Autonomous Drone Charging Station 1
ECE 4512: Design I April 25, 2018
design document for
Autonomous Drone Charging Station
submitted to:
Dr. Bryan Jones
ECE 4512: Senior Design I
Department of Electrical and Computer Engineering
413 Hardy Road, Box 9571
Mississippi State University
Mississippi State, Mississippi 39762
April 25, 2018
Prepared by:
S. Thomas, H. Fowler, D. Giles, Z. Armstrong, and T. Hubbard
Faculty Advisor: Professor Mehmet Kurum
Industrial Advisor: Josh Weaver
Department of Electrical and Computer Engineering
Mississippi State University
413 Hardy Road, Box 9571
Mississippi State, Mississippi 39762
email: {jst212, hgf26, dg704, za59, alh798}@ece.msstate.edu
LIST OF ABBREVIATIONS
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
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FAA - Federal Aviation Administration
GSM - Global System for Mobile Telecommunication
ADCS - Autonomous Drone Charging Station
IPR - Ingress Protection Rating
I2C - Inter-Integrated Circuit
TX - Transmit
RX - Receive
iOS - iPhone Operating System
SIM - Subscriber Identity Module
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Executive Summary
Today, industries are wanting to remotely operate drones from central locations. However, companies must
abide by FAA regulations stating that a drone must be kept in visual line-of-sight during operation. To
perform remote operations, companies need a supervisor to observe any active drones at the remote
location. With continuous operation of drones, a problem arises. Drones have a short battery life and need
to be charged regularly. This causes the supervisor to shift their focus away from any active drones to the
ones that need charging which violates FAA regulations. With the Autonomous Drone Charging Station
(ADCS), manually charging a drone is no longer a burden to the supervisor. The ADCS provides continuous
drone flight for remote operations by autonomously charging the drone when it lands while also serving as
a protective container. Below, Figure 1 shows a visual representation of the ADCS system.
Figure 1 - Autonomous Drone Charging Station
The ADCS must demonstrate durability, reliability, and convenience. For communication reliability, the
ADCS’s location must fall within at least 45 miles of a single cellular tower to ensure a connection between
the ADCS and the device requesting its services. As for durability, the ADCS must maintain functionality
through water splashes and solid particles larger than a grain of sand. It must also lift a load of up to 300
lbs. Convenience is another constraint, as the web application for the project must be able to deliver
commands to and retrieve status reports from the ADCS at any time.
To provide communication between the ADCS and a device requesting its services, a cellular module was
installed inside of the ADCS. When a request from the web application is sent to the ADCS, the cellular
module receives the request and sends it to the microcontroller that controls the ADCS. The microcontroller
processes the command and acts accordingly. An “open” command causes the doors for the ADCS to open
and the 300 lb-rated actuator begins raising the platform on which the drone will land and charge. A “close”
would perform the opposite, giving the drone a protected place to charge once it lands. To begin the
charging process, the ADCS must test each charging plate to see if there is contact with a compatible leg
of the drone. Once the two contacts are found, the plates are polarized appropriately and the charging
commences. As for status report request, the microcontroller will gather key information about the ADCS
and send it back to the web application, providing the user with the state of the station.
Because the ADCS houses drones up to 3.5ft. in diameter, it accommodates larger drones than other
competitors. Implementing inductive charging would significantly improve the project by eliminating the
need of charging plates. This would free up the processing power used to find the charging contacts of a
drone and reduce the weight of the platform, therefore lightening the load on the actuator. The ADCS’s
success would bring about true continuous operation, simultaneously saving time and money.
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TABLE OF CONTENTS
1. 39
2. 207
2.1. 197
2.2. 199
2.3. 1910
3. 1911
3.1. SYSTEM OVERVIEW 11
3.2. Error! Bookmark not defined.2
3.3. Error! Bookmark not defined.8
4. Error! Bookmark not defined.26
4.1. Test Certification - Lift Load2426
4.2. Test Certification - Drone Charging2527
4.3. Test Certification - Drone Sensing 325
4.4. Test Certification - Application 32
4.5 Test Certification - Drone Size 34
4.6 Test Certification - Laser Sensor 36
4.7 Test Certification - Remote Operation 37
4.8 Test Certification - ADCS Complete System 38
5. 2539
6. 2539
7. Error! Bookmark not defined.39
8. Error! Bookmark not defined.41
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1. PROBLEM STATEMENT
1.1 Historical Introduction
Unmanned aerial vehicles (UAVs) first appeared in 1849 when Austria planned an airstrike on the city of
Venice using balloons equipped with 30 pound bombs. Five decades later, Nikola Tesla contributed to the
development of UAVs by providing them with radio control. The more commonly known term “drone”
would come about in 1935 when the U.S. created a military UAV known as the DH-82B Queen Bee, which
was used for target practice. Fast-forward to 2013; Amazon CEO Jeff Bezos announced that Amazon will
invest research into drones for shipping, fueling the expansion of commercial drones [1].
As technology advances, drones and their usage have dramatically changed through the years. The growing
market for drones will impact a number of industries including private security, law enforcement, real
estate, construction, mining, agriculture, and utilities. Outlook for the growth of the commercial drone
sector will grow at a compound rate of 19 percent between 2015 and 2020 [1]. With the popularity of
commercial drones on the rise, the need for drones to accomplish multiple remote tasks from a central
location becomes a necessary factor. By doing so, this will eliminate the need for traveling to the work site
and maximize the pilot’s production from his/her fixed location.
With the usage of drones changing from viewer visual line-of-sight to remote operations and scheduled
autonomous flights, a challenge arises: abiding by the Federal Aviation Administration (FAA) regulations.
To abide these regulations pilots are required to have visual line-of-sight of the drone at all times [3]. For
remote operation of drones to take place, two modes of operation are plausible. The first mode calls for an
observer at the remote location to keep visual line-of-sight of the drone(s) at all times. Therefore, the pilot
can remain at a central location and operate a drone remotely. The second mode of operation requires the
drone to have collision avoidance technology, which can be expensive for small companies. By
implementing the latter mode of operation, the FAA will grant a waiver allowing autonomous flight;
therefore, an observer’s presence is no longer essential.
Because these remote tasks may run for extended periods of time, the demand for improved battery life
increases. Today, the average flight time of a drone is roughly 15 minutes until the battery needs changing
or plugging in for charging by hand. This can become an obstacle for observers who need to keep visual
line-of-sight of the drones. When dealing with multiple drones, charging and observation of drone activity
become two separate tasks. This presents the issue of the observer having to watch the drone while it is in
operation and also attempt to change the battery of the other drones all at once. These actions do not fall
within the regulations of the FAA and doing both simultaneously is simply not feasible. With the
Autonomous Drone Charging Station (ADCS), the hassle of companies manually charging drones will
become obsolete. By allowing the ADCS to charge the drones autonomously, the observer’s sole job
becomes monitoring the drone’s activity. This, in turn, will permit FAA-approved continuous operation.
1.2 Market and Competitive Product Analysis
The market for commercial drones has exploded within the past five years because of the increases in
funding, advances in technology, and decreases in cost. Contributing around 64 million dollars, 3DR is one
of the largest U.S. companies to invest in commercial drones. Since 2017, the drone market has amassed a
worth of around two billion dollars, making it a heavily rewarded investment [1]. Industries such as
agriculture and surveillance would benefit significantly from remote operation. For example, agricultural
companies are using drones to help monitor crop growth and increase crop production. Drone agriculture
revenue today accumulates to 500,000 dollars and is projected to grow to four million dollars by 2024 [4].
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Unfortunately, autonomous charging stations have not reached the mainstream market. Only a handful of
companies have developed autonomous charging stations for drones, creating little competition. To remedy
this, companies such as Skysense and The Dronebox have developed charging stations that automate the
process of charging a drone, allowing for continuous flight time. These companies aided in solving these
problems but have yet to fully meet the needs of the industry. Products of these competitors limit consumers
by placing restrictions on drone size; for instance, the Dronebox and Skysense charging stations support
only quadcopter drones that have an average wingspan of one foot and five inches. The Dronebox charging
station also requires the consumer to buy their custom drone and does not allow for much modification [2].
As a result, companies would have to conform to these restrictions, which costs consumers more money.
The market’s situation has created a need for our product, the ADCS. The ADCS team’s charging station
will allow consumers to use their own drone of choice, and the only requirement is that the maximum size
of the drone be approximately five feet and six inches. The ability to modify the drone and use different
sizes offers a large variety of missions that can be completed, compared to competitors, and saves the
consumers money. Our product will allow the use of any type of drone meeting the previously stated size
constraint. The ADCS will allow companies to operate remotely from a central location and, at the same
time, serve as a protective container for the drone.
1.3 Concise Problem Statement
The problem with continuous remote drone operation is that drones have a short battery life and the drones
need to be charged. Since the major objective of autonomous flight is eliminating human interaction, the
drone must charge autonomously. As stated earlier, companies using drones must abide by the FAA
regulations stating a drone can only be operated as long as the drone is within eyesight [3]. However,
companies can receive a waiver to operate these drones without the need of keeping the drone in line-of-
sight. In 2015, 1,000 permits were granted, and this number more than tripled in 2016 with 3,100 permits
granted [1]. This raises two points: the need exists for remote operations and fully autonomous flight, and
the FAA is more than willing to allow it now.
Drawing the big picture, the main service of the ADCS is to provide continual drone flight for remote
operations by autonomously charging the drone and serving as a protective container. The core functions
of the ADCS are to sense when the drone is near and open the roof to allow it to land. After the drone has
landed, the ADCS needs to know the landing pad can descend and the roof can close without damaging the
drone. Finally, the ADCS must be able to charge the drone autonomously, swiftly, and effectively. These
requirements must be met in order for this project to work.
1.4 Implications of Success
The ADCS will make continuous drone operation at any common geographic location possible by allowing
companies to charge their drone remotely and autonomously. If the ADCS becomes a standard for remote
drone operations, the ADCS may be able to acquire FAA permits for all charging stations, no longer
requiring pilots to apply for this permit. This allows companies with autonomous drones to use the ADCS
and the drone in unison without the need for an observer. If the companies do not have an autonomous
drone, or do and still want an observer to watch the drone, the ADCS still meets FAA regulations.
After the market has accepted the product and begun to use the ADCS, drones will be more useful with the
increase in battery life through the ADCS. Another additional benefit of this product is in the field of
security. Monitoring large crowds is hard for someone on the ground, but seeing everything through a
bird’s-eye view can help spot malicious activity. This idea currently cannot be implemented because of the
limitations of drone batteries. The ADCS will fix this problem by setting up multiple charging stations
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around the city, and when the drone starts to lose power, it can locate the nearest charging station. With a
massive setup of drones and charging stations, then a whole city could potentially be kept safe with eyes in
the sky.
2. DESIGN REQUIREMENT/CONSTRAINTS
The main goal of the Autonomous Drone Charging Station (ADCS) is to provide continual drone flight for
remote operations by autonomously charging the drone and serving as a protective container. Today, FAA
regulations limit remote drone operation by requiring the pilot to have visual line-of-sight of the drone. To
allow remote drone operation that abides by FAA regulations, users of the ADCS must meet one of two
regulations: have an observer at the remote location who has visual line-of-sight of the drone at all times,
or meet waiver requirements by outfitting the drone with collision avoidance technology. In either case, the
ADCS will allow autonomous operation of drones by eliminating the need for human interaction. A drone
can simply land and start charging. The remainder of this document is divided into two sections: the
technical constraints and the practical constraints. The technical constraints lay out the details the ADCS
design must follow to ensure it allows drones to charge autonomously and be protected while inside the
station. The practical constraints present the conditions and regulations within which the ADCS must
operate.
2.1 Technical Design Constraints
On the following page, Table 2.1 contains the five technical design constraints that must be met upon
completion of this system.
Table 2.1 Technical Design Constraints
Name Description
Communication The ADCS must be within 72.4 kilometers of a
cellular tower, depending on the tower’s
technology, and communicate via the cellular
network.
Maximum Load The ADCS will have a lift component that must
lift a maximum load of 60 pounds.
Drone Charging The ADCS charger will be controlled by a
microcontroller which delivers a voltage of ±12
with a ±5% variability.
Application The ADCS must provide information to the user’s
smartphone regarding the station’s status. Some
examples would be battery life, roof open or
closed, etc.
Drone Size The ADCS will support drone size up to 3’5”.
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2.1.1 Communication
An application on the user’s phone will be used to control the ADCS through cellular network. The ADCS
must be within 3G coverage of any local cellular carrier tower. With cell towers coverage gets deterred at
certain ranges; therefore, we want to keep the ADCS relatively close, within 45 miles, of a cell tower. Based
on this requirement, the placement of the ADCS must be considered accordingly. Because of how the ADCS
remotely operates, distance is not an issue when positioning the station. As long as these requirements are
met, the station should function properly.
2.1.2 Maximum Load
The ADCS will contain two mechanisms: retractable doors and a floor lift. As for the retractable doors, the
force required to open and close the ADCS will be less than lifting the platform up and down. The lift will
require a greater force. The metal frame of the lift must be capable of raising the platform containing the
drone and any other hardware components placed on the platform. To be more specific, the lift must be able
to raise and lower a maximum load of 60 pounds in order to function properly. The 60 pounds accounts for
the charging hardware and the weight of a drone. The 60 pound constraint will allow any weight drone be
used with the ADCS.
2.1.3 Drone Charging
Autonomous drone charging is one of the key functions of the ADCS. Properly charging the drone’s
batteries with the correct voltages will be crucial. The ADCS will be able to charge any Li-Poly/Li-Ion
battery with the cell range of 2 - 4. Theses batteries require a specific voltage range to charge that is
between 3.3 volts and 4.2 volts. Exposure to any voltages outside this range will cause damage to the
drone’s battery and could result in failure of the battery by not allowing it to hold a charge or possibly
explode. In order for the ADCS to be a successful product, it must deliver the required voltage range of
whatever drone battery is being used. This can all be done by using precautions when charging the drone's
battery.
2.1.4 Application
The application for the ADCS will operate on a website which allows all devices that can access the world
wide web to be used. The application is necessary to command the station to open the roof and retrieve
battery data from the ADCS. The user should be able to use this application from any location and maintain
consistent communication with the ADCS as long as the user abides by the operating location constraints.
Also, every five seconds the application will request a report from the ADCS regarding its status. Each
report will consist of two major components: the station’s battery life and the state of the station. The state
section of the report will describe to the user if the ADCS’s roof is open or closed, if the charging platform
is raised or lowered, and if charging is taking place.
2.1.5 Drone Size
The size of the ADCS will be able to contain drones as large as the average hexacopter (3’5” wingspan).
Competitors’ autonomous charging stations limit consumers by only supporting smaller drones, which sizes
average around one foot and five inches. Having a larger drone creates more real estate for attachments that
can be installed and room for an extra battery. This, in turn, allows the drone to carry heavier loads, operate
for longer periods of time and take on tasks that require more complex hardware that smaller drones simply
cannot hold.
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2.2 Practical Design Constraints
Table 2.2 contains the five practical design constraints.
Table 2.2 Practical Design Constraints
Type Name Description
Economic Cost The ADCS’s $1500 price tag will make it a competitive
product on the charging station market.
Ethical Legality The ADCS users must comply with FAA regulations
unless permitted otherwise.
Health and Safety Safety The ADCS must be safe for the drone to interact with in
order to avoid damage to the drone.
Manufacturability Parts Availability The ADCS must be large enough to accommodate drone
sizes for up to 3’5” diameter.
Sustainability Durability The ADCS must be able to handle most weather
conditions including rain, hail, snow, and high winds.
2.2.1 Economic
The goal of the ADCS is to create a universal charging station. With the prices of drones increasing due to
high demand, the charging station needs to be economically efficient. Other drone charging station
companies include a drone, and customers must purchase the company’s drone, along with the charging
station, instead of using his or her own drone. Another economic problem with other charging stations is
requiring user’s drones to have fully autonomous software. A customer will pay more because of the
software integrated into the drone and charging station. The ADCS will have just autonomous charging
software, but a person can fully pilot his or her own drone when the drone battery charges to a sufficient
load. The ADCS materials for construction and software should not cost more than $1,500 in total.
2.2.2 Ethical
FAA regulations state that drones must be in visual line-of-sight of the pilot or observer. The ADCS has no
built-in capabilities to determine if the drone is within sight of the user, but the pilot needs to be aware of
these rules to avoid potential fines.
2.2.3 Health and Safety
As engineers, safety is crucial when designing a product and must be the highest priority, not only to the
users but to their property as well. Multiple sensors will be added to the ADCS to ensure that when the
drone is being lowered, and the roof is closing, the drone will not be crushed. To control and monitor these
operations, the user will have an application installed on their phone. The application should be consistent
and rarely miss updates from the ADCS so that the user knows exactly what is happening.
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2.2.4 Manufacturability
The ADCS itself is to be around 6x6x4 (l*w*h) in feet, making it a universal charging station for drones
that meet the size constraints. The construction constraints of the ADCS have been determined to fit almost
any reasonable sized drone from a simple quadcopter to a larger scale octocopter. The supported drone size
range will be anywhere from one foot to three feet in diameter and one to two feet in height.
2.2.5 Sustainability
The ADCS must withstand moderate weather environments. Since there are many parts in the ADCS that
are sensitive to water, the station needs to be water resistant when the roof is closed. In the case where the
ADCS is left in the open environment, it should be able to keep rainwater out as long as there is no flooding
of water greater than one inch. Since the ADCS could be placed anywhere, the outside layer of of the ADCS
needs to be strong enough to be able to stop objects that may fall across it. Also, when temperatures become
abnormally low or high, the performance of most electronic devices tends to slow down or halt, causing
undesired functionality.
2.3 Appropriate Engineering Standards
Along with technical and practical constraints, the ADCS must abide by the engineering standards
contained in Table 2.3 on the following page.
Table 2.3. Appropriate Engineering Standards
Specific Standard Standard Document Specification/ Application
GSM (Global System for
Mobile
Communications)
Sans Institute InfoSec Reading
Room Paper
The application must follow the
standards such as sending 128-bit
random number (RAND) and
checking that the appropriate
response was given back.
IPR (Ingress Protection
Rating)
International Standard EN 60529 The ADCS must be able to withstand
solid objects up to one square
millimeter and protect against water
splash from all directions.
2.3.1 GSM
The ADCS requires long-range communication to the user since the station could potentially be hundreds
of miles away from the user. The best way to communicate to the station is using a mobile chip that talks
to the application using GSM. GSM, also known as Global System for Mobile Communication, was created
in 1991 and has been thoroughly tested since then. It is currently the leading standard for cellular
communication.
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2.3.2 IP44 Environment Resistance
The drone and circuitry will be enclosed within the ADCS. Since the ADCS will be exposed to the open
environment, it must possess a certain level of tolerance to the elements in order to protect these
components. The IP44 standard states that the product must protect against splashes of water from all
directions and solid material up to one square millimeter.
3. APPROACH
The Autonomous Drone Charging Station (ADCS) will serve to provide continual drone flight for remote
operations by autonomously charging the drone while also serving as a protective container. The ADCS
will contain a floor lift, retractable cover, direct contact charging, and system of sensors. By use of a mobile
application, the user can send commands to the ADCS to lift and open for the enclosed drone to ascend for
operation. With the return of the drone, the ADCS will receive and lower the drone to safety and commence
autonomous charging. Use of the ADCS will eliminate the need for human interaction when charging the
drone’s battery or the need to physically plug in the battery for charging. Design constraints have been
established to create a baseline for component, sensor, and software usage, which are discussed in the
following sections.
3.1. System Overview
For the ADCS to be a fully autonomous charging station, several systems will be utilized to eliminate
human interaction during its operation. A mobile application will be used to send commands through use
of GSM. The GSM will then transmit that input to a microcontroller to notify the ADCS to take actions for
operation. The microcontroller will send back information gathered by sensors to inform the user of the
battery life of the ADCS, the drone’s landing status, and whether or not the ADCS can enclose the drone.
Below, Figure 3.1 shows an overview of the ADCS and functionality of the different subsystems that make
up the ADCS.
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Figure 3.1 – ADCS Overview
3.2. Hardware
The ADCS is composed of several hardware systems that include the microcontroller, battery, linear
actuators, and wireless communication module. These hardware systems are discussed in further detail in
the following sections.
3.2.1 Distance Sensor
The distance sensor will sit at the bottom of the ADCS and measure the height of the platform as it rises
and falls. When placed in the ADCS, the sensor must face upward so there is a direct path between itself
and the bottom of the platform. It must reside in a section of the ADCS where no internal objects obstruct
this path because it can only measure the distance of the object immediately in front of it. The sensor
(Adafruit VL53L0X) can measure a minimum height of 50mm (1.97 in.) and stops measuring at a maximum
of 1200mm (3.94 ft.). Since we are measuring heights that fall within the 762mm to 914mm (2.5 to 3 ft.)
range, this sensor works out perfectly for the project. Its accuracy falls within +/- 3 to +/- 12% of the actual
height, depending on the surface it is pointed towards. A limit switch would sound ideal in this situation,
but for status purposes, which tie in with the smartphone application, a laser sensor is capable of providing
more detailed feedback. An example of needing more feedback would be when the ADCS needs to report
the progress it has made in raising the platform. Another example would be if the platform suddenly stopped
raising and the laser sensor can provide the height of the platform for troubleshooting purposes. Also, where
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a bump switch works in a binary fashion, the laser sensor offers a more customizable approach when
adjusting the height. See Table 3.1 below for sensor comparison and detail.
Table 3.1 - Distance Sensor Evaluation
Distance
Sensor
Sensor
Type
Input Voltage
Range
Distance
Measurements (min-
max)
Prog. Language/
Comm. Protocol Accuracy Cost
Adafruit
VL53L0X Laser 3-5V 50-1200mm I2C
+/- 3% to +/-
12% of actual
height
$14.95
Adafruit
VL6180X Laser 3-5V 5-200mm I2C
+/- 3% to +/-12%
of actual height $13.95
Ultrasonic
Sensor HC-
SR04
Sonar 5V 20-4000mm C/C++ +/- 3mm $3.95
The VL53L0X laser distance sensor is a quarter-sized device and uses I2C for communication. The surface
it utilizes to measure the height of the platform can play a role in its accuracy. Because the sensor uses
reflection to measure distance, darker surfaces can produce less-accurate readings due to their light
absorbing properties. If the laser is able to point at a bright and highly-reflective surface, it will provide a
more accurate reading when measuring the height. Although the sonar sensor may have appeared to be a
better choice, its distance measuring capabilities were a slight overkill for what we need for the project.
3.2.2 Microcontroller
The Arduino Mega2560 will control the ADCS. Two reasons show the valuable importance of the Megafor
the project. One reason the team chose the Mega is that everyone in the group is familiar with the Arduino
software, so that makes explaining things to one another very easy. The number of I/O pins and analog pins
prove why the Mega presents efficiency for the ADCS. The ADCS will have three motors for raising and
lowering and for opening and closing. Relays will be used to control these motors and will require two
relays to control one motor and therefore a total of six relays will be needed. This means there will also be
six I/O pins needed to operate the relays. Along with the motor controls the charging patches will be using
16 relays and thus another 16 I/O pins will be needed. Based on this requirement, it was crucial that we
selected a microcontroller that had a sufficient number of pins to meet the 22 I/O pins needed for these two
subsystems. It was clear that the Arduino Mega2560 was the best microcontroller of choice meeting this
requirement while also having more than enough pins left over for other smaller subsystems. Table 3.2
shows a comparison of microcontrollers that were considered in the use of the ADCS.
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Table 3.2 - Microcontroller Comparison Table
Microcontroller Software # of I/O pins # of analog
pins
Arduino Uno R3 Arduino
Software 14 6
Arduino
Mega2560
Arduino
Software 54 16
3.2.3 Battery
To power the ADCS, one 12VDC/120Ah (voltage direct current / amp hour) battery will be powering the
ADCS to provide around 14 charging cycles for charging the drone. The cycle can be justified with the
math in later discussion of the batteries. The ADCS will be operating several mechanical and electrical
components when the drone is ready to land. During flight of the drone, the ADCS will not need to be in
full power operation.
Table 3.3 - ADCS Power Supply Summary
Battery
(ADCS)
Output
Voltage
Life
Expectancy Cost Rechargeable Count
12VDC/120Ah
Deep Cycle
Battery [6]
12 VDC 120 Ah $219.99 Yes 1
The battery life expectancy is large due to the combination of a smart circuit only fully powering up the
mechanics of the ADCS when the drone is ready to enter/exit the ADCS.. Table 3.4 will summarize the
component’s amp-hour while ADCS is idle, and Table 3.5 will summarize the component’s amp-hours
while the ADCS is at full operation.
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Table 3.4 - ADCS Battery Consumption (Idle)
Battery Rating = 120 Ah (12VDC/40Ah rechargeable Deep Cycle Battery)
Component (5V Max.)
(Operating at 5V) Drain for Each Component Total Drain
Arduino Uno Rev 3 (1) [X2] 50mA 50mA
Electron (v005) (1) [X4] 250mA 250mA
Total Current Drain: 300mA
Table 3.5 - ADCS Battery Consumption (Full Operation)
Battery Rating = 120 Ah (12VDC/40Ah rechargeable Deep Cycle Battery)
Component (quantity) [source]
(Operating at 12V) Drain for Each Component Total Drain
RF Receiver (1) [13] 200uA 200uA
Electron (v005) (1) [14] 250mA 250mA
Linear Actuators (3) 3A 9A
16 Module Relay Input (1) 20mA 20mA
16 Module Relay Output (2) 4A 8A
Total Current Drain: 17.3402 A
Life Expectancy of Battery Bank at 100% Drain: 6.92 hrs.
Since the horizontal actuator runs the longest, that will be how long the ADCS takes to run a half-cycle.
The time it takes for the horizontal actuator to fully extend will be 163.64 seconds. By multiplying the time
by two, this gives the total time (full-cycle) it takes for the ADCS to run at full operation. Multiplying the
current draw (17.3402A, from table 3.6) and the time that it approximately cycles through full operation
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(328 seconds), the total Ah consumption would be 0.7879 Ah. This leaves the other running time of the
ADCS as idle. With the assumption that the ADCS charges one drone at a time, the Ah consumption would
be 0.7879Ah plus the power consumption while idle (7.68Ah). This calculation allows the ADCS to have
approximately 14 charging cycles for a drone.
Table 3.6 - Linear Actuator Operating Times
Motions Lift/Lid Displacement Total Time to Operate
Vertical Actuator (Lift) 7” 31 second
Horizontal Actuator (Lid) 36” 163.64 seconds
* linear actuators move the platforms 0.22” per second
When working with the different amp hours, the discharge characteristics can differ at different max
voltages. Figure 3.2 shows the different discharge characteristics at specific voltage for a 55 amp-hr battery.
This shows the possibilities of run time at different battery voltages that the drone may have.
Figure 3.2 - Discharge Time for Different Loads
The drone will need to be equipped with its own small 3.7VDC battery to provide power for an Arduino
Mini that will communicate to an RF transmitter. The RF transmitter will be running when the drone has
landed and when in flight, so it needs to be on its own power supply so that it does not diminish the life of
the drone’s battery. The RF transmitter battery will be hooked up to the same circuit that helps charge the
drone’s battery so the 3.7V batteries can all stay charged. Table 3.7 will summarize what onboard battery
the drone will need to keep power to the RF transmitter.
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Table 3.7 - Drone Onboard Power Supply
Battery
Output
Voltage
Life
expectancy Cost Rechargeable Count
405585 3.7 VDC 3000 mAh $9.99 Yes 2
The 405585 Lithium Polymer Battery was chosen because it has a slim design and has a high life
expectancy. The other useful aspect to the 405585 is that the battery is rechargeable and can be connected
directly to the Arduino mini.
3.2.4 Motors
Along with autonomously charging drones, the ADCS must also serve as a protective container. This
becomes necessary in the case that the ADCS is left at the remote operation. Leaving the ADCS in the open
environment means the drone will need to be kept safe within the ADCS. To make the ADCS a protective
container while still keeping its ability to serve as an autonomous charging station, two mechanical systems
must be installed: a lift to receive, lower, and raise the drone for its mission and a retractable cover to open
and enclose for the drone’s protection. Motors will be required to make these mechanical systems work.
After research, it was determined that linear actuators will be the motor of choice for achieving the
mechanisms of these systems. As for the retractable roof, the force required to push and pull the doors open
will be less than the lift. The motors will only have the load of the doors, but the lift must raise a maximum
of 300 pounds. The 300 pounds account for the metal frame of the lift and the platform the lift will raise
containing the drone and metal patches. To meet this design constraint, it proved crucial to pick the motor
capable of lifting 300 pounds. Table 3.8 outlines noteworthy linear actuators that were considered.
Table 3.8 - Linear Actuator Motor Comparison
DC Motors (by
company name)
Operational
Voltage
Typical
Operation
Current
Speed Max Load Cost
ECO-Worthy 12V 3A 0.22”/sec 330 lb. $70.99
Progressive
Automations 12V 4A 0.27”/sec 330 lb. $149.99
WindyNation 12V 5A 0.39”/sec 225 lb. $78.99
The ECO-Worthy linear actuator met the 300-pound constraint by over 30 pounds. Another specification
that stood out was it needed only three amps of current to operate, making it the lowest current needed for
operation out of the three linear actuators. Although speed was not a concern for the ADCS’ lift, the slow
speed of only 0.22 inches per second made the ECO-Worthy linear actuator less desirable than what was
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expected. This specification led to further research in finding a desired linear actuator capable of a faster
speed.
Further research showed that a high speed linear actuator is costly. WindyNation’s linear actuator proved
to be the most cost-efficient in terms of speed but missed the maximum load constraint by 75 pounds and
resulted in requiring the most current needed for operation. With further research, Progressive Automations’
linear actuator met the maximum load constraint by 30 pounds but only increased speed by .05 inch per
second and is the most costly.
After consideration, the ECO-Worthy linear actuator was the motor of choice for being the most cost-
efficient while also meeting the maximum load constraint.
3.2.5 Wireless Communication Device
The wireless communication device that will be in the ADCS is the Particle Electron. The reasons for
choosing this wireless communication device are its convenience to the developer and the user, and it was
donated by Dr. Kurum. Since this device was donated, the team only looked for communication modules
that would be easier to use than the Electron in both server support and microcontroller setup. Since the
Electron has a built-in microcontroller, there is hardly any setup time. Also, most of the other
communication modules used third party SIM cards, requiring the user to pay for a specific carrier. Since
the Electron has its own custom SIM card, this device can connect to most major carriers around the world
with a low-cost data plan. Through serial communication, the Electron will send commands to and receive
acknowledgements from the Arduino.
Table 3.9 - Wireless Communication Device Evaluation
Communication Module SIM card Custom
Servers? Standard Price
Particle Electron Custom Yes GSM Free
2691 Adafruit 3rd party No GSM $80
Interlogix NX-591NE-GSM 3rd party No GSM $150
3.3. Software
The ADCS uses multiple software packages to implement many of the hardware processes. The software
portion can be broken down to application system and microcontroller system. The main processes are
application state, transmission state, controller state, sensor state, charging state, and status state. Figure 3.3
shows the high-level software design.
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Figure 3.3 - High Level Software Design
3.3.1 Application
The application system of the ADCS is a crucial element because it is the user interface between the station
and the user. Without the application, the user would no longer be able to send the ADCS commands as
well as get information back. Two common mobile application operating systems are iOS (Apple) and
Android (Google). For a prototype, it would be easier to write code for one operating system for now and
add compatibility for both later.
Table 3.10 - Application Specifications Table
Operating
System IDE Language App quality [5] Users [6]
iOS (Apple) Xcode Swift or Objective C 68.5 12%
Android (Google) Android Studio Java 63.3 87%
Table 3.10 shows the different aspects of using iOS and Android. iOS uses Swift for its programming
language, which was developed specifically for iOS and is less prone to errors, while Android uses Java.
Although the amount of Android users is significantly larger than iOS, the ADCS team is choosing iOS
development because of the familiarity of programming in Objective C. Since Apple developed Swift, a
programming language specifically for iOS devices, it has a large amount of support while also having
added built in security.
The application will send http requests to the Particle Electron cloud servers. Those servers will then send
data through GSM to the communication device. GSM uses user data header (UDH), which is a protocol
that specifies the bit order for all packets being transmitted [15]. When the communication device needs to
contact the application, it sends a request to the server. If the app is not responding, then it will sit in the
server until it gets a response from the app.
3.3.2 Application State
The application will act as a user interface to control the ADCS and show its status. As stated above, the
application will use http requests to send data to the Particle Electron servers. For security, the app will
have a login page that will only allow access to the ADCS that the user owns. After the user has logged in,
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they will have access to the menu page where they can record the size of the drone, control the ADCS, or
view the status of the ADCS. When sending commands to the ADCS, the http request will be a POST
request. If the user is wanting a status update of the ADCS, such as the battery percentage, then a GET
request is sent to the servers. The reason for these differences comes from how the server is setup to handle
the requests. Using a POST request indicates that the servers must contact the communication device for
the data, while using a GET request indicates that the data exists on the server. To make things easier,
values such as battery life are stored as variables on the server. So instead of contacting the communication
device for the information, the app only asks the server, allowing it to be more responsive. If a request to
the server does not get a response, then an error message will appear telling the user to try to resend the
request.
3.3.3 Microcontroller
The microcontroller is the head of the ADCS because of all the processes it manages as well as the data it
stores. The main method of communication between the microcontroller and the other devices is serial data
transfer because most of the team is more familiar with it. Since user commands will be coming from the
communication device, the microcontroller will prioritize the data it is sending before any of the other
devices. Below, Figure 3.4 demonstrates the communication process.
Figure 3.4 - Communication Between Microcontroller and Cellular Module
The microcontroller will initially be waiting for commands from the communication device. Once it
receives a command, it will perform the code associated with it. These are some commands that the
microcontroller can receive and should be able to handle:
Open ADCS: This command will tell the microcontroller that the ADCS needs to be fully open. First the
microcontroller will talk to the 16 mod charging relays to see if they are charging the battery. If they are,
then the microcontroller will tell the communication module that opening the ADCS failed. If the drone is
not being charged, then the microcontroller will tell the roof to open. It will then check the sensors to make
sure that the roof is open, and if the check passes, it will tell the platform to raise. Once the sensors show
that the lift is fully raised, the microcontroller will tell the communication device that the ADCS is open
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and wait for more commands. If any unexpected events happen that cause the ADCS to not fully open, then
a failure will be sent to the communication device along with an integer value that maps to a specific error.
Close ADCS: This command will tell the microcontroller that the ADCS needs to be fully shut. First, the
microcontroller will tell the sensors to check if the drone is on the platform. If the drone is not on the
platform, or if it is in a spot where it could be damaged from the ADCS closing, then the microcontroller
will tell the communication device that it failed to close. If the sensors determined that the drone was in a
good position, then the microcontroller will tell the platform to lower. After checking the sensors, if the
platform is lowered, it will then close the roof and then check with the sensors if it did close. If everything
has closed, then the microcontroller will tell the communication device that the command was a success
and wait for more commands. If any unexpected events happen that cause the ADCS to not fully open, then
a failure will be sent to the communication device along with an integer value that maps to a specific error.
Check Battery: This command will tell the microcontroller to check what the battery voltage is. The
microcontroller will use the programmable multimeter and run a simple check to see what the power is.
Once this is found, a numeric value that is related to the power level will be sent to the communication
device as a success. If any unexpected events happen that cause the ADCS to not fully open, then a failure
will be sent to the communication device along with an integer value that maps to a specific error.
3.3.4 Linear Actuator/Motor State
The linear actuator and motors control the roof and platform. The order in which the roof closes or opens
needs to be in line with the sensors and when the platform raises or lowers. If a wrong step is taken, then
the drone could be crushed between the two doors of the roof or between the roof and the platform. In the
linear actuator and motor state, it is crucial in making sure the components are moving properly. When the
motors are given the signal to control a specific part, this state needs to do a continuous loop of moving and
checking to make sure everything is okay. This state is also in control of the speed at which the motors
move, so setting the motors to go faster and slower will be done here. If no initial speed is given to the
motors, then the default one is set. Since the motors are only connected to the microcontroller, there will
be no direct contact with the sensors. This means two things: the motors must be able to swiftly stop moving
when given a command, and stop commands will take top priority over other transmitted data. This state is
also in charge of relaying any error messages that the linear actuators and motors give.
3.3.5 Distance Sensor State
The following figure, Figure 3.5, provides a more visual explanation of the role of the distance sensor in a
sequential cycle. The sensor will initially start off in a wait state in which it waits for the ADCS platform
to rise. In code, a fixed maximum height is set, and when the reading from the sensor reaches or slightly
exceeds that value, a signal is sent back to the microcontroller letting it know that the platform has reached
the appropriate height, stopping the raising process. The sensor will then proceed to another wait state. In
this state, the sensor waits for the platform to be lowered to the minimum height specified in the code. Once
the minimum height criteria have been met, the sensor will send a signal back to the microcontroller letting
it know to stop the lowering process. Once this is complete, the sensor will enter its initial state again and
the cycle will continue to repeat itself until the ADCS is powered down.
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Figure 3.5 - Sensor State Flow Chart
NOTE: Sensor is measuring height during “Wait” states.
3.3.6 16 Mod Relay Charging State
When charging the drone, the key element to know is how much voltage to give to the drone battery. If too
much voltage is given to the battery, then it can explode, and if too little is given, the battery might not ever
hold a charge again. When the drone lands, it will be on small square charging pads, and a voltage sensor
to determine which two pads the drone lands on. Once the voltage meter realizes what pads the drone has
landed, the relays will receive voltage flow through the certain pads and into the drone telling which pads
have become energized. If the drone is only on one pad, then it will tell the communication device that the
drone needs to be moved until it is on two pads. Figure 3.6 shows how the polarity of each pad gets added
and how the voltage is regulated.
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Figure 3.6 - Charging State Flow Chart
3.3.7 Battery State
The battery state allows the user to accurately know the battery life of the ADCS. Displaying the battery
life is not as crucial as some of the other processes, but it is very much needed because if the battery is
almost dead, the user needs to know that it should be charged. The method of measuring the battery power
uses a programmable multimeter writing to the microcontroller in order to send battery information back to
the web application. Figure 3.7 shows what happens if the microcontroller requests a battery power reading.
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Figure 3.7 - Battery State Flow Chart
3.3.8 Usage Cases
3.3.8.1 Sunny Day
For ideal conditions, Figure 3.8 shows a simple process that will take place to get the drone up in the air.
The user will open the app and send a request to open the ADCS. Once the communication device receives
the request, it will send a command to the microcontroller to open the doors.
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Figure 3.8 - Typical Open Operation
3.3.8.2 Rainy Day
Below, Figure 3.9 shows a rainy-day case where operations do not work out perfectly. When the drone is
ready to be charged, it will land on the ADCS platform. If the drone is not in the correct position for the
platform to lower, then a failure signal will be sent to the user letting them know to reposition the drone.
Once the drone is in the right position, the microcontroller tells the motors to lower the platform and then
sends a signal that the command succeeded.
.
Figure 3.9 - Typical Closing Operation
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4. EVALUATION
The following sections evaluate the test results, how they were set up, and why they were set up with
specific conditions. While some experiments were tested separately, others were tested in combination with
one another. Table 4.1 shows the design constraints that must be met in order for the ADCS to properly
function. Since these constraints are so crucial to the project, a majority of the tests were designed for the
subsystems that relate to them.
Table 4.1 Technical Design Constraints
Name Description
Communication
The ADCS must be within 45 miles of a cellular
tower, depending on the tower’s technology, and
communicate via the cellular network.
Maximum Load The ADCS will have a lift component that must lift
the platform and all hardware on the platform.
Drone Charging
The ADCS charger will be controlled by a
microcontroller which delivers a voltage of 3 volts
to 4.2 volts for any size battery.
Application
The ADCS must provide information to the user’s
smartphone regarding the station’s status. Some
examples would be battery life, roof open or closed,
etc.
Drone Size The ADCS will support drone size up to 3’5” in
diameter.
4.1 Test Certification - Lift Load
The lift will be tasked with lowering the drone into the ADCS so it can be stored and then raising it so it
can take off. The key aspect to the lift is that it stops when fully lowered and it raises flush with the top of
the ADCS. The tests are discussed further below.
4.1.1 No Load Test
The first test was created to make sure that the lift is functioning properly and that it reached the needed
height of 29 inches to be flush with the top of the ADCS. Before applying a load on the lift, a test needed
to be conducted to determine this best placement of the motor used to operate the lift from the lowest
starting position. To determine the best placement of the motor, the motor was placed at different starting
angles. Power was given to the motor and a recording of the amperage being pulled was recorded. Table
4.2 shows the results from the test.
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Table 4.2 Starting Angle of Motor Current Draw (No Load)
Starting Angle 90° 60° 20°
Max Current Draw 0.65 A 1.3 A > 3 A
These results were helpful in showing that starting angle position of the motor proved to be a factor in the
current draw that it would take to start lifting. The motor used to drive the lift had a rated maximum current
draw of three Amps. These test results show the current draw of the motor with no load on the lift.
Additional weight would result in a higher current draw and it needed to be less than three amps that the
motor could handle. Therefore, selecting a starting angle that left sufficient current draw for a load was
critical. As the Table 4.2 shows, at 90° the lowest current draw was reached and second lowest was at 60°.
The 20° position was automatically excluded based on the fact that the motor was already at its maximum
current draw and any additional weight would exceed the limit of the motor’s rating. Furthering the
selection of the motor starting angle, the 90° starting angle was excluded because it was not able to meet
the height of 29 inches. This resulted in selecting the 60° starting position which only pulled one Amp and
met the height requirement of 29 inches. With this current draw at this angle left us an additional current
draw of two amps with added weight which would be more than sufficient for the load needing to be lifted.
4.1.2 Max Load Test
A second test was created to show how much load the lift could withstand when reaching maximum amount
of current drawn from the motor. Once the motor reaches the max current draw from the load of the lift, the
motor will not perform properly or can even fail. Since the motor would not work with a 90° angle, stated
in the previous section, switching to a 60° angle would suffice for lifting the desired load. The team
determined the max load the lift would encounter, with charging hardware plus drone, would not exceed
30 pounds. Along with the 60° angle, an additional 60 pounds was added to the lift during our max load
test. The success from the test shows that the lift can provide lift support for double the desired weight, and
the initial current drew 1.8 amps. Since the motor’s max current draw is 3 amps, the test shows that the load
can increase on the lift and shows that the motor would continue to work properly.
4.2. Test Certification - Drone Charging
The most crucial part of this drone is to make sure that the ADCS can charge the drone swiftly and
efficiently. When the drone lands and the drone sensing technology gives the “OK” to charge, then the
charging tech must be able to consistently charge it safely. If any problems occur, the ADCS needs to be
able to perform the correct error handling, and tell the user what error the occured. The tests are further
discussed below.
4.2.1 Normal Condition Test
In normal conditions the drone will have landed on the patches of the ADCS and charging will commence.
With an onboard battery monitor, the ADCS will control the charging and battery life of each battery
ensuring proper charge.
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Figure 4.1 - Drone Charging from patches
We will know when the drone is charging because we will be able to monitor the voltage using a voltage
sensor. If the voltage sensor shows any voltage, then the ADCS know the user’s drone is charging.
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Figure 4.2 - Current draw of drone charging Figure 4.3 - No current draw of drone charging
4.2.2 Non-Charging Plates Test
When the drone has landed and the ADCS is charging, the arduino then asks the microcontroller to detect
the two contacts of the drone. By doing this the ADCS only has to power on two relays. This is important
because constantly powering all of the relays costs energy which lowers efficiency.
Figure 4.4 - Current draw of all relays on
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Figure 4.5 - Current draw of only two relays on
4.3 Test Certification - Drone Sensing
When the drone lands into the ADCS, two of the pads will be used to charge the drone. The problem is to
find which of those two pads are being used, and to see how close they are to the edge of the ADCS. If the
charging plates indicate that the drone is not correctly in the box, then an error must be sent to let the user
know. The tests are further discussed below.
4.3.1 Normal Condition Test
In normal situations, the drone will land in the middle of the ADCS and begin charging. This test simulates
a good landing where the drone’s contacts are touching two plates and there is no bridge created by those
contacts. While performing this test, the arduino was able to figure out which plates the drone’s contact
were on.
Figure 4.6 - Drone landing in most optimal position
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4.3.2 Bad Drone Position Test
In bad situations, when the drone is approaching the ADCS there may be conditions where the drone can
not land as accurately as wanted so the drone lands a foot or more off to the side.
Figure 4.7 - Drone landing with one contact hanging off patches
If this situation occurs, then the ADCS will notify the user that drone cannot charge and needs to be
repositioned.
4.3.3 Plate Shorting Test
In worst case situations, when the drone lands and the contacts fall between two plates a short is formed in
the circuit. When checking for drone position, a current sensor needs to recognize large spikes in current
and turn off power to the plates immediately. This test simulates a bridge between two plates.
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Figure 4.8 - Drone contacts touching more than one patch (possible short)
While performing this test, the arduino was able to sense the high spike in current, turn off the plates, and
send a message to the user telling them to reposition the drone.
4.4 Test Certification - Application
The application allows a remote user to control the ADCS. Since it is displaying status updates to the user,
it also needs to be fast as well as handle faulty responses.
4.4.1 Speed Test
To ensure that the user has quick access to the ADCS, the application needs to be as fast as possible. Burp
suite is used to check the round trip time (RTT) of the requests and responses. Figure 4.8 is a picture of
where the RTT can be found. Table 4.3 shows the average response time from the web application and the
ADCS.
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Figure 4.8 - RTT Location
Table 4. 3 Command Test
Commands/Checks Average Round Trip
Time
Open Approx. 1 sec
Close Approx. 1 sec
Check Charge Approx. 2 sec
Check Signal Approx. 2 sec
Check Drone Approx. 2 sec
4.4.2 Faulty Request Test
Since some packets can get dropped when communicating through GSM, the web application needs to
validate the data that it receives from the ADCS. A faulty response was sent to the application from the
ADCS to simulate a packet being dropped through bad connection/tampering. Figure 4.10 shows the error
that the application generated when it received a false response.
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Figure 4.10 Generated Errors
4.5 Test Certification - Drone Size
One of the major selling points of the ADCS is its ability to accept multiple sized drones. With this,
customers can have their own drones with different modifications on them. Since the size of the drone is
an unknown variable, extensive testing with different sizes and different drone legs will be done to ensure
compatibility with a wide range of drones.
4.5.1 Multiple Size Drone Test
Since the patches use 8.5” by 8.5” square sheet metal, the minimal distance between contacts on the legs of
any drone must be at least 12.5”. This is important because if the drone lands and both contacts reside on
the same patch, no charging will occur since the polarity on each contact has to be opposite of the other to
do so.
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Figure 4.11 – Distance between the contacts on the legs of the drone is too small. No charging will
take place.
4.5.2 Pad Charging Anywhere Test
A drone may not always land in the center of the platform because of imperfections in flight and landing
positions of a drone. The platform will have 16 charging plates, setup in a 4x4 grid, allowing the drone to
land in an area roughly over 1156 square feet. Whether the drone lands in the center, corners, or sides of
the platform, it is capable of receiving a charge. As long as both contacts of the drone are touching two
separate plates on the platform, the ADCS can find the drone contacts and allow proper charging.
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Figure 4.12 - Drone is getting charge no matter the orientation of the contacts in respect to the
patches
4.6 Test Certification - Laser Sensor
The ADCS utilizes a laser sensor, the VL53L0X Time of Flight Distance Sensor, to measure the height of
the platform so the microcontroller knows when to stop the lifting and lowering process. Though a bump
switch would have seemed more ideal in this situation, the laser sensor is more robust when adjusting the
stopping height of the platform. This sensor was selected because its measuring capabilities fall perfectly
within the requirements of the project. To test the sensor, it was initially set up according to the code and
schematic provided by the Adafruit website. Sensor accuracy was tested using a sheet of paper to act as the
object being measured and a ruler. Based on the results, the readings from the sensor fell within ±10mm of
the actual height of the sheet of paper. This proved to be sufficient for our project. It was determined that
if the object being measured fell outside of the maximum height the sensor was capable of measuring, a
reading of “Out Of Range” was given. Also, because the sensor measures whatever object is directly in
front of it, errors can occur if a foreign object obstructs the direct line of measurement. Such errors would
be the lift failing to stop at a specified point due to the inability of the sensor to monitor height. Since the
actuators possess a current limiter, the failure of this device would not be detrimental to the ADCS, but the
lift would fully extend or descend with no control of its height. This would also affect the status report of
the drone if one is requested. To remedy this issue, a timeout is placed in code so that if an acknowledgement
is not sent back within a certain amount of time, then the system knows that something has gone wrong
with the sensor. This malfunction would then be recorded in the status report, notifying the user of this
occurrence.
4.6.1 Laser Accuracy/Distance Test (Test the accuracy and the distance of the lasers.)
Table 4.4 on the following page shows the accuracy of the laser sensor when performing test at three
different heights.
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Table 4.4 - Laser Accuracy Test
Height in Code
(HC) Test #1 Test #2 Test #3 Average of Test
(± of HC)
100mm 98 102 104 ±1.33
300mm 300 305 297 ±0.67
500mm 501 502 498 ±0.33
4.7 Test Certification - Remote Operation
Remote charging presents the is ADCS’s most important function, and it will control the ADCS from
anywhere as long as the user has access to the internet. Remote charging means that the user might not be
able to physically see the station, so there is a need for proper error handling. The tests below discuss this
further.
4.7.1 Normal Condition Test
Two tests show that the ADCS can be remotely operated. The first request to control the ADCS was sent
over wifi. The next one was sent through mobile data. Table 4.4 below shows that remote operation works
for both methods.
Table 4.5 - Remote Application Test
Method Requests Sent Requests Succeed
Mobile Data 25 25
Wifi 25 25
4.7.2 Status Update Test
To ensure that the user receives the most recent data, certain tests need to prove that the ADCS sends
constant data back to the application. When the application goes inactive, the ADCS will still need to send
data back to the cloud, When the application turns on, the ADCS can receive the most relevant data from
the cloud. The test done proves battery status changing ,and watching battery status changing proves the
web application works properly.
4.7.3 Error Test
To prevent damaging the drone and the ADCS, error handling must be implemented. Upon an error, the
user also needs to be notified so that they can take precautionary actions. During this test an error was
created from the ADCS to check and see if the application received it. Figure 4.13 is taken from the web
application after the error is created. After generating an error, it took about 10 seconds for it to be seen on
the web application.
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Figure 4.13 - Error Test Web Application
4.8 Test Certification - ADCS Complete System
These last tests ensure that the ADCS functions properly. The tests below are in depth and use all of the
findings from the previous tests to make sure that the ADCS functions properly when there are unexpected
occurrences.
4.8.1 Full Normal Condition Test
The team tested a situation where the ADCS opened, the drone landed in the middle, then the ADCS closed
and began charging. The entire test took about three minutes and was fully successful.
4.8.2 Full Error Simulation Test
For this test the team tested a situation where the ADCS opened, but the drone did not land on the charging
pads. The system worked as expected because the application told the user that the drone was not in the
correct position. We then repositioned the drone and checked the position again. The application noticed
that the drone was in the correct position, lowered the ADCS and then began charging. Figure figure
4.14shows the web application telling the user to reposition the drone.
Figure 4.14 - Drone Reposition Test
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ECE 4512: Design I April 25, 2018
5. SUMMARY AND FUTURE WORK
The purpose of ADCS was to create a charging station for drones that would allow for continual drone
flight for remote drone operations. At the end of the semester we successfully created a working prototype
that a user could communicate to through the use of a web application. This communication was crucial
and gave the user the ability to control the ADCS with commands that opened and closed the ADCS and
also send commands to start and stop charging of the drone. Statues of the battery life of the ADCS and
whether the ADCS was opened or closed was also in the web application. With our success the ADCS
eliminates the need for human interaction with changing or charging of the battery of a drone. Drones can
land on the ADCS and charging can commence all while being protected inside the ADCS.
The future work and and improvements of the ADCS would include a better way of powering the system
of the ADCS. As of now, the ADCS is powered by a 12 volt deep-cycle battery which would require needed
human visits to change the battery or charge it. We would like to introduce solar power to the ADCS system
that would allow the charging of the 12 volt deep-cycle battery, making the ADCS more sustainable. Work
to come would include making a PCB and enclosing the ADCS container with walls and roof that would
ensure the protection of the drone.
6. ACKNOWLEDGEMENTS
We wish to acknowledge Dr. Mehmet Kurum and Dr. Bryan Jones of Mississippi State University and
Raytheon of Forest, Mississippi along with Shane Morrison for their continued support and feedback
regarding this project. Our team enjoyed working with each of you as you all provided wealthy knowledge
in working with this project.
7. REFERENCES
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ECE 4512: Design I April 25, 2018
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Autonomous Drone Charging Station 41
ECE 4512: Design I April 25, 2018
8. APPENDIX: PRODUCT SPECIFICATION