Automatic TCAS Demonstration onboard Barracuda TCAS Demonstration onboard Barracuda ... • Barracuda Autopilot mode is changed to dedicated “Vdot-Mode ... IFR 6000 Ramp Test Set

Automatic TCAS Demonstration onboard Barracuda

Jörg MeyerProject Manager Sense&Avoid

CassidianCassidian Air Systems

COEMN1 Rechliner Str.

D-85077 Manching Tel.: +49 (0) 8459 81-79180

[email protected]

2© 2010 Cassidian - All rights reserved Page

Jörg Meyer

Contents

• Introduction

• Objectives

• Definition of the cooperative

Sense&Avoid system

• Human-Machine-Interface (HMI)

• Validation and Verification

• Flight Demonstration

• Consequences of TCAS usage

onboard UAS


Jörg Meyer

• Sense&Avoid is considered as THE enabling capability required to allow routine operation of UAS in non-segregated airspace

• UAS Roadmap Study concluded on a stepwise integration of UAS into the airspace.

• Initial step to allow operation in airspace classes A-C only (with special procedures for transit in and out), whereas a second step would cover operation in all airspace classes.

• Initial step excludes separation and collision avoidance against non-transponding intruders (considered technologically challenging)

• No separation capability is required, as separation (IFR vs. IFR and IFR vs. VFR) in airspace classes A-C is performed by ATC

• Project was initiated in autumn 2009, with flight demonstration being scheduled for June 2010

• Project was fully funded by Cassidian Air Systems

IntroductionFraming Conditions


Jörg Meyer

• Analysis of a potential solution for a cooperative collision avoidance system based on TCAS II to enable routine operation of the UAS in airspace classes A-C with special procedures required to transit to and from these airspace classes

• System demonstration as a risk mitigation for a future Initial Operational Capabilities (IOC) Sense&Avoid system

• System development according to the Barracuda development process, involving Validation and Verification

• Setup of a closed-loop Hardware-In-the-Loop Simulation (HILS) as a risk mitigation for in-flight demonstration

• Demonstration goal: In-flight demonstration onboard Barracuda UAS with a real intruder

ObjectivesKey Objectives


Jörg Meyer

Definition of the cooperative Sense&Avoid systemBarracuda cooperative Sense&Avoid system - Principal Setup


Jörg Meyer

Barracuda Collision Avoidance System and Control Authority

• TCAS was connected to Barracuda FCS and FCS plausibility checks are being performed

• TCAS RA is executed automatically, i.e. without operator approval, independent on data link

• Automatic execution was performed immediately after RA issue, i.e. without pilot or communication delays

• Barracuda Autopilot mode is changed to dedicated “Vdot-Mode”

• Barracuda Operator has the ability to abort the automatic execution at any time (and to command a different action using standard Barracuda control means)

• Barracuda Operator has the ability to enable/disable TCAS RA execution completely (safety measure not to interfere with other test points)

• Previous Autopilot mode (before TCAS activation) is activated after TCAS “Clear of Conflict” signal

Barracuda Collision Avoidance SystemControl Authority


Jörg Meyer

TCAS

10

20

N

S

EW

+20

–15

–00

+05

–07

+12

–10

Range circles, mandated by DO 185A

TCAS “TA Traffic” symbol

TCAS “Proximate Traffic” symbol

Barracuda Ownship Symbol

TCAS “RA Traffic” symbol

Selection of TCAS Traffic Display (on/off)

TCAS “Other Traffic” symbol

Human-Machine Interface (HMI)TCAS Intruder Visualisation on Map Display


Jörg Meyer

NAV

+20

10

20

N

S

EW

GS 170 TAS 192249/16

WPT01/048°12.1 NM

12:32

0.1L1.2°

α 02.3°1.0 g

QNH 1012

+05

Design� In critical situations

(e.g. imminent terrain conflict, sudden power loss, …), selecting TA ONLY will

- prevent the generation of new RAs

- convert existing RAs to TAs and force the UAV back to F-PLN

0 0 0 0

TA ONLY

TCAS

XPDR

IDENT

AUTO

TRAFFIC

Human-Machine Interface (HMI) TCAS TA on Command & Control HMI – TA Output


Jörg Meyer

NAV

+20

10

20

N

S

EW

GS 170 TAS 192249/16

WPT01/048°12.1 NM

12:32

0.1L1.2°

α 02.3°1.0 g

QNH 1012

+05

Design• Immediate fully

automatic execution of vertical manoeuvre proposed by TCAS

• Standard callout (limited to 2-3 repetitions) supplemented by text bar with alert details (vertical rate etc.)

• All HL-commands blocked while TCAS RA persists

TCAS CLIMB 1500 FT/MIN

0 0 0 0

TA/RA

TCAS

XPDR

IDENT

AUTO

Human-Machine Interface (HMI) TCAS RA on Command & Control HMI – RA Output


Jörg Meyer

• Barracuda System V-Model Development Process was applied, involving requirement definition and breakdown from system top level to equipment level

• Requirement engineering and tracing was done using DOORS

• In order to ensure requirements correctness and completeness, a validation matrix was set up to formalize the system validation activities

• Formal verification of the system was performed to ensure that the system design correctly implemented the requirements.

• Verification was performed using different means of verification, involving closed-loop Hardware-In-the-Loop simulations

• HILS setup consisted of the system under test embedded in a closed loop simulation involving:

• Flight Control System (FCS) of the Barracuda UAS demonstrator

• Communication system involving LOS data link simulation

• Ground Control Station (GCS) for UAS operator situation awareness and monitoring system operation

Validation and Verification


Jörg Meyer

Barracuda TCAS RIG

Patch Panel

HILS Computer

IFR 6000 Ramp Test Set

Directional Antenna

ARINC 429

Hub

Connector

Connector

Multi-FunctionMIL-STD-1553

PCI Card

Ethernet

4 PortRS422/485PCI Card

Analog I/OPCI Card

Interface to A/C Hardware

ConnectorARINC 429PCI Card

TCAS Equipment(Computer, MCU, Antenna)

Connector

IFF Mode STransponder

FCC Dat

a M

anag

er

Sha

red

Mem

ory

A/C

Sim

ulat

ion


Jörg Meyer

Intruder:

• Chase A/C was used, piloted by experienced Cassidian test pilot

• Intruder was equipped with Mode-S transponder, but not with a TCAS (Lack of TCAS is not considered limiting)

Environmental Conditions

• For safety reasons, TCAS test points were flown visually by the intruder pilot and therefore required good visibility

Safety Measures

• Barracuda FCS performed plausibility checks on the TCAS commanded manoeuvres

• Barracuda UAS Operator and Intruder pilot coordinated themselves through radio communication

• Barracuda UAS Operator had an ability to disable the coop. S&A system in total

Flight Test DemonstrationTest Setup and Safety Measures


Jörg Meyer

Test execution and Vertical and Horizontal separation

• Test points increased from approaches from behind to high closing speed frontal conflicts

• Each test point had been flown several times, confirming the results observed

• Vertical separation before TCAS activation has been around 50ft

• Horizontal separation before TCAS activation has been around zero

• Vertical separation at “Clear of Conflict” has been around 350ft, in line with expectations

Flight Test DemonstrationTest execution and results


Jörg Meyer

EUROCONTROL Unmanned Aircraft Systems – ATM Collision Avoidance Requirements:

• "Certification of any UAS equipage with ACAS II should be conducted on a case-by-case basis for each airframe/equipment configuration.”

• “It would need to be established that ACAS II surveillance was adequate for the purposes of collision avoidance, and that the UAS was able to comply with ACAS II RAs promptly and accurately.“

EUROCONTROL CAUSE study

• "Limitations in ACAS hardware (particularly antennae and their siting) may become apparent when ACAS is deployed on a UAS airframe, and limitations in the ACAS software (particularly tracking algorithms) may become apparent if the UASaerodynamic performance exceeds that expected from a commercial civil fixed-wing aircraft. These limitations will manifest themselves as degraded surveillance performance and lower reliability and quality of the tracking of targets."

• "These RAs require a response within a specified time, at an acceleration of a specified strength, to achieve a specified vertical rate. If for any reason the UAS cannot achieve this standard response the efficacy of the RA can be compromised."

Consequences of TCAS usage onboard UASRegulations


Jörg Meyer

• Automatic TCAS RA Execution has been certified for Airbus A380 (and will be extended to other Airbus A/C as well)

• Automatic execution of the TCAS avoidance manoeuvre is performed by a dedicated, specialized autopilot mode, being far more precise in following the TCAS defined resolution advisory compared to a human pilot, thereby reducing deviation from the expected trajectory

Consequences of TCAS usage onboard UASImpact of automatic TCAS RA execution

• Precise execution of the TCAS RA directly correlates with the risk of inducing new collision threats – the more accurate a TCAS RA is followed, the less induced new collision threats, thereby improving the TCAS risk ratio

• TCAS risk ratio also depends on the time duration between issue of a Resolution Advisory by the TCAS system and initiation of the execution of the TCAS RA– an automatic execution therefore leads to a decrease in risk ratio

Source: “Safety Analysis of TCAS on Global Hawk using Airspace Encounter Models”, Billingsley and Kuchar et. al., 26.05.2006


Jörg Meyer

• Suitability of the UAS platform itself needs to be considered (i.e. UAS climb/descend performance, ACAS antennae siting).

�This is no different to certification for manned aircraft, where compliance with the same requirements must be demonstrated.

• Requirement for prompt and accurate compliance with ACAS II RAs is an issue which needs to be covered by the design of a cooperative collision avoidance system based on TCAS together with the capabilities of the UAS FCS.

• Demonstrated solution is considered an intermediate step towards a product level system that will be applicable to any UAS which complies with the defined requirements for TCAS installation

Consequences of TCAS usage onboard UASWay Ahead

Documents

Automatic TCAS Demonstration onboard Barracuda TCAS Demonstration onboard Barracuda ... • Barracuda Autopilot mode is changed to dedicated “Vdot-Mode ... IFR 6000 Ramp Test Set