Behn, Carsten; Adaptive [lambda]-tracking and stabilization for relative degree two systems. - In: 8th Conference on Dynamical Systems - Theory and Applications, (2005), S. 467-474
A wide range of control theory deals with the problem that, for a known system, a controller has to be designed in order that the feedback system achieves the prespecified control objective like stabilization or tracking. The fundamental difference between this approach and that of adaptive control (in this paper) is that the system is not known exactly, only structural information about the system, like the relative degree or the minimum phase condition, is available. We consider nonlinearly perturbed multi-input u, multi-output y, minimum phase systems with strict relative degree two. We suppose for the analysis of these systems, that they are not known precisely. Therefore, the adaptive control law has to be designed so that the controller learns from the behaviour of the system, and based on this information, it adjusts its parameters. The objective is not to obtain information about the system, but simply to control the unknown system, where we use the high-gain property of this system, see Ilchmann 1991. This approach is called non-identifier-based high-gain adaptive control in the literature, see Ilchmann 1993. Since this paper deals with nonlinearly perturbed multi-input, multi-output systems, which are not necessary autonomous, particular attention is paid to the adaptive lambda-tracking control objective. This means, that the output of the system should stay close to (track) a given reference signal (absolutely continuous and bounded with bounded derivatives up to order two), where a prespecified small tracking error of size lambda is tolerated. The goal is achieved by the so-called lambda-tracker. This controller is simple in its design, relies only on structural properties of the system (and not on the system's parameters) and does not invoke any estimation or identification mechanism. It only consists of a feedback strategy and a simple parameter adaptation law, and, moreover, does not have to depend on the derivative of the output of the system. This controller which includes a dynamic compensator is due to a controller of Miller and Davison (1991). The system class is more general and the controller is much more simpler than the introduced and considered one in Ye (1999). It is proved that using this controller lambda-tracking and stabilization can be achieved for the considered nonlinearly perturbed systems with unknown parameters, see Behn (2005). The feedback strategy reduces in dimension (the number of used variables calculated by internal differential equations) if we restrict the class of systems to single-input, single-output systems with the centre of the zeros in the open left-half complex plane.
Kolev, Emil; Stoyanov, StefanFestigkeitsuntersuchungen an Kuttermessern für die Fleischindustrie. - In: Vibracionnye mašiny i technologii, (2005), S. 79-83
In der Lebensmittelindustrie werden sehr viele verschiedene Messertypen zum Zerkleinern von frischen und gefrorenen Fleischsorten in der Kuttermaschine angewendet. Die Formen der Messer sowie ihre Schnittwinkel variieren sehr stark und sind empirisch entstanden. Es konnte festgestellt werden, dass zu den Messerformen, zum Schneidvorgang und zu den Kräften im Messerkörper keinerlei gesicherte wissenschaftliche Überlegungen existieren. - Durch die ständige Leistungssteigerung der Maschinentechnik kann eine Festlegung der Messerkörpergeometrie rein aus der Erfahrung auch bei einer günstigen Stahlauswahl keine Sicherheit gegen Bruch gewährleisten. Diese Tatsachen erfordern eine wissenschaftliche Vorgehensweise bei der Festlegung der Messerparameter.
Zentner, Lena; Böhm, ValterZur Anwendung nachgiebiger Mechanismen. - In: Konstruktion, ISSN 0373-3300, Bd. 57 (2005), 11/12, S. 49-50
Nachgiebige Mechanismen finden immer breitere Anwendung und ersetzen erfolgreich bei vielen Aufgaben konventionelle Starrkörpermechanismen. Die im Beitrag beschriebene Klassifikation nachgiebiger Strukturen entstand während langjährigen Entwicklungs- und Untersuchungsarbeiten mit nachgiebigen Mechanismen an der TU Ilmenau. Diese strukturierte Darstellung nachgiebiger Strukturen hilft dem Anwender die Aufgabenstellung zu formulieren und die nachgiebigen Mechanismen dafür gezielt einzusetzen. Außerdem zeigt die dargestellte Klassifikation die zukunftsorientierten Entwicklungsmöglichkeiten nachgiebiger Mechanismen.
Behn, Carsten; Zimmermann, Klaus Biologically inspired locomotion systems and adaptive control. - In: Proceedings of multibody dynamics 2005, (2005), insges. 18 S.
This paper deals with the (adaptive) control of a mechanical system, which is inspired by biological ideas. We present some theoretical investigations of a worm-like locomotion system that has the earthworm as a living prototype. This system is modelled in the form of a straight chain of k=3 interconnected point masses. The ground contact can be described by non-symmetric dry friction. We consider the case where different point masses are under the action of external forces, hence these forces can be regarded as control inputs. Therefore, this system is described by a mathematical model that falls into the category of nonlinearly perturbed, multi-input, multi-output systems, where the outputs of the system are, for instance, the positions of the point masses. In general, one cannot expect to have complete information about a sophisticated mechanical or biological system, but instead only structural properties (e.g. minimum phase condition, strict relative degree) are known. Therefore, the method of adaptive control is chosen in this paper. The aim is to design a universal adaptive controller, which learns from the behaviour of the system, so automatically adjusts its parameters and achieves a pre-specified control objective. Since we deal with nonlinearly perturbed multi-input, multi-output systems, which are not necessary autonomous, particular attention is paid to the [lambda]-tracking control objective. Simple adaptive mechanisms which achieve tracking of a given reference signal for any pre-specified accuracy [lambda] are introduced. [lambda] > 0 denotes the size of the tracking error. The feedback strategy reduces in dimension (the number of used variables calculated by internal differential equations) if we restrict the considered system class to single-input, single-output systems with zero-centre in the open left-half complex plane. We stress that the introduced adaptive controllers consist of very simple feedback mechanisms and adaptation rules. These controllers are only based on information about the output of the system no knowledge of the system parameters is required.
