System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and...

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System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and Director, CASA and CERT School of Aerospace Engineering Georgia Institute of Technology Atlanta, GA 30332-0150

Transcript of System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and...

Page 1: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

System Safety Risk Management: An Autonomous UAV Example from a

Course on Safety By Design and Flight Certification

Dr. Daniel P. SchrageProfessor and Director, CASA and CERT

School of Aerospace EngineeringGeorgia Institute of Technology

Atlanta, GA 30332-0150

Page 2: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Presentation Outline

Overview of Georgia Tech graduate program in Aerospace Systems Design

Brief description of the Safety By Design and Flight Certification Course

Example from Safety Course for an Autonomous Unmanned Aerial Vehicle (UAV) – The GTMAX

Page 3: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Georgia Tech Practice-Oriented M.S. Program

in Aerospace Systems Design

Legend: Core Classes Elective Classes

SummerSemester IISemester I

IPPD Methods/Techniques

Special

Project

DesignSeminars

IntegratedProduct/Process

Development

Disciplinary Courses

PropulsionSystemsDesign

SystemsDesign IAppliedDesign I

SystemsDesign IIAppliedDesign II

IPPD Tools/Infrastructure

ModernDesign

Methods I

Modern Design

Methods II

ProductLife Cycle

Management

Internships

Mathematics (2 Required) Other Electives

Safety ByDesign

Page 4: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Safety By Design and Flight Certification Course

First taught in 1998 as a project oriented course to orient students on the role of safety by design and flight certification in the design iteration process

Course builds on the Integrated Product/Process Development (IPPD) through Robust Design Simulation (RDS) environment created in the Georgia Tech Aerospace Systems Design Laboratory (ASDL)

Course taught in the summer semester to allow students to analyze the designs they developed during the fall and spring semesters (Fixed Wing,V/STOL Rotorcraft, Space, and Missiles)

Course has been continuously improved each year to address more of the issues in moving to a risk based managed process

Course has sought to incorporate user friendly tools for System Reliability Prediction, FTA, FMEA and Markov Analysis

Emphasis on the course taught this summer was on the interaction of Hardware, Software, and Liveware (Human) reliabilities & partnerships with industry and government

Page 5: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Course Projects for Summer 2002

Quiet Supersonic Aircraft – in conjunction with Gulfstream Aerospace Corporation

The ICBM Peacekeeper as a Commercial Launch Vehicle – in conjunction with the FAA Space Systems Development Division

A VTOL Personal Air Vehicle (PAV) – in conjunction with the NASA PAV Evaluation program

*An Autonomous UAV: GTMAX – in conjunction with the DARPA Software Enabled Control (SEC) program and the GT Entry in the International Aerial Robotics Competition (IARC)

* Example to be illustrated

Page 6: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Development of a Certification Plan(ARP 4754:Cert Considerations For Highly-Integ or Complex Aircraft

Systems)

Each Plan should include: A functional and operational description of the system and the aircraft

on which the system will be installed A statement of the relationship of this certification plan to any other

relevant system certification plans A summary of the functional hazard assessment (aircraft hazards, failure

conditions, and classification) A summary of the preliminary system safety assessment (system safety

objectives & preliminary system development assurance levels) A description of any novel or unique design features that are planned

to be used in meeting the safety objectives A description of the new technologies or new technology applications to

be implemented The system certification basis including any special conditions The proposed methods of showing compliance with the certification

basis A list of the data to be submitted and the data to be retained under

configuration control, along with a description or sample of data formats The approximate sequence and schedule for certification events

Page 7: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

The Overall GT Safety By Design Approach

FHA/FTA

Other PSSA Methods

PROBABILISTIC ASSESSMENT

(CRYSTAL BALL)

MARKOV ANALYSIS(MEADEPS)

SYSTEM RELIABILITY(PRISM)

CRITICALITYMATRIX

DO-178B

ARP 4754

ARP 4761

NO

YES

RELIABILITYPREDICTION

SAFETYPREDICTION

AIRCRAFT/SPACECRAFTSYSTEM DESIGN

SATISFIED?

PREDICTIONPROGRAMS

RELIABILITY SIMULATION

ANALYSISTECHNIQUES

APPLY

Technology Insert.TIF/TIES ?

FHA/FTA

Other PSSA Methods

PROBABILISTIC ASSESSMENT

(CRYSTAL BALL)

MARKOV ANALYSIS(MEADEPS)

SYSTEM RELIABILITY(PRISM)

CRITICALITYMATRIX

System FHA/FTA

Other PSSA Methods

PROBABILISTIC ASSESSMENT

(CRYSTAL BALL)

MARKOV ANALYSIS(MEADEPS)

SYSTEM RELIABILITY(PRISM)

CRITICALITYMATRIX

DO-178B

ARP 4754

ARP 4761

DO-178B/160D

ARP 4754

ARP 4761

NO

YES

RELIABILITYPREDICTION

SAFETYPREDICTION

AIRCRAFT/SPACECRAFTSYSTEM DESIGN

SATISFIED?

PREDICTIONPROGRAMS

RELIABILITY SIMULATION

ANALYSISTECHNIQUES

APPLY

Technology Insert.TIF/TIES ?

SafetyGoals

Aircraft/SpacecraftFHA/FTA

Page 8: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

SBD Process Overview

Aircraft FHA•Functions•Hazards•Effects•Classifications

System FHA•Functions•Hazards•Effects•Classifications

Aircraft FTA•Qualitative•System Budgets•Intersystem Dependencies

System FTA•Qualitative•Subsystem Budgets

DDMA

SystemFMEAsFMES

System FTAs•Qualitative•Failure Rates

PSSA SSA

CCA

Concept Development

PreliminaryDesign

DetailedDesign

Design Validation& Verification

Particular Risk Analysis

Common Mode Analysis

Zonal Safety Analysis

Page 9: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMaxPreliminary Safety Assessment and Certification Plan

Han Gil ChaeAdeel KhalidKayin CannonColin PouchetHenrik B. Christophersen

Page 10: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Overview Introduction

General facts about GTMax GTMax Certification

General Information of UAV Certification Analysis for particular system Human Errors Proposed system improvement Proposed Certification plan

Conclusions

Page 11: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Introduction

System Description System Requirements

Page 12: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMax : Development

Originally developed for aerial pest control

Modified for DARPA SEC Program and for Aerial Robotics

Test bed for Manned Vehicle

Electronic System

Page 13: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Software Enabled Control (SEC)

Dr. John Bay

DARPA/IXO

The objective of SEC is to co-develop advanced real-time control system algorithms and the

software services and infrastructure necessary to implement them on distributed embedded processors in a robust and verifiable way

The objective of SEC is to co-develop advanced real-time control system algorithms and the

software services and infrastructure necessary to implement them on distributed embedded processors in a robust and verifiable way

Page 14: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

DARPA SEC Participants Open Control Platform (OCP) Developers:

-Georgia Tech - Boeing Phantom Works- UC Berkeley -Honeywell Technology Labs

SEC Technology Developers (Active State Modelers, On Line Control Customization,Coordinated Multi-Modal Control, High Confidence Software Control Systems):

-Georgia Tech - UC Berkeley - Rockwell Collins- Cornell - MIT - Northrop Grumman Corp- Cal Tech - Draper Labs - Honeywell Labs- U of Min - Vanderbilt- OGI - Stanford

University Led Experiments (Rotary Wing): Georgia Tech Industry Led Experiments (Fixed Wing): Boeing Phantom

Works

Page 15: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

The Georgia Tech GTMAX : A Truly Modular Open System Testbed

The Georgia Tech GTMAX consists of The Yamaha RMAX Remotely Piloted Helicopter: a

rugged, proven air vehicle which is becoming the vehicle testbed choice for VTOL UAV autonomous vehicle research

The Georgia Tech Modular Avionics Package: built for reconfigurability, growth and easy upgrade

The Boeing - Georgia Tech OCP: a Real Time CORBA based open system software architecture

As a system the GTMAX provides an excellent resource for the UAV community for developing and evaluating UAV technologies, both hardware and software, as well as Home Security Experiments

Page 16: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMAX : Vehicle Specifications

Weight Gross Weight : 204.6 lb Empty Weight : 127.6 lb Payload : 66 lb

1800

3630

3115

720

1080

(mm)

Engine Gasoline 2-Cylinder Water Cooled Power output : 21Hp

Performance Fuel : 6L (1.6 gal) Endurance : 60 min

Page 17: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GT Research UAV: GTMAX

Georgia TechOnboardAvionics

RCReceiver

Data Link I

RC Transmitter

Data Link IGround

Computer(s)And

NetworkEthernet

GPS Reference

On-board Avionics

Ground Control Station

Safety Pilot

Yamaha Attitude Control System

(YACS)

Data Link II Data Link II

GPS

Actuators

GEO

RG

IA T

EC

HY

AM

AH

A

3x RS-232 Serial

Boeing-GT OCP

Page 18: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Onboard Avionics Hardware Architecture

WirelessSerial

WirelessEthernet

D-GPS

IMU

RadarAltimeter

SonarAltimeter

Magneto-meter

Servo-Interface

EthernetHub

PowerDist

Ext Power

Serial DataEthernetPower

Computer#1

Computer#2

Video Camera,Radar and PossiblyLidar to be installedthis summer

Page 19: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMAX Avionics HW Integration

GTMAX hardware is packaged into exchangeable modules:

Flight Computer Module GPS Module Data Link Module IMU/Radar Module Unused Module (Growth) Sonar/Magnetometer

Assemblies Power Distribution System

Each module has self-contained power regulation and EMI shielding

Shock-mounted main module rack

Page 20: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMAX Hardware Integration

Power System On-board generator

outputs 12V DC, 10 A Power source hot-

swappable between on-board and external

Each module is powered via individual circuit breakers

Interfacing and Wiring Interface Types: RS-232

Serial, Ethernet, 12V DC All interfaces on module

back-sides Aviation-quality wiring

harness

Page 21: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Limitations of State-of-the-ArtComplex Control Systems:• Tightly coupled• Difficult to adapt or evolve• Complex, inflexible data interchange• Computationally limited• Closed, proprietary systems

Desired Capabilities:• Adaptibility and dynamic reconfigurability• Plug-and-play extensibility, component interchangeability• Real-time quality of service• Interoperability, distributed communication• Openness

Open Control Platform Motivation

Page 22: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Boeing-GIT Baseline Open Control Platform (OCP) Software Implementation on the GTMAX

GPS

IMU

Magnetometer

sonar

receiver commands

Vehicle Health

RMAX Attitude sensors

Navigation ModuleComponent

ControllerComponent

Sensors SerialInterface

Vehicle SerialInterface

Controls API Input Port

Controls API Output Port

RMAX Actuator demultiplexer

Actuator SerialInterface

ControlData_out

ControlData_in

NavControl_out

NavControl_in

NavData_out

NavData_in

timeout_in

100 HzTimer

50 Hz

50 Hz 50 Hz

100 Hz

I/OComponent

DataLink InterfaceEthernet “Serial” Port

Serial port

Ethernet “Serial” Port

Serial port1 Hz & 10 Hz

1 Hz & 10 Hz

Input datalink portsread @ 100 Hz

m0 written at 10 Hzm1 written at 1 Hz

Page 23: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Mission Intelligence Flow for GT Research

Mission Planning

Mode Selection

Mode Switching

Flight Control System

UAVUAV

Sensors

Sensor Fusion

Obstacle/Target Detection

Obstacle/Target Identification

Obstacle/Target Tracking

Situation Awareness

Diagnostics

Fault Tolerant Control

Continue Mission

Continue MissionEmergency ?

Yes

No

Page 24: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

15 min

GTMax : Aerial Robotics Mission & SEC Scenario

Get Information from the Inside

Identify Structure

No Need to Return after the Mission

T/O (manually) 3KmFly Autonomously

Page 25: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

GTMax Certification Certification Basis Analysis (Functional, FHA, PSSA) Human Errors Strategy for achieving compliance Sequence of certification events

Page 26: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

FAA Certification

Design Production Operation

Type Design Approval

Type Certificate

Quality AssuranceApproval

Type DesignConformity

Production Certificate

Airworthiness

Certificate

Continued Airworthine

ss

Defect found in operation

Page 27: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Certification Basis

Suggested Regulations

Rotorcraft- FAR 27

No Certification Basis for UAVs

Safety Assessment- SAE APR4761

System Design/Analysis- AC 25.1309-1A

Page 28: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Certification basis?

Presently no certification basis for unmanned aircraft.

Unmanned vs. manned aircraft: Increased reliance on electronic flight control

systems in unmanned aircraft Safety = threat to persons and property outside

aircraft Flight over populated areas vs. isolated areas Ground Control System

Page 29: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Suggested Regulations

Flight crewmember(s) on the ground Safety equipment for occupants not required

Impact protection for occupants Safety belts Oxygen Warning lights

Flight Control System Certification Ground Control System Certification Categories of unmanned aircraft

Page 30: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Certification basis

Amended FARs FAR Part 1: Definitions and Abbreviations FAR Part 21: Certification Procedures for Products and

Parts FAR Part 27: Airworthiness Standards: Normal Category

Rotorcraft FAR Part 33: Airworthiness Standards: Aircraft Engines FAR Part XX: Airworthiness Standards: Electronic Flight

Control Systems for Unmanned Aircraft FAR Part XX: Airworthiness Standards: Ground Control

Systems for Unmanned Aircraft

Page 31: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Functional AnalysisTop Level

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Page 32: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Maintain Equipment

Maintain mission vehicle(s)

Maintain Ground Station Equipment

Maintain Supporting Equipment

Manage Organization

Manage Operation Manage Personnel Manage finances Manage

sales/marketing Manage supporting

equipment/facilities

Functional Analysis

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Page 33: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Receive Mission AssignmentAND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Functional Analysis

Receive Mission Description

3.1

Study map of route

3.2

Checkweather

3.4

Make preliminary flight plan

3.3

AND AND

Request additional

information from customer

3.6

Negotiate rate with customer

3.8

Evaluate Mission

3.7

Ref. 2.0 Maintain

Equipment

Investigate regulatory issues

3.5

NO GO

GO

NO GO

Ref. 2.0 Maintain Equipment

Ref. 4.0 Prepare for mission.

Page 34: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Prepare for mission

Verify readiness of UAV Create flight plan File NOTAM Verify that all necessary equipment is

loaded and ready Obtain/sign release form Depart for launch site

Functional Analysis

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Page 35: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Execute Mission (UAV)

Functional Analysis

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Arrive at launch site

5.1

Prepare UAV

5.2

Preflight UAV

5.3

Take offand climb

5.4

Cruise

5.5

Search for target

5.6

Locate target

5.7

Search for portals

5.8

Find open portal(s)

5.9

Prepare for subvehicle

launch

5.10

Deploy subvehicle

5.11

Hover in relay position

5.12

Cruise (return)

5.13

Descend andland

5.14

Start executing

mission

Finished Executing Mission

Page 36: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Execute Mission (GCS)

Functional Analysis

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Arrive at launch site

6.1

Prepare GCS for launch

6.2

Brief crew

6.4

Upload software/flight

plan to UAV

6.6

Perform BIT

6.7

Prepare fortake off

6.9

Activate flight plan

(autonomous flight)

5.8

Monitor UAV during mission

execution

5.9

Start executing mission (GCS)

Finished Executing Mission (GCS)

Simulate mission in GCS

6.3

AND

Troubleshoot and repair

6.8

AND

Perform autonomous

take off

6.4

Perform manual take off

6.3

OR OR

Establish communication

link with UAV

6.5

GO

NO GO

ABORT MISSIONControl UAV(high- level commands)

5.9OR OR

Land UAV upon return to Launch

site

6.3

Download data from UAV as

needed

6.3

Shut down GCS

6.3

Prepare for next flight

Page 37: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

FHA & FTA : Flight Control as Critical System Safety Subsystem

Control System (Collective)

Electronic SystemMechanical System

Page 38: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

FHA & FTA : Mechanical System

Function Failure Condition Phase Effect of Failure Condition Classfication Ref. To SupportingMaterial

Verification

A1.1 Generate Rotor Force Loss of Lift Force of Rotor FTA

a. Loss of Rotor structure All Causes whole aircraft failure and crash.May cause severe damage of people onthe ground

Catastropic

a. Loss of Transmissionstructure

All Causes loss of rotor capability Catastropic

A 2.1 Control CollectivePitch

Loss of Control Capability All Causes whole aircraft failure and crash.May cause severe damage of people onthe ground

Catastropic

a. Loss of Control sys. Structure

b. Loss of electricityc. Loss of Command

A 2.2 Control Cyclic Pitch Loss of Control Capability All Causes whole aircraft failure and crash.May cause severe damage of people onthe ground

Catastropic

a. Loss of Control sys. Structure

Loss of Collective PitchControl capability

Loss of MechanicalLinkage Capability

Loss of ActuatorCapability

Loss of Electiricity

Failure ofMechanical

Component ofActuator

Loss of steeringcommands from

Flight ControlComputer

Loss of steeringcommands fromRemote Control

Receiver

Failure of WireHarness

Loss of BatteryCapability

Failure of GroundStation

Failure of On-BoardSystem

1E-6

1E-5

Loss of Collective PitchControl capability

To ElectronicSystem

Page 39: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

FHA & FTA : Electronic System

Function Failure Condition Phase Effect of Failure Condition Classfication Ref. To SupportingMaterial

B1 Generate actuatorsteering commands

Loss of validcommands from FCS.

a. Invalid or missingoutput from FCS.

T/O &Landing

Safety pilot will assume control ofaircraft and bring it to a safelanding.

Minor (D)

b. Invalid or missingoutput from FCS.

Cruise(within RCrange)

Safety pilot will assume control ofaircraft and bring it to a safelanding.

Minor (D)

a. Unable to sendtelemetry data to GCS

T/O,LandingandCruise

The GCS will not have the up-to-date information about the currentlocation of the UAV

Minor (D) toMajor (C)

B3 Monitorsystems/performance

Failure to detectproblema. Failure to detectMain Computer failure

T/O,Landingand in-rangeCruise

Problem will not surface unlessthere is an actual Main Computerfailure. Safety pilot may takecontrol.

Minor (D)

Loss of steering commandsfrom Flight Control

Computer

Loss of steering commandsfrom Flight Control

Computer

Loss of steeringcommands from

Backup Controller

Loss of steeringcommands fromMain Computer

Failure of HeartbeatMonitor to switch toBackup Controller

3E-31E-4

Failure of MainComputer to

discontinue sendingheartbeats.

Internal failure inHeartbeat Monitor

Heartbeat Monitorswitches incorrectly

to Backup Contr.

Loss of steeringcommands from

Backup Controller

1E-3 1E-4

1E-3 1E-4

To MechanicalSystem

Page 40: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

PSSA : Software Exploration

MEADEPPrism Crystal Ball

System failurerate modeling

Markovanalysis

Monte CarloSimulation

Whatfor ?

Easy ?

Redundancy MultipleEvents

DistributionFuctions

Database

Page 41: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Monte Carlo Simulationfor

Whole System

PRISMfor

Mech. Components

PSSA : Strategy

Loss of Collective PitchControl capability

Loss of MechanicalLinkage Capability

Loss of ActuatorCapability

Loss of Electiricity

Failure ofMechanical

Component ofActuator

Loss of steeringcommands from

Flight ControlComputer

Loss of steeringcommands fromRemote Control

Receiver

Failure of WireHarness

Loss of BatteryCapability

Failure of GroundStation

Failure of On-BoardSystem

1E-6

1E-5

Loss of steeringcommands from

Backup Controller

Loss of steeringcommands fromMain Computer

Failure of HeartbeatMonitor to switch toBackup Controller

3E-31E-4

Failure of MainComputer to

discontinue sendingheartbeats.

Internal failure inHeartbeat Monitor

Heartbeat Monitorswitches incorrectlyto Backup Contr.

Loss of steeringcommands from

Backup Controller

1E-3 1E-4

1E-3 1E-4

Fault Tree based on FHA

Markov Analysisfor

Mechanical System& Electronic SystemMech.

Elec.

Page 42: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

PSSA : Prism modeling

Mechanical components

Prism Database Total Failure

Rate - 1.76 E-3/Op.

hr

Failure/M calendar hr Failure/Operation hr

Linkage 27.089 9.36E-04

Yoke 8.1256 2.81E-04

Main Rotor 3.7443 1.29E-04

Swash P 2.8822 9.96E-05

Servo 9.2274 3.19E-04

Failure rates

Page 43: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

PSSA : Markov Analysis

Mechanical System

MTTF -

6023.275 /hr

Reliability - 93.57 hr

Page 44: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

PSSA : Markov Analysis

Electronic System

MTTF -

1000.249 /hr

Reliability - 90.48 hr

Page 45: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Loss of Collective PitchControl capability

Loss of MechanicalLinkage Capability

Loss of ActuatorCapability

Loss of Electiricity

Failure ofMechanical

Component ofActuator

Loss of steeringcommands from

Flight ControlComputer

Loss of steeringcommands fromRemote Control

Receiver

Failure of WireHarness

Loss of BatteryCapability

Failure of GroundStation

Failure of On-BoardSystem

1E-6

1E-5

Loss of steeringcommands from

Backup Controller

Loss of steeringcommands fromMain Computer

Failure of HeartbeatMonitor to switch toBackup Controller

3E-31E-4

Failure of MainComputer to

discontinue sendingheartbeats.

Internal failure inHeartbeat Monitor

Heartbeat Monitorswitches incorrectlyto Backup Contr.

Loss of steeringcommands from

Backup Controller

1E-3 1E-4

1E-3 1E-4

Fault Tree from FHA

MechanicalComponent of

Actuator

BatteryCapability

WireHarness

On-BoardSystem

GroundSystem

Steering commandsFrom Flight Control

Computer

Electricity

Steering command from RemoteControl Receiver

MechanicalLinkage

Capability

Actuator Capability

Simplified Block Diagram

PSSA : Monte Carlo Simulation

1 2 3

4

5 6

7

overall =

1 + 2 + 3 + (5 + 6) × 4 + 7

Page 46: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Frequency Comparison

.000

.004

.008

.012

.017

0.00290 0.00300 0.00310 0.00320 0.00330

Overlay Chart Same order as Inputs

MechanicalComponent of

Actuator

BatteryCapability

WireHarness

On-BoardSystem

GroundSystem

Steering commandsFrom Flight Control

Computer

Electricity

Steering command from RemoteControl Receiver

MechanicalLinkage

Capability

Actuator Capability

PSSA : Monte Carlo Simulation

Normal curve fit gives = 3.1×10-5

= 7.0 ×10-5

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4 Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

Mean = 0.00

0.00 0.00 0.00 0.00 0.00

B4

1E-5 1E-5

1E-5

1E-51E-6

1E-6

1E-6

Page 47: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

PSSA : Reliability Goals

General Aviation Loss Of Aircraft (LOA)

10 / 100,000 flight hrs = 1E-4 / flight hr

60%- Mechanical system failures- “Other” external causes

Human error plays significant roll in UAV

10%Reliability GoalLOAFlight Control= 1E-5

Page 48: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Human Errors : Introduction

Direct or Indirect Intentional or Unintentional

Flying into Electrical Lines

- Mission planner

- Ground control

- Maintenance

Page 49: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Human Errors : Human Safety and Reliability

Increased Mission Success

Increased Safetyof ROA and Environment

Better Working Environment

Increased Worker Safety

Reduced DelaysDue to Injury

Increased Worker Reliability

Increased ROAReliability

Page 50: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Human Errors : Working Environment

Some important factors and issues

Information - There are power lines here

Documentation - Stay 500 feet from power lines

Communication - We should move away

Workload - What? I’m busy

Visual/Aural Alerts - Warning!

Training - What do I do now?

Page 51: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Human Errors : Environment

Possible Dangers in the Environment High workload / Time critical workload / High

stress Unnoticed errors / no quality assurance Too many details to consider Hazardous equipment and materials Distractions

AND

Execute Mission(GCS)

6.0

Execute Mission(UAV)

5.0

Receive Mission

Assignment

3.0

Maintain Equipment

2.0

Manage Organization

1.0

AND

ANDAND

GO

NO GO

Prepare for mission

4.0

Each Top Level Function has a Different Environment

Page 52: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Human Errors : Launch Site Setup

Major Dangers: Suggestions:

High workload

Unnoticed errors

Hazardous equipment and materials

Weather and terrain

Document procedure

Range safety officer

Labels and color

Information about launch site

before arrival

Familiarization with all equipment

Page 53: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

New technology

Fault tolerant software Fault tolerant system architecture

Page 54: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Fault Tolerant Design: Software

LPE Step 1 Mission Objective Abstract Mathematical Language

Mission Objective

4)(: UloperationaAssumption t

|.|)(..: DposvuloperationaTtUuGoal tt

Page 55: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Fault Tolerant Design: Software

LPE Step 2 Mission Plan Flowchart

Language Formal Proof

Page 56: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Fault Tolerant Design: Software

LPE Step 3 Control System Destination Vector Formation Vector Proven Algorithm Automatically

Generated Code

Page 57: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Fault Tolerant Design : Software

Open-Control Platform

APIReal-Time Reconfig.Mediator

High-Level Abstraction

Located On-Board

LPE Step 1Math. Expression

LPE Step 2Flowchart Validation

MPC, Control, Communication

LPE Step 3Executable CodeSeveral LanguagesCode Validation

Page 58: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Fault Tolerant Design : system architecture

PrimarySensor

SecondarySensor

Rotor(Mech.systems)

Actuators

Power plantsystem

Generator

RMaxbattery

HB Monitorand Steering

Relay

SteeringCommandsMain Flight

Computer

BackupFlight

Controller

Sensordata

BackupBattery

Trickle charge

Primary Avionics DC Bus

Secondary Avionics DC Bus

Page 59: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Strategy for showing compliance

Today: No Certification basis for unmanned aircraft

The “5-year plan”:1. Demonstrate product2. FAA cooperation3. Initial NPRM4. Amendments to FARs 5. Start formal Certification process

Page 60: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Structure is not so expensive

GTMax is already flying

Certification PlanActivity

Application to FAA O

Develop. Certification Basis

GCP Develop.

Cert. Schedule Develop.

Initial Type board meeting O

Test Plan Submital

GCP Review and Approval

Interm. Type board meeting O

Drawing Release

Prototype 1 Fab/Assemble

Prototype 1 1st FLT

Envelope expansion

Load level survey

Systems/Weather/Lightning

Prototype 2 Fab/Assemble

Prototype 2 1st FLT

Envelope expansion

Performance & HQ

Mod into GTV

GTV Ground Tests

Rotor & XMSN Bench Test

Static tests

Final Type Board Meeting O

Certification O

Year 1

Tests for Autonomous flight & Control system

Page 61: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Conclusions

Summary Further study

Page 62: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

What was accomplished Suggested Certification basis Functional Analysis, FHA, PSSAQuantified System ReliabilityConsidered Human FactorsDeveloped fault tolerant flight

controlProposed strategy for compliance

Page 63: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Further Study

Current work to include UAVs in FARs

Obtain more accurate failure ratesAnalysis for aircraft level reliabilityComplete safety assessment

process on all aircraft systemsDevelop systems through

operational experience

Page 64: System Safety Risk Management: An Autonomous UAV Example from a Course on Safety By Design and Flight Certification Dr. Daniel P. Schrage Professor and.

Questions ?

Thank you