Getting Some Air


Issue 3, September 2017

You may recognise CREATE UNSW from last month’s VIVID Installation feature. Well, they’re back - this time with some amazing UAV designs!

Unmanned Aerial Vehicles (UAVs) are already at the forefront of commercial minds, solving everything from autonomous pizza delivery, to tactical operations for defence. CREATE UNSW have been tackling some of the objectives head on. We caught up with the team to see what it’s all about.

CREATE UNSW has created several UAVs, and you’re now working on your third big design. Tell us a bit about what the goals are, and what’s driving the outcomes.

Individuals and companies are starting to see the potential of UAVs in civilian applications. Each of our UAVs are designed for competitions; they challenge this emerging technology and demonstrate the utility of UAVs for civilian applications, particularly in applications that will save people’s lives in the future, and that will improve workflow in the agricultural industry.

The MUGIN was designed for the 2016 UAV Outback Challenge: Medical Express, where they require teams to fly their UAV through a narrow corridor to a nominated GPS location more than 30km away. The UAV then has to search for a fellow called “Outback Joe”, survey a landing site, detect obstacles, and land autonomously once he is found. “Outback Joe” will then place a “blood sample” on board and arm an activation switch. The UAV will then take off autonomously, and navigate back to home base.

CROW was designed for the 2017 Land O’lakes Drone Challenge, where they required teams to be able to record orthorectified crop images, and autonomously determine an appropriate flight path to image a field, after having received a file that has field bounds. It also had to be capable of autonomously operating (i.e. take off, collect data, land, transmit data), as well as function unattended for multiple days, take multiple flights per day, use wireless connectivity to transmit and receive data, operate in winds of up to 32km/h, and use data connection to determine if weather conditions are safe for flight.

IBIS is being designed for the 2018 Outback Challenge: Medical Express. The competition is much the same as the 2016 competition, but now teams must detect an A2-sized landing marker and have the option to take on further autonomous related tasks, such as dynamic geofences.

Substantial planning goes into every build and modification along the way.

That’s quite a challenge - sounds like you had (and still have) your work cut out for you! It’s hard to gauge size from the images on paper, but when you see someone working on it, it looks massive. What’s the wingspan of these UAVs?

The MUGIN had a wingspan of 2.6m, CROW has a wingspan of 2m and IBIS is going to have a wingspan somewhere between 2m and 2.8m (it’s still under discussion).

Wow, that’s huge! What materials have been used in construction?

With our small budget we tend to use materials that are cheap. Most of the team have a RC hobbyist background so we wanted to develop UAVs that used materials that were widely available off the shelf. The MUGIN was a store-bought airframe with a plywood wing structure, carbon fibre rods to reinforce the fuselage, fibreglass fuselage, and a skin on the wing made from balsa and film. The wing was modified to attach the carbon fibre booms for the vertical lift motors using machined mounts from ABS.

With CROW we wanted to experiment with making our own fuselage and structural components. Due to time constraints, the wing was store-bought. It’s a foam core, Kevlar-skinned glider wing - yes, it’s very fancy but it’s lightweight and extremely strong, plus we got it at an awesome price! The tail control surfaces are hand-laid fibreglass on balsa wood. The interior structure of the fuselage is plywood, the fuselage shell is from hand-laid fibreglass, the vertical motor booms are carbon fibre, the motor mounts are machined from ABS (potentially aluminium, very soon) and the various fairings and joining mounts are 3D printed from ABS (they may be machined in the future).

In contrast, for IBIS we are aiming to experiment with laying other composites such as carbon fibre. None of us have had the opportunity to lay carbon fibre and use the vacuum bagging process, so it’s going to be an awesome experience. We are aiming to make everything ourselves, including the wing.

Controller with instructions!
This controller comes with some instructions!
Some innovative construction methods are used.

Anytime you can learn new fabrication techniques it’s a great idea, so you then have that knowledge for future projects! The wings are styled like a drone for vertical takeoff/landing but with forward propulsion once it’s airborne, is that right?

Yes! The style of aircraft we make is called a QuadPlane - quad motors for vertical lift and a plane to give it long-range horizontal flight. QuadPlanes have their pros and cons but for situations where you need high cruising speeds, endurance, and vertical takeoff and landing (VTOL) QuadPlanes are the best suited.

Tailsitters and tiltrotors can be more efficient but there is mechanical complexity in the design. In order to maximise the efficiency the props need to be variable pitched because in vertical mode, props that have a flat pitch perform more efficiently in static air (vertically). However, in dynamic air (moving horizontally) props with a sharper pitch perform better and provide more thrust.

QuadPlanes can take this to their advantage; because it can vertically take off, you can design your forward flight prop and motor to be efficient at cruising speeds, since you do not need to take into consideration the thrust requirements for taking off.

That’s awesome! It’s definitely a great hybrid. Blending easier landing with high forward speed is definitely a great idea. Was there an existing design leveraged for this style of UAV, or did you start from scratch?

When we first started working on a QuadPlane design back in 2015, there was only a few teams and hobbyists working on the designs and code for Ardupilot (a shout out goes to Andrew Tridgell and the team from Canberra UAV, and the Arduplane development team for working on developing the QuadPlane firmware).

One of the ones that caught our eye was someone named “wcolby” on YouTube who converted a Hobby King Bixlar 3 into a QuadPlane. This prompted us to convert our Bixlar 3 (that we used for training) to a QuadPlane. There were no plans available so it was pretty much “let’s strap some aluminium tubing from an old quadcopter, stick some motors on and let’s see what happens”. At this point in time the Arduplane firmware for QuadPlanes was still in beta so we had some interesting near misses. After learning the design quirks with the Bix QuadPlane, we transferred what we learned into the MUGIN.

CROW took some design features from Textron and Carbonix, such as the method of mounting the motors and the V-tail.

Nothing like bolting two ideas together to see what happens! What’s powering these UAVs?

The MUGIN was a hybrid system of a two-stroke DLE30 petrol engine with a 19-inch prop, and an X8 configuration of eight T-motor U7 KV420 electric motors running 18-inch props. It used two 6s 5000mAh LiPo batteries - one for each side. It drew a whopping 600 amps and had about a 3 minute flight time in vertical mode.

CROW was an all electric system. We had to optimise the power system and propulsion system to get more endurance out of the two 6S 5000mAh LiPo batteries. It uses four T-motor Antigravity 4006 KV380 running 14-inch props and one T-motor MN3110 700KV with an 8-inch prop. We can get around one hour in forward flight and five minutes in vertical flight.

For IBIS, we are going back to a hybrid system just for endurance and the energy density of fuel.

Wow - 600A for vertical flight! Fuel definitely makes sense there, and we can understand retaining hybrid technology to keep it all going! Tell us a bit about the special autonomous functions of your UAVs.

The MUGIN was designed for the 2016 Outback Challenge: Medical Express, so it was designed to be a long range medical delivery UAV. IBIS will have the same function as it is being designed for the 2018 Outback Challenge: Medical Express. These UAVs fly completely autonomously to a known GPS point, search for a target, find a suitable and clear landing spot, land, shutdown, collect a blood sample, start up and fly back home. They are designed for 60km round trips.

CROW is an autonomous agricultural surveying system. CROW can take off, survey a field, land onto a base station, recharge and transfer data to the base station completely autonomously. CROW will also check weather data and avoid flying if the weather is bad. It also has “scuttle buggy” landing gear, which allows the UAV to move on the base station to align itself to charge.

UAS team
UAS team looking at flight plans.
Learning UAVs
One of the learning UAVs.

It really is autonomous! With all that thinking going on, what sort of control system are you using?

On all our UAVs, we are big fans of the Pixhawk flight controller. Pixhawk is an open-hardware project aiming at providing high-end autopilot hardware to the academic, hobby and industrial communities, at low cost and high availability. When we first started we were using the Pixhawk 1 and now we have moved up to the newly released Pixhawk 2. It uses the open-source Ardupilot software. For all the capabilities it has it’s the cheapest, most robust flight controller; in my opinion, it’s as good as flight controllers priced at $5000+.

Ardupilot is the software we use on the flight controller. It’s a professional-grade open-source, unmanned vehicle Autopilot Software Suite, capable of controlling autonomous multirotors, helicopters, fixed-wing and VTOL model aircraft, ground rovers, model boats, model submarines and antenna trackers.

Paired up with the flight controller is a companion computer. A companion computer allows us to improve the autonomous capabilities of our aircraft. We run a stripped down version of Ubuntu MATE with ROS, which is a pseudo operating system designed for robotics. One major reason for using ROS is that it allows us to create nodes for each process, so if one process fails it will restart it without causing the aircraft to fall out of the sky. ROS has a lot of useful libraries for SLAM, image recognition and path planning.

“Not falling from the sky” is pretty high up there on the desired feature list, that’s for sure! What did you learn from the first few developments that could be used on a subsequent builds?

When we first started we had the good old hobbyist mentality, where we strapped things together and hoped they would work on the first try. That can work well but when you are in a competition with top teams you need to have a bit more structure in the design and manufacturing process, and allow plenty of time to test your design.

No matter how hard you work, things don't always go to plan.

We have now adopted this build process:

  • Break competition rules into functional specifications.
  • Split functional specifications into mechanical, electrical and software categories.
  • Decide on sub teams under each engineering team.
  • Explore conceptual design.
  • Undertake design and verification, which involves researching, testing concepts, developing the CAD of our aircraft and testing software on our spare UAVs.
  • Review the preliminary design.
  • Apply further design and verification, taking in the changes from the PDRs.
  • Finalise the design with a Critical Design Review.
  • Begin manufacturing.

Once manufacturing is completed, we then:

  • Test the aircraft in manual and make any necessary changes.
  • Tune the autopilot.
  • Test autonomous features and make changes.
  • Continue testing and making changes until we are happy with the UAV.

That’s a great procedure, and a solid process that can be applied time and time again. When did the UAS team get started at CREATE UNSW?

In early 2014, members in CREATE ventured into UAV research, and began experimenting with flight controllers and multirotors. We then decided to launch CREATE’s Unmanned Aerial Systems (UAS) team in July 2014, as a student-led project group that was run under CREATE. From there, we developed connections with academics who were researching the area, and we decided to enter a team to compete in the UAV Challenge: Medical Express competition in September 2016.

Fine tuning
Fine tuning never ends.
Learning UAV
UAS have several "learning UAVs" to help with experimentation and familiarisation.

Today the UAS team includes 30 undergraduate and masters students from electrical, mechanical, mechatronics, aerospace, computer and software engineering, and computer science.

That’s amazing. Thanks for taking us through this epic journey. We look forward to seeing IBIS take flight!

UAV Comparason
Left to Right: MUGIN, CROW, IBIS
MUGIN CROW IBIS (in development)
FLIGHT TIME 110 minutes 65 minutes 120 minutes
IMAGING SENSOR One angled target searching camera and one face down optical flow camera. Slantrange 3P - other sensors can be implemented. One angled target searching camera and one face down optical flow camera.
FLIGHTBOARD & NAVIGATION Pixhawk with Dual GPS modules - RTK Module set allows for accuracy of 3-10cm. Pixhawk 2 with Dual GPS modules - RTK Module set allows for accuracy of 3-10cm. Pixhawk 2 with Dual GPS modules - RTK Module set allows for accuracy of 3-10cm.
WINGSPAN 2600mm 2000mm 2000-2800mm
LENGTH 2000mm 1000mm -
HEIGHT (TAIL TO BASE) 500mm 450mm -
WEIGHT 10kg (including aiframe, electronics and sensors) 3.8kg (including aiframe, electronics and sensors) 6-8kg (including aiframe, electronics and sensors)
CRUISE SPEED 110km/h 100km/h 120km/h
STALL SPEED 45km/h 48km/h -
MAXIMUM ALTITUDE 1500m 800m 1500m
ENDURANCE 120km/h for one hour plus three minutes of vertical flight. 100km/h for one hour plus five minutes of vertical flight. Minimum 120km/h for one hour.
MTOW 12kg 4.2kg -
MAX. DATA RANGE - 520 acres/hr at 20m/s (assuming one large field and returning back to base station) or 5.2 acre to 70 acre fields in a 2.4km radius at 20m/s -

ATTENTION SPONSORS: UAV development is an expensive project, especially when experimenting with different styles of airframe and manufacturing processes. Therefore, CREATE UAS is looking for sponsors who can provide in-kind or financial support.

By sponsoring CREATE UAS you will have exposure to potential graduates who have practical skills with leadership qualities and technical knowledge that exceeds the experience and capabilities of normal students. You will also be investing in innovative technologies and ideas that will shape our future. You will also be part of the development of a booming industry.

Exposure to local communities will allow your company to directly market new products and services, build positive relationships with the club and the University of New South Wales, as well as with other companies that are involved with the project. Additionally, you’ll boost your brand awareness through media exposure and positive word-of-mouth. To find out more about sponsorship opportunities with CREATE UAS email uas@createunsw.com.au

Team with MUGIN
Some of the team with MUGIN.