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IASTED International Conference on Applied Simulation and Modelling, ASM 2011

作者： Ji, Yang Bals, Johann Department of System Dynamics and Control Institute of Robotics and Mechatronics German Aerospace Center Wessling Germany

ISBN: (纸本)9780889868939

Compared with traditional electric machines, switched reluctance machines exhibit a significant improvement on production, robustness and efficiency. However, some inherent drawbacks of those kinds of machines such as noise and high torque ripple at low speed have to be well managed. In the last years, some dedicated control strategies to overcome the high torque ripple of switched reluctance machines have been proposed, where an accurate mathematical model is often necessary. In this paper, a novel Mod-elica library for physical modeling of switched reluctance machines is addressed. Both linear and nonlinear models of switched reluctance machines are regarded. By using physical modeling approach with Modelica language, the maximal reusability, flexibility and range of modelling can be ensured. Furthermore, fundamental control units both for current based controller design and direct torque controller design are also incorporated into the library. The Modelica switched reluctance machine library allows quick virtual prototyping and simulation of a switched reluctance machine with various relevant controller. One application example with a 16 stator 12 rotor poles 4 phase switched reluctance machine is presented to illustrate the use of the developed Modelica switched reluctance machine library.

关键词： Reusability

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Inherent robust stability of driver support systems

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Science China(Technological Sciences) 1999年第4期42卷 437-448页

作者：王龙 J. Ackermann Robust Control Group Institute of Robotics and System Dynamics German Aerospace Research CenterD-82230 Wessling Germany)

Presented are the fact that the transfer function from the front steering angle to yaw rate is strictly positive real, irrespective of the uncertain mass and uncertain velocity, how to determine the positivity margin for this transfer function (some stabilization results are obtained), and how to check the positivity of a controller family. Furthermore,by exploiting the intrinsic structure of system equations and uncertainties, a nonconservative PID stabilization criterion for driver support systems is established. Some interesting results on positivity and connections of PID controllers are shown. Finally, some extreme point results on PID α-stabilization are obtained. These results give certain explanations and justifications for the simulation results performed at German Aerospace Research center.

关键词： driver support systems PID controllers positivity uncertain parameters stabilization car steering systems parameter space extreme point results.

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Multi-level power quality assessment towards virtual testing of more electric aircraft

Multi-level power quality assessment towards virtual testing...

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2010 9th International Power and Energy Conference, IPEC 2010

作者： Ji, Yang Bals, Johann Department of System Dynamics and Control Institute of Robotics and Mechatronics German Aerospace Center Muenchnerstr. 20 Wessling Germany

ISBN: (纸本)9781424473991

This paper introduces a multi-level power quality assessment approach towards virtual testing of more electric aircraft. Three levels with increasing accuracies are rough, approximated and exact power quality assessment. The requirement to the accuracy of power quality assessment strongly depends on different analysis jobs. With the multi-level power quality assessment approach, both sufficient accuracy and minimal cost can be ensured. Advanced steady-state analysis approaches for the switched power electronic systems with regard to the exact power quality assessment are introduced. The convergence performance of the applied steady-state analysis approaches is significantly improved by estimation of the state variables at steady-state using a generalized averaging technique. The proposed approach that has been implemented in Dymola is demonstrated by a pulse width modulated buck converter. ©2010 IEEE.

关键词： DC-DC converters

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Optimization based steady-state analysis of switched power electronic systems

Optimization based steady-state analysis of switched power e...

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2010 IEEE 12th Workshop on control and Modeling for Power Electronics, COMPEL 2010

作者： Ji, Y. Pfeiffer, A. Bals, J. Department of System Dynamics and Control Institute of Robotics and Mechatronics German Aerospace Center Muenchnerstr. 20 Wessling Germany

ISBN: (纸本)9781424474639

This paper introduces an optimization based approach towards steady-state analysis of switched power electronic systems. The convergence performance of the optimization is improved by the estimation of the state variables in steady-state. Accurate state variable estimation can be achieved by previously simulating a set of multi-resolution approximations - averaged models of the original topological model using generalized averaging technique. An unified harmonic state space representation for a wide class of power electronic systems is presented to allow automatical generation of the averaged models with selective approximation accuracy. The proposed approach that has been implemented in Dymola is demonstrated by a pulse width modulated buck converter.

关键词： State space methods

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Heterogeneous, multi-tier wheel ground contact simulation for planetary exploration

Heterogeneous, multi-tier wheel ground contact simulation fo...

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2015 ECCOMAS Thematic Conference on Multibody dynamics, Multibody dynamics 2015

作者： Lichtenheldt, Roy Hellerer, Matthias Barthelmes, Stefan Buse, Fabian Robotics and Mechatronics Center Institute of System Dynamics and Control Münchener Straße 20 Weßling82234 Germany

ISBN: (纸本)9788494424403

Today's growing scientific interest in extraterrestrial bodies increases the necessity of extended mobility on these bodies. Thus, planetary exploration systems are facing new challenges in terms of mission planning, obstacle and soil traversability. In order to fit the tight schedules of space missions and to cover a large variety of environmental conditions, experimental test setups are complemented by numerical simulation models used as virtual prototypes. In this context we present an integrated simulation environment which allows for using different available contact models, ranging from simple but real-time capable approximations based on rigid-body modeling techniques up to very accurate solutions based on Discrete Element Method (DEM). For this work, a one-point Bekker based approach and the so-called Soil Contact Model (SCM), which is a multipoint extension of the Bekker-Wong method taking soil deformation into account, are used. These two contact models are applied for homogeneous models with only one type of contact model for all wheels as well as for a heterogeneous multi-tiered model with different contact models for the wheels. It will be shown that the multi-tiered approach enhances the simulation result accuracy compared to the results of a homogeneous model with a low level of detail while speeding up the simulation in comparison to a homogeneous higher tier model.

关键词： Finite difference method

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Physical modeling of switched reluctance motors using modelica

Physical modeling of switched reluctance motors using modeli...

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作者： Ji, Y. Bals, J. Department of System Dynamics and Control Institute of Robotics and Mechatronics German Aerospace Center Muenchnerstr. 20 Wessling Germany

ISBN: (纸本)9789881925121

This paper presents a novel Modelica library for physical modeling of switched reluctance machines. In order to deal with the nonlinear characteristics of switched reluctance drives, an analytical approximation function is applied when building a motor model. Furthermore, the look-up table based approach derived by the finite element method for computing the nonlinear model is also considered. Compared with other modeling approaches, physical modeling using the object-oriented modeling language-Modelica often exhibits a significant progress regarding model reusability, flexibility and range of modeling. One application example with a 16 stator 12 rotor poles 4 phase witched reluctance machine is presented to illustrate the use of the developed Modelica switched reluctance machine library.

关键词： Reusability

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Autonomous parking using a highly maneuverable robotic vehicle 19

Autonomous parking using a highly maneuverable robotic vehic...

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19th IFAC World Congress on International Federation of Automatic control, IFAC 2014

作者： Schaub, Alexander De La Cruz, Juan Carlos Ramirez Burschka, Darius Institute of System Dynamics and Control Robotics Mechatronics Center - DLR Wessling82234 Germany Institute of Robotics and Mechatronics Robotics Mechatronics Center - DLR Wessling82234 Germany Department of Computer Science Technische Universität München Garching bei München85748 Germany

ISBN: (纸本)9783902823625

This work presents a novel autonomous parking concept for a four wheel-steerable robotic electric vehicle called ROboMObil (ROMO). Its extraordinary maneuverability, including rotations and lateral driving, and its capability of autonomous driving is demonstrated in the application of parallel parking. The whole process is described starting with the perception to identify a suitable parking spot in the near environment, planning the maneuver, and executing it autonomously. The proposed parking method is free of assumptions and does not use any information about the environment from an external source. Test results with the real vehicle are presented to show the feasibility of the concept. © IFAC.

关键词： Maneuverability

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Design and flight testing of manual flight control laws

Design and flight testing of manual flight control laws

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AIAA Guidance, Navigation and control Conference 2011

作者： Lombaerts, T.J.J. Looye, G.H.N. German Aerospace Center DLR Münchner Straße 20 82234 Wessling Germany Institute of Robotics and Mechatronics Department of System Dynamics and Control Germany

ISBN: (纸本)9781600869525

This paper describes the design of a manual flight controller, based upon nonlinear model-based control laws. These control laws include the previously developed concept of Pseudo control Hedging (PCH). This PCH algorithm adapts the reference model for the system output in case of unachievable commands due to control input saturation. This control algorithm has been applied in the body angular rate control loops of a high fidelity simulation model of the VFW-614 ATTAS (Advanced Technologies Testing Aircraft system) laboratory aircraft, where its beneficial influence has been illustrated. Test flights have been performed with ATTAS to evaluate the flight control technique in a relevant environment. © 2011 by Thomas Lombaerts and Gertjan Looye, German Aerospace center DLR. Published by the American institute of Aeronautics and Astronautics, Inc.

关键词： control theory

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Aerodynamic model identification of Frauke UAV

Aerodynamic model identification of Frauke UAV

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AIAA Atmospheric Flight Mechanics Conference 2012

作者： Lombaerts, T.J.J. German Aerospace Center DLR Münchner Straße 20 82234 Weßling Germany Institute of Robotics and Mechatronics Department of System Dynamics and Control Germany

ISBN: (数字)9781624101847

ISBN: (纸本)9781624101847

This paper describes the methods and results of an identification campaign, which has been set up for the mini UAV Frauke. The estimated parameter values will be used to elaborate an accurate non-linear simulation model of the UAV, which will subsequently be used to develop model based non-linear control techniques for the vehicle. The identifica- tion procedure has been performed with the so-called two step method. First, the aircraft states are estimated based upon the aircraft kinematics, after which the aerodynamic model parameters are identified. It has been found that, due to the dynamic behaviour of the UAV, a more extended aerodynamic model including nonlinear terms is needed. Residual analysis confirms the accuracy of the obtained results. © 2012 by Thomas Lombaerts, German Aerospace center DLR. Published by the American institute of Aeronautics and Astronautics, Inc.

关键词： Unmanned aerial vehicles (UAV)

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A constrained inverse modeling approach for trajectory optimization

A constrained inverse modeling approach for trajectory optim...

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AIAA Guidance, Navigation, and control (GNC) Conference

作者： Mueller, Reiko Looye, Gertjan Robotics and Mechatronics Center Institute of System Dynamics and Control Department of Aircraft Systems Dynamics Deutsches Zentrum für Luft und Raumfahrt Münchner Str. 20 82234 Wessling Germany

ISBN: (纸本)9781624102240

In aircraft trajectory optimization, modeling almost always relies on the usage of standard (forward) three- or more degrees of freedom equations of motion for the aircraft. The usual practice for simulating the trajectories is either to continuously trim the aircraft along the desired flight path and speed profile, and/or to use reduced point mass models that are defined in the vertical plane only. Alternative approaches became prominent in recent years, whereas in this paper the inverse modeling technique and an important extension to it is considered. First, inverse models have several advantages for trajectory optimization, the most important ones being the faster computation time and easy generation of start solutions, compared to standard forward models. In this work it is combined with speed- and flightpath-control loops to cancel the position error introduced during model integration. Still, an important problem remains: saturation limits and dynamics of the control systems used in the actual forward model are normally not considered when inverting the model equations, therefore losing the information of the limitations of the aircraft. In the presented case, the inversion becomes invalid, when the aircraft thrust is outside of the limits due to the commands of the inverse model inputs. This problem is addressed in the model by a pseudo-control-hedging (PCH) approach for altitude and velocity commands. By this means the inverse model inputs are automatically altered depending on the error between commanded and available thrust and the generated trajectory is rendered yable.

关键词： Degrees of freedom (mechanics)

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