Bulk Material Transport
SHIFTY
(Critterus Shiftius)
MEEN 4264: Senior Design
April 28, 2005
Mitchel Smolik
Alan Elps
Eric Cox
Lance Cross
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TABLE OF CONTENTS
Table of Contents .......................................................................................................ii
Abstract ......................................................................................................................iii
Introduction ................................................................................................................1
Objective ....................................................................................................................2
Design Development ..................................................................................................3
Analysis......................................................................................................................13
Manufacturing ............................................................................................................19
Schedule .....................................................................................................................22
Budget ........................................................................................................................24
Conclusion .................................................................................................................25
References ..................................................................................................................27
Appendix A: ASME Student Design Competition Rules ..........................................28
Appendix B: Photos ...................................................................................................31
Appendix C: Hand Calculations ................................................................................35
Appendix D: Finite Element Analysis ......................................................................41
Appendix E: Detail Drawings ....................................................................................44
Appendix F: Procurement Packet ..............................................................................59
Appendix G: Drive System Specifications ................................................................63
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ABSTRACT
The purpose of this senior design project is to design and build a bulk material transport device
that will be used to overcome a specific barrier. The American Society of Mechanical Engineers
(ASME) issued this challenge to engineering students around the world. This simplifies the first
phase of the project, since the problem is defined in entirety for us ASME, as part of their 2005
student design competition, specified the criteria for the design, and the obstacle to be traversed.
This project commenced in May 2004 with the concept phase. Once the 3D solid computer
model was completed we obtained sponsorships to fund the materials and parts. We built and
tested the vehicle and made minor modifications to the original design. The design preformed
well and placed 3rd in the regional ASME competition in Spring 2005.
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INTRODUCTION
The purpose of this project is to design and build a bulk material transport device that
will be used to overcome a specific barrier. The American Society of Mechanical Engineers
(ASME) issued this challenge to engineering students around the world. This simplifies the first
phase of the project, since the problem is defined in entirety for us. The design problem
description is located at the ASME student design competition web site [2]. Along with the
stated problem definition, there is a question and answer forum to determine other contest
legalities. Figure 1, Obstacle Drawing is a visual depiction of the problem statement and directly
shapes our design. A full version of these rules can be found in the Appendix A; ASME Student
Design Competition Rules.
Figure 1.
Diagram of stair obstacle course [1].
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OBJECTIVE
The objective of this project is to create a vehicle to transport as much granular material
(rice) over the obstacle and dump it into the container. This can be done as many times as
possible within 10 minutes.
Specifications
No quantitative design specifications are given for the vehicle, except the size constraints
given in the rules (25x25x30cm). Based on initial concepts, a goal is set for at least 50 lb. of rice
in 10 minutes, and a minimum load per trip value is set at 17 lb. In relation to the previous, the
vehicle minimum top speed is specified to be 3 in/s. The driving motor/s are expected to be
capable of providing a force on the ground equal to or greater than the weight of the vehicle at
the speed specification. So, should the vehicle be capable of sticking to a vertical wall, it will be
able to climb it at 3 in/s.
DESIGN DEVELOPMENT
Track Design
It is important to start the project with a good foundation. It was decided early on that a
tracked vehicle would provide this. The rest of the project would be based from this decision so
it was critical to choose a good design early on. As can be seen by Figure 2; Track Design
Progression, several concepts were evaluated before choosing the final ‘W’ design. The first
concept shown in the figure is a traditional tank-type tread, ruled out for the angle it would attain
when climbing. The second is a movable cantilever design, capable of either spanning an extra
step, or lifting the back end of the vehicle. The third is closely related to the chosen design, but
is intended to climb in one direction.
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Figure 2.
Progression track designs.
Bed Slide Design
During our concept phase, this ‘W’ track design accompanied a movable bed, to control
the center of gravity. This would be completely necessary, since most of the weigh was at the
top of the vehicle; a rollover would be unavoidable without it. Two choices were available for
consideration. The first was a double slide, letting double the slide distance over the single slide
option. Figure 3; Bed Slide shows the single slide that was used for this project. The decision
was made that the linear distance needed would not require the more complicated, and spacehogging slide.
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Figure 3.
Bed slide mechanism.
The slide design never strayed from a gear motor-driven rack-and-pinion drive, but the
details took time to develop. Initially the rack was connected to the bed, which tilted on an axis
at the end of the slide rods. This meant that the pinion would separate from the rack to dump
rice. We didn’t think there would be too much trouble getting them to mesh when they
reconnected, given the fine pitch of the teeth. But, keeping the correct backlash, and meshing
and unmeshing the gears seemed risky. It was decided at some point to keep the drive motor
stationary, since it would be the lowest member of the assembly. If it moved with the bed, there
would likely be interference issues with other parts. Eventually, the assembly evolved to have a
rack attached to the slide bearings. The current design has a motor mount spanning between the
rod mounting blocks, which means the motor now lifts with the bed, slide rods, and rack. The
whole top of the vehicle flips up, not only yielding a more reliable assembly, but gives easy
access to the innards for a quick battery change, and makes it easier to build. This results in
more weight to lift when dumping, but being able to slide the bed nearly all the way to the
fulcrum makes the bed easier to dump.
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Bed Design
The other major mechanical assembly was the bed itself. At first the intention was to use
one large bed. However, the question and answer forum revealed the legality of assembly after
the vehicle was in the starting area. Armed with this information, the design took a radical turn.
The payload capacity could be doubled by utilizing slide outs that fit within the require
dimension prior to starting and then be extended in the starting area. Side slide outs were not
feasible due to the necessity of a complicated dumping door that folds out. To simplify this, a
fore and aft approach was taken as shown by Figure 4; Bed Extension.
Figure 4.
Bed extension mechanism.
Motors
Geared, DC motors were the only alternative considered; we didn’t want to take the time, or
waste the space to attempt our own gearbox. The chosen motor was a Pittman design, capable of
a continuous 500 in oz of torque, as limited by the gears. Together they are capable of providing
62.5 lb at the ground. This figure is taken at the ground, not considering drivetrain losses. The
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same motors would be used to drive the tracks and bed slide, so that it would be necessary to
carry only one spare [2].
DISCUSSION OF CURRENT DESIGN
………Body of Report……………..
……………….
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SCHEDULE
The schedule for this project begins in May 2004. This is when it was decided to undertake the
challenge and recruit the team. We scheduled tasks in categories including design concept, solid
modeling, sponsorship procurement, build, and test phases, as shown in Figure 5 and Table 1.
The Gannt Chart has been updated reflect the actual completion of tasks.
Figure 5.
Schedule of Shifty Design, Fabrication and Testing
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BUDGET
Early on in the project we knew funding would be an issue. Since the solid model was completed
we used it to create a packet, which was used to sell our project to potential sponsors. The break
down of sponsorship is as follows in Table 1.
Table 1
Breakdown of Sponsorships
FMC
Driver/PG (Anaheim Automation)
Salvage Materials (CCAD)
Scrap Iron (Alan Elps)
Drive Motors (Click Automation)
Drive Belts (Econobelt)
CMT Discounts
Total Donations
$400
$135
$297
$146
$330
$60
$67
$1,435
Table 2 shows our parts list break down and reflects the actual project cost.
Table 2
Parts List Breakdown and Actual Project Cost
20o pressure angle gear rack
20o pressure angle spur gear material 0.667 pitch diameter
17-4 PH Stainless Steel slide rod material
0.25” X 1” 2024 Aluminum flat bar for cross members
Shipping cost for above items
3 ea. Geared drive motors 36 rpm, 2.6 lb-ft continuous torque (donated)
3 ea. 8mm HTD timing belts (donated)
2” X 36” 6061 Aluminum bar stock for wheel material (donated)
0.1875” X 12” X 12”Aluminum plate for side frame material (donated)
0.0625 X 3’ X 3’ Aluminum sheet metal for bed construction (donated)
Electrical components used from items donated by CCAD (donated)
32 ea. Rolled Blade Abec #1 bearings for idle wheels (donated)
Linear Actuator for tilting bed
Switches for controlling motors
C cell battery holders
C cell batteries used for testing and competition
Driver/ Pulse Generator
Total Expenses
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$75.53
$20.63
$21.93
$17.10
$30.00
$330.00
$60.00
$100.00
$20.00
$60.00
$150.00
$50.00
$136.00
$40.00
$15.00
$80.00
$135.00
$1,341.00
CONCLUSION
After considerable time in the concept phase, an accurate parametric model was created
of the ‘W’ track concept with the sliding bed. Manufacturing started late in the detail design
phase as drawings were produced. Many parts were made before the entire design was complete.
The finished prototype performed well after several minor modifications. All original
specifications were met and exceeded. This project proved the viability of our ‘W’ track design
combined with a controllable center of gravity for stair climbing vehicles in general.
Specifically, we won 3rd place out of 37 teams competing in the ASME Region X Student
Design Competition.
Lessons Learned and Future Work
The single most important advantage the competition had was power. The teams with
robots carrying more rice used CTA batteries. Although their capacity is similar to an Alkaline,
there are capable of providing in the range of 10 times the current without significant voltage
drop.
After the fact, it appears that in a project like this should spend as much time in the
concept phase as possible to ensure that the concept chosen is optimized for all given parameters.
There is always pressure to stay on schedule, and to make the prototype work. But, this
competition was lost in the concept phase. We could have used more, different ideas. Judging
from the competition, we should have expanded the bed upward to gain more capacity. This
wasn’t possible for us though. The rules of the competition took shape slowly, as more questions
were asked. So teams that formed or modified their concepts after they had full understanding of
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the rules had a distinct advantage. With the schedules of our team members, we had no time to
waste arguing about the rules. Additionally, unlike many schools, we procured our own funding,
which took considerable time. Regardless, we are satisfied in completing, on time, a project that
met our goals and did well against the competition.
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REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
Grimm, T.A., “3D Printer Benchmark: North American Edition,” T.A. Grimm & Associates Inc,
www.tagrimm.com, June 2010.
ASME Student Design Competition , 2005,
www.asme.org/students/Competitions/designcontest/2005/Design_Problem_Description.html,
May 2004 – April 2005.
Peel, L.D., Baur, J., Foster. D., Phillips, D., McClung, A., “The effect of scaling on the
performance of elastomer composite actuators,” SPIE Smart Structures/NDE 2010, March 2010.
Zhou, H, Ting, K. L., Topological Synthesis of Compliant Mechanisms Using Spanning Tree
Theory, ASME Journal of Mechanical Design, Vol. 127, No. 7, 2005.
Zhou, H., Ting, K. L., Shape and Size Synthesis of Compliant Mechanisms Using Wide Curve
Theory, ASME Journal of Mechanical Design, Vol. 128, No. 3, 2006.
Zhou, H, Topology Optimization of Compliant Mechanisms Using Hybrid Discretization Model,
ASME Journal of Mechanical Design, Vol. 132, No. 11, 2010.
J. K. Ali; "A new miniaturized fractal bandpass filter based on dual-mode microstrip square ring
resonator," Systems, Signals and Devices, 2008. IEEE SSD 2008. 5th International MultiConference on , vol., no., pp.1-5, 20-22 July 2008.
Peel, L., Meija, J., Narvaez, B., Thompson, K., Lingala, M., “Development of a Simple Morphing
Wing using Elastomeric Composites as Skins and Actuators,” J. Mech. Des., Vol. 131, Issue 9,
doi:10.1115/1.3159043, Sep. 2009
Peel, L., Ball, C., “Fabrication and Testing of a Simple Bionic Arm,” ASME Conference on
Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2010), Philadelphia, PA,
Sept. 2010.
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