On the Significance of the Biography and Thought of Pilgram Marpeck for a Responsible Engineering Perspective

In the general scope of an aspirational approach to engineering practice and ethics, this article follows the paradigm of learning from biography and presents Pilgram Marpeck, an engineer and Anabaptist reformer of the 16th century, as a possible early role model for the engineering professional. A biographical review of his life and all-encompassing participation in the society of his time is followed by a self-contained summary of his thought on selected topics. When considering the bearing of these on engineering ethics and practice, Marpeck\u27s thought and several of his concerns are found of current relevance

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This paper proposes a gain-scheduling control design strategy for a class of linear systems with the presence of both input saturation constraints and norm-bounded parametric uncertainty. LMI conditions are derived in order to obtain a gain-scheduled controller that ensures the robust stability and performance of the closed loop system. The main steps to obtain such a controller are given. Differently from other gain-scheduled approaches in the literature, this one focuses on the problem of H∞ loop shaping control design with input saturation nonlinearity and norm-bounded uncertainty to reduce the effect of the disturbance input on the controlled outputs. Here, the design problem has been formulated in the four-block H∞ synthesis framework, in which it is possible to describe the parametric uncertainty and the input saturation nonlinearity as perturbations to normalized coprime factors of the shaped plant. As a result, the shaped plant is represented as a linear parameter-varying (LPV) system while the norm-bounded uncertainty and input saturation are incorporated. This procedure yields a linear parameter-varying structure for the controller that ensures the stability of the polytopic LPV shaped plant from the vertex property. Finally, the effectiveness of the method is illustrated through application to a physical system: a VTOL “vertical taking-off landing” helicopter

Conversion of descriptor representations to state-space form: an extension of the shuffle algorithm

This paper proposes a systematic procedure for the determination of state-space models from an available descriptor representation of a linear dynamic system. The goal is to determine a state equation, a set of algebraic equations and an output equation in terms of the state and input variables. It is shown that standard methods may fail to convert the descriptor representation to state-space form, even for simple electrical circuit models obtained from Kirchoff’s laws and constitutive element equations. A novel procedure to address this problem is then proposed as an extension of the classic shuffle algorithm combined with a singular value decomposition approach. In addition to an illustrative example involving a simple electrical circuit, the proposed method is employed in a case study involving the modeling of three-dimensional RLC networks with a large number of components

Constrained pre-equalization accounting for multi-path fading emulated using large RC networks: applications to wireless and photonics communications

Multi-path propagation is modelled assuming a multi-layer RC network with randomly allocated resistors and capacitors to represent the transmission medium. Due to frequency-selective attenuation, the waveforms associated with each propagation path incur path-dependent distortion. A pre-equalization procedure that takes into account the capabilities of the transmission source as well as the transmission properties of the medium is developed. The problem is cast within a Mixed Integer Linear Programming optimization framework that uses the developed nominal RC network model, with the excitation waveform customized to optimize signal fidelity from the transmitter to the receiver. The objective is to match a Gaussian pulse input accounting for frequency regions where there would be pronounced fading. Simulations are carried out with different network realizations in order to evaluate the sensitivity of the solution with respect to changes in the transmission medium mimicking the multi-path propagation. The proposed approach is of relevance where equalization techniques are difficult to implement. Applications are discussed within the context of emergent communication modalities across the EM spectrum such as light percolation as well as emergent indoor communications assuming various modulation protocols or UWB schemes as well as within the context of space division multiplexing

On the Implementation of the Eigenvalue Method for Limit Cycle Determination in Nonlinear Systems

In many practical systems, limit cycles can be predicted with suitable precision by frequency domain methods using describing functions. Within such an approach, limit cycles can be predicted using the “eigenvalue method” [Somieski, G., Nonlinear Dynamics 26(1), 2001, 3–22]. This contribution presents a novel and advantageous implementation of this method, using singular value instead of eigenvalue calculations, and enhancing computational efficiency by avoiding a so called “frequency iteration”. Key words describing functions - eigenvalue

A Comprehensive Approach to Pulse Modulation for Attitude Control with Thrusters Subject to Switching Restrictions

A pulse modulation scheme based on two modulation curves is proposed for applications in spacecraft attitude control using thrusters which may be subject to switching restrictions. These constraints are taken into account explicitly during the design of the modulation scheme which can implement arbitrary bounded functions between constant modulator input and averaged modulator output

Persistent Motion and Chaos in Attitude Control with Switching Actuator

In systems with switching actuators persistent motions of different nature may occur, such as limit cycles, quasi-periodic and chaotic motions. In this contribution the nature of persistent motions in an attitude control system with switching actuators subject to switching restrictions are examined as a function of controller parameters. Bifurcation diagrams are used to describe ovservations. In the light of the bifurcation diagrams, control issues and earlier results obtained with the describing function method are assessed from a more general perspective

Schaltende Aktuatoren mit Schaltungseinschränkungen in Lageregelungssystemen

In diesem Beitrag wird das dynamische Verhalten von Lageregelungssystemen mit schaltenden Aktuatoren und Schaltungseinschränkungen behandelt. Schaltungseinschränkungen werden explizit berücksichtigt. Anhand einer eingehenden simulationsgestützten Parameterstudie wird gezeigt, dass periodische, quasi-periodische oder chaotische Systemverhalten auftreten können. Als Visualisierungswerkzeuge werden unter anderem Verzweigungsdiagramme benutzt. Über die analytische Berechnung von Verzweigungsgrenzen und über den Reglerentwurf werden auch Aussagen gemacht

Pulse modulation for attitude control with thrusters subject to switching restrictions

A pulse modulation scheme based on two modulation curves is proposed for applications in spacecraft attitude control using thrusters which may be subject to switching restrictions. These constraints are taken into account explicitly during the design of the modulation scheme which can implement arbitrary bounded functions between constant modulator input and averaged modulator outpu

Improved efficient, nearly orthogonal, nearly balanced mixed designs.

Proceedings of the 2011 Winter Simulation ConferenceSEED Center PaperDesigned experiments are powerful ways to gain insights into the behavior of complex simulation models. In recent years, many new designs have been created to address the large number of factors and complex response surfaces that often arise in simulation studies, but handling discrete-valued or qualitative factors remains problematic. We proposed a framework for generating, with a (given) limited number of design pointsn, a design which is nearly orthogonal and also nearly balanced for any mix of factor types (categorical, numerical discrete, and numerical continuous) and/or mix of factor levels