airspeed Sensor
1.1
Device Manuals
1.2
Pugh Analysis
1.3
Test Results
Section 2
Altitude Sensor
2.1
Device Manuals
2.2
Pugh Analysis
2.3
Test Results
Section 3
GPS Sensor
3.1
Device Manuals
3
3.2
Pugh Analysis
3.3
Test Results
Section 4
IMU Sensor
4.1
Device Manuals
4.2
Pugh Analysis
4.3
Test Results
Section 5
Microprocessor
5.1
Device Manuals
5.2
Pugh Analysis
5.3
Test Results
Section 6
Assembly
6.1
Box Part Drawings
6.2
Box Assembly Instructions
6.3
Pitot Tube Assembly Instructions
6.4
Wire Assembly Instructions
Section 7
Bill of materials
7.1
Individual Box BOM
7.2
Complete Project Cost
4
Section A
A.1
The mission of the Measurements group is to provide a means for measuring and
calculating all the necessary parameters for the flight of Unmanned Aerial Vehicles.
Primarily through the use of superior measuring devices, and accurate dynamic
characterizations. We strive to provide accurate data from our measurement systems
for in-flight control and monitoring. We strive to exceed engineering standards while
encouraging an environment for intellectual growth.
Specific roles and responsibilities or varying team members will be divided according to
academic major and specialty.

Mechanical Engineer
Dynamic Characterization (Fluid/Structural); Sensor Design and Placement;
Sensor Testing and Calibration

Electrical Engineer
DAQ; Power Management; GPS Implementation; Sensor Design and Placement;
Sensor Testing and Calibration
The work done will allow other teams in the R09230 - Open Architecture, Open Source
Unmanned Aerial Vehicle for Imaging Systems Roadmap to control and monitor the
airframe for continual safe flight. Initial testing will be done in the wind tunnel, or on
basic test frames provided from other groups, the final measurements system will be
integrated into the primary airframe and will directly interface with the on board control
system.
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A.2Senior Design Project Data Sheet
Project #
Project Name
Project Track
Project Family
P09233
Airframe Measurements
Vehicle Systems and
Technologies
R09230
Start Term
Team Guide
Project Sponsor
Doc. Revision
20082
Dr. Jason Kolodziej
RIT ME Department
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Project Description
Strategy & Approach
Project Background:
Assumptions & Constraints:
The long term goal of this project is to create,
field and implement a full system of
measurement devices that will be used to control
an unmanned aerial vehicle. This will be the first
quarter that the project is being worked on, and
the primary goal will be to implement off the shelf
measurement devices to characterize the
necessary parameters for in-flight control of an
unmanned aerial vehicle.
1.
2.
3.
4.
Access to necessary testing equipment.
Group knowledge of all aspects required for
the completion of the project
Access to necessary calibration tools.
The budget needs of the group as stated in
DPM will be available (~$2860.00).
Issues & Risks:
Project Issues/Risks/Constraints
Problem Statement:
The project will combine several sensors to
measure the fundamental parameters of in-flight
movement
to
calculated
the
nessassry
information to sustain flight. The project will
deleiver this data in a user friendly interface.
Objectives/Scope:
1.
2.
3.
Measure real time position of test platform
Measure flight parameters
Ensure measurements are accurate and
reliable
Deliverables:



- Project Knowledge

New Project

New Area of Study for Some
- Available Resources

Obtainin Resources

Ordering Parts

Lead Times

Meeting Time
- Understanding all of the Nessassary
Measurements Needed for In-Flight Control

Getting up to Speed on Sensor
Implementation

Using Hardware/Software
Test platform that can measure the
characteristics need for in-flight control
Processed data for use in a control system
Documentation of the calibration and use of
the test platform
Expected Project Benefits:


Inexpensive and reliable measurements
platform.
Basis for future Senior Design development.
Core Team Members:







Michael Skube – Team Lead
James Hunt – Team Lead
Heidi Morgan
John Isely
Joseph Peters
Kevin Li
William Atkinson
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B.1.1 Airspeed Sensor
The Pitot - static tube is used to measure the velocity of the object the Pitot tube is
attached to, through a fluid. For most applications that fluid is air and for this the project
that is also the case.
A Pitot tube works by measuring the Total or Stagnation Pressure, P o, which is
measured at a hole pointing directly into the flow that creates a stagnation point; and the
Static Pressure, P, measured through a port that is perpendicular to a given flow. The
operational range of a Pitot tube and especially for this project, the Bernoulli Equation
(Eq 1.) can be used to calculate the velocity of the craft from the measured Total and
Static pressures from the Pitot tube. The Bernoulli Equation is valid because of four
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assumptions: 1) The flow is along a Streamline; 2) The flow is inviscid; 3) The flow is
steady; 4) The flow is incompressible. The fourth assumption had to be checked
because of the speeds that the UAV was going to be flying at (0 – 50 mph). For the flow
to be considered incompressible, the speed of the flow must be less than or equal to
three tenths of the speed of sound (≤0.3a). To find the speed of sound the equation a =
(γRT)1/2 was used and the speed of sound was found at two extremes, the summer and
winter in Rochester, NY. In the summer, a was found to be 349m/s, meaning the
compressibility limit was 104.7m/s or 234.2mph. During the winter, a was found to be
327.2m/s, giving a compressibility limit of 98.2m/s or 219.6mph. The UAV is flying at a
speed well below these two limits, therefore the flow can be treated as incompressible
and the Bernoulli Equation is valid.
𝟏
𝝆 𝑽𝟐
𝟐
Eq 1. – Bernoulli equation to calculate velocity, V
𝑷𝒐 = 𝑷𝒔𝒕𝒂𝒕𝒊𝒄 +
In most Pitot tubes today, there is temperature compensation. This means that the Pitot
tube is measuring the Total Temperature of the flow through the total pressure port,
which Tstatic can be found from. With most applications and this project the working fluid
is air and that can be considered an ideal gas, therefore the ideal gas equation (Eq. 2)
can be used to find the density. This density can then be used in the Bernoulli equation
the find velocity.
𝑷𝒔𝒕𝒂𝒕𝒊𝒄
𝑹𝑻
Eq 2. – Ideal Gas Equation to find density, ρ
𝝆=
The Pitot tube is important because it provides the pilot or the control system with the
important measurement of velocity. The velocity measurement is important because the
pilot or the control system needs velocity to help them navigate, find aero coefficients
that are dependent on velocity, for example coefficient of Drag and Lift, for the control
system, flight times (e.g. ETA or time to a waypoint), and fuel consumption. This makes
the Pitot tube an important part of this project because it will be one of the important
sensors that will help make this UAV autonomous.
B.1.2 Design Specification
The main requirement that is expected out of the Pitot tube is velocity, whether it is
velocity or a voltage that can be converted to a velocity. The next set of design
requirements involves physical attributes, power requirements, and inputs. The design
requirements for a suitable Pitot tube are as follows:
1. Weight 1 oz. or less
2. Smaller than 1” x 1” x 1” for a chip and no longer than 6” for Pitottube
3. Capable of measuring both static and dynamic pressure
4. Measure Speeds from 0 to 100 mph
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5. Resolution of ± 1 mph
6. Input voltage of 3.3V
7. Sample rate of no less than 1 sample/second
These design specs (1, 2, 4) came from the customer (Airframe B, P09232) in which the
sensors had to be light and small, so as to leave more room and weight for the payload
that the UAV is to carry. Some of them also can from the MCU (Microcontroller Unit),
which uses 3.3V (6). Other design specs (3, 5, 7) were set by the team thinking from the
point of view of the control systems team; in this case the MAV Controls team was
consulted, P09122.
B.1.3 Pugh Analysis
After the different types of sensors were laid out as to what was needed to fly a UAV,
each member picked and then researched that sensor. In regards to the Pitot-tube,
there were three Pitot-tubes that fit the bill of being capable of meeting the customer
needs. These three Pitot-tubes are, in no particular order: 1) Eagle Tree Systems
Airspeed Microsensor; 2) Eagle Tree Systems Airspeed Microsensor w/ eLogger; and 3)
Space Age Control Pitot-Tube 300933.
The first step in the Pugh Analysis is the Concept Screening Matrix. The selection
criteria in the Concept Screening Matrix was based on what the team as a whole felt
was most important to accomplish the customer’s needs, along with one or two extra
selection criteria’s that were important to that individual sensor. For the Pitot-tube, the
individual sensor selection criteria’s are Airspeed, Live Data, and Calibration. Using the
standard Eagle Tree Systems Airspeed Microsensor as the reference, each sensor was
given a “+”, “0”, or “-“, depending on how it measured up to the reference sensor. After
this was completed, the Space Age control Pitot-tube was dropped and the two Eagle
Tree Systems Airspeed Microsensors moved on to the Concept Selection Matrix. The
main reason that the Space Age Control Pitot-tube did not move on was the fact that
this was just a shell of a Pitot-tube. To make this a functioning Pitot-tube, pressure
transducers, temperature transducers, tubing and wiring would be needed and bought
separately. This greatly increased the cost, as a single pressure transducer was more
expensive than the Eagle Tree Systems Airspeed Microsensor.
In the Concept Selection Matrix, the same selection criteria were used along with the
individual selection criteria for each individual sensor. The difference is that in the
Concept Selection Matrix, a percentage out of 100% is given to each selection criteria.
These percentages were discussed and decided upon as a team. Then each sensor
was rated, 1 through 5 on each selection criteria and then weighted according to the
percentage assigned to that selection criteria. Once each selection criteria was
weighted, they were added up and the sensor with the highest score was chosen. The
sensor that was on top was the Eagle Tree Systems Airspeed Microsensor w/ eLogger.
The reason that the other Eagle Tree System was not picked was mainly that the two
Eagle Tree Systems are the same Airspeed Microsensor which only measures max
velocity. With the addition of the eLogger, the capability of the Airspeed Microsensor is
greatly increased because the eLogger with the software packaged with the eLogger,
allows the storage and analysis of data, along with real time telemetry.
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The Eagle Tree Systems Airspeed Microsensor w/ eLogger is the best system because
it is ready to go out of the box, directly outputs velocity, is able to store and analyze
data, real time telemetry capability, very small and very light. It is also a complete kit
which helps with troubling shooting and interfacing issues. The Pugh analysis can be
seen in section 1.2 of the appendix.
B.1.4 Components Specification
In the appendix there are more detailed specs as to what the eLogger and Airspeed
Indicator can handle, how they work, and what they output. To use the Airspeed
Indicator and the eLogger, all that needs to be done is to simply connect them together
as shown in the manuals. From the Pitot-Tube, there is a Static port and a Pressure
port. Using the tubing that came with the kit, the Static Port is connected to the minus
sign on the Airspeed chip and the Pressure port is connected to the plus sign on the
Airspeed chip. Then the chip can just be directly connected to the eLogger following the
pattern displayed on the eLogger.
Once this is done the eLogger can be connected to the planes battery for standalone
power or connected to a computer with the eLogger software by USB. When the
eLogger is connected directly to a computer, live telemetry can be viewed while the
eLogger still records data. The Airspeed chip itself directly output velocity to the
eLogger and the eLogger records data anywhere from 1-10 samples a second
depending on what the user desires.
Mounting is simply done with a clamp to hold the Pitot-tube and the Airspeed chip and
eLogger can be placed on small plates that can be placed where they are needed.
To use this device, simply power the eLogger through the plane’s battery or a computer.
This device is not sensitive to anything, vibration, EMF, or temperature. Plus this device
never has to be calibrated before each test. With the temperature measurement that the
Airspeed chip takes, the airspeed is calibrated for the current local atmospheric
conditions. In terms of maintenance and cost, there is no maintenance that needs to be
done for this device and if it breaks, the best course of action would be to by a new
system since it is already fairly inexpensive.
B.1.5 Test Plan
There are four tests planned to test and verify that the Eagle Tree Systems Pitot-tube
works as claimed and is accurate.
Test #1
Wind Tunnel Test of ETS Pitot-Tube in small and large wind tunnel at RIT. This will be
done against a hot wire probe, pressure transducers, and/or and anemometer. This test
will help to verify that ETS Pitot-tube is accurate; can hold a steady velocity reading
without outside noise, like wind; and find the lower limit of the Pitot-tube, ETS claims 2
mph. This test will be done against observations not time.
10
Test #2
“Car test” of ETS Pitot-tube against anemometer. This test will help to see the Pitottube’s delay through live telemetry, also how the Pitot-tube is across changing speeds
and higher speeds, along with the addition of possible winds, angle of attacks and side
slip angles to check that the Pitot-tube will work with these angles. This will be done on
a car with the Pitot-tube pointing forward directly into the flow, along with the
anemometer. Both will be fixed to the outside of the vehicle. One person will drive and
call out when to record, while one person records the live data off of the computer with
the ETS system attached while another person records the data off of the anemometer.
This test will also be against observations not time.
Test #3
This test is a time delay test. With a certain length of tubing there is going to be a
certain time delay as the column of air in the tubing changes and that change is picked
up by the Airspeed chip. It is important to determine this time delay to know how much
tubing can be used to achieve a reasonable time delay. This is also important for the
future knowledge of the Controls Team so they can account for or if necessary, change
the length of the tubing to achieve a desired and acceptable time delay.
Test #4
This will be the final test and will take place in Airframe A. This is an integration test of
all the sensors that will be placed in the “Sensor Box.”
Test #5
Velocity comparison between the GPS and ETS Pitot tube. This will help to determine
how closely related the two velocities are and if they can be considered redundant
systems, with one being possibly eliminated for the sake of weight and simplicity.
B.1.6 Test Results
Test #1 - Small Wind Tunnel at RIT
This wind tunnel can only go up to 5 mph. This was perfect to test the lower limits of the
Pitot-tube. The benchmark for this test was the anemometer. Table 1.3.4 in the
appendix shows the results of this test.
When the speed was below about 5mph, the Pitot-tube was having trouble making a
consistent reading. This is most likely due to the fact that to Pitot-tube is reaching a stall
point and cannot accurately read the velocity. This is not a problem due to the fact that if
the plane is flying this slowly, it has already stalled and will nose dive and pick up speed
above this level. However this test does confirm that the lower limit is 2 mph ± 1mph as
claimed by ETS.
11
Figure 1.3.6 in the appendix shows the test results for the big wind tunnel. This wind
tunnel could go up to 120 mph, so it helped to see where; if at all the ETS Pitot tube had
an upper limit. This was not the case, as the Pitot-tube was able to go all the way up to
120 mph with no problems and match the hot wire probe step for step as the speeds
were increased and then decreased. There are some slight variations between the two
data sets, which is most likely due to the fact that the hot wire probe mount was slightly
at an angle and not directly perpendicular to the flow.
Test #2 - Car test
The car test, shown in the Figure 1.3.5 in the appendix, shows how well the Pitot tube
measures up against the anemometer. This test showed that the Pitot tube can react
very well to changes in velocity and do it accurately. The reason for some of the error is
the fact that the anemometer at times would "stick" when taking a reading and also the
fact that the two sensors were on opposite sides of the vehicle. This could lead to one
sensor being "shielded" from crosswinds or changes in direction of the vehicle leading
to slight differences in values.
Test #3 - Time Delay Test
Figure 1.3.1 in the appendix shows the theoretical time delay for a worst case scenario
where tubing has to be run down the entire length of the wing, in this case 5ft. It can be
seen that the time delay with a step input into the system (linear ODE used in StateSpace) is on the order of tens of nanoseconds. Therefore the time delay can be
assumed to be zero according to the theory.
Figure 1.3.7 in the appendix shows the actual test data for the Pitot Tube Time Delay
Test. In this case the time delay was found to be, on average of 0.01 sec. The
discrepancy between the two is mostly due to the fact that the release of the end of the
Pitot Tube was not entirely instantaneous as is the step input modeled in the theory.
12
B.2.1 Altimeter
This device will be used to measure static pressure at a constant rate in order to output
the airplanes altitude in real time. The altimeter will have a crucial role in autonomous
flight and prevention of crashes due to flying too low for optimal flight conditions. The
altimeter will also have a function related to the relative height of the imaging equipment
to be used in a later project to take aerial photographs.
B.2.2 Design specifications
During weeks 1 and 2 of MSD1, our team’s main goal was to directly identify what
sensors would be needed for completely autonomous flight. A rough list of the main
components was assembled and each team member was given a sensor to research.
13
The altimeter device will output data directly to the microprocessor and will be analyzed
in real time in order to keep the plane at the desired altitude for different functions
including but not limited to a safe flying altitude and required height for appropriate
image capture as outlined by the imaging science senior design team. The initial
function of the altimeter for project P09233 will be to gather a streaming set of data
points that accurately plot the airplanes flight path through the sky. There were a few
different types of altimeters on the market ranging from model RC plane altimeters to
full size aircraft altimeters. Due to the size constraints of airframe B as well as the cost
in acquiring a full size mechanical altimeter, which was much higher and out of our
budget range, the full size altimeter option was not really possible; this left only the RC
plane altimeters.
B.2.3 Pugh Analysis:
After much searching online, the best options for recording altitude for a plane the size
of Airframe B were found. Each altimeter is listed along with its specifications in section
2.3 in the appendix.
Each altimeter had its pro’s and con’s, but in general, they were all roughly the same
size and weight, but with increasing cost, the capabilities of the altimeter also
increased. The main thing that the altimeter must do is to record altitude data live, and
it must be able to output this data to our microprocessor, so that in the future, the data
can be used in flight to analyze how the airplane is moving. The size, weight, power
draw, sampling rate, and accuracy (within reason) were all secondary to the ability to
output the data recorded in real time.
The Pugh analysis, located in the appendix section 2.3, shows the process used for
choosing the altimeter. The ram3 was initially thought to be the best fit for the project,
and was therefore made the reference sensor. In the first part of the Pugh analysis, we
see that the “How High” and “Eagle Tree stand alone altimeter” were poor at interfacing
with the computer and did not record live data, only max height. These were easily
eliminated. In the second phase of the Pugh analysis, weights were given to certain
assets that the altimeters have. Cost, size, weight, interface, resolution, and power
consumption received their weights as part of a group analysis of what would matter for
the project as a whole, not necessarily for each component. The sampling rate,
calibration, and live data weights were decided based on what would be needed for the
altimeter and were different for each sensor. The ram3 and the zlog both had roughly
the same price tag, and the eagle tree eLogger was being purchased for a different
sensor already, so the total cost for the just the altimeter sensor dropped considerably
when you factor that in. The ram3 and Zlog both had accuracy <1ft, while the eagle tree
sensor had only accuracy <1meter. The main concern overall is the interface with
computers for testing, and with the microcontroller for in flight data recording. All three
of the sensors will interface with the computer, but only the Zlog altimeter has the ability
to output the data live, the other two altimeters flight data is stored to the device and
must be pulled later by computer.
14
After the Pugh analysis, it is clear that the Zlog is the best altimeter for this project, it is
small, light, and accurate, and records data live, and has the ability to interface with our
micro controller. This altimeter was purchased before Christmas. At the advice of Dr.
Kolodziej, the eagle tree systems altimeter was also purchased. It had such a low cost
compared to the Zlog and since we had already ordered the eLogger system for the
airspeed sensor by the same vendor, it was decided that we should purchase and test
the sensor as well.
B.2.4 Components Specifications:
The Zlog altimeter is ready to go out of the box. In normal use the sensor will be
powered directly from the aircraft’s power supply, but in our case, we will draw power
from the microcontroller. The Zlog was purchased mainly for its ability to gather data
live and output it while in live data mode via an usb or serial cable. We will use this
feature to output the data directly to the microcontroller instead of a computer. The
microcontroller will store all outputted data on the SD card. Until the microcontroller is
up and running, the Zlog altimeter also comes with a usb cable and recording software
so that we may test the sensor before the measurement box is put in the air. The Zlog
requires there be at least 0.25 in2 area open to atmospheric conditions in order for the
pressure sensor on the altimeter to accurately measure static pressure. This is a
concern, but due to how most model aircraft are constructed, as well as the way that our
box will be constructed, there will be more than enough open surface area exposed to
atmospheric conditions. We can easily use double sided tape or other adhesive to
mount to the measurements box without worry of device failure. The manufacture
normally suggest wrapping the device in bubble wrap or other similar cushioning device,
but our measurements box will have ample cushioning and shock absorption to make
any extra unnecessary. The Zlog altimeter is zeroed every time it is turned on. So each
test the device can be zeroed for atmospheric conditions and the altitude recorded will
be the altitude from the ground, not sea level. The manual and specification sheets for
the Zlog can be found in the appendix.
The Eagletree systems altimeter currently requires the use of the eLogger to capture
and store live data. Our goal for this sensor will be to use the microcontroller as a
replacement for the eLogger and be able to store data from the altimeter live just as the
eLogger would. Again, since the microcontroller isn’t functioning as of now, we also
have purchased the eLogger system in order to do initial tests on both the altimeter and
the airspeed sensor. The eLogger system allows us to use the included data
acquisition program with a computer to store data directly to a hard drive for initial tests.
The eagle tree altimeter also can be mounted very easily directly in the measurements
box in a similar way to the Zlog, but we also have the added possibility of mounting the
altimeter directly to the static port on the back of the Pitot tube thus sharing the static
port with the use of a t fitting. The advantage to this would be that both the altimeter
and airspeed sensor would both be receiving the same static pressure data from the
Pitot tube. This isn’t a requirement for the mounting of this sensor, just an added
option. The eagle tree systems altimeter is zeroed every time it is turned on. So each
test the device can be zeroed for atmospheric conditions and the altitude recorded will
15
be the altitude from the ground, not sea level. The data sheets and manuals for the
eagle tree systems altimeter as well as the eLogger can be found in the appendix.
B.2.5 Test Plan:
The test plan for both sensors will be the same, and whenever possible, the two
sensors will be tested simultaneously to prevent any potential errors.
Test 1: Stair test
This test will be used to determine the accuracy of the two altimeters on a small scale.
The altimeters will be attached to a length of string marked every foot and lowered down
a stairwell. At the bottom of the stairwell, both sensors will be zeroed and the test will
begin. The string will be slowly raised the full height of the stairs, and readings will be
taken from both sensors and graphed against each other to show the altitude increase.
In this particular test, we will use two flights of stairs with a known height of 30’.
Test 2. Altimeter vs. GPS accuracy test
After the GPS sensor is up and running correctly, we will run a test using the altimeter
and the GPS to do a drive around campus measuring altitude along the way. We will
plot the altimeter data and the GPS data on the same graph to show the accuracy of
both sensors.
Test 3: Vacuum Chamber
This will include testing of both sensors in a vacuum chamber. Both sensors will be
placed in the chamber at the same time. The vacuum chamber will then be sealed and
the pressure will be reduced over a short period of time. The pressure in the chamber
will be reduced to that of atmospheric pressure around 1500 ft. The pressure from the
vacuum chamber will be recorded with a pressure sensor (gauge pressure) outputted
on a multimeter. Due to the nature of the pressure sensor, the data will be taken over a
period of events and not based on time. The pressure data will then be converted to
altitude. After the data test, the vacuum chamber data will be plotted against both
altimeters as plot of altitude versus the taken data at each event.
After all these tests are complete; the altimeter should be ready for use with UAV and
imaging applications further down the road.
B.2.6 Test Results
Test 1a: Stair Test with both altimeters
The first stair test was done with both altimeters. The altimeters were lowered down the
staircase and zeroed on the ground floor. The altimeters were slowly raised up the
staircase the full 30’. The graph of the data taken can be seen in the appendix section
2.3.1. It is seen from this graph that the zlog altimeter is much more accurate at smaller
increments than the eagle tree altimeter. The specification sheets for both altimeters
16
document that the eagle tree is accurate to within one meter while the zlog is accurate
to within one foot, so the outcome is not unexpected.
Test 1b: Stair test with the Zlog altimeter
After the reviewing the initial stair test, it was concluded that the zlog was indeed more
accurate than the eagle tree system’s altimeter. We decided to try the test again with
only the zlog, and to pause every one foot while pulling the zlog up the staircase. The
graph in appendix section 2.3.2 shows the results of the test. As shown in the graph,
the zlog is extremely accurate. The +/- 1ft tolerances seem to be fairly reliable as well,
and after this test, we’ve decided to use the zlog in the final design instead of eagle tree
systems altimeter.
Test 2: Altimeter vs. GPS
After the GPS sensor was up and running, we decided to test it against the altitude
measurements given from the GPS. The sea level of Rochester is around 450ft above
sea level. Normally the Zlog will give readings in the 400-500ft range for RIT’s location,
but for some reason on the day of the first test, the zlog altimeter was reading around
100-200 ft range, probably due to a high pressure system over Rochester that day. The
graph in appendix section 2.3.3 shows the readings of the two sensors. The test
doesn’t really yield very good results. After previous tests, we know the altimeter is very
accurate, but it seems that its absolute pressure readings can be off by a fairly
substantial amount.
Test 3: Simulated high altitude in a vacuum chamber.
For this test, we tested both sensors in a vacuum chamber vs. a gage pressure sensor
that measured between 0 and 10 psi. A vacuum chamber simulates altitude as the
pressure drops. With this vacuum chamber we didn’t have very good control over how
little we could change the pressure, and we also didn’t have a data acquisition system
for the pressure sensor, so we used a multimeter and took event based data for all the
sensors at the same time. The data’s graph can be seen in the appendix section 2.3.4.
The two altimeters took excellent data vs. each other, but as the pressure dropped, the
pressure sensor’s data consistently was lower than the two altimeters. This could be for
a correction factor for altitude that the altimeters have built in that the gage pressure
sensor does not. Other then the altimeter’s reading being higher than the pressure
sensor, the test was a success.
17
B.3.1 GPS Sensor
Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting
satellites where 24 of them are in operation and the other three are extras in case one
fails. The GPS receiver's job is to locate four or more of these satellites, and calculate
the distance to each. Using this information, the receiver derives its own location. This
process is based on a simple mathematical principle called tri-lateration.
The GPS receiver must find the distance to three satellites of known positions to locate
it. If the receiver finds that it is X miles from one satellite, it knows that it must be
somewhere on an imaginary sphere, with the satellite as the center and a radius of X. if
the receiver can generate these spheres for two satellites, it knows it can only be
located where the surfaces of the two spheres intersect. The two spheres overlap in a
ring of possible receiver positions. By generating a sphere for a third satellite, the
receiver narrows its possible positions down to two points. The receiver ejects the point
located in space, leaving only one possible position.
The GPS receiver has to know two things to make this calculation, the location of at
least three satellites above you and the distance between you and each of those
satellites.
The GPS receiver analyzes high-frequency, low-power radio signals from the GPS
satellites to calculate both of these things required. The receiver can figure out how far
the signal has traveled by timing how long it took the signal to arrive.
The receiver begins running a digital pattern which has been transmitted from the
satellite along digital pattern. When the satellite's signal reaches the receiver, its
18
transmission of the pattern will be delayed a bit behind the receiver's playing of the
pattern. The delay length is equal to the signal's travel time. The receiver multiplies this
time by the speed of light to calculate how far the signal traveled.
To make this measurement, the receiver and satellite both need clocks that can be
synchronized down to the nanosecond. To make a satellite positioning system using
only synchronized clocks, all the satellites would need to have atomic clocks and the
receiver itself uses an ordinary quartz clock, which it constantly resets. The Quartz clock
has been chosen for the receiver instead of the atomic clock because the atomic clock
is expensive in the range of $70,000 which wouldn’t be in the reach of each individual.
The receiver looks at incoming signals from four or more satellites and estimates its
own inaccuracy so there is only one value for the current time that the receiver can use.
The correct time value will cause all of the signals that the receiver is receiving to align
at a single point in space. That time value is the time value held by the atomic clocks in
all of the satellites. So the receiver sets its clock to that time value, and it then has the
same time value that all the atomic clocks in all of the satellites have.
When the distance to four located satellites is measured, four spheres can be drawn
that all intersect at one point. Three spheres will intersect even if the numbers are way
off, but four spheres will not intersect at one point if the measured values were incorrect.
Since the receiver makes all its distance measurements using its own built-in clock, the
distances will all be proportionally incorrect. The receiver can easily calculate the
necessary adjustment that will cause the four spheres to intersect at one point. Based
on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver
does this constantly whenever it's on, which means it is nearly as accurate as the
expensive atomic clocks in the satellites.
Once the receiver makes this calculation, it can tell you the latitude, longitude and
altitude of its current position. To make the navigation more useful and easier to follow,
most receivers plug this raw data into map files stored in memory. You can use maps
stored in the receiver's memory, and connect the receiver to a computer that can hold
more detailed maps in its memory.
B.3.2 Design Specification:
A standard GPS receiver will not only place you on a map at any particular location, but
will also trace your path across a map as you move. If you leave your receiver on, it can
stay in constant communication with GPS satellites to see how your location is
changing. With this information and its built-in clock, the receiver can give you several
pieces of valuable information such as, how far you've traveled (odometer), how long
you've been traveling, your current speed (speedometer), your average speed, a "bread
crumb" trail showing you exactly where you have traveled on the map, and the
estimated time of arrival at your destination if you maintain your current speed.
19
B.3.3 Pugh Analysis:
A big search was done to find a GPS Receiver that meets our requirements. After
narrowing down our choices, we ended up with ten GPS receivers. A comparison was
done for the ten GPS receivers according to the following features: accuracy, voltage
supply, and power consumption, battery backup pin, built in antenna, baud rate,
dimensions, weight, price, and number of channel tracking. The best four GPS receivers
were picked out of the ten after the comparison was done. See attached spreadsheet in
appendix section 3.2.
Concept screening matrix was the next step, where the four GPS receivers were rated
with a + or – or 0 on each selection criteria in each GPS receiver. The 0 means it
doesn’t have any effect on our ranking decision that is because it is either all the GPS
receivers have the same feature or there is no big difference between them. The +
means it is ranked the best in this criteria over the rest of the other GPS receivers. The
– means this GPS receiver has a weakness in this criteria or it is not preferred
according to the other GPS receivers which have a better rank in this criteria. The
ranking is based on the following selection criteria: Cost, size, weight, resolution, range,
power consumption, interface, and baud rate. When each GPS receiver has been
ranked for each criteria, we sum the ranking rates +’s, -‘s, and 0’s for each GPS
receiver. Then the sum from the –‘s get subtracted from the sum of the +’s, and that will
be the net score. According to the net score we rank each GPS receiver, highest net
score means the top ranked and lowest net score means ranked the last favored. The
highest ranked GPS receivers are picked to continue to the next concept-screening
matrix. See attached spreadsheet in appendix section 3.2.
The second concept-screening matrix is a refinement for the first Pugh’s matrix where
only the highest ranked ones from the first Pugh’s matrix will be in this and the
weighting will be added for each criterion. Weights are selected according to how
important each feature is to our design. The scale will be refined in this stage from 1 to
5, where 5 is the best and 1 is the worst. An average criterion is selected for a
reference, and then a comparison is made for each criterion for each GPS receiver to
reference criteria. Summing weighted scores ranks concepts. Highest ranked will be
the best concept that will be purchased. All three GPS receivers, which were selected to
continue to the second concept-screening matrix, have the same size, weight, range,
power consumption, and interface; the only difference was in the channel tracking, cost,
and baud rate. Choice B and c have the same default baud rate, and same number of
channels, however B is cheaper than C. Therefore choice B is better than C. Choice A
has a higher baud rate and more channels than B. A has 32 channels compared with B
which has 20 channels. Even though choice A cost $99.95 and B cost $61, choice A is
worth the $29 extra since it has almost double the channels which means more reliable.
Therefore choice A was ranked the highest. See attached spreadsheet in the appendix
section 3.2.
20
B.3.4 Components Specification:
The best concept, which was purchased, is the 32 Chan San Jose Nav., part number
GPS-08266 from Spark Fun Electronics. It has a 3.3m accuracy, 3.3-5V-voltage supply,
33-59mA-power consumption; it has a battery backup pin, built in antenna, baud rate of
38400 bps, with dimensions of 1.2 x 1.2 x 0.3'', and weights 15 grams, it has 32 channel
tracking and cost $99.95. This receiver has a 5Hz update rate.
Please note at 5Hz the serial stream is large enough the default baud rate is 38400bps but the unit is completely configurable! The unit configuration is stored in volatile
memory and is reset when power cycled. Use a battery backup to maintain user
settings.
The MiniGPS software that was provided by San Jose Navigation allows for an easy to
use GUI to reconfigure the FV-M8 as well as data log incoming NMEA sentences! It is
able to track over 9 satellites indoors.
Pin Definition
Pin No.
Title
I/O Note
1
Vin
P
Voltage input 3.3~5V DC +/- 10%
2
GND
G
Ground
3
TX1
O
Serial port 1 (leave open if not used)
4
RX1
I
Serial port 1 (leave open if not used)
5
TX2
O
Reserve
6
RX2
I
Serial port 2 (leave open if not used)
7
1PPS
O
Time Pulse (leave open if not used)
8
BAT
I
Backup input voltage 2 ~ 5V DC +/- 10%
P: Power
B.3.5
I: Input
O: Output
G: Ground
Test Plan:
Simulate experimental conditions on the ground by driving around the RIT loop at
approximately 15 mph while the GPS Receiver is connected to the laptop and
21
Evaluation board. Data will be captured every few seconds using the GPS Locator
Utility software. Each sample will show the latitude, longitude, altitude, number of
satellites used, total number of satellites in view, and speed.
Accuracy, orientation effects and material interference will be tested. The
measurements from each test will be compared to results from google map and google
earth measurements.
In addition, Satellite Time Fix will be also tested for the cold, warm and hot start-up
modes. Twelve samples will be tested using the hot and warm start-up mode and 22
samples for the cold start-up mode.
Then, the GPS will be connected to the MCU to collect data by driving around. The
collected driving data will be plotted on Google map.
B.3.6 Test Results:
a) Accuracy test
Data was captured every five seconds. There were approximately 134
samples of data captured. From observing the data results, the maximum,
minimum, and average of available satellites used are 13, 9, and 10
respectively. This means that 83% of the available satellites were used.
GPS altitude measurements were compared with google earth altitude
results. There is a 1% error from the GPS altitude according to google earth
measurements.
Figure 3.3.1 and 3.3.2 shows the speed and altitude for the entire RIT loop,
respectively. Each data sample was plotted on google earth as shown in
Figure 3.3.3, which represents the entire drive test around the RIT loop. The
gray marker represents the starting point, red marker indicates that there was
a stop sign; yellow marker indicates that we had to slow down for a speed
bump or for people crossing the street, and Green marker shows an average
driving speed.
Figure 3.3.4 and Figure 3.3.5 show a closer view for a few sample points.
Figure 3.3.6 shows a sample view of a screen shot to the GPS Locator Utility
software.
22
b)
Orientation effects and Material interface test
Data was captured every seven seconds. There were 105 samples of data
captured. From observing the data results, the maximum, minimum, and
average of available satellites used are 13, 9, and 11 respectively. This
means that 88.8% of the available satellites were used.
GPS altitude measurements were compared with google earth altitude
results. There is a 1% error from the GPS altitude according to google earth
measurements.
Figure 3.3.7 and 3.3.8 shows the speed and altitude for the entire RIT loop,
respectively. Each data sample was plotted on google map as shown in
Figure 3.3.9, which represents the entire drive test around the RIT loop. The
gray marker represents the starting point, red marker indicates that there was
a stop sign and Green marker shows an average driving speed.
Figure 3.3.10 show a closer view for a few sample points at the starting and
ending locations. Figure 3.3.11 shows a sample view of a screen shot to the
GPS Locator Utility software at one location and Figure 3.3.12 shows the
same location in google earth. Using Figure 3.3.11 and Figure 3.3.12, we can
compute the percentage error for the altitude measured by the GPS.
c) Satellite Time Fix test
This test examines how long does it take for the GPS receiver to start up
using cold or warm or hot mode. The GPS receiver starts after it views at
least four satellites. 12 starts up trials were done for hot and warm-mode
types and 22 for the cold-mode. Cold-mode will be used and set to the
default. See Figure 3.3.13, Figure 3.3.14, and Figure 3.3.15 for test results.
The maximum cold start up time was 3 minutes and 22 seconds and the
minimum was 53 seconds. On average the cold start up time was 1.9
minutes.
The maximum warm start up time was 2 minutes and 49 seconds and the
minimum was 27 seconds. The average warm start up time was 1.7 minutes.
The maximum hot start up time was 3 minutes and 4 seconds and the
minimum was 17 seconds. The average warm start up time was 1.4 minutes.
It is clear from these results that it takes the longest time to start up if it is in
cold start up mode, less time if it is in warm start up mode, and the fastest
23
start up time when it is in the hot start up mode. Fast start-up time means
more power consumption.
Figure 3.3.16 shows a box plot trend for the three start-up modes and Table
3.3.1 shows the 25th percentile, minimum, mean, 50th percentile, maximum,
and 75th percentile start-up time in seconds for each mode.
d) Drive test while the GPS is connected to the MCU inside the box
The GPS was tested after it has been connected to the MCU by driving
around. Two driving test were done and the data were collected every 2
seconds. More than 400 sample points were captured for each driving test.
The speed for each driving test was plotted verses time as shown in Figure
3.3.17 and Figure 3.3.18. Each data file was plotted on google map using
GPS Visualizer. First drive test plots are shown in Figure 3.3.19, Figure
3.3.20, and 3.3.21 and Figure 3.3.22. The second drive test is shown in
Figure 3.3.23, Figure 3.3.24, Figure 3.3.25, and Figure 3.3.26.
24
B.4.1 IMU Sensor
An Inertial Measurement Unit (IMU) is a device that uses accelerometers and
gyroscopes to measure axial and rotational accelerations as well as orientation based
upon initial conditions. A six degree of freedom IMU has 3 accelerometers and 3
gyroscopes to measure x, y, and z accelerations and roll, pitch, and yaw. This sensor is
important for UAV’s because it will indicate the aircrafts roll, pitch, and yaw rates, and
accelerations in x, y and z. The IMU will also indicate the aircrafts orientation in space. It
is needed to give this information to a flight control system to allow an aircraft maintain
flight in a particular direction, altitude, and orientation.
B.4.2 Design Specification
The requirements for the IMU are to know the orientation of the aircraft while it is in
flight as well as its horizontal, lateral, and vertical accelerations. The device that we
25
picked out is the ADIS16350 IMU from Analog Devices. The min/max voltage required
for the IMU is between 4.75-5.25 volts.
This IMU satisfies the requirements given to it because it is a six degree of freedom IMU
that is designed to be used in guidance, control, and stabilization. The six degrees of
freedom allows it to measure roll, pitch, yaw, and axial accelerations. These are all the
accelerations that act on an aircraft.
There are several ways to measure orientation and axial accelerations however they all
revolve around the same type of devices: IMU’s, gyros, and accelerometers. A six
degree of freedom IMU uses 3 gyroscopes and 3 accelerometers to measure roll, pitch,
yaw, and accelerations in x, y, and z. Many IMU’s also contain a sensor that tells it in
which direction gravity is pulling it so that it knows its orientation at all times. The IMU is
the simplest solution to this problem because it combines all the sensors needed into
one device. It would be possible to build your own IMU by buying 3 gyroscopes and 3
accelerometers and have them measure the required information. This method would
require more work, in terms of setup time and programming. It might cost less in terms
of dollars but it would cost more time to build your own IMU. For our project it made the
most sense to buy an IMU.
B.4.3 Pugh Analysis
The IMU’s that looked the most promising were the Micro Strain’s and the Analog
Devices. Micro Strain is one of the brands that NASA’s payload directed flight program
uses to measure roll, pitch, yaw, as well as movement in x, y, and z. There were three
IMU’s from Micro Strain we looked at the Inertia-link, 3DM-GX1, and 3DM-GX2. All
three of these IMU’s were very similar in their capabilities with the main differences
being price, power usage, and extra features that were not essential to our project such
as wireless communication and magnetometers. The advantage of using one of the
Micro Strain products is that it is familiar to the team, and is a proven technology. The
main disadvantage with this brand is that all of their IMU’s are very expensive around
$1400 and higher. This is where Analog Devices fits in. All of their IMU’s are relatively
inexpensive at around $300. Like Micro Strain all of the Analog Devices IMU’s look the
same in there specs and it was not really clear what the major differences were
between them based upon their data sheets. The Analog Devices IMU that looked the
best was the ADIS1650 do to its lower price. The advantages of the ADIS1650 to the
Micro Strain IMU’s is that it is smaller, has about the same accuracy, it uses less power,
and it is a lot less expensive. The main disadvantage of the Analog Devices is lack of
experience with the product, and it has fewer input method options.
The Pugh analysis was designed to help compare similar products to one another to
compare chosen qualities against each other to see which one is the best. The first step
of the analysis was to pick a sensor to be the baseline and compare several of the other
makes and models against it, using +’s to indicated something better and –‘s to indicate
areas where it was worse. Six models of IMU’s were chosen from three brands. Three
from Analog Devices because all of them were in our price range, two from Micro Strain
because NASA uses that brand for their UAV’s and one from Gladiator Technologies to
see how it compared. All three Analog Devices and both Micro Strain’s made it through
26
the first screening. Next we weighted the earlier used criteria to compare the products
directly to see which got the best score. The weights were as follows: cost 20%, Size
3%, weight 3%, Resolution 18%, interface 29%, Power Consumption 7%, and Sampling
Rate 20%. It was found that the ADIS16350 got the highest score due largely to its low
cost. The second best was the ADIS16354. The third best was the Inertia-link though
we will not follow up on this one because of its high cost. It received third position due to
the comparison chart.
B.4.4 Components Specification
The IMU interfaces with the MCU through a serial interface and breakout board. It is
mounted in the box though two 1.588mm holes on its base. The IMU will be vibration
isolated using a rubber dampening sheet attached to its base. Vibration dampening is
very important for IMUs in order to read there orientation and accelerations as
accurately as possible.
Detailed Specs of the IMU
The IMU requires between 4.75 and 5.25 Volts
There are three sensitivity setting for this IMU ±300o/s, ±150o/s, and ±75o/s.
The data output rate is 350Hz.
The IMU costs about $500, the one selected for this project was inexpensive compared
to most others. The IMU will likely need to be calibrated/ zeroed every time it is used to
increase its accuracy; this is to prevent errors in its calculations.
There is no/very little maintenance needed for the IMU other than to keep it away from
too much moisture and not to drop it. It is a robust device but it is a very expensive
piece of hardware, and should be treated with care.
B.4.5 Test Plan
We will come up with a test cycle with the MAV team that will test both of our IMU’s.
This test cycle will allow for a direct comparison between our two IMU’s. The IMU’s will
be tested on a test stand that is being designed by the MAV team that will be able to
rotate along two axes. The angular rotation rates of what the IMU’s read will be
compared to that of the test stand cycle as well as against each other.
B.4.6 Test Results
Verification of IMU error while stationary:
Between time 27 and 276 and between 522 and the end of the test the IMU was
stationary on a work bench and was unmoved. The IMU did pick up some changes in its
position; however these fluctuations are within the device specifications of ~+/- 3. The
reason for these fluctuations could be due to vibrations that it picked up through the
desk or simply minor errors in the device. To close this test showed that the IMU while
stationary works as specified.
27
B.5.1 Microprocessor
B.5.2 Design Specification
B.5.3 Pugh Analysis
B.5.4 Components Specification
B.5.5 Test Plan
B.5.6 Test Results
28
B.6.1 Components Box
The box design was based off of the sensors that were purchased to fulfill the needs
of the project, as well as maintain low weight and ensure that the final design would
fit within the confines of the fuselage of Airframe A. The external memory source
needed to be removable from the exterior of the airframe without removing the box
enclosure. To meet these requirements the box was constructed out of light aircraft
plywood and the components were attached to the box with 4-40 bolts and t-nuts. To
ensure that the box fit completely within the confines of Airframe A, a model of
Airframe A was used while modeling the box and mock ups of the sensors were
used to ensure that the components would fit in and out of the box. Because of the
size constraints for fitting into Airframe A, some components, specifically the MCU
needed to be modified to fit. Because of the requirement that the IMU be near the
Cg of the Airframe, its mounting was pre determined, and the box design
accommodates for this.
Picture 1 - Measurements Box
The box was designed in Pro/E Wildfire 3.0 and prototyped in the laser cutter
in the Aero Design Lab at RIT. The box consists of 7 parts all cut out of light aircraft
plywood. The original design was refined after the first prototype to accommodate
changes in mounting as well as added access holes to make the assembly of the
components easier. Drawings of each of the parts as well as 3-D models of the box
can be found on our EDGE website, as well as complete instructions for assembling
the box and the components into the box.
29
Picture 2 - Measurements Box Inside Airframe A
The Pitot-tube and its sensor were placed in the wing tip, because the Pitottube needed to be outside of the prop wash, and outside of the wings boundary
layer, and turbulence created by the fuselage as the aircraft flies through the air. The
sensor was placed on a removable plate in the wingtip as shown below, so that the
sensor could be moved from wing to wing without having to re-run the wires and
tubing required to be the input into the sensor for every wing. Because of the
sensors moderate cost, it was chosen to make this sensor easily accessible. By
mounting the sensor in the wing tip, we have cut down the time delay seen in the
tubing between the sensor and the Pitot-static tube.
Picture 3 – Pitot Static Tube Inside Airframe A
30
Appendix
1.1
31
1.2
32
1.3
Time Delay Calculations
1
P1
P2
Psensor
0.9
0.8
0.7
0.5
0.4
0.3
0.2
0.1
0
0
1
2
Time (sec)
3
4
-11
x 10
Figure 1.3.1
Time Delay Calculations
-4
x 10
2
Mass Flow Rate (kg/s)
Magnitude
0.6
1
0
0
20
40
60
80
100
Pressure Drop (Pa)
120
140
160
180
200
Figure 1.3.2
33
Time Delay Calculations
200
180
160
Pressure Drop (Pa)
140
120
100
80
60
40
20
0
0
10
20
30
velocity (mph)
40
50
60
Figure 1.3.3
Small Wind Tunnel Test
Anemometer
m/s
1
1.3
1.5
2.
mph
2.2
2.86
3.3
4.4
ETS Pitot-Tube
mph
0~2
1~3
3~4
4
Table 1.3.4
34
Pitot Static Tube vs. Anemometer
(Automobile Test)
60
50
40
20
10
Airspeed Sensor
Anamometer
0
0
10
20
30
40
50
60
70
Data Collection Event
Figure 1.3.5
Pitot Tube
Large Wind Tunnel Test
Hot Wire Probe
140
120
100
Speed (mph)
Speed (mph)
30
80
60
40
20
0
0
2
4
6
8
10
12
14
16
18
Event
Figure 1.3.6
35
Pitot Tube Time Delay
1.6
1.4
Voltage (V)
1.2
1
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
Time (sec)
Figure 1.3.7
36
2.1
37
2.2
38
2.3
Figure 2.3.1
Figure 2.3.2
39
GPS
GPS vs Altimeter Altimeter test
Zlog
600
500
Altitude (ft)
400
300
200
100
0
0
100
200
300
400
500
Time (s)
Figure 2.3.3
Vacuum Chamber Pressures
1800
1600
Zlog
1400
Eagle Tree
Pressure Sensor
Altitude (Ft)
1200
1000
800
600
400
200
0
0
5
10
15
20
25
30
Data Collect Event
Figure 2.3.4
40
3.1
41
3.2
42
3.3
Speed
20
18
16
14
Speed (MPH)
12
10
8
6
4
2
0
0
20
40
60
80
100
120
140
160
Sample Number
Figure 3.3.1
Altitude
175
170
Altitude (m)
165
160
155
150
145
0
20
40
60
80
100
120
140
160
Sample Number
Figure 3.3.2
43
Figure 3.3.3
Figure 3.3.4
44
Figure 3.3.5
Figure 3.3.6
45
25
Speed (mph)
20
15
10
5
0
0
20
40
-5
60
80
100
120
80
100
120
Sample Number
Figure 3.3.7
170
Altitude (m)
165
160
155
150
145
140
0
20
40
60
Sample Number
Figure 3.3.8
46
Figure 3.3.9
Figure 3.3.10
47
Figure 3.3.11
Figure 3.3.12
48
Cold start up time
Time (seconds)
300
250
200
150
100
50
0
0
2
4
6
8
10
12
14
10
12
14
Sample number
Figure 3.3.13
Warm start up time
Time (seconds)
250
200
150
100
50
0
0
2
4
6
8
Sample number
Figure 3.3.14
49
Hot start up time
Time (seconds)
250
200
150
100
50
0
0
2
4
6
8
10
12
14
sample number
Figure 3.3.15
GPS - Satellite Time to Fix
250
25th Percentile
200
Time (sec)
Minimum
150
Mean
50th Percentile
100
Maximum
50
75th Percentile
0
Cold
Warm
Hot
Start-up mode
Figure 3.3.15
50
4.1
51
4.2
52
4.3
X-Axis Angular Rate vs. Time
12
9
6
X-Axis Angular Rate
3
0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
-3
-6
-9
-12
Time
Figure 4.3.1
53
X-Axis Angular Rate vs. Time
12
9
6
X-Axis Angular Rate
3
0
14
16
18
20
22
24
-3
-6
-9
-12
Time
Figure 4.3.2
54
5.1
55
5.2
56
5.3
57
6.1
58
6.2
59
6.3
60
6.4
61
7.1
62
7.2
63