autonomous robotic boat platform - bradley university

Autonomous Robotic Boat Platform

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

February 24th, 2015

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

Department of Electrical and

Computer Engineering

Presentation outline

• Background– Objective

– Block diagram

– Division of labor

• R. Burke– GPS/compass finalization and navigation system

• L. Cramer– Detecting buoys with computer vision

• N. Dupes– Motor controller

• D. McDannald– Central processor

– Block diagram

Objective

• Design and build an autonomous boat platform

– Versatile

– Robust

• 8th annual RoboBoat competition

(Virginia Beach, VA)

• Competition time frame: July

4Images taken from [1].

Catamaran Boat Design

5Image taken from [1].

Division of labor

Task Person assigned to task

Central processing Darren McDannald

Image processing Leah Cramer

GPS/compass interfacing Ryan Burke

Motor control Noah Dupes

Remote control Darren McDannald

Navigation Ryan Burke, Darren McDannald

– Block diagram

Gantt chart

GPS/compass unit block diagram

Acknowledge message GPS initialization

MCU GPS

Change baud rate to 115.2 kbaud

Acknowledge message GPS initialization

MCU GPSBaud rate changed successfully

GPS and compass data testing

GPS dataCompass data

Longitude Latitude

Standard deviation 2.48E-06 1.28E-05 0.2223

Variance 6.15E-12 1.65E-10 0.0494

Number of samples 202 202 226

Average value -89.6185 40.6981 181.4

Actual value -89.6184 40.6979 180

Navigation system operation

Progress

– Block diagram

35Amazon.com Bit-tech.net Willowgarage.comImages from:

Image from: http://www.auvsifoundation.org

Competition obstacles

Buoy identification flowchart with circle detection

Circle detection buoy identification results

Hough transform Percentage of frames

True positive (buoy detected) 80%

False positive (incorrect buoy detected) 13.5%

False negative (buoy not detected) 6.5%

Buoy identification flowchart with blob detection

Blob detection with buoy identification results

Blob detection Percentage of frames

True positive (buoy detected) 33%

False positive (incorrect buoy detected) 62%

False negative (buoy not detected) 5%

Project task progress

– Block diagram

T100 thruster

• Brushless DC (BLDC)

• Provides 2.36 kgf ( 5.2 lbf ) of forward thrust

• Sensorless

T100 thruster size comparison

obtained from[1]

A4960 pre-driver configuration

The Allegro pre-driver

A4960 motor controller with

MCU input. Image obtained

and modified from[5]

Pre-Driver

A4960 pre-driver configuration

The Allegro pre-driver

A4960 motor controller with

MCU input. Image obtained

and modified from[5]

Pre-Driver

Digital commutation for a brushless motor

• Utilize a three phase configuration

Figure 1: Y-configuration of a three phase

motor obtained from[2]

Figure 2: Three phase digital commutation obtained

from[3]

High Side

Low Side

High Side

Low Side

0 60 120 180 240 300 360 0 60

High Side

Low Side

Rotor Position(°)

MOSFET driver configuration

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

L-A L-B

H-B H-C

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

High-Side Current Path

Low-Side Current Path

Current path for the driver configuration

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

L-A L-B

H-B H-C

L-A L-B

H-B H-C

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

L-A L-B

H-B H-C

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

Coil Measuring BEMF

Legend

H- High Side Driver

L- Low Side Driver

A- A Phase

B- B Phase

C- C phase

L-A L-B

H-B H-C

Utilizing back electro-magnetic force (BEMF)

• Measured at common terminal, S, between the high

and low side MOSFETS

• Used to determine the rotor position and speed of

the BLDC motor

• A4960 outputs a frequency varying TACHO signal

proportional to the rotors speed

Latest progression of Gantt

Schedule Time Completed Milestone

ID Task nameDec Jan

Motor controller

circuit design and

testing

Assembly of motor

configuration on boat

Research motor

controller and

configuration

4 Progress presentation

Feb Mar

1 Continue designing and building the A4960 motor controller configuration

Expected delivery of T100: January 2015

Research and design the controls algorithm for the diamond thruster configuration

-ndupes,

– Block diagram

Serial communication

• A C++ class to access a subsystem

through serial

• Sets attributes and can have

multiple instances of each

connection

• Able to request and receive data

Project filing system

• Easy compilation using a make

• Saves time by only compiling

when items have been changed

• Related files in single folder

Boat trial script

• A C++ class takes care of the

naming of each frame

• Script makes video automatically

at the end of each run

• Compresses the runs folder

• Script asks for a description of

the surroundings to help testing

Used TinyXML to configure boat

• Use of xml files to make to boat

easily configurable and on the fly

• Used to keep compilation times

GPS class

• Request data from GPS and

compass data

• Store the data

• Path planning

• Motor and speed commands

• Data will be used to navigate

between one location to another

Motor class

• Takes in a speed, direction, and

amount of pivot

• Outputs a string that

corresponds to the four motors

on the boat

calculate(speed, direction, pivot);

Converts direction and pivot to a

vector for each motor

Outputs string over serial

*m1: 120 m2: 35 m3: 25 m4: 25

Schedule

Future Work

• Currently working on a

navigation system

• Finish making the motor class

and test its operation

• Implement an accurate time base

• Threading to process the

different systems

Autonomous Robotic Boat Platform

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

February 24th, 2015

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

Department of Electrical and

Computer Engineering

Appendix

Motor Configuration Selection

• Diamond configuration

• Consists of four motors

• Allows for strafing

• Allows for 360 rotaon

Diamond configuration on a catamaran platform

Transistor Configuration For Three Phase Drive

Three phase drive circuit consisting of six transistors, six flyback diodes,

and a y-configuration three phase motor obtained from[4]

Power Consumption Of Transistors

Type MOSFET BJT IGBT

Power consumption

calculation

Typical values

Power consumption of a

11.5 A drive using typical

transistor values

References

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

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

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

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

[5] 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

[6] St. Cyprain’s Greek Orthodox Primary Academy. (2014). 29.9.14 [Online]. Available: http://www.stcypriansprimaryacademy.co.uk/29-9-14/

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

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

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[6]73

MATLAB Imcontour()-Contour Detection

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

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

L298 H-Bridge Internal Configuration

Image obtained from[7]77

H-Bridge Free Running Motor Stop

H-Bridge Dynamic Motor Stop

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

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

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.

Block Diagram For System

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[8]

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

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)

Three Phase Back EMF Output

Image obtained from [5]88

IRF520 Circuit Configuration

Circuit 1:Motor Drive IRF520

Configuration

Circuit 2:IRF520 Test

Configuration

Circuit Design for the Transistor Switch Configuration

[source: wikipedia]

http://en.wikipedia.org/wiki/Hough_transform

[source: wikipedia]

21HT Hough Transform Method

• Reduces the amount of memory required.

• Uses edge direction

• Two step process

1.) 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

OpenCV Results using:

• RGB Colorspace

• Gaussian Filtering

• Canny Edge Detection

• Hough Transform

autonomous robotic boat platform - bradley university

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