Embedded Microcomputer SystemsAndrew Karpenko

1

Prepared for

Technical PresentationFebruary 25th, 2011

A.R.Drone by Parrot

• A helicopter with four rotors

• Internally stabilized

• Controlled by any device with WiFi

• Originally designed as a game accessory for the Apple iPhone and iPod touch platforms

• On-board computer vision• Front and down facing cameras

for video streaming and object detection

• Down facing ultrasonic distance telemeter

• 6 Degree Of Freedom inertial measurement unit

• 4 ARM7 Microprocessors• 1 ARM9 Microprocessor

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Augmented Reality Drone

Make Platform

• Make Controller Kit• ARM7 Microprocessor• Ethernet• USB• 8 Analog Inputs• 8 Digital Inputs/Outputs• 4 LEDs

• ARM7 Microprocessor• 48MHz• 256KB Memory

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Development Board

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KeypadLCD

Speaker

Motor

Bread Board

Make Controller

Kit

Custom development platform designed by Department of Electrical Engineering at UW.

ProjectsCompleted over a 10 week period in groups of two and four:

• Lab 1• Introduction

• Lab 2• Scheduling, Input/Output

• Lab 3• FreeRTOS, PWM and Drone

Control

• Lab 4• Manual and Autonomous

Drone Control

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Lab 1 - Introduction

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• Learn the basics of the Make Controller and the Development BoardController

• Review and get familiar with the C programming languageC

• Flash Light Emitting Diodes at different frequenciesLEDs

• Display a message on the Liquid Crystal DisplayLCD

Lab 2 – Scheduling, Input/Output

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• Create a simple Operating System for handling multiple tasks

• Build a scheduler that runs tasks in a given time frame

OS

• Read values from an analog sensor• Write to and Read from digital Input/Output pinsI/O

• Drive a motor using pulses• Vary the motor speed using values gathered from

the analog sensorsMotor

• Output motor speed and sensor values on the displayLCD

Lab 3 – FreeRTOS, PWM and Drone Control

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• Transition to the FreeRTOS embedded Real Time Operating System that guarantees executed code will meet deadlinesRTOS

• Implement Pulse Width Modulation to drive the motor based on sensor inputPWM

• Implement an Interrupt Service Routine to measure the revolutions of the motor using a speed encoderISR

• Read values from the keypad• Generate drone commands based on keypad input• Fly the AR.Drone by sending commands to it

Control

Lab 4 – Manual and Autonomous Control

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• Manually control the drone to navigate a physical obstacle course

ManualControl

• Use a Wii Classic Controller as the control interface for the droneController

• Create an algorithm that will autonomously navigate the drone in a predefined path

AutonomousControl

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Quadrotor OperationManual Control

Front

Spin Directions Roll(Left and Right)

Pitch(Forward and Back)

Yaw(Rotation)

front

back

left

right

front

back

left

right

front

back

left

right

front

back

left

right

CommunicationManual Control

• Drone acts as a Router

• 3 Port UDP Communication• 5556: Commands to the drone

• 5555: Video feeds from drone

• 5554: Navigation data from the drone

• Different devices can connect to different ports

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Ethernet

WiF

i

CommandsManual Control

• Send directional commands• Forward/Back

• Left/Right

• Rotate

• Up/Down

• Send all parameters in one command• Back while rotating and

ascending

• Control motor speeds directly (Dangerous)

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Forward

ControllerManual Control

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Wii Classic Controller Pro

Forw

ard

Up

Left/RightRotate

Back

Dow

n

Takeoff

Land

ChangeCamera

• Requires implementing the I2C (Inter-Integrated Circuit) bus

Computer VisionAutonomous Control

• Drone can detect 2D tags and other drones• Up to 4 tags

• Can tell them apart

• Estimates distance to tags

• Detection works based on color pattern of outdoor hull, or stickers for the indoor hull

• Used for Augmented Reality games on the iPhone and iPod touch platforms

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A. Color pattern on outdoor hull

B. Stickers on indoor hull

PathAutonomous Control

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A

B

Target

Target1 m height

2 m height

1 m height

Points are awarded based on how close the drone is to the starting point at the end of the flight

4m x 4m envelope

H Start

End

Our ApproachAutonomous Control

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• Computer Vision• Position Estimation• Closed Loop Control• …?

Summary• A.R. Drone by Parrot

• Make Platform

• Development Board

• Projects 1 - 3• Lab 1 – Introduction

• Lab 2 – Scheduling, Input/Output

• Lab 3 – FreeRTOS, PWM and Drone Control

• Project 4 – Manual and Autonomous Drone Control• Manual Control

• Quadrotor Operation

• Communication

• Commands

• Controller

• Autonomous Control• Computer Vision

• Path

• Our Approach

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Embedded Microcomputer Systems

Andrew KarpenkoUniversity of WashingtonSeattle

18

Prepared for

ELP Onsite Visit Technical PresentationFebruary 25th, 2011

All images are property of their respected owners.The following images were obtained online:

• http://makezine.com/images/06/intefacecontroller1.jpg• http://images.bit-tech.net/content_images/2010/07/parrot-ar-drone-review/AR.Drone-06-

b.jpg• http://www.uncrate.com/men/images/2010/01/wii-classic-controller-pro-xl.jpg• http://www.prepaid-wireless-guide.com/images/wifi-router.jpg• http://media.digikey.com/photos/NXP%20Semi%20Photos/568-64-LQFP,SOT314-2.jpg• http://www.makingthings.com/store/media/catalog/product/cache/1/image/5e06319eda0

6f020e43594a9c230972d/k/i/kit20_askew.jpg

• http://cheesycam.com/wp-content/uploads/2010/10/ar-drone-parrot-quadricopter.JPG• http://lasarobotics.org/downloads/Association/Fundraising/sponsor-supporter_logos/NI%2

0Logo_large2.JPG

Any other images found herein have been personally taken by Andrew Karpenko.