Lilium is leveraging Speedgoat hardware-in-the-loop (HIL) testing solutions to accelerate the development of novel all-electric vertical take-off and landing (eVTOL) aircraft controllers. Speedgoat HIL simulators bestow Lilium Jet engineers the freedom to innovate and validate controller software in accordance with the airworthiness type-certification standards set by aviation regulators.

Lilium is pursuing concurrent type-certification with the European Union Aviation Agency (EASA) and its US counterpart in the Federal Aviation Administration (FAA). Interweaving the certification process with the development of complex airborne controllers, Lilium adheres to Aerospace Recommended Practice (DO178C/DO-331) of Model-Based Design, which underpins the control engineering behind the Lilium Jet. Lilium engineers deploy plant models directly from Simulink onto Speedgoat test systems that behave as digital twins of the Lilium Jet components against which aircraft controllers are continuously tested until full certification. Leveraging these state-of-the-art testing solutions from Speedgoat, Lilium was swift in securing the initial certification basis from both EASA and FAA regulators.

The EASA and FAA demand rigorous verification and validation of the aircraft controllers; Lilium accomplishes these certification tasks following an automated, end-to-end, requirements-based testing workflow that is enabled by Speedgoat HIL simulators. This workflow involves testing aircraft controller software on test rigs that simulate Lilium Jet subsystems, namely, the cockpit instrumentation, propulsion control, flight control, and electrical power systems. These test rigs are HIL test benches provided by Speedgoat in the form of cabinet-sized HIL racks which unite and house:

- Speedgoat test systems featuring the necessary aerospace protocols such as CAN, ARINC, and Ethernet as well as various analog, digital, sensor, and PWM connections;

- Lilium Jet controllers that are also connected to programmable DC power supplies, 1kA battery stack emulators, and breakout panels; and

- I/O routing switches for flexible I/O reconfiguration so that the same HIL simulator can be repurposed for different tasks and setups.

The Speedgoat HIL racks can thus emulate signals of the actual Lilium Jet components and hence create a realistic test environment for the controllers. Reducing time, cost, and risk with these proven HIL testing solutions from Speedgoat, Lilium engineers can focus on the central tasks of verifying and validating controllers.

Lilium continues to leverage Speedgoat solutions in preparation for the next certification milestone: ‘e-bird’ — a functional replica of the complete, fully integrated aircraft. Assembling the ‘e-bird’ involves system integration of the individual subsystems, which is an undertaking that is befitting of the highly scalable, modular, turnkey Speedgoat HIL test systems. Partnering with Speedgoat, Lilium is heading towards EASA and FAA type-certification, achieving airworthiness of the Lilium Jet, and, ultimately, inaugurating the first Lilium pilot for takeoff on the maiden pilot flight in early 2025.