Aerial Robotics

Practical Implementation Details for UAV Design and Test

Steve Carlson

Robotic Workers (RoboWork) Lab

University of Nevada, Reno

CS-491/691

Introduction

About Me

• Designing R/C Aircraft since High School. Electrical Engineer.
• BYU MAGICC Lab, NASA Internship, Aurora Flight Sciences
• Private Pilot – ASEL and Glider Ratings
• Two Years at UNR RWL

CS491/691 Steve Carlson

Introduction

Roadmap

• Part 1: Aircraft Design

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• Part 2: Electronics and Systems
• Part 3: The Flight Test Environment
• Part 4: War Stories

CS491/691 Steve Carlson

Aircraft Design

Planform, Stability and Weight-and-Balance

• L/D, Lift verses Weight
• Airfoil Reflex, Wing Washout, other tweaks
• Estimating Longitudinal and Lateral Stability Modes and Frequencies

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Live Demo:

• XFLR5

CS491/691 Steve Carlson

Aircraft Design

CAD Workflow

• Coordinate Frames
• Geometric trick to find the MAC
• General CAD Fundamentals

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• Simulating Forces and Stress

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Live Demo:

• Autodesk Inventor

CS491/691 Steve Carlson

Aircraft Design

Building and Hand-crafting

• 3D Printing Workflow
• R/C Airplane Hardware

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• Materials

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Live Demo:

• Ultimaker Cura

CS491/691 Steve Carlson

Electronics and Systems

Autopilot Design Elements

• Microcontroller and Voltage Regulators
• IMU(s), Altimeter, Voltage/Current, etc
• External Peripheral Interface and Sanitization
• Connectors – DroneCode Standard
• Logging

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Other Considerations:

• Anti-Vibration Mounting
• IMU Diversity, Software Filtering

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Trade Study:

• mRo PixRacerPro
• Holybro Pixhawk 6C

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CS491/691 Steve Carlson

Electronics and Systems

RF Communications and Link Budget

• Friis Transmission Equation (Link Budget)
• Fresnel Zone (Line-of-Sight != Good Comms)
• RF Propagation and Polarization (How Antennas work)
• Band Selections and Avoiding Inference
• Antenna Tuning and Impedance Matching
• EMI/RFI with onboard components

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Live Demos:

• RTLSDR
• nanoVNA

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CS491/691 Steve Carlson

Electronics and Systems

Electrical Design Workflow

• Problem and Design Solution Elements, Trade Study
• Analog and Digital Simulation
• Schematic Capture and Layout

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Live Demos:

• LTSpice
• KiCAD
• How to search DigiKey

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CS491/691 Steve Carlson

Electronics and Systems

Interacting with the Hardware

• MavLink and MavRos
• SBCs, Off-Board Control, ssh
• ESC Programming
• Serial Terminals, AT Commands for Transceivers

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Live Demos:

• Ardupilot Parameters, Logs Download

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CS491/691 Steve Carlson

Flight Test Environment

Roles and Responsibilities

• Safety Pilot
• Spotter and Telemetry Monitor
• Flight Line: Sanitizing the Test Area, keeping everyone safe
• Equipment: Radios, Fire Extinguisher, etc
• Positive Transfer of Control

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Pilot Inputs:

• Line-of-Sight
• FPV Telemetry
• Radio Telemetry
• Laptop Telemetry

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CS491/691 Steve Carlson

Flight Test Environment

Airspace and Interactions

• Airspace Types in the USA
• TFRs, NOTAMs
• Where and When to fly

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Live Demo:

• SkyVector

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CS491/691 Steve Carlson

Flight Test Environment

Art and Science of Learning In-the-Field

• Flight Test Cards
• Mounting and Synchronizing Cameras
• Chase Plane/Quad
• Scientific Method: Change only one parameter at a time!

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Live Demo:

• Live Ardupilot Telemetry
• MAVExplorer

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CS491/691 Steve Carlson

War Stories

PID Integrator Windup: The Death of Mellow Yellow I

• Upside-Down for the Camera, “Clever” solution
• Everything works great until your boss is watching
• Untested corner-case

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CS491/691 Steve Carlson

War Stories

VTOL Level-Transition Lock-Out: Plane-vs-Mountain

• Trying to run a full autonomous mission
• Vehicle continued towards the mountain
• Photoelectric effect- Pitot Probe never measured sufficient airspeed.

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CS491/691 Steve Carlson

War Stories

Normalization of Deviance: Raining Confetti

• Modular Wing-to-Wing coupling
• Multiple Disconnections, nothing to worry about, right?
• Pitch Oscillations

CS491/691 Steve Carlson

War Stories

How to find your crashed drone

• Finding the Missing Hatch/Lid from telemetry and Google Earth
• Radio RSSI “Fox Hunting” when it is lost in the brush
• Design for Visibility

CS491/691 Steve Carlson

War Stories

GPS Interference Troubleshooting

• Out in the desert for ICRA flights, can’t get T265 to work
• Troubleshooting with Process-of-Elimination
• How to Triage and Salvage the Test

CS491/691 Steve Carlson

Time for Questions !

CS-491/691

CS491/691 Steve Carlson