University of Portland Systems Engineering Paper

University of Portland Robotics Team 1

Systems Engineering Paper

University of Portland Robotics Team

Team Members

Tim Vanderwerf

Kamden McHenry

Laura Coulter

Brian Schimschok

Andrew Lynch

Kyle Oberst

Spencer Boland

Jess Tate

Devin Pentecost

Caleb Pentecost

Sean Doohan

Alissa Tseu

Will Marshall

Kelly Edmond

Bob Alger

Alistair Rockstad

University of Portland

School of Engineering

Faculty Advisor Dr. Deborah Schenberger


ABSTRACT

This paper details the project set forth by the University of Portland Robotics Club,

which involves the designing, building, and testing of a telerobotic or autonomous device,

constrained by the 2011 NASA Lunabotics Mining Competition rules. The device must excavate

at least 10 kg of lunar regolith during a 15 minute timed trial. The University of Portland

Robotics Club is composed of 16 members: 12 mechanical, 3 electrical, and 1 management

undergraduate engineering students. The total projected cost of the project, excluding

competition and travel expenses, is $3,100.22.

The competition takes place May 23-28, 2011 in the Astronaut Hall of Fame Room at

Kennedy Space Center, Florida. Our design this year is based on maximizing simplicity. We

realize that this being our first year of competing in this competition, there is much to be learned

and by minimizing the complexity of our design we can achieve better reliability. Our team is

split into subgroups by the major robot systems: frame, digging components, drive system, and

electrical control and communication systems. This project incorporates elements from many of

the engineering disciplines taught at the University of Portland, and that is reflected in the

diversity of our team.

The first step was research of the requirements for the robot, which helped form a basis

for our design. This year, the method for excavation will be a bucket wheel design similar to

large mining machines. Each mechanical system was designed on SolidWorks, a CAD solid

modeling software program, to get an idea of everything needed to achieve our goal. See

Appendix E for proposed design. From there, parts were purchased and construction was begun.

Once completely built, the robot will be tested to check the performance of the integrated

systems before being shipped to the competition. A schedule is included in Appendix B.

Dr. Deborah Schenberger is the technical advisor and the team has access to all the

manufacturing and testing facilities at the University of Portland.


TABLE OF CONTENTS INTRODUCTION ......................................................................................................................................................................... 4

Introduction ................................................................................................................................................................................... 4

Frame ............................................................................................................................................................................................... 4

Drive System ................................................................................................................................................................................ 5

Bucket Wheel ............................................................................................................................................................................... 6

Conveyor Belt and Arm ............................................................................................................................................................ 7

Electrical Control and Communication System .............................................................................................................. 7

Requirements ........................................................................................................................................................................... 7

Subsystems ............................................................................................................................................................................... 8

Safety, Dust and Heat ........................................................................................................................................................... 9

Verification and Validation .................................................................................................................................................. 10

Risk Assessment ....................................................................................................................................................................... 10

PROJECT MANAGEMENT ................................................................................................................................................... 10

CONCLUSION .............................................................................................................................................................................. 11

REFERENCES .............................................................................................................................................................................. 12

APPENDIX A: Competition Rules ........................................................................................................................................ 13

APPENDIX B: Proposed Schedule ........................................................................................................................................ 20

APPENDIX C: Budget ............................................................................................................................................................... 21

APPENDIX D: Figures ............................................................................................................................................................... 22

APPENDIX E: System Interfaces .......................................................................................................................................... 26

APPENDIX F: Decision Matrices .......................................................................................................................................... 27

APPENDIX G: Action Item Log Example ......................................................................................................................... 28


INTRODUCTION In order to encourage students to utilize skills

learned through studies in engineering, NASA

sponsors a competition that involves designing

and constructing a robot that could operate and

collect regolith samples on the moon. Students

must use skills including time management,

group communication, creative thinking, and

design decisions.

A group of engineering undergraduates at the

University of Portland have constructed a

lunabot with a bucket wheel as the method of

collection. Several ideas were analyzed which

included overall designs, material selection, and

risk assessment and through evaluating all of the

desired criteria, the design of a bucket wheel

was selected. With this design in mind, each

member of the team was assigned to a system of

the overall device, and detailed designs were

created. From these designs, parts were ordered

and the robot was constructed. Upon

completion of construction, the robot will

undergo testing, and improvements may be

made.

This report details the process of robot design,

analysis, and construction that occurred at the

University of Portland.

SYSTEMS ENGINEERING INTRODUCTION:

The design of the excavator began, most

importantly, with the method in which the

regolith was to be collected. Once this was

finalized, then the general shape and size

regarding the surrounding frame was

finalized. The next step was to design the

robot in SolidWorks in as much detail as

possible. The main components of the

excavator that will be discussed are the

Bucket Wheel, Conveyor and Collector

Assembly, Frame, Drive system, and

Control System. One important factor in the

design of all the mechanical components

was the extensive ability of the team to

fabricate all our own parts, namely, the

ability to weld steel and aluminum

ourselves. This allowed for greater freedom

in all stages of design.

FRAME:

The frame was to be built with as much

versatility and simplicity as possible.

According to the bucket wheel design that

the robot was basically built around, the

frame had to be large enough and long

enough so that the bucket wheel and the

conveyer portion of the robot would fit

within. The overall size of the frame was

designed to be as close to the largest

dimensions allowed so that all of the

components would fit onto the frame. The

design for this frame would preferably be

welded, because it would be experiencing

mild vibrations, and therefore it would be

possible for fasteners to come loose. Lastly,

the frame had to be able to hold a

considerable amount of weight over 100

pounds.

The design was reliant on the type of

material selected, and there were several

which were reviewed as possibilities to

fabricate the frame from. A materials

selection chart (Table F.3) was created to

identify the best material for this robot.

After looking over several typical materials

that may have been used on a lunabot, the


material selected was 1060 Aluminum. This

material scored high in all of the priority

areas for the building of this lunabot. The

main benefits of this material selection were

as follows: the ease of access, high strength,

and the low cost of the material.

Once the material was selected, the design

for the frame was modeled using

SolidWorks. It was designed using standard

square tubing that would be very strong and

light, and was readily available with the

funds that had been gathered at the time.

The frame was made of square tubing with

dimensions of 1 in by 1 in, and also some

1060 angle iron that was used sparingly to

reduce the weight of the overall system.

This material was also a good selection

because of its ability to be easily welded.

These materials were superior to titanium

and fiberglass because those materials

would have had a complicated procedure for

fastening.

Before the building process began, a

detailed list of the sizes needed for the

building of the frame was established, and

then marked out on the material. The pieces

of the square tubing were cut using a metal

horizontal band saw, and the angle iron was

cut using a plasma cutter. Once all the

pieces were prepped and then cleaned so

that they could be welded, they were aligned

at the angles necessary using a square, and

then they were welded and ground down

using a hand air grinder. The frame was

completed to specifications.

The frame is very strong, and has the ability

to hold 200+ lbs, so this frame is strong

enough for the application it is going to be

used under. Also, another important

specification was that the robot frame had to

be low in weight, and the frame has a total

weight of around 28 pounds.

DRIVE SYSTEM:

There were many considerations which were

taken into account during the design of the

drive train. Important factors considered

were using tracks versus wheels, the number

of driven wheels, the steering method, the

speed at which the lunabot would be

traveling, the terrain the lunabot would have

to cover, and the manner in which power

would be transmitted to the wheels, among

other considerations. One of the major

factors behind the design of the drive system

was simplicity to avoid as many competition

problems as possible.

It was decided that wheels would be the best

for the lunabot, as they would be easier to

set up than a track system and would still

provide sufficient driving capabilities over

rough terrain. The initial design consisted of

4 powered wheels, two on each side. It was

necessary for there to be all powered wheels

for a robot traveling over this kind of terrain,

in case a wheel lifted off the ground. Having

all wheels powered prevents halting of

mobility. The driving force is also more

equally distributed if all wheels are driven..

Steering of the lunabot is achieved through a

differential drive system. During turning

operations, the motors are programmed to

spin in opposite directions, theoretically

allowing the lunabot to turn in circles while

being standstill. However, during early

testing stages, this was not the case. The

lunabot was able to drive forward and

backwards, but there wasn‟t enough torque

to turn the lunabot when the wheels were

spun in opposite directions. A theory for


this failure is that the wheelbase is not

square, resulting in sideways friction on the

wheels as they try to turn. Also, the current

motor controllers restrict the amount of

amperage that is able to be provided to the

motors, thus decreasing the total torque

available. To remedy these problems, more

robust motor controllers were purchased and

the wheels were moved closer to each other

for a squarer wheelbase.

In total, there are 4 CIM motors, identical to

the ones used by FIRST robotics

competitors. These motors were chosen

because they provide both ample power and

torque for their size, and proved to be much

better than the other alternatives considered.

There are two motors for each side of the

robot, which are geared down for more

torque through a CIMple gearbox, which is

also used by FIRST competitions (Figure

D.5). The gearbox has an overall ratio of

4.67:1. It was decided to gear the motors

down because overall torque is more

necessary than speed and power for this

application. Wheels that spin too fast may

dig tracks into the regolith, which may be

difficult to drive out of. Thus the motors are

geared down so the lunabot will have

enough torque to both carry its weight and

the collected regolith weight, but also

enough torque to climb rough terrain. The

angle of incline of the terrain or an obstacle

can greatly increase the amount of torque

required for the lunabot to move.

The output shafts of the gearboxes each

have two sprockets on them (Figure D.5).

This is done so that power can be

transmitted to both the front and the back

wheel at the same speed. There are four

powered axles on the lunabot, which are

conjoined to the gearbox with a chain and

sprocket set up. The axles are each

supported by two pillow blocks, which are

mounted directly onto the long section of the

frame. On the outer end of the lunabot, the

axle is flush against the side of the frame, so

as to adhere to the size constraints of the

competition. The axle is cantilevered on the

inner end of the lunabot, at the end of which

the sprocket and chain are attached (Figure

D.8). The wheel is keyed to the axle and sits

in between the two pillow blocks. The axle

is locked into place by means of collars on

the inner end of the pillow blocks. Any

linear translation in the axle may cause

stresses in the chain and the sprocket from

being out of line, so it is important to

constrain any horizontal axle movement.

The wheels chosen are 8 inch solid rubber

treaded tires, with plastic hubs. They are

each rated for 1,100 lbf, so they are easily

strong enough to support the weight of the

lunabot. Solid rubber tires were chosen as

inflated ones would not be effective in a

lunar environment. The bearings are simple

plane bearings made of a polymer material.

Plane bearings were chosen as they are

greaseless, “self-lubricating” and are not

adversely affected by the abrasive regolith.

Ball bearings were specifically avoided as

the regolith may have potentially mixed with

the grease, effectively rendering the bearings

useless. The bearing pillow blocks have

slots in them, which allows easy adjustments

in the tension on the chain. The axles and

sprockets are both made from aluminum,

chosen for both its light weight and easy

machinability (especially for keying shafts).

BUCKET WHEEL:

The priority in the design of the collection of

regolith was that the method must be very

proactive in obtaining the stimulant. There

were three main designs considered for this

part: a Ferris wheel, a broom and dustpan,

and a waterwheel. The Ferris wheel had too


many complicated parts, and the broom

design‟s effectiveness was questionable, so

the waterwheel or bucket wheel was chosen.

The bucket wheel was designed to consist of

two concentric cylinders or drums with their

axis horizontal to the ground. The outer

drum would rotate about the stationary inner

drum, and buckets would be welded onto the

outer drum to scoop up sediment. The upper

part of the inner drum was to be cut away

and replaced with a funnel of sorts to help

move the regolith from the buckets to the

conveyor belt. The regolith would be

collected from the individual buckets into

the inner area of the bucket wheel via a one

inch by two inch slot in the back of each

individual bucket. As each bucket reached

the top of the wheel, the regolith would fall

through the slot due to gravity, into the

funnel and onto the conveyor.

The bucket wheel of the assembly posed

some challenges. First, it is difficult to

manufacture two concentric cylinders of

slight different diameter from sheet metal in

a basic university machine shop. If they are

not perfectly circular, they will not be able

to freely rotate with respect to each other.

Also, while it is easy to attach the outer

drum to a rotating shaft to cause it to spin,

there was concern about how to keep the

inner shaft from rotating as well. This was

solved by securing it with the conveyor arm

so even with the friction between the

moving surfaces it will hold its place.

CONVEYOR BELT AND ARM:

After the collected regolith slides off the chute

on the bucket wheel, it lands on a conveyer belt

where it is carried up to a collection bin to be

stored until deposited in the drop box. The belt

material selected is used in the pulp industry. It

is light-weight, yet strong due to metal thread

reinforcing. The belt had two major obstacles,

first how to drive it and second, how to keep the

material from sliding back down its almost 50

degree incline.

To drive the belt, two students designed

sprockets which were then machined. The

teeth on the sprockets catch grommets

placed in the belting allowing the sprocket

to turn the belt. The sprockets are attached

to the same shaft as the bucket wheel for

simplicity and thus are driven by the same

motor. To keep the material from sliding

down the belt, foam poster board was cut

and folded into slats and then glued to the

belting using a flexible silicon adhesive.

Also, at the base of the belt is a catch basin

to allow the maximum amount of the

excavated regolith to be carried up by the

belt instead of falling back to the ground

The whole assembly is held together and

attached to the frame by a long arm that was

designed based on requirements of bucket

wheel and conveyor belt. The arm is made

out of light-weight aluminum tube. The arm

has two parallel tubes braced by diagonal

cross-tubes for rigidity. The bucket wheel is

attached to one end of the arm and the other

end attaches to the frame at the top rear

cross-bar of the frame. The conveyer belt

runs along either side of the arm, going up

along the top, and down along the bottom.

This way the arm can provide support to the

belt, but also not interfere with the slats on

the belt.

ELECTRICAL CONTROL AND

COMMUNICATION SYSTEM:

REQUIREMENTS

Specifications for the project demanded an

electronic control and communication


system which would allow the robot to be

telerobotically operated from a remote

control room over an IEEE 802.11b/g

standard wireless network. While the NASA

Lunabotics Rules allow for an autonomous

robot, the team determined that designing

and implementing a remote directly operated

control system would be the best use of

resources. The University of Portland

Robotics Team needed a control system

which:

Allows remote operation from a control

room approximately 150 to 200 feet

away.

Operates over an IEEE 802.11b/g

wireless network.

Drives multiple bidirectional 12V DC

motors.

Allows the robot to operate for at least

15 minutes with an onboard power

source.

SUBSYSTEMS

The entire electrical control and

communication system was separated into

three interconnected subsystems, two of

which are onboard the robot. These are the

embedded control subsystem, the mission

control base station, and the power

subsystem. Figure D.1 is a block diagram of

the electrical control and communication

system, showing the three subsystems.

On board the robot, the embedded control

system consists of an Arduino Duemilanove

microcontroller board and a Dell notebook

computer. The Arduino board is based

around the ATmega168 8-bit

microcontroller. The Arduino platform was

chosen due to the powerful and open source

Arduino Integrated Development

Environment (IDE), which offers a high

level programming language based on the

C/C++ family of languages. While the

Arduino is more expensive than other

microcontrollers, such as a PIC

microcontroller, its ease of programming

and additional features outweighed the costs.

Following the selection of the Arduino, the

team began designing a way to connect the

Arduino to a wireless network in order to

receive commands from the mission control

room. Initially, the team planned on using

the Async Labs Wishield. The Wishield

connects to the Arduino board and provides

wireless internet connectivity. However, the

Wishield uses a number of valuable

input/output (I/O) pins on the Arduino

board, which made it a less attractive option.

At that time, the team received word that the

University of Portland Media Services

would donate a Dell laptop to the Robotics

team. As the Arduino directly connects to a

computer via a USB cable, the team decided

to use the laptop onboard the robot as the

wireless network connection. The laptop

communicates with the Arduino using serial

communication over the USB cable.

The mission control room subsystem

consists of another laptop and a Linksys

wireless router. Rather than program a

complicated network solution to interface

the control room computer with the onboard

laptop, it was decided to simply use

Microsoft Remote Desktop to directly

access the onboard laptop over the network.

This solution allows the remote operator to

communicate with the Arduino

microcontroller directly, by virtually using

the console on board the robot. A major


disadvantage to this approach is that joystick

input is not transmitted over the remote

connection, thus requiring the excavator to

be keyboard controlled. However, the

distinct advantage of not requiring the

writing of a complicated network program

outweighs this shortcoming. In particular,

adding a camera to the excavator merely

requires plugging it in and bringing up the

video feed on the computer rather than

manually sending video over the network.

To interface the laptop with the Arduino, a

C++ program was written. This program

reads in a keystroke by the operator and

sends an integer value corresponding to that

key over the COM port to the

microcontroller. Another program, written

with the Arduino IDE and running on the

Arduino board itself, then interprets these

integer command and acts appropriately,

such as sending a pulse width modulation

(PWM) signal to the motor controllers.

The third subsystem is the power system. A

12 volt lead acid battery provides all electric

power for the robot, except to the embedded

control subsystem, which is powered off of

the laptop battery. 8 gauge wire runs from

the terminals of the battery into the

electronics box, where it is routed into the

emergency stop button. Parallax HB-25

motor controllers are powered by the

battery. These motor controller modules

accept a source voltage from 6 to 16 Volts

DC, and each is able to provide 25 amps

continuous and a 35 amp surge to a motor.

They are H-bridge motor controllers,

meaning they can power the motors in either

direction. These motor controllers accept a

PWM signal from the microcontroller, with

the width of the pulse determining the

output to the motor.

On startup of the excavator, the onboard

laptop is powered on and connected to the

proper wireless network. Additionally, the

emergency stop button is disengaged,

allowing the motor controllers to receive

power from the battery. The remote operator

logs onto the onboard laptop via a remote

desktop connection, and initializes the C++

program. At this time, the excavator is fully

functional. When the operator presses a

valid key on the keyboard, such as „w‟ for

forward, the C++ program interprets the

keystroke and sends it to the Arduino. The

Arduino interprets the command, and sends

a 5 volt pulse signal to the correct motor

controller, with the width of that pulse

varying from 1 millisecond to 2

milliseconds. 1 millisecond is full reverse,

and 2 milliseconds is full forward, with 1.5

milliseconds as neutral. The motor

controllers receive and interpret the pulse,

powering the corresponding motor. When

the operator releases the key, the C++

program sends a signal to the Arduino,

telling it to stop the motors. A 1.5

millisecond pulse is then sent to the motor

controllers, and all motor activity ceases,

until another key is pressed.

SAFETY, DUST AND HEAT

If, at any time, the emergency button is

pushed, power is immediately disconnected

from the motor controllers, which stops all

motors. While the Arduino and laptop are

still powered, the excavator is completely

immobile until the button is released.

Additionally, if the motor controllers fail to

receive another input signal pulse in four


seconds, they will disconnect power from

the motors. This way, should the network

connection be lost from the control room, in

four seconds the excavator will be

immobilized. The HB-25 motor controllers

are also equipped with automatic fault reset

and 25 amp fuses as additional safety

features.

The simulated lunar regolith is likely

harmful to the onboard delicate electronics.

Though tests have not been conducted to

determine the validity of this statement, the

team has decided to protect the electronics

in an acrylic case. Little dust will be able to

penetrate the case, thus keeping the

electronics safe.

However, the electronics, especially the

motor controllers, generate a great amount

of heat. In the enclosed case, that heat may

accumulate, harming the performance of the

electronics. To remedy the issue, an air filter

is attached to the case. Also, the motor

controllers and laptop are equipped with

their own heat sink and fans.

The team understands that such a cooling

system would be ineffective in a lunar

environment. However, according to the

2011 NASA Lunabotics FAQ, it is

“reasonable to allow actively fan cooled

electronics. This is a part of not having to be

space qualified.” (Page 3). The fan based

cooling system is used as a practical

solution.

VERIFICATION AND VALIDATION:

Initial verification of the individual and

integrated systems was conducted using

SolidWorks 3D modeling program to check

compliance of physical characteristics

(dimension, mass, etc.) to competition rules.

As these were assembled and manufactured,

before integration on the final device, they

were verified a second time. The first

systems completed were the frame and

drive. The welded frame met all of the

requirements set forth in the design phase;

the drive system did not. Modification of the

original drive design was required to

increase the maneuverability of the lunabot.

The system was then verified against the

system requirements as defined by the

Competition Rule Book.

To date, the frame, drive, electrical control

and communication systems have been

integrated and are in the process of

verification. The conveyor belt, arm, and

bucket wheel have been verified in

SolidWorks, but require further assembly

before integration with other subsystems.

RISK ASSESSMENT:

Of the four major subsystems, drive system

is currently high risk. To reduce complexity,

this system was designed using differential

steering like a tank. Currently, the motor

controllers for this system were designed to

limit current usage to maximize battery life.

This combination resulted in underpowered

motors, resulting in low maneuverability.

Appendix E lists the important system

interfaces.

PROJECT MANAGEMENT Regardless of the scale of an engineering

project, it is important to assemble a team of

competent professionals with the necessary


technical expertise to achieve the objective

desired. Our team was composed of 16

undergraduate engineering students from

sophomore to senior level in a range of

disciplines.

There was a team lead that oversaw the

entire project and held the responsibility of

keeping the team on schedule to meet their

deadline; a head for each major subsystem

to ensure completion of the systems as per

the schedule; and the remaining team

members were placed under the leadership

of subsystem heads.

Action Item Logs were implemented as a

means of contracting specific portions of the

work load to individual team members.

These included a date of assignment and

completion, task description, and were

signed by the individual to assure

fulfillment. A sample action item log can be

found in Appendix G.

CONCLUSION The University of Portland team underwent a

process that involved evaluating several

different possibilities in order to select a design

that best matched the group‟s goals. Upon

choosing this design, the team underwent a

series of processes that involved constructing the

original device, testing, and improving the

original design. This series has allowed the

group to meet its goals in readiness for the

competition.


REFERENCES

1. Auburn Team Pumpernickel. Systems Engineering Paper, 2010.

2. Lunabotics Mining Competition FAQ, Revised 8 April, 2011,

http://www.nasa.gov/pdf/485336main_Lunabotics%20FAQ%202011%20Revised.pdf

3. Lunabotics Mining Competition Rules, 11 January 2011,

http://www.nasa.gov/pdf/390619main_LMC%20Rules%202010.pdf

4. Lulay, Ken. University of Portland, Mechanical Engineering Student Reference

Materials, http://faculty.up.edu/lulay/MEStudentPage/ME-Student-Page.htm

5. NASA Systems Engineering Handbook,

http://education.ksc.nasa.gov/esmdspacegrant/Documents/NASA%20SP-2007-

6105%20Rev%201%20Final%2031Dec2007.pdf


APPENDIX A: COMPETITION RULES








APPENDIX B: PROPOSED SCHEDULE


APPENDIX C: BUDGET

Table C.1: Budget by system.

Description Unit Cost Count # Units Cost Totals

# Frame

1 Aluminum Tube 1" x 1" x .12" $39.69 per 21ft 164 9 357.21$

2 Aluminum Sheet 1/16" $105.6 per 4ft x 4ft 6 2 211.20$

3 Pillow Block Bearings $10 8 8 80.00$ 648.41$

Construction

4 Welding Cost 100.00$ 100.00$

Control System

5 Laptop $25 1 1 25.00$

6 EnerSys Sealed Lead Acid Battery $83 2 1 83.00$

7 Wire- 8 gage $0.72 1ft 20 14.40$

8 Wire- 20 gage $0.72 1ft 40 28.80$

9 Ring Terminal $2.99 per 10 30 3 8.97$

10 Electrical Tape $0.59 per roll 1 1 0.59$

11 HB-25 Motor Controller $49.99 1 10 499.90$

12 Victor 884 Motor Controller $89.99 1 5 449.95$

13 Red Emergency Button $54 1 1 54.00$

14 Wireless Router $100 1 1 100.00$

15 Arduino Duemilanove $29.99 1 2 59.98$ 1,324.59$

Drive System

16 2.5 inch CIM, Brushed DC Motor $25 1 6 150.00$

17 8" Solid Rubber Tire $7 1 6 41.94$

18 #25 Single Strand-Riveted Roller Chain $20 10 ft 2 40.00$

19 Axles $13 5 5 65.00$

20 CIMple Box, Single Stage Gearbox $68 1 2 136.00$

21 Toughbox Mini am-0654 $90 1 1 90.00$

22 S25-32L Aluminum Sprocket $11 1 6 66.00$

23 S25-36L Aluminum Sprocket $11 1 6 66.00$ 654.94$

Conveyor Belt & Arm, Bucket Wheel

24 Aluminum Sheet 1/16" $105.6 per 4ft x 4ft 11.8 sq ft 2 105.60$

25 Schedule 80 Pipe- OD 3/4", ID 1/2" $6.68 per 2ft 2ft 1 6.68$

26 Conveyor Belt $10 10ft 1 10.00$

27 Bearing ID 3/4", OD 1-5/8" $50.00 1 5 250.00$ 372.28$

3,100.22$ Total Robot Cost:


APPENDIX D: FIGURES

Figure D.1: Block diagram of the electronic control system.

Figure D.2: SolidWorks assembly of frame, drive, and digging systems.


Figure D.3: German Mining Rig that the bucket wheel is based off.

Figure D.4: Aluminum tube frame assembled.


Figure D.5: Two CIM motors, CIMple gearbox, and output shaft.

Figure D.6: Verification of frame, drive, and electrical control and communication systems.


Figure D.7: Placement of bucket wheel.

Figure D.8: Robot with conveyor belt and bucket wheel.


APPENDIX E: SYSTEM INTERFACES

Fixed to Fixed Electrical to Dynamic

Frame to Digger/ Pivoting Mount Onboard Laptop Victor 884 MC

Conveyor Assembly

to Motors

Frame to Wheels Pillow Blocks Onboard Laptop Victor 884 MC

to Winch

Fixed to Dynamic

Electrical to Electrical

Frame to Motors Gearbox mounts

Batteries to Wired Connection/

Frame to Winch Fixed Plate Motor Controllers

Emergency Stop

Drive to Motors Chain and Sprocket Controller to Wireless Router/

Onboard Laptop

Remote Desktop

Digger Arm to Winch Cable

Connection

Fixed to Electrical Onboard Laptop to Arduino

Victor 884 MC

Microcontroller

Frame to Batteries Custom Mount

Frame to Electrical Rigid Box

Components


APPENDIX F: DECISION MATRICES

Table F.1: Rubric

Assigned

Number

Excellent 4

Good 3

Meets

Requirements

2

Poor 1

Table F.2: Digging Mechanism

Ease of

Construction

Collection

Rate

Avoids

interference with

other parts

Cost

Effective

Total

Bucket

Wheel

3 3 4 4

14

Auger 2 1 4 3 10

Scoops 4 3 1 3 11

Table F.3: Material Selection

AISI 1080 Titanium Fiberglass 1060 Aluminum

Cost Effectiveness 5 1 1 5

Strength 5 5 2.5 4

Hardness 5 5 3.5 4.5

Weldability/ Ease of Fastening 5 1.5 1 4

Ease of Manufacturing 4.5 2.5 1 5

Suitable for the Given Environment 5 5 4.5 5

Weight Effectiveness 2 4.5 5 5

Total 31.5 24.5 18.5 32.5

Quality : 1 Low Performance 5: High Performance


APPENDIX G: ACTION ITEM LOG EXAMPLE


Date post:	22-Feb-2015
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