Christoph Krause

Designing a system automation for a novel UAV demonstrator

The SAGITTA Research Demonstrator is a flying-wing UAV testbed. Its digital flight control system, which is being developed by the Institute of Flight System Dynamics of the Technical University Munich, consists of cascaded control loops. In a UAV operation scenario, different control loops need to be engaged at different times or connected in different ways to fulfill a given mission. This has to be done with respect to commands from the flight operator or even automatically based on sensor information or data link availability. The task is handled by a system automation module which is part of the flight control system software. Its structure and implementation are introduced and described in this paper.

Automatic flight path control of an experimental DA42 general aviation aircraft

An automatic flight path controller, as part of a modular automatic flight guidance and control system, is presented, along with initial flight test results using a DA42 M-NG flying testbed. The basic principle for the flight path control is a reference model based dynamic inversion of the kinematic equations of motions, with pseudo-control hedging to account for inner loop dynamics and plant response deficits. The kinematic frame flight path commands are transformed into body-frame commands executed by inner loop and autothrust controllers for transverse and linear force control. Initial flight test results are presented, demonstrating the feasibility of the path control approach, with good tracking and disturbance performance already during early flight testing.

Online trajectory generation using clothoid segments

In this paper, a trajectory generation algorithm within an integrated flight guidance and control system is presented. The approach uses clothoids to deal with the problem of curvature steps during the transition phase between straight line and arc flight. The algorithm is designed in interaction with a trajectory controller for 2nd order error dynamics, which hence requires more trajectory information than a conventional approach. The presented test results were obtained via in-flight tests with an experimental CS 23 aircraft.

Flightplan flight tests of an experimental DA42 general aviation aircraft

The recent emergence of unmanned aerial vehicles asked for both well-performing auto-flight systems and fly-by-wire architectures. Towards this end, the trajectory control module of an integrated auto-flight control system is introduced in this paper, which utilizes nonlinear second-order error dynamics of the position error and uses nonlinear dynamic inversion as a control methodology. Flight test results of a flightplan mission conducted on the institutes general aviation aircraft — a DA42 augmented with experimental fly-by-wire — are presented and the controllers performance is evaluated.

Development of an Automatic Flight Path Controller for a DA42 General Aviation Aircraft

The development of an automatic flight path controller, as part of a modular automatic flight guidance and control system, is presented, along with flight test results using a DA42 M-NG flying testbed. The basic principle for the flight path controller is a reference model based dynamic inversion of the translational equations of motions, with pseudo-control hedging to account for inner loop dynamics and plant response deficits. The kinematic frame flight path commands are transformed into body-frame commands executed by inner loop and autothrust controllers for transverse and linear force control. Requirements and verification activities are briefly discussed. Flight test results demonstrates the feasibility of the path control approach, with good tracking and disturbance performance.

Active Control Objective Prioritization for High-Bandwidth Automatic Flight Path Control

Inherent flight path control objective conflicts arise when energy rate or path curvature controls are saturated, precluding arbitrary flight path and speed target tracking, and arbitrary, concurrent vertical and lateral plane maneuvering. Flight envelope protection to protect airspeed and prevent loss of control are usually a last line of defense, and not an integrated strategy for smooth and deterministic control objective resolution during normal operation. In this paper, active energy rate and force distribution prioritizations, as integrated parts of the flight path controller of a modular flight guidance and control system, are presented. The prioritizations allow speed or flight path angle maneuvering to be prioritized in case of saturated energy control, with automatic speed priority at the edges of the envelope in order to ensure the energy integrity of the aircraft, and lateral or vertical plane maneuvering in case of saturated transverse force control. The approach is validated using high-fidelity simulations and initial flight testing.

Model-based Implementation of an Onboard STANAG 4586 Vehicle Specific Module for an Air Vehicle

This paper describes aspects of the system and model-based software design for a Vehicle Specific Module compliant to the NATO interoperability standard STANAG 4586 Edition 3 for Unmanned Air Vehicle Control Systems. The module enables controlling and monitoring of an air vehicle from a ground control station. It thereby serves as converter between custom interfaces of the controller on the one side, and an event-based communication based on data link messages described by the standard on the other side. The paper discusses important concepts of STANAG 4586 and outlines their adaption for the use in a manned research aircraft. Based on the system concept, the model-based software design in MATLAB Simulink/Stateflow is derived. Software details concerning a hybrid architecture merging auto-generated and conventionally programmed code as well as software interfaces are highlighted and presented in the context of modeling techniques for high-integrity systems.