Introducing the Quadrotor Introducing the Quadrotor Flying Robot - - PowerPoint PPT Presentation

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Introducing the Quadrotor Introducing the Quadrotor Flying Robot - - PowerPoint PPT Presentation

Aug 18, 2022 121 likes •324 views

Introducing the Quadrotor Introducing the Quadrotor Flying Robot Flying Robot Roy Brewer Organizer Phila ilade delph lphia ia Robo Robotic ics s Meet etup up Group up Phila ilade delph lphia ia Robo Robotic ics s Meet etup

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SLIDE 1

Introducing the Quadrotor Introducing the Quadrotor Flying Robot Flying Robot

Roy Brewer Organizer Phila ilade delph lphia ia Robo Robotic ics s Meet etup up Group up Phila ilade delph lphia ia Robo Robotic ics s Meet etup up Group up August 13, 2009

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13 Aug 09 2

  • R. Brewer - Philly Meetup Quadrotor

What is a Quadrotor?

  • A vehicle having 4 rotors

(propellers) at each end of a square cross

  • Typically remote controlled;

can be autonomous or semi- autonomous

  • Home built, research, and

professional versions exist

  • Typically built using r/c

components, electric motors, microprocessors, servos, sensors, batteries

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13 Aug 09 3

  • R. Brewer - Philly Meetup Quadrotor

What is a Quadrotor Used For?

  • Fun radio controlled “toy”
  • Aerial Photography / Video
  • Surveillance
  • Robotics and/or Control Systems Research
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  • R. Brewer - Philly Meetup Quadrotor

How Does a Quadrotor Fly?

  • Rotor thrust and torque proportional

to rotor speed squared

  • 2 sets of counter rotating blades.
  • Torque inherently balanced
  • 4 inputs allow independent

actuation of pitch, roll, yaw and thrust

Controlling Roll/Pitch Controlling Roll/Pitch Controlling Altitude Controlling Altitude Controlling Yaw Controlling Yaw

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13 Aug 09 5

  • R. Brewer - Philly Meetup Quadrotor

How to Obtain a Quadrotor?

  • Buy

– http://www.asctec.de – http://www.microdrones.com – http://www.draganfly.com

  • Build (existing kits & plans)

– http://aeroquad.info/bin/view/Main/WebHome – http://mikrokopter.de – http://uavp.ch/moin (Why are there so many German quads? :-)

  • Comprehesive list:

– http://multicopter.org/wiki/Multicopter_Table

  • Design Our Own!
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  • R. Brewer - Philly Meetup Quadrotor

University Research

  • STARMAC – Stanford

– http://hybrid.eecs.berkeley.edu/index.php?section=37

  • MIT

– http://vertol.mit.edu/index.html

  • EPFL

– http://asl.epfl.ch/research/projects/VtolIndoorFlying/indoorFly

ing.php

  • Brigham Young

– http://www.ece.byu.edu/roboticvision/HelicopterPlatform/Heli

copterPlatform.html

  • Many more...
  • Many technical research papers available on-line
  • Task is equivalent to B.S Eng Project up to PhD Thesis!
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13 Aug 09 7

  • R. Brewer - Philly Meetup Quadrotor

Skills / Knowledge

My contribution:

  • Control Theory & Algorithms (PID etc.)

I Have Some Knowledge of:

  • Sensors (MEMs, GPS, Compass)
  • Microcontrollers, Embedded Systems, & Software
  • DSP / Filtering

What I need to learn:

  • Radio Control Equipment
  • (Brushless) Motors & Servos
  • Vision processing
  • Airframe Design & Construction
  • PC / ground station programming
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13 Aug 09 8

  • R. Brewer - Philly Meetup Quadrotor

Personal Goals:

  • Professional Development

– UAV – Advanced Controls – Sensor Processing / Sensor Fusion

  • Kalman, Complementary Filters, etc
  • Personal

– Microcontrollers – Embedded S/W – Electronics – Radio Control – Website / Blog / Magazine Articles

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13 Aug 09 9

  • R. Brewer - Philly Meetup Quadrotor

Project Goals:

  • Manual (Radio Control) Operation

– Acrobatic mode: angular rate & thrust command – Stable Mode: Translational rate command / position and

altitude hold

  • Semi Autonomous Operation

– Telemetry to Laptop-based ground station – Voice operation

  • Fully Acrobatic
  • Automatic P.I.D. Gain tuning
  • Other

– Provide Write-ups of Quad Dynamics, Control Loops (and theory),

& S/W Design

– Use Open Souce / Free S/W tools where possible

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  • R. Brewer - Philly Meetup Quadrotor

Project Status

  • Software

– Math / Simulation Model

  • Needs some work – drag models, etc.
  • Good enough to begin code prototyping

– Code

  • About to prototype control ideas
  • Hardware

– Controller

  • My friend Brijesh has designed, built and is testing a

custom AVR ATMega644p based board:

– Airframe, motors, ESCs, R/C gear, propellers, etc.

  • Some ideas, but nothing yet purchased
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  • R. Brewer - Philly Meetup Quadrotor

Math Model / Scicos Simulation

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13 Aug 09 12

  • R. Brewer - Philly Meetup Quadrotor

Custom Controller Card

* ATMEGA644p processor ( Same as Sanguino). * 20 MHz clock rate. * Serial port 1 : USB or Xbee link.

  • Arduino bootloader supported on both USB

and Xbee links. * Serial port 2 : Venus GPS module from Sparkfun. * 4 Channel RC receiver input. Interrupt based de- coding. * 4 Channel Hardware PWM/Servo pulse. * Terminals to distribute power to 4 ESC's from battery. * 4 pole Butterworth Anti-aliasing filters on all sensors inputs. * Gyros

  • IDG500 Break out board connector (X and Y

axis) + IDG500 output selectable between 100 Deg/sec or 500 Deg/sec via a jumper.

  • LISY300AL break out board connector (Z

axis) * Accelerometer: Two options available

  • MMA7260 breakout board connector. (Ana-

log outputs).

  • LIS302DL breakout board connector, (I2C in-

terface). * Battery voltage monitoring. * 3inx3in Dimensions with 4 mountings holes.

  • http://sites.google.com/site/pushpakquadrotor
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  • R. Brewer - Philly Meetup Quadrotor

Technical Challenges - Control

  • Airframe Dynamics Are:

– Non-linear:

  • 3-D Attitude (orientation): Trig functions,

Singularities, Quaternions

– Coupled:

  • Translation requires attitude changes
  • Attitude change requires thrust change to avoid

altitude (height) change

  • Many control schemes are employed

– “Simple” Proportional Integral Derivative (PID) – More advanced non-linear concepts – Distributed control – split on-board and laptop

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  • R. Brewer - Philly Meetup Quadrotor

Control Concept

  • Acrobatic mode: Rate command/attitude hold; direct thrust command
  • Precision mode: Velocity command/position hold;rate of climb command / altitude hold
  • Autonomous commands (possibly via laptop over telemetry)
  • Automatic or manual switching between modes

Quadrotor Sensors Comp. Filters R/C Joystick Or Laptop Attitude Command Rotor Mixing PID/ Other Feedback Velocity Command PID/ Other Feedback + - + -

Software

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13 Aug 09 15

  • R. Brewer - Philly Meetup Quadrotor

Technical Challenges - Sensors

  • Must sense position & orientation to control them
  • Gyroscopes

– Sense angular rates – Suffer from bias – Must be integrated to determine attitude – Usable only in a medium frequency range

  • Accelerometers

– Sense linear acceleration – Very noisy – Gravity must be handled carefully – Useable only in a low frequency range

  • Other sensors:

– GPS, Sonar, Magnetometer/Compass, Vision, etc.

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13 Aug 09 16

  • R. Brewer - Philly Meetup Quadrotor

Sensor Fusion

  • Complementary Filter

– Concept: utilize each sensor over the frequency range

where they provide good attitude data

– Integrate and High Pass filter gyro data – Low Pass Filter accelerometer ATAN data – Tune filter based on data – Inverse of stereo woofer/tweeter network

  • Kalman Filter

– Contains model/observer/predictor – And corrector feedback loop with varying gain – Uses statistical parameters – Much more complicated to understand and implement

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  • R. Brewer - Philly Meetup Quadrotor

Complementary Filter Design - 1

1/s 1/s

+ + + +

  • k

*k 2*k

1 2 1

Gyro (deg/s) Gyro (deg/s) Accel (deg) Accel (deg)

SCICOS Model

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  • R. Brewer - Philly Meetup Quadrotor

37.0 37.5 38.0 38.5 39.0 39.5 40.0 40.5 41.0

  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0 2.5 T im e (sec) Attitude (deg) & Rate (deg/s) Gyro Accel Filter T rue Angle

Complementary Filter Design - 2

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  • R. Brewer - Philly Meetup Quadrotor

The Bigger Picture

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13 Aug 09 20

  • R. Brewer - Philly Meetup Quadrotor

Other Links from the Meetup

  • DIY Drones – UAVs - http://diydrones.com
  • Sparkfun – Electronic Parts & tutorials - http://www.sparkfun.com
  • Arduino – Microprocessors simplified - http://www.arduino.cc/
  • AVR Freaks – lots of info for AVR microprocessors

http://www.avrfreaks.net

  • Scilab/Scicos – Free Matlab clone - http://www.scilab.org;

http://scicos.org; http://scicoslab.com

  • Open Office – MS Office “clone” - http://www.openoffice.org
  • Magazines

– Nuts and Volts – general electronics - http://www.nutsvolts.com – Servo – robotics - http://www.servomagazine.com – Circuit Cellar – pro electronics - http://www.circellar.com – Elektor – UK electronics -http://www.elektor.com/magazines.46742.lynkx – Robot – robotics - http://www.botmag.com