Automated Drink Machine
Project Final Report
Michelle Advena
Alex Horejs
Jefferson Medel
Connor Petilli
12/15/2015
The Automated Drink Machine is a system that makes mixed drinks.
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Contents
I. Overview .................................................................................................................................................... 5
Needs Statement ...................................................................................................................................... 5
Objective Statement ................................................................................................................................. 5
Description ................................................................................................................................................ 5
Marketing Diagram ................................................................................................................................... 6
II. Requirements specification ...................................................................................................................... 7
Needs ........................................................................................................................................................ 7
Analysis to justify specifications ............................................................................................................... 9
Drink Platform Subsystem .................................................................................................................... 9
Control System .................................................................................................................................... 10
III. Concept selection................................................................................................................................... 10
Survey of Existing Systems ...................................................................................................................... 10
The Inebriator ..................................................................................................................................... 10
Coca-Cola Freestyle ............................................................................................................................. 11
Bartendro 15 ....................................................................................................................................... 11
Concepts Considered and Chosen ...................................................................................................... 11
Rationale ............................................................................................................................................. 12
Survey of Dispensing Methods ............................................................................................................... 13
Optics .................................................................................................................................................. 13
Actuators ............................................................................................................................................. 13
Peristaltic Pumps................................................................................................................................. 13
Solenoid Valves ................................................................................................................................... 14
Pressurized Air .................................................................................................................................... 14
Methods Chosen and Rationale .......................................................................................................... 14
Drink Platform Systems Considered and Chosen with Rationales .......................................................... 15
Survey of Possible Platforms ............................................................................................................... 15
Platform 1 - Driven directly by a motor .............................................................................................. 15
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Platform 2 - Driven by a motor through gears.................................................................................... 15
Survey of Possible Motors .................................................................................................................. 16
DC motor ............................................................................................................................................. 16
Servo motor ........................................................................................................................................ 16
Stepper motor ..................................................................................................................................... 16
Survey of Possible Sensors .................................................................................................................. 16
Photo cell ............................................................................................................................................ 16
Break beam sensor.............................................................................................................................. 16
Systems Considered and Chosen ........................................................................................................ 17
Cup Dispenser Systems Considered and Chosen with Rationales .......................................................... 20
Survey of Possible Sensors .................................................................................................................. 20
Survey of Possible Motors .................................................................................................................. 21
Control Systems Considered and Chosen with Rationales ..................................................................... 21
IV. Design .................................................................................................................................................... 23
System Diagram ...................................................................................................................................... 23
Subsystems ............................................................................................................................................. 23
Alcohol Dispensing .............................................................................................................................. 23
Mixer Dispensing................................................................................................................................. 23
Drink Platform ..................................................................................................................................... 24
Control System .................................................................................................................................... 26
User Interface and Control ..................................................................................................................... 29
Engineering Standards ............................................................................................................................ 31
Multidisciplinary Aspects ........................................................................................................................ 31
Mechanical Engineering ...................................................................................................................... 31
Computer Engineering ........................................................................................................................ 31
Electrical Engineering .......................................................................................................................... 31
Computer Science and Networking .................................................................................................... 31
Background ......................................................................................................................................... 31
Outside Contributors .......................................................................................................................... 31
V. Constraints and Considerations .............................................................................................................. 32
Extensibility ............................................................................................................................................. 32
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Manufacturability ................................................................................................................................... 32
Reliability................................................................................................................................................. 32
Economic Context ................................................................................................................................... 32
Health and Safety Issues ......................................................................................................................... 32
Societal Context ...................................................................................................................................... 32
Sustainability ........................................................................................................................................... 33
Ethical...................................................................................................................................................... 33
VI. Costs....................................................................................................................................................... 33
VII. Testing................................................................................................................................................... 35
Drink Platform Subsystem ...................................................................................................................... 35
Component Testing ............................................................................................................................. 36
Control System ........................................................................................................................................ 36
VIII. Risks ..................................................................................................................................................... 37
Subsystem Risk Assessments .................................................................................................................. 37
Platform Subsystem Design ................................................................................................................ 37
Control System Communication ......................................................................................................... 37
Additional Risk Assessments ................................................................................................................... 38
IX. Milestone Charts .................................................................................................................................... 38
X. Critical Evaluation ................................................................................................................................... 42
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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) dispenses measured amounts of liquids to create
mixed drinks. Food-safe materials are be used for all parts involving the storage and dispensing
of liquid ingredients. Motion controllers and sensors inform the controller as to the status of the
platform holding the cups and drinks. There are six dispensers and every dispenser corresponds
to a different liquid. The ADM is controlled via a command line interface. When turned on, the
ADM centers the platform and displays a menu, giving the user several options. These options
include dispensing single shots, dispensing a drink from a database, and adding a new drink to
the database, Once the user selects an option, the ADM will wait for a cup to be placed on the
platform, upon which it begins executing the selected option. Reaching for a drink while the
platform is in motion will trigger a response from the IR break beam sensors, and stop the
platform .
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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
elevated client
provide
a
simplistic
method
for
changing
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23
The system shall provide social media features.
(Posting to Facebook timeline, Tweeting from Twitter)
24
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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
multiple of 35mL.
2
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M
Ability to measure and dispense a specified amount of a
mixer (e.g, ½ cup or ¾ cup)
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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
Analysis to justify specifications
Drink Platform Subsystem
The platform is circular to make it as compact as possible. Any other shape would cause
gaps and unused space when rotating it. The moving platform holds cups which contain liquid
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inside of them, so the motor driving it moves at a slower and smoother rate. Sensors are the best
way to detect if something is moving or in place. Sensors are mounted in grooves on the bottom
of the platform so as to be less obtrusive. The grooves also make sure that the cups stay in place
while the platform moves. The platform is divided into color-coded sectors to allow 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 is 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
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
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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.
Table 3: System Comparison Chart
Feature
The Inebriator
Coke Freestyle
✓
Drink queue
Drink database
Custom mix (real-time)
Planned
(this project)
✓
✓
✓
✓
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Drink selection automatically
updates based on availability
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✓
Cooling system
✓
ice dispenser
(manual fill)
✓
Carbonation system
Drink Platform
unknown
mobile,
linear
stationary
mobile,
rotational
✓
Remote ordering
Cup detection/sensing
✓
✓
Precise volume measurement
✓
✓
Push-and-hold to dispense
✓
Self-cleaning
✓
Phone app
✓
✓
Touch interface
✓
✓
Low/empty level detection
✓
✓
Rationale
The Automated Drink Machine (ADM) attempts 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 is not provided.
Additionally, to facilitate the use of custom drinks, a dynamic drink database is used to allow for
the most accurate drink creation and selection. With this system, the user does not have to worry
about drinks that have been emptied or removed and are no longer available. These drinks 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.
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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.
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
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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
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.
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Table 5: Pugh Table for Dispensing Methods
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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
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
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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 use 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
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
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broken and there is an obstruction. Both components are required on opposite sides of the area
being monitored.
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..
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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
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
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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
Table 9: Pugh Table for Interruption Detection Systems
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 does 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.
Automated Drink Machine
Survey of Possible Motors
Table 11: Pugh Table for Cup Dispensing Motor Systems
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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.
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
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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, are used to dispense alcohol. Two linear actuators, working
in tandem, are required to fully pull up on the optic arm to actuate the optics and perform a clean
pour.
Mixer Dispensing
Peristaltic Pumps are used to dispense the mixers. The pumps operate by pumping a preset
number of “ticks” which represent quarter turns of the pumping mechanism. These ticks were
calculated to dispense the same amount as the optics.
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Drink Platform
The chosen system design takes the best of each field and combines them. The system
uses a platform driven by a stepper motor with gears as intermediaries and both sensors. The
photocells were used to detect cups, while the break beam sensor detected interference. The
platform is 23.5” in diameter. Medium Density Fiberboard (MDF) was chosen as the material
for the platform and its base due to being easily milled and easy to acquire.
The subsystem design can be split into two main components. The first are the gears and
motor, while the second is the platform and sensors. The platform was placed in top of a gear.
The platform’s gear was then connect to the gear attached to the stepper motor via a belt and
pinion gear. A hole in the platform’s support allowed 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. The platform was supported by three caster wheels to reduce
friction in the system. It was further supported by a cam roller to keep the platform centered for
smooth rotations. The platform had six slots with which it could hold a cup, each marked by its
own unique color. The slots are a half inch thick, allowing it to hold cups in place. The sensor is
placed directly below a slot, allowing the system to register that a cup is there when it is almost
completely dark. Surrounding the platform on the stationary portion of the system,next to each
dispenser, are several break beam sensors. A diagram of the platform overhead and cross-section
can be seen in Figures 3 and 4.
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Figure 3: A top-down view of the platform-sensor system
Figure 4: A cross-section of the platform-sensor system
Page 25
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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.
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 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. The underlying structure has been designed to allow for many possible
scenarios of user interaction so as to provide a somewhat generic solution.
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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
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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. Figure 6 shows a general purpose interface that represents the general flow of user
interaction. The figure shows the main user functionality from login to drink ordering with
intermediary actions of drink modifying and current order monitoring. Underlying the graphical
version of the user interface will be a command line interface that allows for the same
functionality. This version of the interface will be used for intermediary testing as it provides a
more development friendly way to modify and test subsystems with rapid changes. These rapid
changes may be necessary as the platform, and possibly hardware interfaces change to meet new
design needs.
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Figure 6: Mobile Interface Prototype
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Engineering Standards
❖ USB 2.0
❖ WiFi
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 requires 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 requires a large number of motors and sensors that are wired to a controller
and will draw non trivial amounts of power. A consideration for power consumption may be
necessary.
Computer Science and Networking
A large component of the ADM is the web interface. This requires 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.
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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
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 forces a large initial 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 is 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 does 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.
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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.
VI. Costs
Table 13: Cost Estimates
Description
Cost
Our Cost
Availability
Timing Belt (22” / 110T)
6.00
5.70
Timing Hub Pulley 60 teeth /
3.80” diam.)
8.00
7.99
10 tooth pinion pulley (.25" bore
/ .0.63" diam.)
7.00
6.99
IR Break beam sensor (2x)
6.00
5.70 Adafruit
12.00
11.70 Adafruit
Photocell Sensor (6x)
Bartendro Dispenser (no liquid
level detector)
120.00
119.99
35 ml optic and bracket set (2x)
50.00
47.88
1/2" x 2' x 2' MDF (2x)
10.00
3/4 x 3/4 x 1/8 Angle iron (20')
16ga CR Sheet (36'' x 96'')
2 in. Swivel Caster with NonMarking Rubber and Brake (2x)
11.90
7.00
6.49
40.00
33.00
16.00
Party Robotics Store
17.88
Online
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2 in. Swivel Caster with NonMarking Rubber (2x)
16.00
15.92
1" Plastic Caster Wheel (4x)
7.00
6.99
Beaglebone Black, Rev. A6A
55.00
0.00
$360.00
$298.13
Total
Beaglebone
*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
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 remain in place and do not spill liquid when the platform starts
moving, stops moving, or is in motion. The test should be
performed for at least one hour of continuous use.
B, E
3
The photocell sensor returns 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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Component Testing
●
●
IR Break Beam
○ 5mm sensor - The effective range of this sensor at 3.3V and 5V operation was
found to be approximately 20”” at 22” respectively, with both returning a voltage
of 4.9V while the break beams were unbroken, and below .1V when broken.
○ 3mm sensor - The effective range at 3.3V and 5V operation was found to
approximately 13” and 14” respectively, and returned voltages of 4.9V and 4V
respectively while the brake beam remained unbroken. They returned below 1V
when broken.
Photocell Sensors
○ All of the photocells were tested using an Ohmmeter.
○ “Light” - Conditions with some light result in a resistance of 5-15kOhms
○ “Dark” - Conditions with little to no light result in a resistance of 200K->1MOhms
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
Unit Test:
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)
User
Ensure users can be created and deleted as well as authenticated.
Authentication (Method of authentication TBD)
User Interface
Ensure interface provides all functionality of system.
Ensure interface works on desired platforms.
(Virtual interface for purely aesthetic verification, non-functioning)
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Social
Interface
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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
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
Subsystem Risk Assessments
Platform Subsystem Design
Several risks were considered when designing the platform. The belt connecting the
central gear and motor needs to be tight. This introduced the problem of the platform shifting off
center. A cam roller was selected to minimize this problem. The motor may not be powerful
enough to rotate the platform efficiently. An easily millable material was selected so that the
platform could be made lighter. The slots may allow in too much light for the photocells to
accurately detect when a slot if overhead. While this does not affect the detection of a cup being
placed on the platform, it makes it difficult for the photocells to be used to center the platform.
A thin film with a smaller hole was selected to be placed under each slot to prevent excess light
from being detected.
Control System Communication
A major risk to consider when selecting the proper network based technologies is the
security of these technologies. Allowing remote access to the system controller presents a
security concern in terms a malicious attacker attempting to hijack the machine so to speak and
operate it. As such, when connecting to the machine, it will be important to use some sort of
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secure communication or encryption protocol. For serving web resources this would most likely
be SSL/TLS encryption. This would also apply to the command line interface communication
which would be accomplished via an SSH connection with system level user login serving as the
protection.
Additional Risk Assessments
The Platform is both heavy and not water resistant. As such the motion of the motor will
be hindered and if not checked properly could lead to spillage which might damage the platform.
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.
IX. Milestone Charts
Platform Subsystem
Desc
Completion
Date
Team
Member
Modified
Date
Comments
Sensor Materials Acquired
9/10/15
J.M.
10/19/15
Completed
Motor Acquired
Platform and Gears Acquired
Platform, gears, and motors assembled
Subsystem Platform and Motor Testing
Verify Sensor specifications and
functionality
Sensors added to Platform subsystem
Subsystem Sensor Testing
Platform subsystem interfaces correctly
with controller
Platform cut
9/10/15
9/10/15
9/17/15
9/21/15
--
J.M.
J.M.
J.M.
J.M., C.P.
J.M.
9/17/15
11/22/15
11/30/15
12/1/15
11/5/15
Completed
Completed
Completed
Completed
Completed
9/22/15
9/27/15
10/25/15
J.M.
J.M.
J.M., A.H.
12/1/15
12/1/15
12/1/15
Completed
Completed
Completed
11/6/15
J.M., M.A.
11/22/15
Completed
Completion
Date
9/24/15
9/10/15
9/10/15
9/10/15
9/12/15
Team
Member
M.A.
M.A.
M.A.
M.A.
M.A.
Modified
Date
10/5/15
10/23/15
10/5/15
N/A
10/23/15
Comments
Drink Dispenser Subsystem
Desc
Optics and Brackets acquired
Linear Actuators acquired
Peristaltic Pumps and tubing acquired
Sensors for Pumps acquired
Optics and Actuators tested manually
Completed
Completed
Completed
Removed
Completed
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Pumps/Tubing assembled
Pumps tested manually
Bracket/Optic/Actuator rig assembled
Pump/Sensors assembled
9/15/15
9/22/15
9/30/15
9/30/15
M.A.
M.A., C.P.
M.A., C.P.
M.A.
12/1/15
11/21/15
Software for controlling actuators
written
Software for controlling pumps written
Integration of software with
pumps/actuators/optics
10/10/15
A.H., M.A
11/19/15
Completed
Completed
In Progress
Removed
(integrated)
Completed
10/10/15
10/25/15
A.H., M.A
A.H., M.A
11/19/15
12/1/15
Completed
Completed
N/A
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Control Subsystem
Desc
Page 40
Completion
Date
9/1/15
Team
Member
M.A.
Controller Programmed
Controller/Platform
subsystem connectivity
Controller/Dispenser
Subsystem connectivity
Controller/Sensor connectivity
Subsystems Integration
9/15/15
10/25/15
A.H.
A.H., J.M.
10/25/15
Website/Interface setup
Command Line Interface
Overall System Functionality
10/15/15
Beaglebone Acquired
Frame Subsystem
Desc
Angle iron acquired
Sheet metal acquired
Cut sheet for waterjet
submitted
Sheet metal cut
CAD model drawn
Support rings and cross-bars
soldered
Rings soldered to angle iron
Wheels attached to frame
Modified
Date
Comments
11/30/15
Completed, donated
by Dr. Becker-Gomez
Completed
Completed
A.H., C.P.,
M.A.
A.H.
A.H., M.A.,
C.P., J.M.
A.H.
A.H.
A.H., M.A.,
C.P., J.M.
11/30/15
Completed
112/1/15
12/1/15
Completed
Completed
N/A
12/1/15
12/1/15
Removed
Completed
Completed
Completion
Date
10/21/15
10/21/15
10/21/15
Team
Member
M.A.
M.A.
M.A.
Modified
Date
10/21/15
10/21/15
10/28/15
Completed
Completed
Completed
10/18/15
11/2/15
11/4/15
M.A.
C.P.
M.A.
10/28/15
11/15/15
11/1215
Completed
Completed
Completed
11/4/15
11/9/15
M.A.
M.A.
11/20/15
11/22/15
Completed
Completed
10/25/15
11/10/15
11/20/15
Comments
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PHASE TWO
Cup Dispenser Subsystem
Desc.
Completion
Date
Team
Member
Modified
Date
Comments
Cup Dispenser Materials Acquired
N/A
N/A
N/A
N/A
Cup Dispenser Assembly Completed
N/A
N/A
N/A
N/A
Cup Dispenser Integrated with
Software
N/A
N/A
N/A
N/A
Cup Dispenser Functions
Independently
N/A
N/A
N/A
N/A
Cup Dispenser Tests Passed
N/A
N/A
N/A
N/A
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X. Critical Evaluation
The frame, platform, and dispensal systems were assembled with the help of RIT’s
machine shop, whom were instrumental in getting the platform to a mechanically functioning
state. General difficulty with the mechanical aspects however, required the design itself to be
modified a number of times throughout the semester to account for new information with regards
to how the platform would operate and what may or may not be possible in the given design. As
such, difficulties were encountered when trying to decide the appropriate way to construct the
platform. In hindsight, using MDF as the platform may not have been an appropriate choice due
to the fact that it is both heavier than anticipated and easily ruined by water without and type of
waterproofing. The overall structure, while solid in terms of its construction, had difficulty with
staying rigid while the platform was in motion. This lead to difficulties in achieving a solid spin
rate on the platform, which by itself already had difficulties achieving a consistent spin rate. All
of these factors contributed to what we would consider a mechanically challenging project that
may have been better accomplished with a more mechanical engineering minded approach.
The original design called for graphical user interface, but what was realized was a
simple command line interface. While this interface provides functionality to the user in terms
creating and ordering drinks, it does not achieve all of the desired software interface goals.
Specifically, the lack of visual feedback is an unfortunate omission that might have significantly
increased the project's overall appeal.
The control system was able to interact successfully with the stated hardware to provide a
method for rotating the platform, detecting cups, and dispensing liquids. These basic hardware
functions allow the platform to achieve its ultimate goal but did so in a very different way that
originally envisioned. Because the stepper motor was unable to consistently step, the count of the
stepper motor could not be used for accurate rotation. As such,. the photocell sensors were used
to detect cups as they passed over them. This allowed the platform to detect not only when a cup
was in position, but when the platform was rotated to a state such that the slots were aligned with
the dispensers. These modifications in how the control system interacted with the hardware
peripherals constituted changes to the original design but were able to achieve similar results to
the intended ones.
As an overall observation, many of the challenges we faced might have been avoided, or
at least handled more effectively had better communication been employed. It’s clear that a very
fluid channel of communication is critical to a project's success. Given the chance to implement
this design again, a more communicative approach would definitely be attempted to facilitate the
group's understanding of the project as a whole and the effectiveness in their individual tasks.