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mode, there will be a full manual control

option – indeed, the company is using

a standard short-range line-of-sight

system in the flight test programme. This

is a 5-10 km set-up, de Villiers says, with

custom options for longer range missions.

The system includes an antenna tracking

base station in a single-operator Pelican

case with a built-in screen.

“Right now, for long-range data

telemetry, we are using 800/900 MHz

and are looking at encrypted data links

for higher end clients who need them,”

he says.

Alti is considering providing a standard

data link for command and control and

video, but which again can be tailored to

customer needs in terms of characteristics

such as the frequencies used.

The ground control station (GCS) itself is

another area in which the company is still

considering its options. The software will

be a custom version of the QGC system

outlined above, while the hardware could

be supplied by Hungarian company

Horus, which makes and customises a

range of military flight cases, GCSs and

antenna tracking systems.

“We will offer a range of GCSs, and

the client can also add onto the system

as required,” de Villiers says. “Our

29

UAV development platform.

“PX4 has the potential to become the

backbone of the rapidly growing drone

industry,” says Lorenz Meier, the doctoral

computer science student at ETH Zurich,

who initially created the software. “The

PX4 software will be to drones what

Android is to many smartphones.”

PX4 is already in use aboard thousands

of small UAVs, says ETH Zurich, and

Meier argues that the partnership with

Qualcomm will extend it to the next

generation of unmanned vehicles, which

will be capable of completing far more

complex tasks and avoiding obstacles, so

the software’s range of functions is being

constantly enhanced.

As open source software, PX4’s

source code is freely available, and

any unmanned vehicle manufacturer

can tailor it to their own needs, as

smartphone manufacturers can with

Android, adding their own apps such

as camera controllers. It enables UAVs

to take off and land autonomously and

follow moving targets, for example.

Open source ground control

PX4 works with the QGroundControl

(QGC) mobile and desktop interface

software used to configure the system

and execute missions. Again initiated and

largely developed by Meier, QGC is also

open source software that also supports

open standards and provides full ground

station support to the PX4 flight stack and

MAVLink data links, and runs on Windows,

OS X, Linux and Android tablets.

QGC provides 2D and 3D aerial maps

with drag-and-drop waypoints, and

supports Google Earth. It also allows

in-flight manipulation of waypoints and

vehicle parameters via an EEPROM chip,

supports real-time plotting of sensor and

telemetry data and plotting of sensor logs.

It also supports the Universal Datagram

Protocol (UDP), serial radio modem and

mesh networks, and multiple autopilot

types in addition to PX4-based systems.

The MAVLink protocol supports up to 255

vehicles in parallel and allows custom

messages to be added.

PX4 also features several customisable

software packages including obstacle

detection and avoidance that links to the

flight control package, along with visual

inertial odometry, mapping, planning,

simulation and virtual flight testing.

“PX4 offers reliability, features, ease

of use and so on at a favourable price

point compared with other

s

ystems,”

says de Villiers. “I can’t think of any real

drawbacks with a PX4-based system for

our platform or applications. Clients have

the option to integrate payloads with the

autopilot, write custom code and more.”

Alti has developed its own flight control

algorithms with the help of a team of

software engineers based in Switzerland.

GNSS options

The company continues to look at

different GNSS options for integration

with the flight control system and,

because the UAVs are used all over the

world, solutions are likely to involve multi-

GNSS receivers. However, they are also

likely to be customer dependent, with

de Villiers emphasising that comms will

be tailored to the requirements of the

customer and the payload.

While most missions are likely to be

flown in pre-programmed autonomous

Unmanned Systems Technology

| June/July 2016

Alti Transition

|

Dossier

Integrated into the fuselage, the petrol engine drives

the propeller directly and is fixed to the composite rear

bulkhead using elastomeric anti-vibration mounts