Florian Holzapfel
Lehrstuhl für Flugsystemdynamik /Institute of Flight System Dynamics
Technische Universität München

Speech Title:  Addressing Control and Dynamics Challenges of eVTOLs

Abstract:  

Technical progress in fields like electric powertrains and energy storage, miniaturized sensors like MEMS IMUs, lightweight construction, or a tremendous rise in embedded computing power for safety-critical applications has sparked the third revolution in aerospace, leading to a new type of aviation called advanced aerial mobility (AAM), which in China is also known as the low altitude economy. Electric vertical take-off and landing vehicles (eVTOL) are the most visible representatives of AAM.

They are leaving the classical learning curve of previous aerial vehicles at many points. Most notably, the propulsion system becomes part of primary flight controls, where the topology and dynamics of the so-called lift-thrust units (LTU) have a crucial influence on the controllability of the system, especially under failure conditions. In vehicles that combine powered and wing-borne lift, the LTUs and classical control surfaces and tilt units feature very different dynamics, which must be adequately coordinated to feature desired response characteristics. The complex aerodynamic interactions between the different elements and the operation of rigid propellers at unusual slipstream conditions lead to significant uncertainties.

A consistent design and control methodology developed at the TUM Institute of Flight System Dynamics over the last ten years will be presented to provide a safe vehicle with guaranteed performance characteristics. First, maneuverability requirements based on desired response models are derived. Using an uncertain simulation model, the LTU topology can be optimized to push the probability of failing to comply with the maneuvering requirements below the admissible threshold value.

Dynamic extended incremental nonlinear dynamic inversion (dynamic E-INDI) is then used with an active control allocation method to provide the desired closed-loop characteristics (response, disturbance rejection, and stability margins) despite control effectors with different dynamics.

The methods presented have been applied to vehicles between 5kg and 2.7 tons, with especially some of the larger ones already flying.

Bio-Sketch: 

Florian Holzapfel is Full Professor at Technische Universität München (TUM). After his diploma in Aerospace Engineering and a short industrial attachment, he pursued his Ph.D. in nonlinear adaptive flight control of UAVs at TUM from 2000 to 2004. From 2004 to 2007, he was a flight simulation and control project leader at IABG mbH in Ottobrunn, Germany.

In October 2007, he joined the TUM Institute of Flight System Dynamics (FSD) as its director, covering modeling, simulation, guidance, navigation, and control of aerial vehicles and aspects of avionics, safety, and certification.

TUM-FSD is dedicated to applied research, following a holistic approach from fundamental research to product development.

In close collaboration with national and international research organizations, but preferably with small and medium-sized enterprises and start-ups, his institute contributed to the development of different eVTOLs over the last decade, including multicopters, lift-and-cruise, and vectored thrust configurations.