Control Systems Considered and Chosen with Rationales

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Automated Drink Machine
Preliminary Project Proposal
Michelle Advena
Alex Horejs
Jefferson Medel
Connor Petilli
4/28/2015
The Automated Drink Machine is a system that makes mixed drinks.
Automated Drink Machine
Contents
I. Overview
Needs Statement
Objective Statement
Description
Marketing Diagram
II. Requirements specification
Needs
Engineering Specifications
Analysis to justify specifications
Drink Platform Subsystem
Control System
III. Concept selection
Survey of Existing Systems
The Inebriator
Coca-Cola Freestyle
Bartendro 15
Concepts Considered and Chosen
Rationale
Survey of Dispensing Methods
Optics
Actuators
Peristaltic Pumps
Solenoid Valves
Pressurized Air
Methods Chosen and Rationale
Drink Platform Systems Considered and Chosen with Rationales
Survey of Possible Platforms
Platform 1 - Driven directly by a motor
Platform 2 - Driven by a motor through gears
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Automated Drink Machine
Survey of Possible Motors
DC motor
Servo motor
Stepper motor
Photo cell
Break beam sensor
Cup Dispenser Systems Considered and Chosen with Rationales
Survey of Possible Sensors
Control Systems Considered and Chosen with Rationales
IV. Design
System Diagram
Subsystems
Alcohol Dispensing
Mixer Dispensing
Drink Platform
Control System
User Interface and Control
Engineering Standards
Multidisciplinary Aspects
Mechanical Engineering
Electrical Engineering
Background
Outside Contributors
V. Constraints and Considerations
Extensibility
Manufacturability
Reliability
Economic Context
Environmental Context
Health and Safety Issues
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Automated Drink Machine
Intellectual Property
Political Issues
Societal Context
Sustainability
Ethical
VI. Cost Estimates
VII. Testing Strategy
Drink Platform Subsystem
Control System
VIII. Risks
IX. Milestone Charts
Page 3
Automated Drink Machine
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I. Overview
Needs Statement
When entertaining groups of people, there are two major options for serving beverages to
guests: hiring someone or employing a self-serve method. Hiring a professional server would
involve a significant expense on the part of the host and is not really feasible for small, personal
events. Though because the host is hiring a professional, it does offer a certain degree of quality
control. Self-serve methods often include single-serve containers or having guests pour
themselves drinks from a selection. A system is needed to dispense mixed drinks efficiently and
accurately without the disorder of open self-serve containers, the inconvenience of measuring out
liquids, or the cost of hiring a third party.
Objective Statement
The objective of this project is to design and prototype a system that will allow guests to
order any existing or mixed drink without having to wait in a queue, allowing them to enjoy the
event free from distraction and prevent them from distracting the other guests. The system will
be controllable remotely. Guests will be able to queue pre-existing or custom ordered drinks for
dispensing and proceed to the dispenser to retrieve the drinks when notified. Social media
functions such as posting to a Facebook timeline or tweeting from Twitter will also be available
to provide ways for the guests to enhance their experience.
Description
The Automated Drink Machine (ADM) will dispense measured amounts of liquids to create
mixed drinks. Food-safe materials will be used for all parts involving the storage and dispensing
of liquid ingredients. Motion controllers and sensors will inform the controller as to the status of
the platform holding the cups and drinks. The platform will be rotated by a motor to align the
cup with the proper dispenser to allow for multiple drinks to be queued. There will be one cup
dispenser, and every other dispenser will correspond to a different liquid. A remotely
controllable server will provide queuing and information from the machine. This server will be
interfaced by a website which customers can access through their phone. The queue will inform
the controller when a cup will be dispensed onto the platform and what liquids will need to be
dispensed into that cup to make the drink. It will only begin dispensing liquid into a cup once
the sensors inform the controller that a cup is in place.
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Marketing Diagram
A preliminary digital, 3-D sketch of system chassis can be seen below. The chassis will
have the drinks, hoses, and various dispensers mounted to it to create the device.
Figure 1: Preliminary Marketing Diagram
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II. Requirements specification
Needs
Table 1 below enumerates the customer’s needs.
Table 1: Customer Needs
No.
Description
1
The system shall
drinks/containers.
2
The system shall correctly dispense a measured amount of fluid.
3
The system will allow cups to move to their proper location.
4
The system will detect when a cup is placed on the platform.
5
The system will detect when a user is reaching for the cup.
6
The system will protect its components from spills.
7
The platform will move smoothly to prevent the liquid in cups from
spilling.
8
The operation of the system shall not be noisy.
9
The dispensing system shall be able to function without manual user
intervention.
10
The user will be notified when he or she needs to refill the cup dispenser
11
The cup dispenser will drop a new cup whenever a new drink is ordered
12
The dispensed drink shall be safe to drink.
13
The system will be able to be controlled remotely.
14
The system can be controlled from various mobile platforms.
15
Multiple clients can use the system at once
16
The system will allow preset drinks to be ordered
17
The system will allow custom drinks to be ordered
18
The system will allow multiple drink orders to be queued
19
The system will allow monitoring of a drink orders status
20
The system status shall be monitored by an elevated client.
21
The system shall provide a list of preset drinks available to the client.
22
The system shall allow the list of preset drinks to be modified by an
provide
a
simplistic
method
for
changing
Automated Drink Machine
elevated client
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23
The system shall provide social media features.
(Posting to Facebook timeline, Tweeting from Twitter)
24
The system shall allow for multiple levels of verified clients.
(provide access to system functions, alcoholic content)
Engineering Specifications
The table below enumerates the engineering specifications and the corresponding customer
need(s).
Table 2: Engineering Specifications
No.
Description
Need(s)
A
The software handling drink orders will have the ability to
queue drinks.
18
B
The device handling drink orders will not need to be
connected physically to the dispensing unit.
13
C
The user shall be able to add and remove drinks manually
from the machine via a provided container.
3
D
A standardized interface/container will be used to store
liquids.
1
E
Cups will be easily replaceable.
1
F
Machine will notify user when cups need to be replaced.
10
G
The platform will be divided into uniquely coded sectors, one
for every cup that the platform can hold.
3
H
The platform will have slots with sensors where a cup will be
placed.
3, 4
I
The system will utilize sensors to detect when a user is
reaching for a cup.
5
J
Relevant portions of the platform will be watertight and
waterproof to at least one full dispensed cup of water
6, 7
K
The platform will be rotated by a low RPM motor
8, 3
L
Ability to measure and dispense a set amount of alcohol in a
2
Automated Drink Machine
multiple of 35mL.
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M
Ability to measure and dispense a specified amount of a
mixer (e.g, ½ cup or ¾ cup)
2
N
Noise from normal operation will not exceed 60 dB.
8
O
All valves, levers, etc. will be electronically (or electromechanically) operable.
9
P
The cup dispenser will be replenished by feed
1
Q
The cup dispenser will have a sensor that will detect the
presence of the bottom cup
10
R
Food-grade parts will be used for all components coming into
contact with the liquids.
12
S
The system will include a wireless network adapter.
13
T
A web-based user interface will be provided.
U
The system shall provide user creation and authentication via
a user database
V
All client actions will be available in the web-based user
interface
16, 17,
18, 19,
21, 22
W
Elevated client actions will be available to authenticated
clients (e.g, modifying drink queue, system power, etc.)
20, 22
X
The system will allow multiple network connected clients.
15, 18
Y
The system will maintain a database of preset drinks.
Z
The drink database shall be modifiable by authenticated
clients.
19, 14
24
16, 21, 22
22, 24
AA
The system will interface with social media APIs. (Facebook,
Twitter)
23
AB
The web-based interface will allow multiple concurrent
connections.
15
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Analysis to justify specifications
Drink Platform Subsystem
The platform needs to be circular to make it as compact as possible. Any other shape will
cause gaps and unused space when rotating it. The moving platform will have cups with liquid
inside of them, so the motor driving it should move at a slower and smoother rate. Sensors are
the best way to detect if something is moving or in place. By making grooves for cups and
placing sensors inside of them, they will be less obtrusive. The grooves will also make sure that
the cups stay in place while the platform moves. Dividing the platform into color-coded sectors
allows the Automated Drink Machine to easily convey where a user’s drink is located, and by
extension, which drink is theirs since there is only once sup per sector. Lastly, the platform
should be waterproof and watertight to ensure that the components used in the system are not
damaged in the case of accidental spills.
Control System
To provide a way for multiple clients to connect from multiple different platforms, the
system will need to have an adapter for a multi-client wireless protocol. Considering the
necessity of cross-platform support, the wireless protocol must further provide a unified form of
communication on multiple platforms. A web-based interface provides both a method of multiple
clients and cross-platform support assuming certain resources like an existing wireless network
are available. Utilizing an existing wireless network, the system can connect and provide a webservice to other users on the network. Not only does this allow multiple wireless clients, but also
a simple avenue for cross-platform support via existing web-based software concepts.
The system must also have a database of drinks to satisfy the need for a client to view,
modify, and select pre-set and custom drinks. An additional user database is also necessary to
allow users to not only be created and authenticated, but also remembered for future events with
the ADM to avoid recreating a user every time.
To specifically provide aspects of social media like custom drink sharing, the software
must have access to high level social media APIs. Most users are likely to be familiar with and
regular users of existing social media services. As such, to provide a way to access and share on
these platforms immediately, the inclusion of standard social media service functions can be
achieve with existing APIs
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III. Concept selection
Survey of Existing Systems
The Inebriator
Website: http://www.theinebriator.com
One of the most popular drink mixers online with a large amount of information available via
blog, the Inebriator was designed to mix alcoholic drinks at parties for attendees who do not have
the inclination to mix their own drinks. It eliminates the need to look up and measure ingredients
and produces repeatable results. Drink selection is made via an attached console with a rotary
encoder. Drink dispensing is managed by an Arduino Mega 2560, while a Fez Panda II manages
the drink selection console. Drink recipes are stored on a SD card in XML format. In addition to
its ability to measure and dispense precise quantities of alcohol, the Inebriator dispenses drink
mixers (e.g. orange juice) and uses a pressurized air tank to push the liquid through the tubes.
RFID is used for to authenticate admin access.
Coca-Cola Freestyle
Website: www.coca-colafreestyle.com/home
The most widely seen, commercially-available, custom drink maker, the Coke Freestyle is a
soda fountain that allows users to mix a variety of beverage bases, (e.g., Coke, Diet Coke, water),
with different flavors, (e.g., vanilla, cherry, lime), to form a customized drink. Micro-dosing
technology is employed in dispensing the flavors, allowing them to be packaged in small
cartridges. Drink selection is made via a touchscreen interface.
Bartendro 15
Website: http://www.partyrobotics.com
The Bartendro 15 is a high-end automated cocktail mixer with a base cost of $3,700. The
system employs 15 peristaltic pumps to dispense accurate and repeatable cocktails. Controlled
via smartphone, users can create custom create drinks, modify existing ones, or add new
ingredients. Precision is emphasized in the setup with dispensing accurate to a ½ oz. When
fully assembled, it is 36”x 24”x 12” and marketed for both home and business.
Concepts Considered and Chosen
The table below provides a comparison of features found in currently available systems as
well as the features to be included in the designed system, where a check mark (✓) indicates the
presence of a feature. The table focuses on the Inebriator and the Coca-Cola Freestyle, as these
represent the private and commercially-available systems, respectively, most closely aligned
with the project’s initial concept.
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Table 3: System Comparison Chart
Feature
The Inebriator
Coke Freestyle
✓
Drink queue
Drink database
✓
Custom mix (real-time)
Drink selection automatically
updates based on availability
✓
Cooling system
✓
✓
✓
unknown
✓
ice dispenser
(manual fill)
✓
Carbonation system
Drink Platform
Planned
(this project)
mobile,
linear
stationary
mobile,
rotational
✓
Remote ordering
Cup detection/sensing
✓
✓
Precise volume measurement
✓
✓
Push-and-hold to dispense
✓
Self-cleaning
✓
Phone app
✓
✓
Touch interface
✓
✓
unknown
✓
Low/empty level detection
Rationale
The Automated Drink Machine (ADM) will attempt to strike a balance between the userfriendly, polished appeal of the Coke Freestyle and the powerful features of a custom system like
the Inebriator. To achieve this balance, a mobile interface with a user-friendly presentation was
selected. To focus efforts on the mobile interface, an at-machine interface will not be provided. If
an interface like that is necessary, one can use a tablet or other mobile device, mounted on the
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machine, functioning exactly like the normal mobile interface. Additionally, to facilitate the use
of custom drinks, a dynamic drink database was selected to allow for the most accurate drink
creation and selection. With this system, the user will not have to worry about drinks that have
been emptied or removed and are no longer available. These drinks should then become
available again immediately upon restocking and updating the database.
To achieve the queue system as described, the specific method of implementation will be
a rotating drink platform. The queueing system allows for the remote ordering system to work
correctly. Without queueing, operation is effectively no different from normal at-machine
ordering. With queuing and the rotating platform however, one can order a drink and have it
begin preparation immediately, rather than after the guest in from of them has ordered.
Survey of Dispensing Methods
Optics
Despite what the name implies, an “optic” (also known as a “non-drip measure”) has
nothing to do with light. Instead, it is the British term used to describe a device that attaches to
the top of a bottle of alcohol and, when inverted, dispenses a measured amount (e.g. 25 mL) of
the spirit. The beauty of these is that they are simple to operate – all that needs to be done to
dispense the liquid is press the lever, as the system is gravity-fed. This could easily be achieved
with some a linear actuator. One drawback of this system is that brackets to hold the optic and
the attached bottle need to be either bought (ideally from the same company that manufactures
the optics) or made. Table 4 shows summarizing prices from the well-known UK optics
manufacturer Beaumont. All optics listed in the table can be operated with a single hand, or in
this case using a linear. actuator.
Table 4: Prices for Beaumont Optics
Product
Price Per Unit*
USD Approximate
25 mL Vogue
£8.50
$12.65
25 mL Metrix SL
£7.00
$10.42
25 mL Solo Professional
£5.18
$7.71
Shelf Bracket
£3.20
$4.71
Wall Bracket
£2.44
$3.59
*At this time it is unknown if minimum purchase is 1 carton (100 units) or 1 unit.
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Actuators
To determine the specifications needed for the actuator, more data on the optic is required.
The main unknown is the amount of force required to operate the optic. This will drive the base
cost of the actuator, as an increase in force corresponds to an increase in torque.
Peristaltic Pumps
Peristaltic pumps are ideal from a contamination standpoint in that no mechanical parts
come into contact with the fluid being moved. Therefore, the only thing that ever needs to be
sterilized is the inside of the tubing. However, this does mean that the tubing needs to be
periodically replaced due to wear. Another potential drawback is that the pump does not provide
a constant flow.
Tubing can be chosen such that it meets any specific requirements for the fluids being
pumped, such as food-safe or compatible with aggressive fluids. For example, McMaster-Carr
manufactures food-safe tubing specifically for peristaltic pumps, “High-Purity White Silicone
Rubber Tubing for Peristaltic Pumps.”
From a “mixers” point of view, peristaltic pumps are ideal in that they can easily move
more viscous fluids. They also provide an easy way to measure the amount dispensed, if sensors
to detect fractions of a rotation are added.
The makers of Bartendro sell the custom peristaltic pump they use (it contains additional
hardware and software), as well as provide free schematics under the Creative Commons
Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) license. Pricing for their dispenser starts
at $120. When the fact that many peristaltic pumps are priced at over $100 is taken into
consideration, the cost doesn’t seem as high.
Solenoid Valves
Solenoid valves could be used either individually or as sets of two. If used individually,
solenoid valves could be used as an on/off switch in a gravity-fed system. In sets of two, the
valves could be used similarly to an optic. Connected by tubing (where the volume between the
two valves is equal to a specified amount, e.g. 25 mL), the top valve would open to allow liquid
into the chamber. Once full, the top valve would close and the bottom valve would open,
allowing the liquid to then flow into the drink. The advantage to using the valves over optics is
that it can be programmed such that the chamber between the valves is only ever filled when a
drink is about to be poured. The downside to that method is that there will be additional wait
time while the chamber fills.
Pressurized Air
The idea behind using pressurized, or compressed, air is that all mixers would be kept a
constant, low pressure. To dispense liquid, the pressure would be increased (forcing more air in)
through one tube, which would in turn force liquid out a second tube. One risk when using
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pressurized air is that the air could potentially introduce impurities into the liquids. Another
major concern is the amount of noise an air compressor would make when running.
Methods Chosen and Rationale
As seen in the Pugh table below, optics had the highest score for dispensing alcohol,
while peristaltic pumps had the highest score for dispensing mixers. Thus, these are the two
methods that will be employed. Note that ‘(A)’ denotes the criterion applies only to dispensing
alcohol, while ‘(M)’ indicates the criterion applies only to dispensing mixers.
Table 5: Pugh Table for Dispensing Methods
Weight
Optics
Peristaltic
Pumps
Solenoid
Valves
Pressurized
Air
Ease of operation
1
1
1
1
1
Sterilization
2
1
1
0
-1
Noise level (quiet)
2
1
1
1
-1
Size (small)
1
1
1
1
-1
Beverage-safe
2
1
1
0
1
Ability to handle viscous
substances (M)
1
-1
1
1
1
Ability to handle
particulates (M)
1
-1
1
0
1
Non-gravity-fed (M)
3
-1
1
-1
1
Gravity-fed (A)
2
1
-1
1
-1
Availability
1
-1
1
1
1
Total (A) /11
-
9
7
7
-3
Total (M) / 14
-
2
14
3
4
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Drink Platform Systems Considered and Chosen with Rationales
Survey of Possible Platforms
Platform 1 - Driven directly by a motor
The motor will be attached directly to the bottom of the circular platform at its center.
This will allow the motor to rotate the platform directly, with the platform’s angle matching that
of the motor.
Platform 2 - Driven by a motor through gears
A large gear needs to be either built into or attached to the bottom of the circular platform.
This will then be connected to a gear attached to the motor. There are several variations
available.
Survey of Possible Motors
DC motor
DC motors are two wire continuous rotation motors. They are generally high RPM and
run until power is removed. The speed of the motor is controlled using pulse width modulation,
a technique that rapidly turns the motor on and off. The rapid pulses make the motor appear to
be running smoothly.
Servo motor
A servo motor is an assembly of four components: a DC motor, gearing set, control
circuit, and position sensor. They are designed to be used for specific tasks where positions need
to be accurately defined. They do not have a free range of motion and are limited to 180 degrees
back and forth from its original position. Servo motors use three wires: power, ground and
control. Servo motors use PWM to determine the position instead of the speed, locking into the
specified position until told to move.
Stepper motor
Stepper motors are also used for specific tasks where the position is important. Unlike a
servo motor however, they uses toothed electromagnets arranged around a central gear to define
position. They require an external microcontroller to control it. Stepper motors have locked
positions of a certain degree for which they move into and are very accurate. Positioning errors
are uncommon since the positions are physically predefined.
Survey of Possible Sensors
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Photo cell
This is a CdS photoresistor that has a high resistance in the dark, and a low resistance in
the light. Photoresistors are small and cheap, but are heavily reliant on proper illumination to
function.
Break beam sensor
The break beam sensor being considered is an infrared (IR) break beam sensor. It has
two components. One emits a beam of infrared light while the other receives it with an infrared
sensitive component. When the second component stops receiving the beam, the beam has been
broken and there is an obstruction. Both components are required on opposite sides of the area
being monitored.
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Systems Considered and Chosen
The table below provides a comparison of the possible platform systems, motors, and
sensors based on their use, attributes, and weighted fields.
Table 6: Pugh Table for Platform Systems
Platform 1
Platform 2
Simplicity
.25
.25
.15
Modifiability
.25
.15
.2
Aesthetic
.5
.3
.45
Score
1
.7
.8
As seen above in Table 6, Platform 2, the platform driven by a motor through gear
intermediaries is a better option. As can be seen in Figure 1, it already fits the current design and
aesthetic by leaving a hole in the center of the platform for tubes and other components to pass
through. While it is more complicated than the platform driven directly by a motor, it is easier to
modify the rotational speed using a single motor since the platform already uses gears..
Table 7: Pugh Table for Motor Systems
DC motor
Servo motor
Stepper motor
Accuracy
.55
.2
.4
.5
Cost
.15
.1
.07
.08
Speed
.3
.1
.22
.28
Score
1
.4
.71
.86
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As seen in Table 7, a stepper motor is the best option for this system. While it is
slightly more expensive than a DC motor, it is by far more accurate. Accuracy of the motor is
paramount for this system since the machine may be run for extended periods of time and will
be forced to rotate the platform numerous times. This system is responsible for making sure
that the cups are in place when dispensing liquid for the mixed drinks. Errors in position may
build up over time and cause spills if the cups are not in place. Furthermore, stepper motors
work well at low speeds.
Table 8: Pugh Table for Cup Detection Systems
Photocell
IR break beam sensor
Accuracy
.35
.18
.35
Cost
.15
.15
.02
Size
.3
.3
.13
Availability
.2
.2
.15
Score
1
.83
.65
Photocells are not as accurate as break beam sensors, and lighting conditions can
produce false positives or negatives. However, this downside can be mitigated by placing the
photocell within the groove to detect cups when they are directly next to it. Furthermore, they
are much smaller, cheaper, and widely available. They can be positioned to be hidden from
view and will not affect the placement of the cups
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Table 9: Pugh Table for Interruption Detection Systems
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Photocell
IR break beam sensor
Accuracy
.5
.25
.5
Cost
.15
.15
.02
Size
.2
.2
.15
Availability
.15
.15
.11
Score
1
.75
.78
Accuracy is just as important when detecting outside interference. The machine needs
to know when to stop operating to prevent spills from occurring. Since there is no way to make
photocells more accurate as when detecting cups, accuracy was weighted more highly. The
break beam sensor is much more expensive, but will not produce false positives or negatives
since it only reports an obstruction when its beam is broken.
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Cup Dispenser Systems Considered and Chosen with Rationales
Survey of Possible Sensors
Table 10: Pugh Table for Cup Dispensing Sensor Systems
Photocell
IR break beam
sensor
Microswitch
Accuracy
.4
1.8
3.5
3
Cost
.1
1.5
0.2
1
Size
.2
3
1.3
0.7
Availability
.35
2
1.5
2
Score
1
2.17
2.205
2.14
As shown above in Table 10, the IR break beam sensor is considered to be the best sensor
for detecting the bottom cup of the dispenser. While IR break beam sensors are not the most
cost-effective solution, they are the most accurate sensor. Accuracy was considered to be the
most important feature for this sensor because the subsystem depends entirely on the presence of
cups in the dispenser.
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Survey of Possible Motors
Table 11: Pugh Table for Cup Dispensing Motor Systems
DC motor
Servo motor
Stepper motor
Accuracy
.3
2
4
4
Cost
.15
1
0.7
0.8
Speed
.4
1
2.6
2.4
Score
1
1.15
2.345
2.28
As shown above in Table 11, the servo motor was chosen to drive the arm of the cup
dispenser. Speed was considered to be the most important property for this motor because the
subsystem needs to complete its task quickly or it will become a bottleneck for the rest of the
machine.
Control Systems Considered and Chosen with Rationales
In general, the system must be complex enough to run a web-server as well as
communicate with multiple sensors, actuators, and motors. From a software standpoint, there are
three major platforms that provide both the software capabilities for running a web-service as
well as the hardware capabilities of connecting to multiple peripherals at reasonable prices.
These are the Arduino, Beaglebone, and Raspberry Pi. When comparing these platforms, all
three have the capability of running high level software. In the case of the Arduino however, the
technologies used for web-services are provided through custom APIs. The same is true for the
inclusion of a High-Level Operating System like a Linux distribution. Both the Beaglebone and
the Raspberry Pi can provide a HLOS whereas the Arduino in general can’t. Comparing just the
Beaglebone and the Raspberry Pi, the software functionalities with respect to this risk component
are essentially equivalent. The same can be said for their hardware interfacing functionalities.
Both provide multiple digital GPIO interfaces but the Beaglebone provides the most digital
GPIO with 65 pins. Both provide serial interfaces capable of point-to-point communication and
bus communication as well.
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Given the challenges of running a full web-service on an Arduino, that platform isn’t
appropriate for this component. As such the two major systems to consider are the Beaglebone
and the Raspberry Pi. For both of these systems, the method of wireless network connectivity is
also relatively simple. With these two systems, the best choice is a USB Wi-Fi module that
conforms to current Wi-Fi standards. For this component, a miniature Wi-Fi USB module was
selected to provide the smallest footprint even though space, given our current design, is not a
major concern. When understanding the context of this specific component and ignoring the
inconsequential differences between the two platforms, the only significant considerations
between the two are hardware interfacing and cost.
In terms of hardware interfacing, although the Raspberry Pi provides both digital GPIOs
and serial interfaces, the Beaglebone provides significantly more digital GPIOs and a multitude
of serial ports including 3 I2C busses, which are a likely choice for sensor communication. In
terms of cost however, the Raspberry Pi, at a base model comes in at $35 which is slightly less
than the $55 for a Beaglebone. However, as a group we have access to both the Raspberry Pi and
Beaglebone platforms. As such, the cost of the platform itself is only a minor consideration. With
that in mind, the most important consideration is hardware interfacing and in those terms, the
Beaglebone black is the clear choice with multiple serial busses and 65 GPIOs for sensors that
may not be accessible via serial protocols.
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IV. Design
System Diagram
Figure 2: Preliminary System Diagram
Subsystems
Alcohol Dispensing
Optics, operated by linear actuators, will be used to dispense alcohol.
Mixer Dispensing
Peristaltic Pumps will be used to dispense the mixers.
Drink Platform
The chosen system design takes the best of each field and combines them. The system
will use a platform driven by a stepper motor with gears as intermediaries and both sensors. The
photocell will be used to detect cups, while the break beam sensor will detect interference. The
final dimensions of the design are still variable and dependent upon other systems. A tentative
description and diagram are shown below.
As can be seen from the Figures 3 and 4, the system can be split into two main
components. The first are the gears and motor, while the second is the platform and sensors. The
platform will be placed in top of a gear. The platform’s gear will then connect to the gear
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attached to the stepper motor. The interacting gears will leave the center of the platform free for
the wires from sensors inside of the platform to connect to other systems like the microcontroller,
as well as allow tubes and other components to pass through unobstructed.
As seen in the overhead view of the platform in Figure 3, it will be divided into sectors. Each
sector has its own unique color. The number of sectors is dependent upon the final number of
cups the machine will hold. Each sector has its own groove to hold a cup in place. The cross
section of the platform can be seen in Figure 4. The sensor is placed directly at the bottom and
will register that a cup is there when it is almost completely dark. Surrounding the platform, on
the stationary portion of the system, will be several break beam sensors. The final number of
break beam sensors is dependent upon the final size of the platform.
Automated Drink Machine
Figure 3: A top-down view of the platform-sensor system
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Figure 4: A cross-section of the platform-sensor system
The system design minimizes costs when possible and attempts to stay true to the initial
design which other systems will be based upon to reduce inconsistencies between them. A break
beam sensor would be more accurate than a photocell when detecting if a cup is in place, but are
at minimum double the cost. They are also bulkier and would be harder to fit into the platform.
A possible risk for the photocells detecting false positives is if there is a spill and a dark liquid is
covering the sensor. This would, however, fall upon the user to stop and clean the machine.
If space is determined to be more important, or is not available, the gear can be integrated
into the bottom of the platform by integrating the teeth. Furthermore, the gear that is attached to
the motor can be swapped out to change the platform speeds and attenuate the positions.
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Control System
In terms of hardware, the setup is relatively simple. The board (Beaglebone Black) will
be configured with a standard flavor of the Ubuntu distribution. This will allow for full
functionality of the device and provide an easy way to configure the device for testing and final
production. From there, a USB Wi-Fi module is connected to the USB port on the board and
configured in Ubuntu for network connectivity. The necessary sensors, when finalized, can be
connected to one of the many serial or GPIO interfaces as necessary and configured from a
kernel level if necessary. This setup allows for a very flexible system that can adapt to the many
different sensors that may be necessary with ease. The remainder of the design constitutes
software design as described below. It should be noted that the specific design of the user
interface is not currently available as the functions of the users and overall functionality of the
system has not been finalized to the point where it is appropriate to layout an initial design for
the interface. The underlying structure has been designed to allow for many possible scenarios of
user interaction so as to provide a somewhat generic solution.
The major entities of the software design are shown in the table below with a description
of their functions.
Table 12: Entity Descriptions for System Controller
Entity
Description
Database
Connection
External Interface
System
Controller
Provides top level interconnection for sub-entities
and overall control of the system.
None
None
Drink Database
None
User Database
None
Drink
Management
Allows for selection and creation of drinks.
User
Provides user management including creation and
Authentication authentication.
User Interface
Provides physical interface for user to interact
with system. (order drink, monitor status)
None
User Device
Drink Queue
System
Manages drink creation and organization and
how it interacts with the hardware controller.
None
None
Hardware
Controller
Allows for reading from sensors and controller
external devices.
None
Sensors,
Actuators,
Motors, ...
Social
Interfaces
Provides common social methods provided by
existing APIs (posting, tweeting, …)
None
Social APIs
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A diagram of the connections between entities in table 12 can be seen in figure 5 below.
In the diagram, the overall component structure can be seen with a box indicating what is
included in the component, and what external entities the component interfaces with.
Figure 5: Entity Connectivity Diagram
User Interface and Control
The user interface will consist of a cross-platform web-service based interface. Any user
with a mobile device capable of connecting to an existing 802.11 Wi-Fi network will have access
to this interface. As such, further methods of authentication will be utilized to confirm only those
with permission have access to the interface. The specifics of the physical layout are not defined
at this time.
Engineering Standards
❖ USB 2.0
❖ I2C
❖ WiFi
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Multidisciplinary Aspects
Mechanical Engineering
The construction of the ADM involves many mechanical engineering aspects. The system’s
chassis and rotating drink platform are both mechanically based. The dispensing mechanisms
also involve mechanical aspects, with linear actuators operating the optics and pumps moving the
mixers.
Computer Engineering
The ADM will require a microcontroller to drive the various motors and sensors required
to function. Allowing the various components of the ADM to work independently and then
merging them together is a computer engineering aspect.
Electrical Engineering
The ADM will require a large number of motors and sensors that will be wired to a
controller.
Computer Science and Networking
A large component of the ADM is the web interface. This will require web design
knowledge in order to create a usable UI and to ensure proper networking and security between a
multitude of devices.
Background
The ADM required several courses including Interface & Digital Electronics, Electronics,
and Software Engineering from the Computer Engineering curriculum. Our team also has
experience in web design and manufacturability, as well as outside knowledge of wines and
cocktails.
Outside Contributors
None.
V. Constraints and Considerations
Extensibility
The components can be modified anywhere from slightly to extensively to introduce a wider
variation of drinks. Modifying components within the machine can allow for the creation of
shaken or mixed alcoholic drinks. Adding a carbonator would allow for custom carbonated
drinks. The concept can also be applied to food instead of drinks. A theme can be selected for
which a machine will accept various ingredients within multiple separated compartments and
create a personalized dish with perfectly measured ingredients and cook time. Variations of a
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dish, like chicken or beef curry, can be selected based on the availability of ingredients, database
recipes, and machine model.
Manufacturability
The ADM requires many custom parts. Some parts, notably the optics, would need to be
shipped internationally. This makes forces an initial large investment. Once the materials are
procured however, mass manufacturability is no longer out of reach, It can be setup quickly by a
small dedicated team, and the program will only have to be written once.
Reliability
The ADM shall be a reliable machine, not prone to malfunctions or breakdowns. The
parts are of good quality and procured from reliable manufacturers. As long as it is handled
appropriately, it should not require constant maintenance.
Economic Context
The ADM is intended to be a direction option for serving drinks either in the foodservice
industry or at a private event.
Health and Safety Issues
This system deals with dispensing beverages, meaning that all containers, tubing, etc.
must meet regulatory standards as set forth by the FDA, 3A, and/or NSF.
Societal Context
The ADM relies on the customers to ensure that minors are not granted access to any
alcoholic drinks. The ADM interface runs on a ticket system in which users are given a ticket by
the ADM’s owner. Thus it falls on an honor code, as in any social gathering, to act and behave
responsibly.
Sustainability
Though it was not designed with sustainability in mind, the ADM should be very
sustainable so long as receives appropriate maintenance as no parts are prone to deteriorating
quickly.
Ethical
A potential ethical issue to take into consideration is that the machine will likely be
unmanned and unattended during a party. It would therefore be simple for someone under-aged
to procure an alcoholic drink.
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VI. Cost Estimates
Table 13: Cost Estimates
Description
Cost
Our Cost
Availability
$55.00
$0
Dr. Becker
Beaglebone Black
$11.95
$11.95
Miniature Wi-Fi Module
TBD
TBD
Platform*1
2
~$4.25 x N
~$4.25 x N
Adafruit
IR Break Beam Sensor* x N
$0.95 x N
$0.95 x N
Adafruit
Photocell x N
$17.95
$17.95
Stepper Motor*3
TBD
TBD
Gears*1
$10.42 x N
$10.42 x N
Contact Manuf.
Beaumont Metrix SL
$3.59 x N
$3.59 x N
Contact Manuf.
Beaumont Bracket
$120.00 x N
$120.00 x N
Party Robotics Store
Bartendro Dispenser
$10.00 x N
$10.00 x N
Online
Linear Actuator
~$300
~$245
Total
*1 The platform and gears will likely be custom made and therefore do not have a cost yet.
*2 There are two types available, one with a 10” range, and the other with 20”
*3 The motor may still change depending on the microcontroller used.
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VII. Testing Strategy
Drink Platform Subsystem
The following tests are based on the engineering specifications table.
Table 14: Drink Platform Test Strategy
No.
Description
Engineering
Spec(s)
1
Several randomly selected people are able to distinguish between the
colors in each sector
A
2
Cups will remain in place and not spill liquid when the platform
starts moving, stops moving, and is in motion. The test should be
performed for at least one hour of continuous use.
B, E
3
The photocell sensor will return a positive only when a cup is in
place above it regardless of lighting. Tests should be done in both
well and dimly lit rooms
C
4
Paper towels should be placed where components would be in the
platform. Water will then be poured on the platform. The test is
successful if the paper towels remain dry.
D
6
The platform is able to rotate at least 180 degrees in both directions
without being obstructed or obstructing other systems in the machine
F
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Control System
The testing for the control system serves as a more software design focused test starting
with unit tests to confirm the functionality of each entity.
Table 15: Control System Unit Tests
Test Type
Hardware
controller
Description
Ensure individual expected functions are available.
(cup detection, dispense functionality, rotate platform)
Drink
Management
Ensure drinks can be searched, modified, and saved.
Drink Queue
System
Ensure drinks can be ordered and monitored.
Ensure multiple drinks can be ordered and are handled.
(Virtual sensors/actuators used until other components complete)
Unit Test:
User
Ensure users can be created and deleted as well as authenticated.
Authentication (Method of authentication TBD)
User Interface
Social
Interface
Ensure interface provides all functionality of system.
Ensure interface works on desired platforms.
(Virtual interface for purely aesthetic verification, non-functioning)
Ensure social functions perform as expected.
After full unit tests are complete, the testing shall move into integration testing for just
the software component. This will consist of testing units and how they interact with each other.
While all units do not necessarily interact with every other unit at this time, all possible
connections will be tested. Specific tests to verify would be interaction of the drink queuing
system and the hardware controller as this is the major element linking software operation and
hardware operation. User verification and the functions it allows will also be a major element to
verify. This testing is allotted 2 Weeks in the beginning of next semester (August 24 to
September 7). This will allow the complete interactions of the units to be examined and verified.
Finally, full integration testing can begin after the integration testing of the software
component is complete. This step relies on the other components as well however, meaning it
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can’t actually begin until all other components are at least in working stages. As such, the time
frame for this testing is TBD.
VIII. Risks
The force needed to operate the optics is still unknown at this time.
The accuracy of dropping the cups onto the rotating platform may require a very small degree of
error.
A user reaching for a cup needs to trigger the break beam sensors in order to stop the platform
from rotating. If they reach at an odd angle the device may not rotate properly, so more break
beam sensors may be required.
Networking security may be a concern as users need to be sure that their drinks cannot be
changed while they are being prepared.
IX. Milestone Charts
Platform Subsystem
Desc
Sensor Materials Acquired
Motor Acquired
Platform and Gears
Acquired
Platform, gears, and motors
assembled
Subsystem Platform and
Motor Testing
Sensors added to Platform
subsystem
Subsystem Sensor Testing
Platform subsystem
interfaces correctly with
controller
Completion Date
9/10/15
9/10/15
9/10/15
Team Member
J.M.
J.M.
J.M.
9/17/15
J.M.
9/21/15
J.M., C.P.
9/22/15
J.M.
9/27/15
10/25/15
J.M.
J.M., A.H.
Drink Dispenser Subsystem
Desc
Completion Date
Optics and Brackets
9/24/15
acquired
Linear Actuators acquired
9/10/15
Peristaltic Pumps and tubing 9/10/15
acquired
Sensors for Pumps acquired 9/10/15
Team Member
M.A.
Modified Date
Comments
In progress
In progress
In progress
Modified Date
Comments
In progress
M.A.
M.A.
In progress
In progress
M.A.
In progress
Automated Drink Machine
Optics and Actuators tested
manually
Pumps/Tubing assembled
Pumps tested manually
Bracket/Optic/Actuator rig
assembled
Pump/Sensors assembled
Software for controlling
actuators written
Software for controlling
pumps written
Integration of software with
pumps/actuators/optics
Control Subsystem
Desc
Page 35
9/12/15
M.A.
9/15/15
9/22/15
9/30/15
M.A.
M.A., C.P.
M.A., C.P.
9/30/15
10/10/15
M.A.
A.H., M.A
10/10/15
A.H., M.A
10/25/15
A.H., M.A
Completion Date
Team Member
Beaglebone Acquired
9/1/15
M.A.
Controller Programmed
9/15/15
A.H.
Website/Interface setup
10/15/15
A.H.
Controller/Platform
subsystem
interconnectivity
10/25/15
A.H., J.M.
Controller/Dispenser
Subsystem connectivity
10/25/15
A.H., C.P., M.A.
Controller/Sensor
connectivity
10/25/15
A.H.
Subsystems Integration
11/10/15
A.H., M.A., C.P.,
J.M.
Overall System
Functionality
11/20/15
A.H., M.A., C.P.,
J.M.
Delayed
Modified Date
Comments
Completed,
donated by
Dr. BeckerGomez
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PHASE TWO
Cup Dispenser Subsystem
Desc.
Completion Date
Cup Dispenser Materials
N/A
Acquired
Cup Dispenser Assembly
N/A
Completed
Cup Dispenser Integrated
N/A
with Software
Cup Dispenser Functions
N/A
Independently
Cup Dispenser Tests Passed N/A
Team Member
N/A
Modified Date
N/A
Comments
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
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