autonomous robotic boat platform - bradley...

Autonomous Robotic Boat Platform

Team: Ryan Burke, Leah Cramer, Noah Dupes, & Darren McDannald

November 20th, 2014

Advisors: Mr. Nick Schmidt, Dr. José Sánchez, & Dr. Gary Dempsey

Department of Electrical and

Computer Engineering

1

Presentation Outline

• Background– Objective– Block Diagram– Division of Labor

• L. Cramer– Circle Detection

• R. Burke– GPS/Compass/MCU Interfacing

• D. McDannald– Central Processing and Remote Control

• N. Dupes– Motor Control

2


3






Objective

• Design and build an autonomous boat platform– Versatile

– Robust

• 8th annual RoboBoat competition

(Virginia Beach, VA)

• Competition time frame: June – July

4Images taken from [1].

Catamaran Boat Design

5Image taken from [1].

Division of Labor

7

Task Person(s) Assigned to Task

Central Processing Darren

Image Processing Leah, Noah

GPS/Compass Interfacing Ryan

Motor Control Noah, Ryan

Remote Control Darren


8






9

C++

Images taken from [2], [3], [4].

10

Competition Snapshots

Images taken from [1].

Circle Detection

11

Simple Background Test Image Complex Background Test Image

Impact of Color Space on Hough Transform

12

XYZ Colorspace RGB Colorspace L*a*b Colorspace

Impact of Edge Detection on Hough Transform

Original Image

13

Results of Canny edge detection and Hough Transform

Impact of Edge Detection on Hough Transform

Results of Sobel edge detection and Hough Transform

14

Impact of Gaussian Filtering on Hough Transform

Results of Sobel edge detection and Hough Transform

16

Circle Detection with OpenCV

Original Image

Processed Image

Experimental OpenCV Results

17

Circle detection results using OpenCV.

Project Task Progress

18

Gantt Chart


19






Gantt Chart Revisions

20

GPS/Compass Unit Block Diagram

21

Processor Interface

22

RS-232 Serial CommunicationFrame format & baud rate:

• 8 data bits

• No parity bit

• 1 stop bit

• 9600 baud

Serial message received after transmitting “a”

23

Compass/Processor Interface

24

Compass Data Collection

Compass readings:

• Values 0 – 3600

• Represent 0.0° – 360.0°

Serial stream containing compass bearings

25

Preliminary GPS Interface

26

Raw GPS Output

GPS readings:

• Six serial data packets

• Transmission every second

• Transmission at 9600 baud

Serial stream directly from GPS sensor

27

Verification of GPS Data

28

GPS/Processor Interface

29

Initialized GPS Output

Initialized GPS readings:

• Single data packet

• 10 Hz transmission

• 115.2 kbaud

Serial stream containing GLL (Geographic Latitude and Longitude) data

30

Compass/GPS/Processor Interface

31

Parsed GPS Data

Parsed NMEA sentence:

• Extracted longitude & latitude data

– Degrees (±)

– Minutes

– Decimal minutes

Serial stream containing GLL and parsed longitude and latitude data

32

Final GPS/Compass Unit Output

Processor message:

• Longitude

• Latitude

• Bearing

Baud Rate:

• 115.2 kbaud

33

Serial stream containing bearing and parsed longitude and latitude data

Progress

34


35



• R. Burke– GPS/Compass/µC Interfacing



Schedule changes

Proposed Gantt Chart

Changes to the Gantt Chart

36

RC Subsystem Block Diagram

37

Futaba T6EX and the R617FS

• 2 joy sticks

• 2 switches

• 2.4 Ghz

38Image taken from [5,6].

How the Remote Works

• X and Y potentiometer for each joystick

• Each potentiometer maps to a channels 1 – 4 respectively

• Two switches maps to channel

5 – 6


Design Approach

• Measure pulse widths using a MCU

• Decide if you send data from the central processor or the RC unit

• Convert pulse widths into motor commands

Output of the RC Receiver Channels 1-4

2.5 ms/devV

olt

age

40

Time calculation

• Fclk_I/0 = 16 Mhz

• N = 256

• Top = 249

• 4 ms to overflow

• Each time step is 16 µs

41

Results

• For the joysticks the neutral position

• Switch 1 is in the on position

• Min = 63 (1 ms)

• Neutral = 94 (1.5 ms)

• Max = 125 (2 ms)

Channels 1 – 4 are the 2 joysticks channel 5 is the kill switch

42

Deciding on an OS for the Central Processor

• Ubuntu 14.04 release

• Open-Source

• ROS support


Serial Communication Between the Central Processor and Various Subsystems

• A C++ class to access a subsystem

• Sets attributes and have multiple instances of each connection

• Able to request and receive data


Camera Driver and Installation of OpenCV on Our Linux Machine

• Installed Camera under the UVC driver

• Ubuntu has a script to install OpenCV

45Image taken from [2,4].

Completion of Tasks

46


47



• R. Burke– GPS/Compass/µC Interfacing



Motor Configuration Selection

• Diamond configuration

– Consists of four motors

– Allows for strafing

– Allows for 360 rotation

Diamond configuration on a catamaran platform

48

Thruster Selection-T100

• Created by Blue Robotics

• Brushless DC (BLDC)

• Sensorless

• Provides 2.36 kgf ( 5.2 lbf )

of forward thrust

• 11.5 A max current

• Weighs 295 g ( 0.65 lbs )

• Costs $110 (budget of $1500) T100 Thruster Size Comparison


Brushless Motors

• Utilize a three phase configuration

Figure 1: Y-configuration of a three phase motor

Figure 2: Three phase digital commutation

50Images taken from [12], [13].

Transistor Configuration For Three Phase Drive

Three phase drive circuit consisting of six transistors, six flyback diodes, and a y-configuration three phase motor


Power Consumption Of Transistors

Type MOSFET BJT IGBT

Power consumption calculation

𝐼𝐷2 × 𝑅𝐷𝑆 𝑉𝐶𝐸(𝑆𝑎𝑡) × 𝐼𝐶 + 𝑉𝐵𝐸(𝑆𝑎𝑡) × 𝐼𝐵 𝑉𝐶𝐸(𝑆𝑎𝑡) × 𝐼𝐶

Typical values 𝑅𝐷𝑆 = 10 𝑚Ω 𝑉𝐶𝐸(𝑠𝑎𝑡) = 2 𝑉

𝑉𝐵𝐸(𝑠𝑎𝑡) = 1.3 𝑉

𝐻𝑓𝑒 = 10

𝑉𝐶𝐸(𝑆𝑎𝑡) = 1.8 𝑉

Power consumption of a 11.5 A drive using typical transistor values

11.52 𝐴 × 10 𝑚Ω=

1.15 𝑊

2 𝑉 × 11.5 𝐴 + 1.3 𝑉 × 1.15 𝐴=

24.5 𝑊

1.8 𝑉 × 11.5 𝐴=

20.7 𝑊

52

Selection of a Three Phase Commutation Driver

• Pre-driver

• Sensorless

• Input complexity

• Output characteristics


Selection of the A4960 by Allegro

The Allegro pre-driver A4960 motor controller attached to a six FET BLDC motor drive configuration. Image obtained from



The Allegro pre-driver A4960 motor controller with MCU input


Latest Progression of Gantt

57

Autonomous Robotic Boat Platform

Team: Ryan Burke, Leah Cramer, Noah Dupes, & Darren McDannald

November 20th, 2014

Advisors: Mr. Nick Schmidt, Dr. José Sánchez, & Dr. Gary Dempsey

Department of Electrical and

Computer Engineering

58

APPENDIX

59

60

[source: wikipedia]http://en.wikipedia.org/wiki/Hough_transform

𝑦 = −𝑐𝑜𝑠𝜃

𝑠𝑖𝑛𝜃𝑥 +

𝑟

𝑠𝑖𝑛𝜃

𝑟 = 𝑥𝑐𝑜𝑠𝜃 + 𝑦𝑠𝑖𝑛𝜃

61


62


63

𝑥 = 𝑎 + 𝑟𝑐𝑜𝑠𝜃

𝑦 = 𝑏 + 𝑟𝑠𝑖𝑛𝜃

65

21HT Hough Transform Method• Reduces the amount of memory required.• Uses edge direction • Two step process1.) The center of any given circle is the intersection point of all the normal lines from the circle edge. A 2-dimensional array is used to record the "votes" along the normal line of each detected edge point.2.) "To identify the radius of circles, the distance of each point from a candidate center is calculated and a radius histogram is produced."

PROS: This method is low on storage space. Only a 2-d array is used and a 1-d histogram.CONS: If the radius threshold is very low (i.e. The 21HT is being used to detect very small circles) there is a risk of many false peaks occurring in step 1. This can increase the amount of computational work necessary in step 2.

Gaussian Filtering

66

𝐺 𝑥, 𝑦 =1

2𝜋𝜎2𝑒−𝑥2+𝑦2

2𝜎2

67

OpenCV Results using:• RGB Colorspace• Gaussian Filtering• Canny Edge Detection• Hough Transform

GPS/Compass Unit Block Diagram

68

GPS/Compass Unit Flow Chart

69

Software flowchartMain ISR(INT0) ISR(INT1) ISR(PCINT)

IDX > 5Mode

Kill Switch

Decode pulse

widths

Encode Motor

Commands

Output Data

Read Data From

Central Processor

Index = 0

Record time

State

Record time

Record Time

Calculate Pulse Width

Index++

Record Time

70

Analysis Approach

• I started by looking at P.W.M. signals

• Decided on how to measure them

• Compared measured to actual

71

Image Processing-Rectangle Detection

• Purpose of Research and Testing: Determine How to Detect Polygons Contained within an Image

• Research– OpenCV Utilizes Contours For Detection Of Polygons

• Contours: Outline or Enclosed Border of a Shape or Form

• The Contour Detection Algorithm Used By OpenCV:

Topological Structural Analysis of Digitized Binary Images by Border Following by Satoshi Suzuki and Keiichi Abe[]

• MATLAB Testing– Imcontour() Implementation

– Contour Algorithm Testing72

MATLAB Imcontour()-Original Image

Image obtained from[16]73

MATLAB Imcontour()-Contour Detection

100 200 300 400 500 600 700 800 900

150

200

250

300

350

400

450

500

550

600

74

H-Bridges

• Purpose of Research and Testing:

Understand the Benefits and Drawbacks of Using H-Bridges

• Features

– Bi-Directional Motor Control

– Four Transistor Configuration

– Provides Dynamic Breaking Capabilities

– Allows For Current Sensing

75

H-Bridge Testing

• L298 H-Bridge

– Contains Two Internal H-Bridge Configurations

– Two Enable Signals

– Allows for a 150w motor(50v, 3A Max Rating)

• Fly Back Diode: 1N4004

• Motor

– 12V

– >2A While In Air

76

L298 H-Bridge Internal Configuration

Image obtained from[17]77

H-Bridge Free Running Motor Stop

78

H-Bridge Dynamic Motor Stop

79

H-Bridge Conclusion

• Benefits:– Simple Configuration

– Easily Controllable

– Provides Bi-Directional Control

• Drawbacks:– Large Power Dissipation

• The Internal BJT Configuration Has Constant Power Dissipation

– Limits Design

80

Choosing A Transistor Type

• There Are Two Primary Transistor Types: MOSFET and BJT

MOSFET BJT

Output Is Controlled By Gate Voltage Output Is Controlled By Base Current

Positive Temperature Coefficients Negative Temperature Coefficients

Power Dissipation Depends On Internal Resistance

Power Dissipation Depends Terminal Voltage Differentials

High Gate Capacitance Low Gate Capacitance

Higher Switching Frequencies Lower Switching Frequencies

81

Choosing A MOSFET

• IPP040N06N – RDS max=4 mΩ

– VDS max=60 V

– ID max= 80 A

– QG max= 44nC

• IPP060N06N – RDS max=6 mΩ

– VDS max=60 V

– ID max= 40 A

– QG max= 32nC

• IRLB8721PbF– RDS max=8.7 mΩ

– VDS max=30 V

– ID max= 44 A

– QG max= 13nC

• IRLB8748PbF * *– RDS max=4.8 mΩ

– VDS max=30 V

– ID max= 44 A

– QG max= 23nC

* * Indicates the current choice for the MOSFET configuration 82

PWM Driven Transistor Configuration

• Purpose of Research and Testing :

Design a Transistor Switch Configuration Driven by a Microcontroller Generated PWM Controlled by an Analog Input.

83

Block Diagram For System

MCU Load

Power

Joystick PWM On/OffTransistor

Configuration

84

Design And Testing

• IRF520

– VDS Max = 100V

– RDS(ON) Max = 0.27 Ω

– Max Gate Charge = 16 nC

• Atmega168 Microcontroller• Minimum Pin Output Voltage = 4.2V

• Maximum Pin Output Current = 40mA

• 2N2222A• Hfe(Gain) = 75

• Max VCE(Sat) = 1.6V

• Max VBE(Sat) = 2.6V

Output Characteristics of the IRF520 obtained from[18]

85

Observations of the Gate Input for the IRF520

Gate input with Rc equal to 1.2KΩ Gate input with Rc equal to 10KΩ Gate input with Rc equal to 100KΩ

86

A4960 Specs

• Absolute Ratings

– Max Load Supply Voltage: 50 V

– Max Logic Supply Voltage: 6 V

– Max Sink Current: 150 mA

– Max Gate Output Turn on/off: 20 ns

– Max System Clock Period: 57 ns (17.5 MHz)

– Minimum Input Pulse Filter Time: 500 us (2 KHz)

87

Three Phase Back EMF Output

Image obtained from [15]88

IRF520 Circuit Configuration

Circuit 1:Motor Drive IRF520 Configuration

Circuit 2:IRF520 Test Configuration

89

Circuit Design for the Transistor Switch Configuration

90

References

[1] AUVSI Foundation. (2014). RoboBoat – Foundation [Online]. Available: http://www.auvsifoundation.org/foundation/competitions/roboboat/

[2] Amazon. (2014). HP Deluxe Webcam [Online]. Available: http://www.amazon.com/HP-KQ246AA-8-0-Deluxe-Webcam/dp/B001D8AGA2

[3] Comtrade Computers. (2014). CPU Intel i3 [Online]. Available: http://www.comtrade-ks.com/product.php?product_id=7591/

[4] Wikimedia. (2014). OpenCV logo with text [Online]. Available: http://commons.wikimedia.org/wiki/File:OpenCV_Logo_with_text_svg_version.svg

[5]RC Radical. (2012) Fubata T6EX 2,4 GHZ [Online] Available: http://www.rcradical.com/en/futaba/925-futaba-t6ex-24ghz.html

[6]rctecnic. (2012) Receptor Futaba R617FS 7 canales 2.4GHz FASST [Online] Available: http://www.rctecnic.com/receptores/2905-receptor-futaba-r617fs-7-canales-24ghz-fasst.html

[7]Berkley. (2014) ME102 Lab 4: RC Servo [Online] Available: http://www.me.berkeley.edu/ME102B/lab4.html

[8]JcoPro. (2014) Ubuntu logo [Online] Available: http://www.jcopro.net/2011/12/19/crashed-hdd-disk-ubuntu-to-the-rescue-day3-first-impressions/ubuntu-logo1/

[9]Honmann Designs.(2014) DB9 Female to Male Serial Cable [Online] Available: http://www.homanndesigns.com/store/index.php?main_page=product_info&cPath=11&products_id=26

91

References cont.

[10] Blue Robotics. (2014). T100 Thruster [Online]. Available: http://www.bluerobotics.com/store/thrusters/t100-thruster/

[11] Global Spec. (2011). Synchronous Motor Grounding [Online]. Available: http://cr4.globalspec.com/thread/67306

[12] Embedded. (2008). Designing a MCU-driver permanent magnet BLDC motor controller: Part 1 [Online]. Available: http://www.embedded.com/print/4007628

[13] Analog Dialogue. (2008). High Current Sensing [Online]. Available: http://www.analog.com/library/analogdialogue/archives/42-01/high_side_current_sensing.html

[14] Allegro MicroSystems. (2014). A4933: Automotive 3-Phase MOSFET Driver [Online]. Available: http://www.allegromicro.com/en/Products/Motor-Driver-And-Interface-ICs/Brushless-DC-Motor-Drivers/A4933.aspx

[15] St. Cyprain’s Greek Orthodox Primary Academy. (2014). 29.9.14 [Online]. Available:

http://www.stcypriansprimaryacademy.co.uk/29-9-14/

[16] SparkFun Electronics. (2014). Dual Full-Bridge Driver [Online]. Available: https://www.sparkfun.com/datasheets/Robotics/L298_H_Bridge.pdf

[17] Vishay. (2011). IRF520 Power MOSFET [Online]. Available: http://www.vishay.com/docs/91017/91017.pdf

92

autonomous robotic boat platform - bradley...

Documents