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  • Preliminary Design Review

    (PDR)

    Collision Encounter Reduction for UNmanned Aerial Systems (CERUNAS)

    University of Colorado at Boulder

    Department of Aerospace Engineering Sciences

    17 October 2013

  • CERUNAS Team

    Eric Brodbine Quinn McGehan

    Jackson Beall Colby Mulloy

    Garrett Brown Mark Sakaguchi

    Chad Hotimsky Chris Young

    CERUNAS Preliminary Design Review Rev-

    2

  • Overview

    Project Summary

    Feasibility Analyses (By Subsystem)

    Manned A/C Componentry

    Communication Componentry

    sUAS Componentry

    Test

    Modeling

    Future Work

    Backup Charts

    CERUNAS Preliminary Design Review Rev-

    3

  • Project Summary

    CERUNAS Preliminary Design Review Rev-

    4

  • Project Summary

    Background and Project Objective PROBLEM

    Increase in unmanned aircraft systems (UAS) from recreational flyers, researchers, industry

    No UAS has been certified to satisfy See and Avoid requirements in VFR conditions

    Future aircraft (manned and UAS) need a collision avoidance system

    SOLUTION

    Design a collision avoidance system(CAS) for sUAS (< 2 lbs)

    sUAS

    Detects beacon from unmanned aircraft

    Interrupts the sUAS autopilot to evade the manned aircraft flight path

    Manned Aircraft

    Propeller-driven (100 m/s)

    Flying straight and level

    Flying in uncontrolled airspace over remote terrain CERUNAS Preliminary Design Review Rev-

    5

  • Project Summary

    Concept of Operations

    CERUNAS Preliminary Design Review Rev-

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  • Project Summary

    Levels of Success Summary of Success Level 1

    Verify Sensing Functionality and characterize Manned Aircraft Encounter Cone (MAEC) via Ground Test.

    Summary of Success Level 2

    Verify and Characterize Avoidance Functionality only via Flight Test.

    Summary of Success Level 3

    Verify full CERUNAS functionality via flight test.

    CERUNAS Preliminary Design Review Rev-

    7

  • Project Summary

    Project Functional Block Diagram 8

  • Project Summary

    Baseline Design - Sensing

    GPS with pressure altitude is the optimal design GPS with pressure altitude on manned aircraft transmits position and

    heading

    Receiver on sUAS decodes manned aircraft parameters and calculates if an avoidance maneuver is necessary using own sUAS GPS

    Note: Illumination design option will be researched further as a feasible baseline design.

    CERUNAS Preliminary Design Review Rev-

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  • Project Summary

    Sensing Concept of Operations

    CERUNAS Preliminary Design Review Rev-

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  • Project Summary

    Baseline Design Avoidance

    Flight Termination Mode is the optimal design

    Interfaces with the autopilot through digital I/O pin (nominally at 3.3V)

    Flight Termination Mode (FTM) already a feature on Data Hawk sUAS

    If sensing option sets digital I/O pin low (0V), sUAS initiates FTM, else sUAS continues on autopilot flight path

    CERUNAS Preliminary Design Review Rev-

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  • Project Summary

    Avoidance Concept of Operations

    CERUNAS Preliminary Design Review Rev-

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    1. Manned Aircraft GPS and Altitude Locations Transmitted

    2. sUAS GPS and Altitude Locations Measured and Manned Aircraft Telemetry Received

    3. Microcontroller on sUAS Calculates Flight Paths of Manned aircraft and sUAS and Determines if sUAS is in Collision Cone

    4. Microcontroller stops outputting the 3.3 V signal and interrupts the autopilot forcing UAV into a dive

    4. Microcontroller Continues to output 3.3V signal and UAV maintains flight path

    Return to step 2

    Yes No

    (XX.XXXXN, XX.XXXXE, XXXft)

    Wireless Transmission

    GPS and Altitude Position

    Calculated Flight Path

    Legend

    Avoidance Flight Path

  • Feasibility Analyses Critical Project Elements Manned A/C Componentry Communication Componentry sUAS Componentry Test Modeling

    CERUNAS Preliminary Design Review Rev-

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  • CERUNAS Preliminary Design Review Rev-

    7 Feasibility Analysis

    Critical Project Elements

    Project Element Identifier

    Critical Project Element Description Rationale for Element

    1 The CAS must determine that the sUAS is in the encounter cone of a manned A/C based on reception of a signal provided by the manned A/C

    Indication of potential manned A/C-sUAS collisions

    2

    The manned A/C mountable CAS transmission device must be able to indicate either or both: The location and heading of the A/C Encounter cone boundaries for a sUAS

    Indication of potential manned A/C-sUAS collisions

    3 The CAS must complete any sUAS maneuvers required to move the sUAS outside of the manned aircraft encounter cone

    Avoidance of manned A/C-sUAS collisions

    4 The sUAS elements of the CAS must have a mass of less than 100g

    Weight key to effective integration of CAS with existing sUAS components

    5 Telemetry data for the sUAS must be collected and downlinked for any collision avoidance maneuvers

    Need to understand CAS effectiveness in real-world flight and to validate mission success

    6 The CAS transmitter and receiver units must each be mass producible for less than $100

    - Cost-effective compared to cost of sUAS - Cost-effective for private pilot implementation

  • Manned Aircraft Componentry

    15

  • CERUNAS Preliminary Design Review Rev-

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    Feasibility Analysis

    Manned A/C - Feasibility Analysis Drivers

    Concerns which Drive Feasibility Analysis

    Concern Description Requirement Requirement Text

    Venus GPS Logger

    Cost because it is a over half of the $100 production cost

    CAS-SYS-018

    The CAS elements for both the manned A/C and sUAS platforms shall be demonstratably reproducible for $100 +/- 10% based on manufacturer input.

    Power System

    Ability to power manned A/C components with minimal impact to manned A/C

    CAS-SYS-004

    The manned A/C mountable element of the CAS shall not impact the functionality of any manned A/C HW or communications systems and shall have the ability to comply with applicable FAA regulations.

  • Feasibility Analysis

    Manned A/C Componentry GPS Trade Study

    Desired GPS Characteristics

    GPS L1 C/A code

    Accuracy: < 2.5 m CEP

    Power Supply: 2.7 3.6 V

    Communication Interface: RS-232, RS-422, USB, UART

    CERUNAS Preliminary Design Review Rev-

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  • Feasibility Analysis

    Manned A/C Componentry Battery Trade Study

    CERUNAS Preliminary Design Review Rev-

    18

    Lithium iron phosphate battery ideal design for manned A/C GPS

    Specific power: >300 W/kg

    Cost: $4.50 - $9.00 (depending on size)

    Safety: minimal risk of delamination or explosion

  • Instrumentation Mass Current Voltage Cost

    Communication Device: Xbee Pro 900 HP

    8g 29 mA 2.1-3.6V $100.00

    Microcontroller: PIC18F47J13

    1g 1.44 mA typical

    2-3.6V $2.76

    GPS: Venus GPS Logger $100

    Mass production will lower cost

  • Communication Componentry

    20

  • Requirements driving Communication System Development

    Concern Description Requirement Requirement Text

    Ability to detect and characterize the motion of an A/C at a minimum range of 2 km.

    CAS-SYS-001

    The initial volume of the MAEC for the manned A/C shall extend 2km in front of the manned A/C at an angle defined by

    the expected velocities for both the sUAS and manned A/C

    Communication System must be low mass CAS-SYS-007 The sUAS elements of the CAS shall have a mass of less than 100g.

    Communication System must be low power CAS-SYS-008 The sUAS elements of the CAS shall draw no more than 2.5W of power.

    Communication System must transmit enough data to fully characterize the motion of an A/C for Avoidance

    and Telemetry

    CAS-SYS-010 Telemetry data for any collision avoidance maneuvers shall be downlinked and saved on the existing sUAS telemetry stream.

    CAS-SYS-011

    Telemetry data for any collision avoidance maneuvers shall be uniquely recorded for a period beginning one (1) maneuver duration before the maneuver start time and extending one (1) maneuver duration beyond the maneuver end time.

    CERUNAS Preliminary Design Review Rev-

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    Feasibility Analysis

    Communication-Feasibility Analysis Drivers

  • Feasibility Analysis

    Transceiver Trade Study

    CERUNAS Preliminary Design Review Rev-

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    XBee transceiver has flight heritage on sUAS Data Hawk

    Interference concern with existing Xbee transceivers on sUAS Data Hawk

  • Feasibility Analysis

    Transceiver Selection

    XBee Pro 900 HP Frequency 902-928 MHz

    Data Transfer Rate 10 or 200 Kbps

    Transmit Power Up to 24 dBm

    Supply Voltage 2.1 to 3.6 VDC

    Transmit Current 215 mA

    Receive Current 29 mA

    Max Published Range 14 km w/ dipole antenna

    Data Interface UART (3V), SPI

    Mass 8g

    Cost (Low Volume) $70 - $150

    Available with RPSMA, wire, or U.FL Antenna

    CERUNAS Preliminary Design Review Rev-

    23

  • Feasibility Analysis

    RF Link Budget Feasibility Analysis

    Overall Transmitter Gain: 24 dBm Receiver Gain (Antenna): 2.1 dB Operating Frequency: 915 MHz Required Operating Range: 2 km Environmental Impedance Factor (n): 2.5 Received Power = -74.97 dBm

    XBee Pro 900HP is rated for

  • sUAS Componentry 25

  • Feasibility Analysis

    sUAS Feasibility Analysis Drivers

    Concerns which Drive Feasibility Analysis

    Concern Description Requirement Requirement Text

    Autopilot Interface

    Need I/O pin to interface with autopilot

    CAS-PRJ-004 The sUAS elements of the CAS shall have minimal

    impact on existing sUAS componentry. Changes to autopilot may make avoidance system prohibitively

    difficult or complex to implement

    Power Limitations

    Limiting power consumption to the 2.5W available on the sUAS

    CAS-SYS-008 The sUAS elements of the CAS shall draw no more

    than 50mA at 6V of power.

    Telemetry Data Recording

    Recording telemetry data during avoidance to demonstrate success of

    system CAS-SYS-010

    Telemetry data for any collision avoidance maneuvers shall be downlinked and saved on the

    existing sUAS telemetry stream.

    CERUNAS Preliminary Design Review Rev-

    26

  • CERUNAS Preliminary Design Review Rev-

    27

    Concern: Need available I/O port for Autopilot interface

    Input from Customer

    There is a digital I/O pin available

    Concern: Changes to autopilot may make avoidance system prohibitively difficult or complex to implement

    Input from Customer

    Changes to Autopilot will be small

    No concerns regarding feasibility of Autopilot at this time

    Feasibility Analysis

    sUAS Feasibility Analysis Drivers

  • Feasibility Analysis

    Microcontroller Choice Microcontroller PIC18F47J13 ATMEL SAM D20J17 ATMEGA128

    Voltage Range 2-3.6 V 1.62-3.6V 1.8-5.5V

    Program Memory 128K 128K 128K

    Data Memory 3.8K 16K 16K

    Peripherals 8 6 8

    Timers 8 8 6

    ADC 13 Channel 12-bit 20 Channel 12-bit 8 Channel 10-bit

    Speed 48 MHz 48 MHz 20 MHz

    Cost $2.76 $3.53 $7.22

    CERUNAS Preliminary Design Review Rev-

    28

    Desired Microcontroller Characteristics Familiarity 3.3V Operation to match Communication

    System Maximize

    Peripherals Program Memory 128k Data Memory 4k ADC Resolution 10-bit

    Minimize Power Consumption

  • Instrumentation Mass Current Voltage Cost

    Battery: LiFePO4 18500

    31.2 g 800 mAh 3.2V $2.99

    Communication Device: Xbee Pro 900 HP

    8g 29 mA 2.1-3.6V $100.00

    Microcontroller: PIC18F47J13

  • Test and Modeling Ground Test for Success Level 1 Flight Test for Success Level 2 Flight Test for Success Level 3 FAA Testing Feasibility

    CERUNAS Preliminary Design Review Rev-

    30

  • Feasibility Analysis

    Test - Feasibility Analysis Drivers

    Concerns which Drive Feasibility Analysis

    Concern Description Requirement Requirement Text

    Ground Testing

    No Concerns N/A N/A

    Flight Testing

    Ability to Comply with FAA Guidelines -- Need to Comply with US government airspace limitations

    Characterization of MAEC Geometry and sUAS behavior during avoidance and Verification of CAS Functionality

    based on Test

    CAS-SYS-002

    The post-CERNUNAS volume of the MAEC shall be determined by the expected velocities of the sUAS and manned A/C along with the time necessary for the sUAS to leave the MAEC at a typical velocity.

    CAS-SYS-006 All avoidance maneuvers implemented by the CAS shall aim for recoverability of sUAS flight after mitigation of the collision situation.

    CERUNAS Preliminary Design Review Rev-

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  • Feasibility Analysis

    Test - Verification of Success Level 1

    Precedent for similar test set by Dr. Lawrence

    Allows for simple characterization of MAEC

    Level 1 Testing is a mild concern

    No difficult technical elements

    No special permissions

    CERUNAS Preliminary Design Review Rev-

    32

  • Feasibility Analysis

    Test - Verification of Success Level 2

    Concern: ability to characterize avoidance based on test (CAS-SYS-006)

    See FAA Regulations chart

    CoA Height limit may cause issues with necessary fall distance

    See FAA Regulations chart

    FAA Limitations are mild concern

    CERUNAS Preliminary Design Review Rev-

    33

  • Feasibility Analysis

    Test - Verification of Success Level 3

    Concern: CoA height limit could limit testing

    Scaled test allows for meaningful verification

    Ground tests could be carried out with similar methodology

    Concern: FAA restrictions on weather balloon flight

    See FAA concerns section

    With Current GPS System, weather balloon is not necessary

    FAA Limitations are mild concern

    CERUNAS Preliminary Design Review Rev-

    34

  • Feasibility Analysis

    Test - FAA Feasibility [1,2] Concern: Procurement of CoA

    FAA will provide a formal response within 60 days from [submission].

    CoAs above 122m (400ft) are difficult to obtain, optimal test altitude is 300m (984ft).

    Can scale test to accommodate lower altitude

    Concern: Ability to broadcast from moored balloon

    FAA allows moored balloons to 500ft AGL without certification

    Issue if CoA > 400ft is approved

    Can scale test to accommodate lower altitude, use permanent high point

    With GPS, altitude mounted transmitter is unnecessary

    FAA compliance is a mild concern

    Contingency plans and test flexibility means that test can continue with minimal redesign

    CERUNAS Preliminary Design Review Rev-

    35

  • Feasibility Analysis

    Modeling - Feasibility Analysis Drivers

    Concerns which Drive Feasibility Analysis

    Concern Description Requirement Requirement Text

    A/C Dynamics Modeling

    No concerns N/A N/A

    MAEC Modeling

    Post-CERNUNAS MAEC modeling CAS-SYS-002

    The post-CERNUNAS volume of the MAEC shall be determined by the expected velocities of the sUAS and manned A/C along with the time necessary for the sUAS to leave the MAEC at a typical velocity.

    Autopilot Modeling

    No concerns N/A N/A

    CAS Modeling

    No concerns N/A N/A

    CERUNAS Preliminary Design Review Rev-

    36

  • CAS

    Feasibility Analysis

    Modeling - System Modeling

    Compute MAEC geometry from model

    Autopilot Simulation

    Simulated manned A/C

    motion

    Determine whether sUAS in MAEC

    Simulated sUAS A/C motion

    Simulated GPS datal from sUAS GPS module

    Simulated GPS data from

    manned A/C

    If in MAEC send signal to autopilot

    KEY MAEC Model

    CAS Simulation

    Simulated GPS signal

    A/C motion simulation

    Autopilot Simulation

    Purpose of Models/Simulations:

    Simulate system in SW to provide initial verification of functionality and characterization of post-A/C MAEC

    CERUNAS Preliminary Design Review Rev-

    37

  • Feasibility Analysis

    Modeling - Encounter Cone Modeling

    Pre-CAS Manned A/C Encounter Cone (MAEC) defined by nominal velocities of manned A/C and sUAS (See Proj...

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