ADATM white p. Oct. 2015 v 08

C&CAS (Control & Collision Avoidance System)

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Ciconia [email protected]

+972507563101

Ciconia White Paper 01:

Contingency plan – safe integration of UAS in the air space

The ADATM (Autonomous Dynamic ATM) approach

The UAS market is fast growing. Near misses happen on a weekly basis. A safety

system must be put in place in the very near future. This paper suggests a contingency

plan to be completed in 3 years. The plan will secure existing aviation and allow as

much use of UAS as possible. This contingency plan will serve as the first build stage

of the UTM strategy: ‘UTM 0’. If adopted, it will allow professionals to lead the

process; otherwise, irreversible decisions might be taken. The ‘UTM 0’ build will be a

part of the NASA UTM 1 build. https://prod.nais.nasa.gov/eps/eps_data/162405-OTHER-001-001.pdf

It is highly advised that a well thought out safety system (collision avoidance system)

serve as the base of a UTM system. We recommend that the ‘C&CAS’ (Control &

Collision Avoidance System) will be onboard all members of the “low & slow”

community in less than 3 years to avoid mid air collisions and unauthorized

penetrations of CTRs and other No Fly Zones. The C&CAS has a smart collision

avoidance and limitations enforcement algorithms specially designed for that market.

C&CAS guidelines:

The ATM (or UTM) will be decentralized. However, the regulator will set the

boundaries within which all participants will operate.

All flying platforms, manned & unmanned, flying “low and slow” will be

equipped with a common Control and Collision Avoidance System (C&CAS).

Transmission of coordinates will be made via radio (not cellular, no internet)

Pre flight coordination is made via cellular (or satellite) and internet.

C&CAS will:

o Enforce no fly zones (CTRs)

o Prevent mid air collisions between flying objects equipped w. C&CAS

o Enforce other limitations on UAS operations (speed limits for example)

o Be ADS-b compatible

o Fit the UAS market: price, weight and power

Once C&CAS is mandatory, all UAS producers will sell UASs with C&CAS

onboard. All users will know they may fly UAS only if C&CAS is installed. Thus,

unsafe encounters will be a result of criminal activities and not of careless use!

C&CAS was developed by Ciconia and tested by the Israeli Air Force.

Ciconia comprises a group of Israeli experts in ATM and aviation.


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Centralized ver. Decentralized Traffic Management:

A centralized system must know in real time where all participants are and must hold real

time communication with all participants at all times. If those conditions are met, a

centralized system may, theoretically, control traffic. However, the price of centralized

control is limited use of the air space. For example, UAS 1 is planned to fly along street A.

UAS 2 is planned to fly along street B. However, street 2 and 1 intersect. Therefore, UAS 1

is allowed to enter the cross-roads only after UAS 2 has passed it. But, UAS 2 was delayed

some 200’ before the cross-roads. Thus, UAS 1 is not allowed to conduct its mission. UAS 1

must wait. And this is only the beginning. UAS 1, after crossing street B is planned to cross

street C, which he needs to cross before UAS 3… and so on.

If there are hundreds or thousands of UAS flying in a city, the system would be over-

saturated.

A decentralized system would set boundaries. For example, let UAS 1, 2 & 3 fly between

08:00 and 08:30 along streets A, B & C. The C&CAS would prevent them from colliding with

each other. Only the UAS or manned platforms in a risk of collision will be directed as to

how to maneuver themselves out of risk.

A decentralized system is much more efficient than a centralized one since it allows much

better use of the air space. However, a decentralized system must have a good collision

avoidance system in place.

System guidelines:

All platforms will be equipped with C&CAS (Control & Collision Avoidance System)

Basic C&CAS (inexpensive, low weight & power) for basic users (hobby, backyard use)

Robust C&CAS for fully autonomous beyond line of sight users

C&CAS will be ADS-b compatible

ADS-b-in may add a collision avoidance algorithm (same as C&CAS) ADS-b-in-cas

All manned platforms flying “low & slow” will install either ADS-b-in-cas or C&CAS

C&CAS sub systems:

ADATM server: central unit, may delegate authority to regional servers, connects to

platforms via internet (cellular / satellite) operated under regulatory agencies

C&CAS, onboard platforms, include:

o Basic C&CAS: GPS, low power radio, processor, autopilot interface unit, SIM card

o High end unit: basic + user interface, inertial unit and satellite communication


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C&CAS principles of operation:

Before takeoff:

C&CAS, via SIM, connects to a server. The server automatically:

o verifies drone’s registration

o verifies drone’s software version

o if needed, downloads latest software version to drone

o downloads to drone notices, limitations and no fly zones relevant to that specific

drone (location & type) for that time

o approves (or requests a change in) the flight plan

o sends green light (takeoff permission)

After takeoff C&CAS (onboard drones and manned platforms):

o sends (low power transmission) and receives GPS coordinates

o calculates trajectories

o enforces limitations (right of way to manned platforms, max range, no fly zones,

geo fences, max density / altitude)

o in case of a risk of collision between platforms, C&CAS produces steering

commands to be displayed to pilots or injected to auto pilots

o Runs BIT (Built In Test) all time

Communication system:

Can be integrated with ADS-B in, though require adaptation from the ADS B.

Low power transmission for C&CAS users: o 3 – 4 km - helicopters and light planes o 2 – 3 km - drones

Narrow bandwidth / very short burst

Sophisticated algorithm for further bandwidth saving

Communication with central control is:

o not for real time safety information

o made through cellular or satellite (IP communication)

All real time safety transmissions are made through radio

Communication traffic load:

o Each packet consists of 128 bites

o Max number of platforms in the air, at the same time, within a 4 km radius: 1000

o Average transmissions per second: 2

o Required bandwidth: 256kb

Comments:

1. The numbers above are higher than the real ones. The above bandwidth

calculation demonstrates that CAS doesn’t exceed bandwidth capacity.


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2. Critical safety information is transmitted via radio, other info is sent through

internet, via cell phone / satellite.

3. C&CAS transmissions are sent and received only by the drones and manned

platforms in close proximity. No ground control is involved.

Conflict resolution and conflict control:

Conflict resolution: the actions taken to avoid a real risk of a mid air collision

Conflict control: the actions taken to control the number of potential conflicts. For

example: geo fence, limitations on ‘beyond line of sight operations’, limitations on the

number of platforms in a given space at the same time (density control), speed limits, are

all means to control the risk of a mid air collision.

Conflict resolution system: a safety system that tells pilots, on time, how to avoid collision

(‘turn right and climb’), or, takes control via autopilot in case of a UAS. This paper suggests that

as a critical safety system, conflict resolution must be based on radio communication (not

internet / cellular). When everything fails, the conflict resolution is the last available measure

to be taken to ensure safety, thus it must be highly redundant and reliable.

Conflict control: the regulator controls the number of potential conflicts by limitations of different kinds. Geo fence, vertical separation and maximum density limit and speed limits are examples of conflict control means since they reduce the number of potential conflicts. All limitations and limitations’ algorithms are stored in a central server or a network of regional servers. The servers send the relevant limitations to all platforms, mostly preflight. Conflict control may be communicated via internet and cellular or satellite. In-flight, C&CAS enforces the limitations (autonomous platforms) and supports pilots of manned platforms or remote piloted platforms. Two layers ensure the safe integration of UAS- conflict control & conflict resolution:


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Classes and CTR enforcement:

1. C&CAS class is determined according to the nature of the user: from basic configuration

for ‘back yard’ user, to full configuration for ‘non line of sight, no cellular coverage’ user:

a. Class A: very basic, single GPS receiver, single radio, processor, SIM card on the

remote control unit (<$100?)

b. Class B: highly redundant, 2 GPS, 2 radios, 2 processors, IMU, SIM card, sense &

avoid

c. Class C: same as B + satellite communication for ground station

2. Authorizations by class:

a. Class A: “back yard use”: line of sight, 600’ radius, must have visual contact at all

times, emergency landing capability, all time communication between remote

pilot and UAV (C&CAS enforces radius limit)

b. Class B: beyond line of sight, day & night use, only under cellular coverage

c. Class C: can operate in areas where cellular coverage is partial / missing

d. Class D: manned platforms

3. Flight procedures:

a. Class A: power on, wait for green light, keep 300’ radius. Fly!

(Via internet, cellular / satellite, server verifies: UAV registered, has updated

software, if needed, latest version downloaded. The Server switches on green

light. The server knows the UAV location. No need for user interface, though UI

is optional)

b. Class B: file flight plan, get clearance, take off

4. CTR enforcement:

a. All CTRs are defined to the C&CAS as a no fly zone, which C&CAS enforces.

b. CTR ground control will be equipped with a C&CAS unit. Thus:

i. All drones will identify the CTR as an object they must avoid

ii. On board C&CAS will not let drones to penetrate the CTR geo fence

iii. Onboard pilots will get an emergency alert and steering commands to

escape the CTR.

iv. The controller’s C&CAS unit will indicate any violation of the CTR by an

equipped platform and also its exact location as well as identification of

the intruder.

v. As result of the above means, any penetration of the controlled area will be a an

intentional violation of the law and not a mistake or negligence.


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C&CAS – Class A: Basic configuration:

The basic configuration will be installed on a UAS that will be in use in limited range and in

constant visual contact & control of the remote pilot.

The server on the right is operated under the regulator’s authority. Once connected to a

platform (in class A, the server connects to the UAV via the pilots’ remote control unit) it

verifies the platform’s registration and its software version. If needed the server downloads

the latest software version to the platform. Then the server initiates a BIT (Built In Test) in the

C&CAS and sends the C&CAS onboard all updates (no fly zones, geo fences, CTR updates, etc.)

Radio communication (TX – transceiver and RX receiver) is low power, among flying platforms

in close vicinity. No central ground control receives the C&CAS radio communication.

SIM card, in the remote control unit, is used to connect to the internet for pre-flight

information.

Satellite communication in the remote unit for operation beyond cellular coverage.

C&CAS sends steering commands to the auto pilot via UAV autopilot interface unit using

MAVLink (lower left of the drawing)


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C&CAS - Class C: fully autonomous, beyond line of sight & no cellular coverage configuration.

The regulator will set limitations for the use of UAS in fully autonomous mode. This may be

allowed in remote areas, designated areas or in specific delineated areas (using geo-fence).

However, C&CAS provides means for fully autonomous UAS operations. Class C configuration is

highly redundant and reliable. Thus, the UAS will operate according to a pre-planned program

while safety measures will be executed by C&CAS commands.

For example: a UAS is launched to conduct a fully autonomous mission - power line /

pipe line inspection. Three fire fighter helicopters are operating nearby. C&CAS

onboard the UAS detects that density limit will be violated; therefore, C&CAS will divert

the UAS to avoid interference with the fire fighters, even if there was not a risk of a

collision.

In C&CAS – class B & C, all sub units are duplicated, the 2 GPS receivers are of different GPS

systems and an inertial unit is in place in case both GPS systems do not provide accurate

location. Class C uses satellite for preflight communication for operations in areas with no

cellular coverage.

If a pilot is in the loop (manned or a remote pilot) then the steering commands will be

displayed to the pilot (upper left of the illustration below). If a remote pilot does not obey the

steering commands, the C&CAS will take control via the autopilot.

A back up battery ensures power supply in case the platform fails to power the C&CAS.


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C&CAS class D – manned helicopters and planes. C&CAS class D doesn’t interfere with the

controls. Rather, it provides pilots with accurate steering inputs to avoid a mid air collision.

Regulators set the rules C&CAS enforces:

• All platforms fly above roof tops except for landing & takeoff

• Limited speed below roof tops

• UAV / RPV up to 700’ (? TBD) AGL except for vertical climb

• Manned platforms above 1000’ (? TBD) AGL except landing & take off

• Minimum distance between manned & unmanned: 250m (? TBD)

• Density parameters: number of air platforms of all kinds in a given space

• Priorities (Medical evacuation before VIP, Etc.)

• Initiates and approves C&CAS upgrades

• Updates are spread all over the country via the internet to all servers

• Delegate authority to regional authorities (geo fence for example). Regulator, on the

national level, sets the boundaries in which regional authorities operate.

Density control mechanism enforces the density limits, the max flying elements in a given

space, as set by regulator.


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C&CAS qualities and features:

C&CAS: strong, reliable, redundant collision avoidance safety layer

Allows formation flight while maintaining safety

Manned and unmanned operate together in harmony

Allows regulator to control the risk of collision (conflict control)

Dynamic density control

Safe operation beyond line of sight

Where cellular coverage is unavailable, communication via satellite

Data collection and machine learning mechanism will ensure continuous improvement

Regulator set priorities C&CAS enforces

Documents

ADATM white p. Oct. 2015 v 08