Virtual Design and Testing of an Autonomous Rescue Drone Speeds Up Product Development

AVILUS was founded by Ernst Rittinghaus and Ph.D. students of Professor Dr.-Ing. Florian Holzapfel’s Institute of Flight System Dynamics at the Technical University in Munich (TUM). The Ph.D. students, including Niclas Bähr, Max Söpper, and Daniel Dollinger, were working in the areas of flight controls, system architecture, and flight physics when Rittinghaus approached them with the need for a “flying stretcher.” In their free time, they developed a technical concept for the flying stretcher within one week.

“Ernst liked the concept so much that he said, ‘Let’s do this,’” Söpper, cofounder and CTO at AVILUS, says. “He wanted to build a prototype and demonstrate that such a scenario can work.”

The idea eventually evolved into the concept of drone-based evacuation systems, and the value proposition set the groundwork for AVILUS. Evacuation drones are invaluable in remote or hard-to-reach areas where the lack of infrastructure or challenging terrain hinders traditional rescue operations. The drones’ ability to navigate difficult landscapes quickly and efficiently makes them an ideal solution for delivering urgent medical care or evacuation services in such locations.

Drones also reduce safety risks since they are operated remotely and don’t need pilots or medical personnel to be on board or to enter potentially dangerous areas. This allows them to do more with less staffing.

Going from concept to creation can be a long and challenging journey for technology companies. Like most startups, AVILUS started out very small. “In the beginning, we were a very small team of about five to eight people at the Institute of Flight Control System Dynamics,” Dollinger, cofounder and head of design, says. “We started with a blank sheet of paper and decided to build the drone from scratch.”

Building the aircraft came with many challenges. The team needed to learn how to make the structure from carbon fiber and aluminum hybrid assembly. They also needed to gain a lot of knowledge on building the vehicle’s electrical powertrain. And they had to do everything on a limited startup budget.

Starting with a blank slate ensured that the vehicle could meet the precise needs of rescue teams without the compromises that might come from adapting existing vehicles. By adopting a minimalist design, they could also cut the costs and time of production considerably.

“We wanted to provide a drone with the capabilities of a rescue helicopter, but at a fraction of the price of a helicopter,” Dollinger says.

From the initial concept of a rescue drone, the product has evolved into a full rescue system named DRONEVAC^©, consisting of the MEDEVAC evacuation UAVs, or Grille drones, a mobile ground station, and further equipment.

One of the keys to the success of the AVILUS team was adopting Model-Based Design, a methodology that uses simulation by using modeling tools to design and analyze systems before they are fully built. Model-Based Design allows engineers to create, test, and iterate systems within a virtual environment, significantly streamlining the development process from conceptual design through implementation and testing.

The use of Model-Based Design and MATLAB^® made it easier to perform the hardware-in-the-loop tests. The team used Embedded Coder^® to transform the Simulink models from high-level algorithms into low-level C code that could run on the drones’ embedded processors.

“We usually start on an interface database, which is then used to create a Simulink model template with input and output ports based on your physical system architecture,” Dollinger says. “When we implement our algorithm, this template model becomes the design model. From this design model, we generate the code and then integrate it into our embedded framework based on the hardware we have.”

During hardware-in-the-loop testing, the real-time system generates synthetic sensor data, representing what the sensors would perceive during an actual flight. This data is fed to the hardware components being tested, such as the flight control computer, to see how they react to various flight scenarios.

After the hardware-in-the-loop tests, the team conducted “tethered flights,” which involved securing the aircraft to a pole that allowed the vehicle to move up and down without full airborne risks. This setup provided a safe environment to test the aircraft’s behavior under near-real conditions without the full risk of free flight. After that, the system was ready for full flight tests.

AVILUS has already delivered its first product, the Grille drone. But it has not stopped its research and development. Thanks to the design process the AVILUS team created, they are rapidly improving their vehicles and shipping new ones.

“The great thing about Model-Based Design is that it’s easy to make changes to the model because we’ve already set up the processes and toolchains,” Söpper says. “We have built up the processes, the tool structure, and the team to do the same thing again for new design iterations. We expect that our second product will take only one-fifth the time than our first since we can leverage existing models.”

The team is currently flight-testing their second unmanned aircraft and has started building a third one with additional functionalities. However, building every new aircraft becomes faster and easier as the team continues to expand its tool base and automate the design, test, and deployment process.

“Now we have all these experiences and have integrated the system that accounts for 80% of the challenging work,” Söpper says.

However, the AVILUS team’s biggest takeaway from this design approach is the improved process for learning and innovation as a startup, especially one in a highly regulated and sensitive industry.