Philipp Hartmann

Unified Approach for Velocity Control and Flight State Transition of Unmanned Tiltwing Aircraft

This paper presents a unified approach for velocity control of tiltwing UAV within their entire flight envelope ranging from hovering flight to wing-borne flight. With their capability of VTOL operation and hovering in combination with long endurance and high payload capacity a tiltwing aircraft offers multiple benefits in UAV applications. Due to significant changes in flight mechanical characteristics during transition from thrust-borne to wing-borne flight the control of a tiltwing, in particular for fully automated flight, is challenging. The presented velocity and flight state transition controller includes a mapbased feedforward controller to maintain trimmed straight-lined flight and utilizes virtual control surfaces to provide a unified attitude control scheme. Changes of flight state are conducted by a dedicated flight state transition controller. Flight state trajectories are defined deterministically and safely with respect to flight envelope limitations. The control concept avoids any differentiation between discrete flight states. The implementation for the RWTH Aachen unmanned tiltwing demonstrator is based on characteristic flight mechanics data gathered in wind tunnel investigations. Flight tests were conducted and results indicate very good performance of the controller within the entire flight envelope.

Erratum to: Administration of 17β-Estradiol Improves Motoneuron Survival and Down-regulates Inflammasome Activation in Male SOD1(G93A) ALS Mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease manifested by the progressive loss of upper and lower motoneurons. The pathomechanism of ALS is complex and not yet fully understood. Neuroinflammation is believed to significantly contribute to disease progression. Inflammasome activation was recently shown in the spinal cord of human sporadic ALS patients and in the SOD1(G93A) mouse model for ALS. In the present study, we investigated the neuroprotective and anti-inflammatory effects of 17β-estradiol (E2) treatment in pre-symptomatic and symptomatic male SOD1(G93A) mice. Symptomatic mice with E2 substitution exhibited improved motor performance correlating with an increased survival of motoneurons in the lumbar spinal cord. Expression of NLRP3 inflammasome proteins and levels of activated caspase 1 and mature interleukin 1 beta were significantly reduced in SOD1(G93A) mice supplemented with E2.

Unified Velocity Control and Flight State Transition of Unmanned Tilt-Wing Aircraft

This paper presents an approach for velocity control of tilt-wing aircraft over their entire flight envelope, ranging from hovering flight to wing-borne flight. With their capability of vertical ta...

Mission Control Concept for Parcel Delivery Operations Based on a Tiltwing Aircraft System

This paper presents a mission control concept for flight operations of a fully automated aerial parcel delivery system. The parcel delivery operation requires long distance flight as well as landing on small platforms also in challenging weather conditions. A tiltwing aircraft was selected for this purpose, because it best combines vertical take-off and landing capabilities with efficient and low noise cruise flight. Key challenges to be solved for this task were the fully automated control of the tiltwing aircraft during transition between hover and cruise flight. Safety procedures, e.g. during transition and during cruise flight, required that the mission control system was well harmonized with the basic flight control system. In this contribution focus is set on the mission control system, which is augmenting the flight control system by doing the overall phase of flight management. This includes operational and safety procedure handling, as required for an automated beyond visual line of sight operation. In cooperation with ‘DHL Parcel’ the tiltwing aircraft system was deployed within a three-month Parcelcopter delivery trial operation in the Bavarian Alps, working as intended and demonstrating the robustness and reliability of the mission control system.

Nonlinear Model Predictive Flight Path Control for an Unmanned Powered Paraglider

This paper describes a model preditictive control scheme for the horizontal flight guidance of an unmanned powered paraglider (PPG). These aircraft are characterized by their comparatively high wind-to-airspeed ratio and slow, nonlinear flight dynamics. The proposed control scheme consists of two cascaded loops: The inner loop is the heading controller, which is implemented using conventional feedback control; the outer loop controls the horizontal flight path and is implemented using a model predictive controller. Due to the high wind-to-airspeed ratio, wind needs to be taken into account during prediction. To this end, we adopt a simple and robust wind estimation, based only on inertial velocities and heading information. To solve the computationally demanding nonlinear, constrained optimization problem we use a domain-specific heuristic enabling the implementation on a microcontroller. The control scheme is validated using simulations and flight tests, demonstrating good, reproducible flight path following capabilities.