Difference between revisions of "S17: Sphero Droid"

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=== Grading Criteria ===
 
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<font color="green">
 
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*  How well is Software & Hardware Design described?
 
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*  How well can this report be used to reproduce this project?
 
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*  Code Quality
 
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*  Overall Report Quality:
 
−
**  Software Block Diagrams
 
−
**  Hardware Block Diagrams
 
−
**:  Schematic Quality
 
−
**  Quality of technical challenges and solutions adopted.
 
−
</font>
 
  
−
== Project Title ==
 
−
'''Wake up Barista'''
 
  
−
== Abstract ==
+
[[File:CmpE244_S17_SpheroDroid_Botview.gif|600px|thumb|center|Sphero Droid]]
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This section should be a couple lines to describe what your project does.
 
  
−
== Objectives & Introduction ==
+
=== Abstract ===
−
Show list of your objectives. This section includes the high level details of your project. You can write about the various sensors or peripherals you used to get your project completed.
+
Robots are revolutionizing almost every industry, primarily in the sectors where human safety is at risk. In hazardous working conditions such as in the mining industry, the lack of knowledge about the geographic nature and the environmental conditions of the mine hinder the rescue operations. Autonomous robots are being employed to improve the plight of mine workers and rescue operators. The robotic vehicle can explore the inaccessible and unworkable mines and disaster-affected areas and send valuable information to the teams to assist in search and rescue operations. But traditional robots could be rendered useless if they are overturned or in terrains having staircases and ledges. Also, there is a possibility of failure of the electrical and mechanical components exposed to the harsh environmental conditions. An autonomous spherical robot is a better option since its shape offers better robustness and rigidity. The spherical robot will enclose all the components within it and will not have any wheels or legs on its exterior. This feature enables it to operate in any hazardous conditions since there will be very less chance for the components to get damaged by the surrounding environment. The spherical design allows it to easily maneuver in different types of terrain, be it stairs or corners, and have no risk of being overturned. These advantages enable the robot for many applications such as exploration and mapping of access routes, surveillance and rescue operations in uncomfortable working conditions.
 +
 
 +
== '''Objectives & Introduction''' ==
 +
The objective of this project is to design an autonomous spherical robot with sensors, Global Positioning System (GPS) module, Bluetooth module and other control units interfaced to the microcontroller, which navigates its way exploring the path and avoiding obstacles. The temperature and the route followed by the robot can be logged on the SD card. These features enable the robot for many applications such as exploration and mapping of access routes, surveillance, and rescue operations in uncomfortable working conditions.
 +
 
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_Botzoomview.jpg|370px|thumb|left|Sphero Droid front view]]
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|
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|
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|
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|[[File:CmpE244_S17_SpheroDroid_Botsideview.jpg|250px|thumb|center|Sphero Droid side view]]
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|
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|
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|
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|[[File:CmpE244_S17_SpheroDroid_internal_view.jpg|450px|thumb|right|Sphero Droid Internal view]]
 +
|}
  
 
=== Team Members & Responsibilities ===
 
=== Team Members & Responsibilities ===
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*  Chien Wei Lan
+
[[File:CmpE244_S17_SpheroDroid_Teampic.jpg|right|500px|thumb|GPS interface with SJOne board via UART]]
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**  
+
*  <font color="clouds"> [https://www.linkedin.com/in/harshitha-bura-4926727a/ Harshitha Bura]
−
* Mingyang Wang
+
** GPS and Temperature Sensor<br>
−
**  
+
** SDCard<br>
−
* Lin Zheng
+
** Wiki page reporting<br>
−
**  
+
** Code integration[Gps and Sdcard card tasks]<br>
−
*  Zhixuan Zhou
+
* <font color="red"> [https://www.linkedin.com/in/naveenbr/ Naveen Kumar Bhuthakatanahalli Ramalingaiah]
−
**
+
** SDCard<br>
 +
** Bluetooth module and Android Aplication<br>
 +
** Hardware design and implementation <br>
 +
** Code integration[Andriod task integration with overall tasks integration]<br>
 +
* <font color="green"> [https://www.linkedin.com/in/shivam-chauhan-a1ab2ba3/ Shivam Chauhan]
 +
** PCB Designing<br>
 +
** Servo Motor<br>
 +
** Ultrasonic Range Finders<br>
 +
** Hardware design and implementation <br>
 +
** Code integration[Overall tasks integration]<br>
 +
* <font color="carrot"> [https://www.linkedin.com/in/sushma-nagaraj/ Sushma Nagaraj]
 +
** Servo Motor<br>
 +
** Ultrasonic Range Finders<br>
 +
** Wiki page reporting<br>
 +
** Code integration[Servo,DC motor and Sensor tasks]<br>
 +
*<font color="black"> [https://www.linkedin.com/in/virginia-allita-menezes Virginia Menezes]
 +
**  DC Motors <br>
 +
** Wiki page reporting<br>
 +
** Code integration[Servo and DC motor tasks]<br>
  
−
== Schedule ==
+
== '''Schedule''' ==
−
Show a simple table or figures that show your scheduled as planned before you started working on the project.  Then in another table column, write down the actual schedule so that readers can see the planned vs. actual goals.  The point of the schedule is for readers to assess how to pace themselves if they are doing a similar project.
 
  
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
 
! scope="col"| Week#
 
! scope="col"| Week#
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! scope="col"| Date
+
! scope="col"| Start Date
 +
! scope="col"| End Date
 
! scope="col"| Task
 
! scope="col"| Task
−
! scope="col"| Actual
+
! scope="col"| Status
 +
! scope="col"| Actual Completion Date
 
|-
 
|-
 
! scope="row"| 1
 
! scope="row"| 1
−
| 3/19
+
| 3/21
−
| Finalized Schedule and materials
+
| 3/27
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| Completed
+
|
 +
* Requirement analysis and team discussion to order parts.
 +
* Determine individual tasks and assigning work based on different modules in project
 +
| Done
 +
| 3/29
 +
|  
 
|-
 
|-
 
! scope="row"| 2
 
! scope="row"| 2
−
| 3/26
+
| 3/28
−
| Test water pump, timer, and heater
+
| 4/3
−
| In process
+
|
 +
* Configure and interface the GPS module with the SJOne board
 +
* Configure and interface individual sensor with SJOne board
 +
* Interface motors with the SJOne board
 +
* Upload code on GitLab
 +
| Done
 +
| 4/9
 
|-
 
|-
 
! scope="row"| 3
 
! scope="row"| 3
−
| 4/2
+
| 4/9
−
| Design Schematics & build up prototype
+
| 4/18
−
| Plan
+
|
 +
* Designing PCB
 +
* Team discussions to integrate the design and work on the algorithm
 +
* Continue work on individual module (Sensors, motors, GPS) working with SJOne board
 +
| Done
 +
| 4/21
 
|-
 
|-
 
! scope="row"| 4
 
! scope="row"| 4
−
| 4/9
+
| 4/18
−
| Refine prototype
+
| 4/25
−
| Plan
+
|
 +
* Integrate the different modules
 +
* Build the sphere with bearings and enclose the components within it
 +
| Done
 +
| 4/28
 
|-
 
|-
 
! scope="row"| 5
 
! scope="row"| 5
−
| 4/16
+
| 4/25
−
| Testing and Debug
+
| 5/2
−
| Plan
+
|
 +
* Test in different environments and fix bugs based on different issues
 +
* Team discussion on extra features that can be implemented
 +
| Done
 +
| 5/7
 
|-
 
|-
 
! scope="row"| 6
 
! scope="row"| 6
−
| 4/23
+
| 5/2
−
| Finish project report
+
| 5/9
−
| Plan
+
|  
 +
* Testing and Debugging
 +
* Work on extra features
 +
* Work on Project Report on Wiki
 +
| Done
 +
| 5/16
 
|-
 
|-
 
! scope="row"| 7
 
! scope="row"| 7
−
| 4/30
+
| 5/9
−
| Find project presentation
+
| 5/20
−
| Plan
+
|
 +
* Testing and Debugging
 +
* Project Presentation and update Wiki
 +
| Done
 +
| 5/24
 
|-
 
|-
 
! scope="row"| 8
 
! scope="row"| 8
−
| 5/7
+
| 5/16
−
| Ready for Demo
+
| 5/23
−
| Plan
+
|
 +
* Complete Wiki Report and Final Demo
 +
| Done
 +
| 5/25
 +
|}
 +
 
 +
== '''Parts List & Cost''' ==
 +
 
 +
{| class="wikitable"
 +
! align="center"|Qty
 +
! align="center"|Description
 +
! align="center"|Manufacturer
 +
! align="center"|Part Number
 +
! align="center"|Cost
 +
! align="center"|Links
 +
|-
 +
|1
 +
|SJ One Board [http://www.socialledge.com/sjsu/images/d/de/2012SJOneBoardSchematic.pdf]
 +
|Preet
 +
|SJ-one
 +
|$80
 +
|http://www.socialledge.com/sjsu/index.php?title=SJ_One_Board
 +
|-
 +
|2
 +
|DC Motor
 +
|RobotShop
 +
|Pololu 4.5V, 80rpm Right Angle Plastic Gear Motor
 +
|$4.95
 +
|http://www.robotshop.com/en/pololu-80rpm-right-angle-plastic-gear-motor.html
 +
|-
 +
|1
 +
|Servo Motor
 +
|Fry's electronics
 +
|Metal Gear Digital Servo Part No. LS-0009AF
 +
|$19.99
 +
|http://www.frys.com/product/7027281
 +
|-
 +
|1
 +
|Motor Driver
 +
|Fry's electronics
 +
|Motor Driver
 +
|$9.99
 +
|http://www.frys.com/product/8353697
 +
|-
 +
|1
 +
|GPS Logger
 +
|Spark fun Electronics
 +
|Venus638FLPx
 +
|$59.95
 +
|https://www.sparkfun.com/products/10920
 +
|-
 +
|1
 +
|Bluetooth Module
 +
|Amazon.com
 +
|HC-05 Bluetooth
 +
|$8.49
 +
|https://www.amazon.com/dp/B01G9KSAF6?psc=1
 +
|-
 +
|3
 +
|Ultrasonic sensor
 +
|Amazon.com
 +
|LV Maxsonar -EZ MB1010
 +
|$74.85
 +
|https://www.amazon.com/Maxbotix-MB1010-LV-MaxSonar-EZ1-Range-Finder/dp/B00A7YGVJI
 +
|-
 +
|1
 +
|Antenna GPS Embedded SMA
 +
|Spark fun Electronics
 +
|VTorch Datasheet
 +
|$11.95
 +
|https://www.sparkfun.com/products/177
 +
|-
 +
|1
 +
|PCB components
 +
|Amazon.com
 +
|(7805, 2 pin SPDT switch, 4004 diode, LD1117, Female pin header, male pin header, USB type B female jack, DC power jack, power supply module)
 +
|$72.00
 +
|https://www.amazon.com/gp/product/B01LRXIJRY/ref=oh_aui_detailpage_o03_s02?ie=UTF8&psc=1
 +
|-
 +
|2
 +
|Wheels
 +
|Amazon.com
 +
|70 x 8mm Black Robot Wheels
 +
|$12.00
 +
|https://www.amazon.com/gp/product/B00T3MQDHU/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
 +
|-
 +
|2
 +
|Bearing
 +
|Amazon.com
 +
|2 Pcs 22mm Outside Dia Plastic Coated Ball 
 +
|$7.93
 +
|https://www.amazon.com/gp/product/B00HR5SJKE/ref=oh_aui_detailpage_o08_s01?ie=UTF8&psc=1
 +
|-
 +
|1
 +
|Hollow spherical ball
 +
|Amazon.com
 +
|Giant Chinchilla Run-About 11-1/2-Inch Exercise Ball
 +
|$15.76
 +
|https://www.amazon.com/gp/product/B0006IK0LA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
 +
|-
 
|}
 
|}
  
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== Parts List & Cost ==
+
== '''Design and Implementation''' ==
−
Give a simple list of the cost of your project broken down by components. Do not write long stories here.
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=== '''System Block diagram''' ===
 +
The Sphero Droid contains ultrasonic, motors, GPS, Bluetooth as the main modules of communication. This is illustrated in the image below. The robot is controlled and navigated via a load which pulls it down and wheels which touch the ball from within. This will facilitate the ball movement.  
 +
{|
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|[[File:CmpE244_S17_SpheroDroid_Bot_modules.JPG|left|500px|thumb|Robot interface]]
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|[[File:CmpE244_S17_SpheroDroid_Bot_parts.JPG|right|400px|thumb|Within the Robot]]
 +
|}
  
−
== Design & Implementation ==
+
=== System State Diagram ===
−
The design section can go over your hardware and software design. Organize this section using sub-sections that go over your design and implementation.
+
The operation of SpheroDroid is divided into states as shown below. This mainly constitutes the start, operational and stop stages. The start is provided by Android application and the device moves forward. Different tasks will start when start condition is provided. The device will stop and when signalled from android application. The MCU will later send the GPS coordinate values which was written and restart when EOF is reached, moving to state one again.
 +
[[File:CmpE244_S17_SpheroDroid_Bot_state_diagram.JPG|center|700px|thumb|State Diagram]]
  
 
=== Hardware Design ===
 
=== Hardware Design ===
−
Discuss your hardware design here.  Show detailed schematics, and the interface here.
+
We have four distinct hardware modules used in this project:
 +
* Ultrasonic Range Finders (sensors)
 +
* Motors
 +
* GPS Module
 +
* Bluetooth Module
 +
 
 +
==== Ultrasonic Range Finders ====
 +
Used MB1010 LV-MaxSonar-EZ21 Ultrasonic Rangefinder sonar sensors, which can from 6-inches to 254-inches, with 1-inch resolution. Any object from 0-inches to 6-inches is typically
 +
ranged as 6-inches. They are used in PW mode for outputting. For efficient working of sensors without any crosstalk, we have configured 3 sensors in the chaining mode called AN output commanded loop. This mode of configuration uses 5 pins of each sensor such as VCC = +5V, GND, TX, RX, and PWM. While triggering, the first sensor RX pin is held high for a time period > 20μs and < than 48ms.This will start the sensor chain. The first sensor will range, then trigger the second sensor to the range and so on for all the sensor in the array.
 +
 
 +
Mounting of the sensors is made on a curved platform such that the sensors are aimed with a positive slope and not horizontally. This decision is made in order to avoid interference with the ground due to the wide range of detection by the sensors.
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_MaxSonarsensor.png|left|600px|thumb|MB1010 LV-MaxSonar-EZ21 Ultrasonic sensor]]
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|[[File:CmpE244_S17_Sensors_timing_diagram.PNG|centre|400px|thumb|Sensor timing diagram]]
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|[[File:CmpE244_S17_SpheroDroid_SensorMounting.jpg|right|350px|thumb|Sensor's mounting platform]]
 +
|}
 +
 
 +
==== Motors ====
 +
 
 +
* '''DC Motors'''
 +
The DC motors used in the project are 100 RPM low-cost single shaft straight geared motors. They are suitable for lightweight robots that do not require high power or torque.<br> The DC motors are connected to the wheels which are in contact with the base of the ball. The DC motors are driven by a driver module which controls the motor direction and speed.
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_motors.jpg|left|200px|thumb|Plastic geared motor]]
 +
|[[File:CmpE244_S17_SpheroDroid_Motor_Driver.JPG|center|400px|thumb|Driver module]]
 +
|[[File:CmpE244_S17_SpheroDroid_Motors-Motor_Driver.JPG|right|500px|thumb|Control inputs of driver module]]
 +
|}
 +
 
 +
* '''Servo Motors'''
 +
LS-0009AF Servo motor used is controlled by sending an electrical pulse of variable width or pulse width modulation (PWM), through the control wire.  Maximum deflection which can be achieved by using this servo is 90°.The motor's neutral position is defined as the position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise direction. The PWM sent to the motor determines the position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor will turn to the desired position. The servo motor expects to see a pulse every 2000 microseconds and the length of the pulse will determine how far the motor turns. For example, a 1500microseconds pulse will make the motor turn to the 45° position. Shorter than 1500microseconds moves it in the counter-clockwise direction toward the 0° position, and any longer than 1500microseconds will turn the servo in a clockwise direction toward the 90° position.
 +
 
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||||||||||||||||||||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_ServoMotorBasic.JPG|left|300px|thumb|Servo motor LS-0009AF]]
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|[[File:CmpE244_S17_SpheroDroid_ServoMotor_working.gif|right|400px|thumb|Servo motor dutycycle]]
 +
|}
 +
 
 +
The hardware implementation of how the DC motors are connected to the wheels which are driven from the SJOne board and how the servo motor is connected with the pendulum to steer the robot in right or left direction can be viewed in the figure below.
 +
 
 +
[[File:CmpE244_S17_SpheroDroid_Bot_motors_hardware_design.JPG|center|500px|thumb|Internal Hardware connection (Motors)]]
 +
 
 +
==== GPS module ====
 +
 
 +
In the project, we use GPS module ''Sparkfun Venus638FLPx'' to log the current location of the robot. An antenna is connected to the SMA connector of the GPS module. The software Skytraq GPS viewer is used to configure it. The module is configured to send information in NMEA message format (using the GPGGA (Global Positioning System Fix Data). We configured it to run at a baud rate of 38400bps and update rate of 2 Hz.
 +
 
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_BT.jpg|right|200px|thumb|GPS Module]]
 +
|[[File:CmpE244_S17_SpheroDroid_GPS_Logger_Antenna.jpg|right|200px|thumb|Antenna for the GPS module]]
 +
|[[File:CmpE244_S17_SpheroDroid_GPS_Viewer.PNG|right|600px|thumb|GPS Configuration Software]]
 +
|}
 +
 
 +
There are three modes of operation:
 +
 
 +
1. '''Hot Start''': This enables the GPS to obtain a fix in a very less time if it is connected to a 3.3v coin cell battery and it is switched on again within two hours after switching it off. Connecting the battery will help it to store information about the previous fix.
 +
 
 +
2. '''Warm Start''': In this mode, it will take the GPS more time to obtain a fix compared to the hot start as the module has been switched off for more than hours. But as the battery is connected and the information of the previous fix is available it will take less time compared to the cold start.
 +
 
 +
3. '''Cold Start''': As the battery is not connected and information about the previous fix is not available in this mode, it will take a lot of time to obtain a fix.
 +
 
 +
In our project, we have connected a 3V external battery (VBAT) to the module so that it does not take a long time to get a satellite fix even after turning off and on.
 +
 
 +
The NMEA message looks as follows:
 +
 
 +
  GGA - Global Positioning System Fix Data :  '''$GPGGA,hhmmss.sss,ddmm.mmmm,a1,dddmm.mmmm,a2,V,xx,x.x,x.x,M,,,,xxxx*hh<CR><LF>'''
 +
 
 +
  where,
 +
        Time              - hhmmss.sss
 +
        Latitude          - ddmm.mmmm
 +
        Direction        - (a1) - N or S
 +
        Longitude        - dddmm.mmmm
 +
        Direction        - (a2) - E or W
 +
        Validity          - V - 0 or 1. 0 means invalid and 1 means valid.
 +
 
 +
After this data is received by the SJOne board, string manipulation is done to extract the latitude and longitude from the string (if the data is valid) and they are converted to decimal minutes so that they can be sent to an android application where they are plotted on a map.
 +
 
 +
==== Bluetooth module ====
 +
 
 +
Bluetooth module HC-05 is used to communicate between the spherical robot and mobile application. It is implemented to establish the connection between the two so that we can remotely control the robot (to send start and stop signals) and receive the data from the robot directly on the Android application. The data being sent by the robot is current GPS location, ultrasonic range sensor values, and temperature sensor values.
 +
 
 +
{|
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||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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[[File:CmpE244_S17_SpheroDroid_HC05_module.jpg |thumb|left|250px|Bluetooth module HC-05]]
 +
|[[File:CmpE244_S17_SpheroDroid_Bluetooth_HC05.JPG |thumb|center|250px|HC-05 Pin connections]]
 +
|}
  
 
=== Hardware Interface ===
 
=== Hardware Interface ===
−
In this section, you can describe how your hardware communicates, such as which BUSes used. You can discuss your driver implementation here, such that the '''Software Design''' section is isolated to talk about high level workings rather than inner working of your project.
+
We have four major hardware modules interfaced with a single SJOne board using different communication protocols.
 +
For simplicity sake, we have given a description of how each module is individually interfaced with the SJOne board.
 +
In reality, all these modules are connected to a single SJOne microcontroller.
 +
 
 +
==== Ultrasonic Range Finders ====
 +
The ultrasonic range finders have been interfaced with the SJOne board using PWM. To avoid the crosstalk between the sensors and to improve the efficiency, sensors are configured to work in chaining mode. In our project, the Right sensor is triggered first by holding the RX pin high for >20μs and < 48ms.This will start the sensor chain. The Right sensor will range, then trigger the Front sensor to the range which in turn trigger the last Left sensor.
 +
 
 +
{|
 +
||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_Sensor_interface.png|left|400px|thumb|Ultrasonic range finders interfacing with SJOne board via PWM]]
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|[[File:CmpE244_S17_SpheroDroid_Sensorschainedtriggering.png|600px|thumb|right|Sensor's chained triggering]]
 +
|}
 +
 
 +
==== Motors ====
 +
 
 +
The DC motor is connected with the SJOne board via the motor driver module using GPIO.
 +
The GPIO signals from SJOne board provide inputs to the motor driver module, which in turn drives the DC motors in forward or reverse direction or stop signal.
 +
Servo motor is interfaced with the SJOne board using PWM.
 +
 
 +
{|
 +
|||||||||||||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_DCMotor_interface.JPG|left|400px|thumb|DC Motors and driver module connected to SJOne board using GPIO]]
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|[[File:CmpE244_S17_SpheroDroid_Servomotorinterfacing.PNG|right|500px|thumb|Servo motors interface with SJOne board via PWM]]
 +
|}
 +
 
 +
==== GPS Module ====
 +
GPS module communicates with SJOne board via UART. The antenna is connected to the SM connector of the GPS module. A 3.3v supply is given to the module and its Rx and Tx pins are connected to the Tx and Rx pins of the SJOne board respectively. UART 2 of the SJOne board is used for the GPS module and it is configured to run at a baud rate of 38400bps.
 +
{|
 +
|
 +
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_GPS_Connections.png|center|500px|thumb|GPS interface with SJOne board via UART]]
 +
|
 +
|}
 +
 
 +
==== Bluetooth module ====
 +
 
 +
The Bluetooth HC-05 module is connected with the SJOne board via UART communication.The bluetooth module communicates using the Tx and Rx pins of HC-05. This device independently connects to any external bluetooth master device. The HC-05 can work as a Master or a Slave. For our application the device sends the GPS data from SD card and also receive data from Android Application. Since the device can be connected independently without the MCU it can be connected and used with MCU restarting and not affecting the connectivity. UART3 is used for serial communication. The Baud rate set is 9600 for communication between bluetooth device and Android Application.
 +
 
 +
 
 +
{|
 +
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 +
[[File:CmpE244_S17_SpheroDroid_BT_interface.jpg|center|500px|thumb|Bluetooth connection with SJOne via UART]]
 +
|}
  
 
=== Software Design ===
 
=== Software Design ===
−
Show your software design.  For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level.  Do not show the details of the code.  For example, do not show exact code, but you may show psuedocode and fragments of code.  Keep in mind that you are showing DESIGN of your software, not the inner workings of it. 
 
  
−
=== Implementation ===
+
==== Ultrasonic Range Finder and Motors ====
−
This section includes implementation, but again, not the details, just the high level.  For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.
+
The motors working depends on the input values of sensors (ultrasonic range finders). Depending on whether the sensors can detect an obstacle in its path, the motors continue to run in the forward direction or the servo motor steers the robot towards right or left. The diagrams below shows the algorithm of the logic behind it.
 +
{|
 +
||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_Sensors_logic.jpg|left|400px|thumb|Sensors logic]]
 +
|||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_motor_logic.jpg|right|550px|thumb|DC and servo motor logic]]
 +
|}
  
−
== Testing & Technical Challenges ==
+
==== GPS module ====
−
Describe the challenges of your project.  What advise would you give yourself or someone else if your project can be started from scratch again?
 
−
Make a smooth transition to testing section and described what it took to test your project.
 
  
−
Include sub-sections that list out a problem and solution, such as:
+
The GPS-SJOne board communication is done via UART. Whenever data is received by the SJOne board from the GPS module, a UART interrupt occurs and the data is stored in a buffer. The data is checked if it is valid or not. If it is valid, the latitude and longitude are written to the SDCard. Otherwise, it is written that no GPS signal was available at that point. The flowchart is shown below.
  
−
=== My Issue #1 ===
 
−
Discuss the issue and resolution.
 
  
−
== Conclusion ==
+
[[File:CmpE244_S17_SpheroDroid_GPS_Flowchart.jpg|center|700px|thumb|Software Flow for the GPS]]
−
Conclude your project here. You can recap your testing and problems.  You should address the "so what" part here to indicate what you ultimately learnt from this project. How has this project increased your knowledge?
+
 
 +
=== PCB Design ===
 +
 
 +
We have used EAGLE software to design the PCB layout. The PCB layout is the most crucial part of the project, it may make or break the performance and working of the circuit. The first step towards designing the PCB is including all the required components into the schematic workspace and making connections between them. Once the schematic is ready, next step is to create the board layout from the schematic, which is easy, since EAGLE links the layout file and schematic together automatically.
 +
 
 +
 
 +
[[File:CmpE244_S17_SpheroDroid_PCBschematic.PNG|center|800px|thumb|PCB Schematic]]
 +
 
 +
 
 +
[[File:CmpE244_S17_SpheroDroid_PCBboard.PNG|center|600px|thumb|PCB layout]]
 +
 
 +
 
 +
 
 +
{|
 +
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_PCB.jpg|center|400px|thumb|PCB board with components]]
 +
|[[File:CmpE244_S17_SpheroDroid_PCBwithSJone.jpg|right|400px|thumb|PCB board connected to SJOne board]]
 +
|}
 +
 
 +
=== SD Card Writing ===
 +
The data from the GPS, temperature sensor, accelerometer and ultrasonic range finders is continuously being logged onto an SDCard. The purpose of this is to send the data to a remote location once the robot's exploration is complete. In our case, we are reading the data from the SDCard and sending it to a mobile application. The mobile application will receive the latitude and longitude values and will plot a path on a map connecting the geographical locations the robot has visited. Screenshots of the data being logged are shown in the following figures. It can be observed that different GPS locations are being logged onto the SDCard as the robot travels.
 +
 
 +
{|
 +
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_Data_written_in_text_file_GPS_Data1&2.png|300px|thumb|left|GPS Location 1 and 2 written to SDCard]]
 +
|
 +
|
 +
|
 +
||||||||||||||||||||||||||[[File:CmpE244_S17_SpheroDroid_Data_written_in_text_file_GPS_Data3&4.png|300px|thumb|right|GPS Location 3 and 4 written to SDCard]]
 +
|
 +
|
 +
|
 +
|}
 +
 
 +
=== Android Application ===
 +
The Android Application development was divided into multiple stages:
 +
 
 +
 
 +
1. Building the first App with interactive buttons
 +
   
 +
2. Communicating with Bluetooth module, hence tried and used many approaches.
 +
 
 +
3. Sending and Receiving data between Activities within Android App
 +
 
 +
4. Transmission and Reception of data from bluetooth device connected to SJ One board.
 +
 
 +
5. Plotting the data on Google Maps using google maps API.
 +
 
 +
 
 +
 
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidAppIcon.jpg|left|200px|thumb|Android App Icon]]
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidBluetoothTurnOn.png|left|200px|thumb|Permission to turn ON Bluetooth]]
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidBluetoothPairedDevices.png|left|200px|thumb|Android App connected to Bluetooth]]
 +
|}
 +
{|
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidStartButton.png|right|200px|thumb|Kick start off from the Android App]]
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidStartReceivedData.png|right|200px|thumb| GPS location values received from Sphero droid]]
 +
|[[File:CmpE244_S17_SpheroDroid_AndroidStartGPSlocationsonMap.png|200px|thumb|right|GPS location on Google Map]]
 +
|}
 +
 
 +
== '''Testing & Technical Challenges''' ==
 +
 
 +
1. '''Incorrect sensor values at different voltage levels''' - This was solved by providing stable IC output at 3.3V.
 +
 
 +
2. '''Unbalanced weight distribution and unstable platform''' - Because of unbalanced weight distribution, the sensors platform connected to the axle was unstable while running.
 +
This solved by changing the hardware positioning internally.
 +
 
 +
3. '''Abnormal restart of the microcontroller when motors begin''' - This was solved by providing sufficient power supply and running all modules on single voltage of 3.3V
 +
 
 +
4. '''Problem in steering the robot''' - This issue was solved by increasing the weight connected to the servo motor and the length of the pendulum.
 +
 
 +
5. '''Difficulty in finding the end of file while reading from the SD Card''' - A special character was used to while writing into the file to indicate the end of the file.
 +
 
 +
6. '''Unable to read corrupted SD card''' - On starting the robot, we first validate if the SD card is ready to communicate using sd_initialize(), and if not, then the robot will not respond to start from the application.
 +
 
 +
7. '''Initially, we had to dismantle the robot every time and remove the internal modules to restart the robot''' - We avoided this by using a volatile variable that is sent from the android application. The low priority task that runs will check if the variable has changed, and if changed then it will restart.
 +
 
 +
== '''Conclusion''' ==
 +
 
 +
We have successfully designed and implemented an autonomous spherical robot. This project has helped us understand the implementation of FreeRTOS concepts like prioritizing tasks and using semaphore and mutex for SD card reading and writing. We learned to implement our own communication protocol drivers such as UART and I2C. Even though the hardware implementation was tedious and challenges like unbalanced weight distribution and unstable platform took some time to resolve, it was all an overwhelming learning experience.
  
 
=== Project Video ===
 
=== Project Video ===
−
Upload a video of your project and post the link here.
+
 
 +
1. Final project video - https://youtu.be/8crZVj166tY
 +
 
 +
2. Sensor and motor testing - https://youtu.be/_Tye2R-DpHY
 +
 
 +
3. First Indoor run (checking mechanical structure) - https://youtu.be/JykHXq53Ipg
 +
 
 +
4. Steering of the robot using pendulum with the servo motor - https://youtu.be/N-BSanpUjbk
  
 
=== Project Source Code ===
 
=== Project Source Code ===
−
*  [https://sourceforge.net/projects/sjsu/files/CmpE_S2016/ Sourceforge Source Code Link]
 
  
−
== References ==
+
*  [https://github.com/SushmaNagaraj/Sphericalrobot/tree/Final_Master_branch/Final_Master_branch SpheroDroid Github Link]
−
=== Acknowledgement ===
+
 
−
Any acknowledgement that you may wish to provide can be included here.
+
== '''References''' ==
 +
=== '''Acknowledgement''' ===
  
−
=== References Used ===
+
We would like to thank Prof. Preetpal Kang for encouraging us and guiding us throughout the semester. We are grateful to you for making this class such a valuable learning experience for us. We would also like to thank the ISA members who have been there to help us and for being approachable anytime.
−
List any references used in project.
 
  
−
=== Appendix ===
+
=== '''References Used''' ===
−
You can list the references you used.
+
[1] CMPE 244 Lecture notes from Preetpal Kang, Computer Engineering, San Jose State University. Jan-May 2017.
 +
[2] [http://stackoverflow.com Android & Java Forums(www.stackoverflow.com)]
 +
[3] [https://developer.android.com/training/index.html Android References (Developer Android)]
 +
[4] [http://www.maxbotix.com/documents/LV-MaxSonar-EZ_Datasheet.pdf MaxSonar datasheet]
 +
[5] [http://www.gearbest.com/other-accessories/pp_227678.html?currency=USD&lkid=10133927&gclid=CLaiv83FmtACFRB0fgode7oD0g Bluetooth Module HC-05]
 +
[6] [http://www.gpsvisualizer.com GPS Visualizer]
 +
[7] [http://vcrossley.com/survey.pdf A literature review on the design of spherical rolling robots by V. Crossley]
 +
[8] [http://cdn.sparkfun.com/datasheets/Sensors/GPS/Venus/638/doc/Venus638FLPx_DS_v07.pdf Datasheet for the Venus GPS Module]

Latest revision as of 19:03, 11 July 2017


Sphero Droid

Abstract

Robots are revolutionizing almost every industry, primarily in the sectors where human safety is at risk. In hazardous working conditions such as in the mining industry, the lack of knowledge about the geographic nature and the environmental conditions of the mine hinder the rescue operations. Autonomous robots are being employed to improve the plight of mine workers and rescue operators. The robotic vehicle can explore the inaccessible and unworkable mines and disaster-affected areas and send valuable information to the teams to assist in search and rescue operations. But traditional robots could be rendered useless if they are overturned or in terrains having staircases and ledges. Also, there is a possibility of failure of the electrical and mechanical components exposed to the harsh environmental conditions. An autonomous spherical robot is a better option since its shape offers better robustness and rigidity. The spherical robot will enclose all the components within it and will not have any wheels or legs on its exterior. This feature enables it to operate in any hazardous conditions since there will be very less chance for the components to get damaged by the surrounding environment. The spherical design allows it to easily maneuver in different types of terrain, be it stairs or corners, and have no risk of being overturned. These advantages enable the robot for many applications such as exploration and mapping of access routes, surveillance and rescue operations in uncomfortable working conditions.

Objectives & Introduction

The objective of this project is to design an autonomous spherical robot with sensors, Global Positioning System (GPS) module, Bluetooth module and other control units interfaced to the microcontroller, which navigates its way exploring the path and avoiding obstacles. The temperature and the route followed by the robot can be logged on the SD card. These features enable the robot for many applications such as exploration and mapping of access routes, surveillance, and rescue operations in uncomfortable working conditions.

Sphero Droid front view
Sphero Droid side view
Sphero Droid Internal view

Team Members & Responsibilities

GPS interface with SJOne board via UART
  • Harshitha Bura
    • GPS and Temperature Sensor
    • SDCard
    • Wiki page reporting
    • Code integration[Gps and Sdcard card tasks]
  • Naveen Kumar Bhuthakatanahalli Ramalingaiah
    • SDCard
    • Bluetooth module and Android Aplication
    • Hardware design and implementation
    • Code integration[Andriod task integration with overall tasks integration]
  • Shivam Chauhan
    • PCB Designing
    • Servo Motor
    • Ultrasonic Range Finders
    • Hardware design and implementation
    • Code integration[Overall tasks integration]
  • Sushma Nagaraj
    • Servo Motor
    • Ultrasonic Range Finders
    • Wiki page reporting
    • Code integration[Servo,DC motor and Sensor tasks]
  • Virginia Menezes
    • DC Motors
    • Wiki page reporting
    • Code integration[Servo and DC motor tasks]

Schedule

Week# Start Date End Date Task Status Actual Completion Date
1 3/21 3/27
  • Requirement analysis and team discussion to order parts.
  • Determine individual tasks and assigning work based on different modules in project
 Done 3/29
2 3/28 4/3
  • Configure and interface the GPS module with the SJOne board
  • Configure and interface individual sensor with SJOne board
  • Interface motors with the SJOne board
  • Upload code on GitLab
 Done 4/9
3 4/9 4/18
  • Designing PCB
  • Team discussions to integrate the design and work on the algorithm
  • Continue work on individual module (Sensors, motors, GPS) working with SJOne board
 Done 4/21
4 4/18 4/25
  • Integrate the different modules
  • Build the sphere with bearings and enclose the components within it
 Done 4/28
5 4/25 5/2
  • Test in different environments and fix bugs based on different issues
  • Team discussion on extra features that can be implemented
 Done 5/7
6 5/2 5/9
  • Testing and Debugging
  • Work on extra features
  • Work on Project Report on Wiki
 Done 5/16
7 5/9 5/20
  • Testing and Debugging
  • Project Presentation and update Wiki
 Done 5/24
8 5/16 5/23
  • Complete Wiki Report and Final Demo
 Done 5/25

Parts List & Cost

Qty Description Manufacturer Part Number Cost Links
1 SJ One Board [1] Preet SJ-one $80 http://www.socialledge.com/sjsu/index.php?title=SJ_One_Board
2 DC Motor RobotShop Pololu 4.5V, 80rpm Right Angle Plastic Gear Motor $4.95 http://www.robotshop.com/en/pololu-80rpm-right-angle-plastic-gear-motor.html
1 Servo Motor Fry's electronics Metal Gear Digital Servo Part No. LS-0009AF $19.99 http://www.frys.com/product/7027281
1 Motor Driver Fry's electronics Motor Driver $9.99 http://www.frys.com/product/8353697
1 GPS Logger Spark fun Electronics Venus638FLPx $59.95 https://www.sparkfun.com/products/10920
1 Bluetooth Module Amazon.com HC-05 Bluetooth $8.49 https://www.amazon.com/dp/B01G9KSAF6?psc=1
3 Ultrasonic sensor Amazon.com LV Maxsonar -EZ MB1010 $74.85 https://www.amazon.com/Maxbotix-MB1010-LV-MaxSonar-EZ1-Range-Finder/dp/B00A7YGVJI
1 Antenna GPS Embedded SMA Spark fun Electronics VTorch Datasheet $11.95 https://www.sparkfun.com/products/177
1 PCB components Amazon.com (7805, 2 pin SPDT switch, 4004 diode, LD1117, Female pin header, male pin header, USB type B female jack, DC power jack, power supply module) $72.00 https://www.amazon.com/gp/product/B01LRXIJRY/ref=oh_aui_detailpage_o03_s02?ie=UTF8&psc=1
2 Wheels Amazon.com 70 x 8mm Black Robot Wheels $12.00 https://www.amazon.com/gp/product/B00T3MQDHU/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
2 Bearing Amazon.com 2 Pcs 22mm Outside Dia Plastic Coated Ball  $7.93 https://www.amazon.com/gp/product/B00HR5SJKE/ref=oh_aui_detailpage_o08_s01?ie=UTF8&psc=1
1 Hollow spherical ball Amazon.com Giant Chinchilla Run-About 11-1/2-Inch Exercise Ball $15.76 https://www.amazon.com/gp/product/B0006IK0LA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Design and Implementation

System Block diagram

The Sphero Droid contains ultrasonic, motors, GPS, Bluetooth as the main modules of communication. This is illustrated in the image below. The robot is controlled and navigated via a load which pulls it down and wheels which touch the ball from within. This will facilitate the ball movement.

Robot interface
Within the Robot

System State Diagram

The operation of SpheroDroid is divided into states as shown below. This mainly constitutes the start, operational and stop stages. The start is provided by Android application and the device moves forward. Different tasks will start when start condition is provided. The device will stop and when signalled from android application. The MCU will later send the GPS coordinate values which was written and restart when EOF is reached, moving to state one again.

State Diagram

Hardware Design

We have four distinct hardware modules used in this project:

  • Ultrasonic Range Finders (sensors)
  • Motors
  • GPS Module
  • Bluetooth Module

Ultrasonic Range Finders

Used MB1010 LV-MaxSonar-EZ21 Ultrasonic Rangefinder sonar sensors, which can from 6-inches to 254-inches, with 1-inch resolution. Any object from 0-inches to 6-inches is typically ranged as 6-inches. They are used in PW mode for outputting. For efficient working of sensors without any crosstalk, we have configured 3 sensors in the chaining mode called AN output commanded loop. This mode of configuration uses 5 pins of each sensor such as VCC = +5V, GND, TX, RX, and PWM. While triggering, the first sensor RX pin is held high for a time period > 20μs and < than 48ms.This will start the sensor chain. The first sensor will range, then trigger the second sensor to the range and so on for all the sensor in the array.

Mounting of the sensors is made on a curved platform such that the sensors are aimed with a positive slope and not horizontally. This decision is made in order to avoid interference with the ground due to the wide range of detection by the sensors.

MB1010 LV-MaxSonar-EZ21 Ultrasonic sensor
Sensor timing diagram
Sensor's mounting platform

Motors

  • DC Motors

The DC motors used in the project are 100 RPM low-cost single shaft straight geared motors. They are suitable for lightweight robots that do not require high power or torque.
The DC motors are connected to the wheels which are in contact with the base of the ball. The DC motors are driven by a driver module which controls the motor direction and speed.

Plastic geared motor
Driver module
Control inputs of driver module
  • Servo Motors

LS-0009AF Servo motor used is controlled by sending an electrical pulse of variable width or pulse width modulation (PWM), through the control wire. Maximum deflection which can be achieved by using this servo is 90°.The motor's neutral position is defined as the position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise direction. The PWM sent to the motor determines the position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor will turn to the desired position. The servo motor expects to see a pulse every 2000 microseconds and the length of the pulse will determine how far the motor turns. For example, a 1500microseconds pulse will make the motor turn to the 45° position. Shorter than 1500microseconds moves it in the counter-clockwise direction toward the 0° position, and any longer than 1500microseconds will turn the servo in a clockwise direction toward the 90° position.

Servo motor LS-0009AF
Servo motor dutycycle

The hardware implementation of how the DC motors are connected to the wheels which are driven from the SJOne board and how the servo motor is connected with the pendulum to steer the robot in right or left direction can be viewed in the figure below.

Internal Hardware connection (Motors)

GPS module

In the project, we use GPS module Sparkfun Venus638FLPx to log the current location of the robot. An antenna is connected to the SMA connector of the GPS module. The software Skytraq GPS viewer is used to configure it. The module is configured to send information in NMEA message format (using the GPGGA (Global Positioning System Fix Data). We configured it to run at a baud rate of 38400bps and update rate of 2 Hz.

GPS Module
Antenna for the GPS module
GPS Configuration Software

There are three modes of operation:

1. Hot Start: This enables the GPS to obtain a fix in a very less time if it is connected to a 3.3v coin cell battery and it is switched on again within two hours after switching it off. Connecting the battery will help it to store information about the previous fix.

2. Warm Start: In this mode, it will take the GPS more time to obtain a fix compared to the hot start as the module has been switched off for more than hours. But as the battery is connected and the information of the previous fix is available it will take less time compared to the cold start.

3. Cold Start: As the battery is not connected and information about the previous fix is not available in this mode, it will take a lot of time to obtain a fix.

In our project, we have connected a 3V external battery (VBAT) to the module so that it does not take a long time to get a satellite fix even after turning off and on.

The NMEA message looks as follows: 

 GGA - Global Positioning System Fix Data :   $GPGGA,hhmmss.sss,ddmm.mmmm,a1,dddmm.mmmm,a2,V,xx,x.x,x.x,M,,,,xxxx*hh<CR><LF>
 
 where,
       Time              - hhmmss.sss 
       Latitude          - ddmm.mmmm
       Direction         - (a1) - N or S 
       Longitude         - dddmm.mmmm
       Direction         - (a2) - E or W
       Validity          - V - 0 or 1. 0 means invalid and 1 means valid.

After this data is received by the SJOne board, string manipulation is done to extract the latitude and longitude from the string (if the data is valid) and they are converted to decimal minutes so that they can be sent to an android application where they are plotted on a map.

Bluetooth module

Bluetooth module HC-05 is used to communicate between the spherical robot and mobile application. It is implemented to establish the connection between the two so that we can remotely control the robot (to send start and stop signals) and receive the data from the robot directly on the Android application. The data being sent by the robot is current GPS location, ultrasonic range sensor values, and temperature sensor values.

Bluetooth module HC-05
HC-05 Pin connections

Hardware Interface

We have four major hardware modules interfaced with a single SJOne board using different communication protocols. For simplicity sake, we have given a description of how each module is individually interfaced with the SJOne board. In reality, all these modules are connected to a single SJOne microcontroller.

Ultrasonic Range Finders

The ultrasonic range finders have been interfaced with the SJOne board using PWM. To avoid the crosstalk between the sensors and to improve the efficiency, sensors are configured to work in chaining mode. In our project, the Right sensor is triggered first by holding the RX pin high for >20μs and < 48ms.This will start the sensor chain. The Right sensor will range, then trigger the Front sensor to the range which in turn trigger the last Left sensor.

Ultrasonic range finders interfacing with SJOne board via PWM
Sensor's chained triggering

Motors

The DC motor is connected with the SJOne board via the motor driver module using GPIO. The GPIO signals from SJOne board provide inputs to the motor driver module, which in turn drives the DC motors in forward or reverse direction or stop signal. Servo motor is interfaced with the SJOne board using PWM.

DC Motors and driver module connected to SJOne board using GPIO
Servo motors interface with SJOne board via PWM

GPS Module

GPS module communicates with SJOne board via UART. The antenna is connected to the SM connector of the GPS module. A 3.3v supply is given to the module and its Rx and Tx pins are connected to the Tx and Rx pins of the SJOne board respectively. UART 2 of the SJOne board is used for the GPS module and it is configured to run at a baud rate of 38400bps.

GPS interface with SJOne board via UART

Bluetooth module

The Bluetooth HC-05 module is connected with the SJOne board via UART communication.The bluetooth module communicates using the Tx and Rx pins of HC-05. This device independently connects to any external bluetooth master device. The HC-05 can work as a Master or a Slave. For our application the device sends the GPS data from SD card and also receive data from Android Application. Since the device can be connected independently without the MCU it can be connected and used with MCU restarting and not affecting the connectivity. UART3 is used for serial communication. The Baud rate set is 9600 for communication between bluetooth device and Android Application.


Bluetooth connection with SJOne via UART

Software Design

Ultrasonic Range Finder and Motors

The motors working depends on the input values of sensors (ultrasonic range finders). Depending on whether the sensors can detect an obstacle in its path, the motors continue to run in the forward direction or the servo motor steers the robot towards right or left. The diagrams below shows the algorithm of the logic behind it.

Sensors logic
DC and servo motor logic

GPS module

The GPS-SJOne board communication is done via UART. Whenever data is received by the SJOne board from the GPS module, a UART interrupt occurs and the data is stored in a buffer. The data is checked if it is valid or not. If it is valid, the latitude and longitude are written to the SDCard. Otherwise, it is written that no GPS signal was available at that point. The flowchart is shown below.


Software Flow for the GPS

PCB Design

We have used EAGLE software to design the PCB layout. The PCB layout is the most crucial part of the project, it may make or break the performance and working of the circuit. The first step towards designing the PCB is including all the required components into the schematic workspace and making connections between them. Once the schematic is ready, next step is to create the board layout from the schematic, which is easy, since EAGLE links the layout file and schematic together automatically.


PCB Schematic


PCB layout


PCB board with components
PCB board connected to SJOne board

SD Card Writing

The data from the GPS, temperature sensor, accelerometer and ultrasonic range finders is continuously being logged onto an SDCard. The purpose of this is to send the data to a remote location once the robot's exploration is complete. In our case, we are reading the data from the SDCard and sending it to a mobile application. The mobile application will receive the latitude and longitude values and will plot a path on a map connecting the geographical locations the robot has visited. Screenshots of the data being logged are shown in the following figures. It can be observed that different GPS locations are being logged onto the SDCard as the robot travels.

GPS Location 1 and 2 written to SDCard
GPS Location 3 and 4 written to SDCard

Android Application

The Android Application development was divided into multiple stages:


1. Building the first App with interactive buttons

2. Communicating with Bluetooth module, hence tried and used many approaches.

3. Sending and Receiving data between Activities within Android App

4. Transmission and Reception of data from bluetooth device connected to SJ One board.

5. Plotting the data on Google Maps using google maps API.


Android App Icon
Permission to turn ON Bluetooth
Android App connected to Bluetooth
Kick start off from the Android App
GPS location values received from Sphero droid
GPS location on Google Map

Testing & Technical Challenges

1. Incorrect sensor values at different voltage levels - This was solved by providing stable IC output at 3.3V.

2. Unbalanced weight distribution and unstable platform - Because of unbalanced weight distribution, the sensors platform connected to the axle was unstable while running. This solved by changing the hardware positioning internally.

3. Abnormal restart of the microcontroller when motors begin - This was solved by providing sufficient power supply and running all modules on single voltage of 3.3V

4. Problem in steering the robot - This issue was solved by increasing the weight connected to the servo motor and the length of the pendulum.

5. Difficulty in finding the end of file while reading from the SD Card - A special character was used to while writing into the file to indicate the end of the file.

6. Unable to read corrupted SD card - On starting the robot, we first validate if the SD card is ready to communicate using sd_initialize(), and if not, then the robot will not respond to start from the application.

7. Initially, we had to dismantle the robot every time and remove the internal modules to restart the robot - We avoided this by using a volatile variable that is sent from the android application. The low priority task that runs will check if the variable has changed, and if changed then it will restart.

Conclusion

We have successfully designed and implemented an autonomous spherical robot. This project has helped us understand the implementation of FreeRTOS concepts like prioritizing tasks and using semaphore and mutex for SD card reading and writing. We learned to implement our own communication protocol drivers such as UART and I2C. Even though the hardware implementation was tedious and challenges like unbalanced weight distribution and unstable platform took some time to resolve, it was all an overwhelming learning experience.

Project Video

1. Final project video - https://youtu.be/8crZVj166tY

2. Sensor and motor testing - https://youtu.be/_Tye2R-DpHY

3. First Indoor run (checking mechanical structure) - https://youtu.be/JykHXq53Ipg

4. Steering of the robot using pendulum with the servo motor - https://youtu.be/N-BSanpUjbk

Project Source Code

References

Acknowledgement

We would like to thank Prof. Preetpal Kang for encouraging us and guiding us throughout the semester. We are grateful to you for making this class such a valuable learning experience for us. We would also like to thank the ISA members who have been there to help us and for being approachable anytime.

References Used

[1] CMPE 244 Lecture notes from Preetpal Kang, Computer Engineering, San Jose State University. Jan-May 2017.
[2] Android & Java Forums(www.stackoverflow.com)
[3] Android References (Developer Android)
[4] MaxSonar datasheet
[5] Bluetooth Module HC-05
[6] GPS Visualizer
[7] A literature review on the design of spherical rolling robots by V. Crossley
[8] Datasheet for the Venus GPS Module

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