A.R.E.S Platform
Automated Reconnaissance for Emergency Services
Rob Pfingsten
B.S. Civil Engineering
The University of Akron Honors College
Contents
Inception ....................................................................................................................................................... 3
Requirements................................................................................................................................................ 4
Initial Design.................................................................................................................................................. 5
Motor Sizing .................................................................................................................................................. 6
Motor Controller ........................................................................................................................................... 9
Drivetrain .................................................................................................................................................... 10
Frame Design .............................................................................................................................................. 11
Material Selection ................................................................................................................................... 11
Progression of design .............................................................................................................................. 12
Final Design ............................................................................................................................................. 13
Control ........................................................................................................................................................ 17
Cameras ...................................................................................................................................................... 18
Pictures ....................................................................................................................................................... 21
Project Cost ................................................................................................................................................. 27
2
Inception
Officer Mark Northrup from the Akron Police contacted Dr. Tom Hartley in the fall of 2010 with
a potential project. He wanted a robot that could go into locations in the place of officers or dogs to
investigate potential threats. The Akron Police regularly receive calls or tips about situations that may
require intervention from the SWAT Team. A call to the SWAT Team is typically a last resort and all
attempts are made to prevent their involvement when not necessary. The problem lies in that gathering
information on a situation is often very dangerous. For example, a call may be received concerning
someone who is in a house threatening to take his or her own life. When the police arrive at the scene
they do not know if the person is armed, if there are others in the house, or even where the subject may
be. There is too much risk associated with directly entering the house, meaning a call to the SWAT Team
seems like the only alternative. If SWAT finds an armed person in the house then the call was
worthwhile. Conversely, if the threat was not legitimate then SWAT was arguably not necessary, wasting
time, money, and manpower.
With a robot, a scene such as the one described above could be much more simply dealt with. A
robot can be sent into a room with an armed subject and there is no risk to officers. Equipped with
surveillance technology it can provide live visual and acoustic feedback to officers. A robot with the
ability to climb stairs and navigate narrow hallways will be an invaluable tool for gathering information
in a hazardous environment, making its development more than worthwhile. The demand for such a
tool has led to the development of the A.R.E.S Platform.
3
Requirements
As described in the above section, the robot will have several special requirements. It must be
equipped with cameras to provide visual information and to allow it to be driven remotely. The robot
must also be relatively substantial in size so that it may not be simply thrown or kicked. Vital
components must be bulletproof so that small arms fire cannot disable the robot’s operation. The robot
must also be agile enough to climb stairs and small enough to maneuver through doorways and narrow
hallways. Ease of use, simple maintenance, and overall durability are also high priorities.

Bulletproof

Cameras and two-way audio

Ability to climb stairs

Substantial enough not to be disabled by subject

Small enough to navigate narrow hallways

Easy to drive

Easy to recharge

Easy to repair
4
Initial Design
The preliminary design considerations for the robot were as follows. The overall length and
width were restricted to 36 inches and 30 inches, respectively. Length is required to prevent rollover
when climbing stairs. The width was limited to enable passage through narrow doorways.
The robot was intended to have rhombic side cross-section, similar to WWI tanks. This would
permit the engagement of steps and other large objects while still being symmetrically operational in
the event of rollover. A tracked drive was chosen as the best means for providing traction on stairs. The
majority of the design was inspired by the Lunar Robot developed earlier by The University of Akron
Robotics Team. The LunarBot used an extruded aluminum frame and many of the components similar to
those shown below. For the A.R.E.S Platform, an extruded aluminum frame was used, the design of
which will be described later in this report. The robot will use as few modified parts as possible in order
to reduce production time and cost as well as to allow the easy replacement of parts.
Figure 1 – Stainless steel table chain (MasterCarr)
Figure 3 - Base mount bearing (MasterCarr)
Figure 2 - Table chain drive sprocket and idler (MasterCarr)
Figure 4 – Stainless steel precut shaft (MasterCarr)
5
Motor Sizing
The robot was estimated to have a maximum weight of about 150 pounds. With this much
weight, rather large motors were required, especially since the robot must have the ability to climb
stairs. There are countless motors available on the market, so selecting the right type and size was
critical. For ease of use, it was decided to use a 12 volt system throughout. The power for the robot will
be from a 12 volt Yellow Top Optima deep cycle 38Ah marine battery. An arbitrary 0.5 feet/second
velocity up stairs was selected. For strength, a gearmotor, which reduces the speed of a motor in
developing high operating torque, was necessary for each track. Since the robot is tracked, two motors,
one for each track, sit parallel to each other in the center of the chassis. This means that right-angleoutput gearmotors were best suited. The following calculations show the rest of the procedure for
determining the size of the motors.
Assumptions
-
6 inch diameter sprockets
Location of CG
Weight of robot = 150 pounds
No slippage
Design speed up stairs of 0.5 ft/sec
150 lb
45°
106.07 lb
Figure 5 - Free body diagram of prototype on stairs
6
Angular velocity
v = linear velocity = 0.5ft/sec
r = radius of drive = 3 inches = 0.25 ft
∴ ω = angular velocity = 2 rad/sec = 0.32 rev/sec
Required torque
r =0.25 ft
F = drive force = 106.07 lb
∴ T = drive torque = 26.52 ft-lb*
*Required torque is half of this (2 motors) = 26.52/2 = 13.26 ft-lb
Required power
T = 13.26 ft-lb
ω = 2 rev/sec
∴ P = 26.52 ft-lb/sec
P = (26.52 ft-lb/sec)(746W/(550ft-lb/sec)) = 35.97 W
7
Based on the above calculations, 12 volt DC right-angle gearmotor capable of delivering about 160 inchpounds of torque at 20 rpm was required. The motor chosen for the task was the Dayton 5LAF4.
Figure 6 - Dayton 5LAF4 Gearmotor
Table 1 - Dayton 5LAF4 specifications
8
Motor Controller
To drive the motors, Dimension Engineering provided the Sabertooth Dual 25 Amp Motor
Driver. The purpose of the motor driver is to use an input, in this case a pulsed RC input from an RC
receiver, to drive a motor. The motor controller is powered from the 12 volt source and delivers current
to each motor per the provided signal. Since there are two motors, two signals are required. The benefit
of using the Sabertooth is the mode that mixes the signal inputs for an intuitive drive method. This
means that using one control stick on the RC transmitter the robot can be controlled in two dimensions.
Figure 7 - Dimension Engineering Sabertooth motor controller
Specifications
25A continuous
50A peak per channel
6-24V nominal
30V absolute maximum
Synchronous regenerative drive
Ultra-sonic switching frequency
Thermal and overcurrent protection
Lithium protection mode
Input modes
Analog
R/C
Simplified serial
Packetized serial
Size
2.6” x 3.2” x .8”
65 x 80 x 20 mm
9
Drivetrain
The motors will be connected to the tracks using a set of chain sprockets and ANSI 40 chain rated to
about 500 pounds. A direct drive was the initial expectation, but this was abandoned for the following
reasons:

A direct drive requires a coupler to transfer the torque from the motor drive shaft to the track
drive sprocket axle. It was difficult to source a 5/8 inch to 1 inch coupler. In addition to this, a
coupler would add about three inches to the width of the drive, adding six inches to the overall
width of the robot.

A direct drive also requires that the motors and track axels be perfectly aligned, which would
require much more work when designing the frame. The track pulleys are under tension and are
also subject to movement, and it is preferable not to have any vibration transferred to the
motors.

The motors are each right-angle gearmotors, and the output shaft is not reversible. This means
for the motors to be mounted collinearly, one would have to be upside down.

A direct drive does not allow for any speed/torque conversion. In the case that the robot were
heavier or slower than expected, changing gear ratios on a chain drive allows for fine tuning of
the output characteristics.
10
Frame Design
Material Selection
The frame was one of the components that required the most consideration. Heading into this
project, it was assumed that a welded frame would be used. Building a custom frame would provide
strength while still offering unlimited customizability. Welding a steel frame does have drawbacks,
however. Precision is essential, and it is difficult to ensure with a welded frame. Welding is also
permanent, meaning any mistakes or changes would prove difficult. Significant preparation is required
prior to making a weld, and this does not ensure that the weld itself will be quality. Additionally, a steel
frame will be heavy.
With these concerns in mind, an alternative for a frame design was sought. The answer was
found in aluminum. A company called Item America, just a few minutes away from the university, makes
extruded aluminum profiles for any application. Though relatively expensive, using extruded aluminum
members provides a lightweight, high-strength, adjustable, precise alternative to steel. Item America
has an extensive catalog, involving small to very large profiles, connectors, and thousands of other
compatible fixtures.
Now that a system for building a frame was chosen, the frame had to be designed. Profiles from
Line 6 Light were selected due to their smaller size and high availability of components. Line 6 struts are
30 mm square, and a few example profiles are shown on the following page.
11
Figure 8 - Item America Line 6 extruded aluminum profiles
Using CAD, the frame was drawn using the cross-sectional profiles provided on Item’s website.
When a finalized design had been drawn, it was sent to the engineers at ITEM for refinement.
Progression of design
Initially, the robot was designed as a parallelogram. As the design progress, however, it was
necessary to push the rear upper set of idlers rearward. This was to make room for the battery within
the tracks. The tracks were to be the most protruding surface of the robot to allow for driving in the
case of a rollover. The dimensions were tailored so that the robot would meet the following criteria:

Narrow enough to clear narrow doorways (36” is standard, but design was limited to 24”)

Less than 34” long end-to-end. This was to provide a large enough footprint when climbing stairs
but short enough to turn on a 36” square landing.

Low center of gravity. This is to minimize the chance of rollover when climbing stairs. Minimizing
the overall height of the robot is beneficial for easy transport as well.

Tracks must be the most exterior part of the robot, as mentioned above.

The frame must be efficient. Member placement was adjusted to optimize strength, material
use, customizability, and ease of construction.
12
Final Design
Considering all of the above requirements, a final design was selected and sent to the engineers
at Item America for revision. The only change that was to me made was to replace the miter cut
members at the front of the frame with a built-up section using sections of angle stock. This was purely
a cost saving measure, as there is much more machining required for miter cut connections. The
strength difference is negligible. Below are computer drawings of the final version of the frame and
critical components that were sent to Item America.
Figure 9 - Final CAD overall design
13
Figure 10 - Google SketchUp rendering
14
Figure 11 - Google SketchUp rendering
15
Figure 12 - Final isometric drawing returned by Item America Engineers
16
Control
A method for controlling the robot remotely needed to be simple and very reliable. A typical 2.4
GHz RC plane controller was selected for reliability, ease of use, and compatibility with the motor
controller. The model shown below has 7 channels to allow for driving control as well as control of
additional accessories such as the cameras, lighting, and mace.
Figure 13 - HK-7X 2.4Ghz 7ch w/ 5 Model Memory TX & RX V2 (Mode 2)
17
Cameras
Since the robot is driven remotely, it must be equipped with several cameras. Cameras will also
provide visual information about the environment into which the robot will be sent. Wireless webcams
were going to be used for this task due to their availability and ease of use. After some research,
however, these were found to lack sufficient transmitting power. The average wireless webcam relies on
an integrated 10 mW transmitter to send the video signal. This amount of power will not be suited for
long distances or transmission through one or several walls. Instead, a higher power, 1000 mW
transmitter was selected. To this are wired 4 individual cameras and a video switch. So that 4 individual
transmitters are not required, the video switch will allow the operator to select which of the four
camera signals will be sent to the transmitter. Powering the cameras is a 2200 mAh lithium polymer 3S
pack. This pack will provide the required 12 volts and enough capacity to power the cameras for several
hours.
Figure 14 - 1000 mW transmitter, receiver, and camera
18
Figure 16 - 1/3-inch SONY CCD Video Camera (NTSC)
Figure 15 - NGH 12V 4-channel video switch
19
On the receiving end of the cameras is a USB video capture card. This device takes the analog signal
from the video receiver and outputs a digital signal through USB that a laptop can use. The provided
software will allow the user to then view a live camera feed as well as record the session.
Figure 17 - KWorld DVD Maker USB 2.0 VS- USB2800 USB 2.0 Interface
Figure 18 - Sample screenshot of video capture software
20
Pictures
Figure 19 - Laying out the Item America frame kit
21
Figure 20 - Assembling the frame
Figure 21 - Assembling the frame
22
Figure 22 - Motors mounted
Figure 23 - One set of tracks installed
23
Figure 24 - Completing the final idler shafts
Figure 25 - Completed frame with motors and tracks
24
Figure 26 - Unarmored robot with control equipment
25
Figure 27 - Control station for robot
26
Project Cost
Qty.
Refdes
Part Num.
Description
Suggested Vendor Vendor Part Num.
Catalog #/Page #/Website
Unit Cost Total Cost
Grainger Supply
2
5LAF4
DC Gearmotor, RPM 20, 12VDC
Grainger
5LAF4
http://www.grainger.com
440.00
880.00
McMaster-Carr
6378K51
http://www.mcmaster.com
183.77
551.31
McMaster-Carr
6369K931
http://www.mcmaster.com
23.14
138.84
McMaster-Carr
5913K64
http://www.mcmaster.com
12.69
152.28
McMaster-Carr
6435K18
http://www.mcmaster.com
3.12
37.44
McMaster-Carr
6061K604
http://www.mcmaster.com
8.14
48.84
McMaster-Carr
1497K145
http://www.mcmaster.com
23.36
46.72
McMaster-Carr
2500T422
http://www.mcmaster.com
13.27
26.54
McMaster-Carr
2500T465
http://www.mcmaster.com
17.05
34.10
McMaster-Carr
6261K446
http://www.mcmaster.com
20.70
20.70
McMaster-Carr
5913K64
http://www.mcmaster.com
12.69
50.76
McMaster-Carr
6369K831
http://www.mcmaster.com
45.26
90.52
McMaster-Carr
98870A245
http://www.mcmaster.com
4.52
4.52
McMaster-Carr
98870A130
http://www.mcmaster.com
3.39
3.39
McMaster-Carr
6061K604
http://www.mcmaster.com
8.14
48.84
McMaster-Carr
1497K145
http://www.mcmaster.com
23.36
46.72
McMaster-Carr
2500T422
http://www.mcmaster.com
13.27
26.54
McMaster-Carr
2500T465
http://www.mcmaster.com
17.05
34.10
McMaster-Carr
6261K446
http://www.mcmaster.com
20.70
20.70
McMaster-Carr
5913K64
http://www.mcmaster.com
12.69
50.76
McMaster-Carr
6369K831
http://www.mcmaster.com
45.26
90.52
McMaster-Carr
98870A245
http://www.mcmaster.com
4.52
4.52
McMaster-Carr
98870A130
http://www.mcmaster.com
3.39
3.39
McMaster-Carr
6261K193
http://www.mcmaster.com
0.78
2.34
Abrasion-Resistant SBR Rubber Black, 1/8" Thick,
2" Width, 36" L, 75A Durometer
McMaster-Carr
8634K22
http://www.mcmaster.com
4.05
16.20
University of Akron Robot Frame
Item North America
QE11020090
http://www.itemamerica.com/
682.00
682.00
McMaster Carr
3
6378K51
6
6369K931
12
5913K64
12
6435K18
6
6061K604
2
1497K145
2
2500T422
2
2500T465
1
6261K446
4
5913K64
2
6369K831
1
98870A245
Series 815—Type 304 Stainless Steel 3 1/4" (3
sections of 10')
Idler Wheels 820/815 1" Bore 6.08"
Stamped-Steel Mounted Ball Bearing--ABEC-1 2Bolt Base Mount, for 1" Shaft Diameter
Shaft Collar One-Piece Clamp-On 1" Bore
Hardened Precision Steel Shaft 1" Diameter, 6"
Length
Fully Keyed 1045 Steel Drive Shaft 1" OD, 1/4"
Keyway Width, 9" Length
Steel Hardened-Teeth Finished-Bore Sprocket for
#40 Chain, 1/2" Pitch, 10 Teeth, 5/8" Bore
Steel Hardened-Teeth Finished-Bore Sprocket for
#40 Chain, 1/2" Pitch, 14 Teeth, 1" Bore
Standard ANSI Roller Chain #40, Single Strand,
1/2" Pitch, .312" Dia, 6'L
Stamped-Steel Mounted Ball Bearing--ABEC-1 2Bolt Base Mount, for 1" Shaft Diameter
Sprocket w/25 Teeth, 820 Series Belt, 1" Bore
2
Plain Steel Machine Key Square Ends, Undersized,
1/4" Square, 2" Length
Plain Steel Machine Key Square Ends, Undersized,
98870A130
3/16" Square, 3/4" Length
Hardened Precision Steel Shaft 1" Diameter, 6"
6061K604
Length
Fully Keyed 1045 Steel Drive Shaft 1" OD, 1/4"
1497K145
Keyway Width, 9" Length
Steel Hardened-Teeth Finished-Bore Sprocket for
2500T422
#40 Chain, 1/2" Pitch, 10 Teeth, 5/8" Bore
Steel Hardened-Teeth Finished-Bore Sprocket for
2500T465
#40 Chain, 1/2" Pitch, 14 Teeth, 1" Bore
Standard ANSI Roller Chain #40, Single Strand,
6261K446
1/2" Pitch, .312" Dia, 6'L
Stamped-Steel Mounted Ball Bearing--ABEC-1 25913K64
Bolt Base Mount, for 1" Shaft Diameter
6369K831
Sprocket w/25 Teeth, 820 Series Belt, 1" Bore
1
98870A245
1
6
2
2
2
1
4
1
3
4
Plain Steel Machine Key Square Ends, Undersized,
1/4" Square, 2" Length
Plain Steel Machine Key Square Ends, Undersized,
98870A130
3/16" Square, 3/4" Length
6261K193
ANSI 40 Connecting Link
8634K22
Item North America
1
QE11020090
Advance Auto Parts
0.00
1
AC47385700
PRIM WIRE 10 GA-RED
6.49
6.49
1
AC46485702
PRIM WIRE 10 GA-BLK
6.49
6.49
1
841353
DBL CRIMP TERMINAL
5.49
5.49
1
AC167A1510422
MARINE BAT TERM
5.19
5.19
1
852053
WTHRPRF TERMINAL
5.99
5.99
AC44CX112
RTCHT TIE DWN 13'
10.99
10.99
1/4" SAE Flat Washers Zinc
4.55
4.55
HK-7X 2.4Ghz 7ch w/ 5 Model Memory TX & RX V
59.95
59.95
99.99
99.99
1/3-inch SONY CCD Video Camera (NTSC)
16.99
67.96
1
Home Depot
1
30699198221
HobbyKing
1
1
HK7x-M2
CN100024RX4T 2.4GHZ 1000mW Tx/Rx & 1/3-inch CCD Camera NT
4
FPV_CCDN
2
Z22003S15C
ZIPPY Flightmax 2200mAh 3S1P 15C
12.29
24.58
1
HX8080
hexTronik Balancer/Charger Dual Charge Capab
24.95
24.95
Total
$3,435.21
27