Arvid Hellmich

Increased Performance of a Hybrid Optimizer for Simulation Based Controller Parameterization

The controller parameterization is often carried out by applying basic empirical formulas within an integrated automatic design. Hence, the determined settings are often insufficient verified by the resulting system behavior. In this paper an approach for the controller parameterization by using methods of simulation based optimization is presented. This enables the user to define specific restrictions e.g. the complementary sensitivity function to influence the dynamic behavior of the control loop. A main criterion for practical offline as well as controller internal optimization methods is the execution time, which can be reduced by applying a hybrid optimization strategy. Thus, the paper presents a performance comparison between the straight global Particle-Swarm-Optimization (PSO) algorithm and the combination of the global PSO with the local optimization algorithm of Nelder-Mead (NM) to a hybrid optimizer (HO) based on examples.

Non Invasive Identification of Servo Drive Parameters

For the tuning of servo controllers as well as for monitoring functions, significant parameters of the controlled system are required. In contrast to identification methods with determined input signals, the paper focuses on the problem of identification with regular process movements (non invasive identification), leading to a lack of power density in some frequency ranges. A nonlinear Least Squares (LS) approach with single mass system and friction characteristic is investigated regarding the accomplishable accuracy and necessary constraints. The proposed method is applicable on industrial motion controllers and has been carried out with a multitude of input sequences. To verify the performance of the approach, achieved experimental results for the model parameters are exposed.

Aufbau und Auslegung funktionsbestimmender Werkzeugmaschinen-Baugruppen

Aus den auf einer Werkzeugmaschine zu realisierenden Fertigungsprozessen resultieren vielfaltige durch die Maschine zu erfullende Funktionen. Diese erfordern einen komplexen Aufbau, der durch das Zusammenwirken einzelner Baugruppen erfullt wird. Fur die funktionsbestimmenden Baugruppen von spanenden Werkzeugmaschinen werden typische Funktions- und Aufbauprinzipien erlautert und deren Auslegung dargestellt. Dabei bilden die fertigungstechnischen Anforderungen die Basis, so dass die Baugruppen von „innen nach ausen“, d. h. von der Hauptspindel als Werkzeug–/Werkstuckaufnahme uber die Antriebe und Fuhrungen bis zu den Bauteilen fur die Gestelle betrachtet werden. Fur die Gesamtfunktionalitat der Maschine ist deren Steuerung verantwortlich, die abschliesend in ihrem Funktionsumfang erlautert wird.

Improved Controller Performance for Electromechanical Axes

The cascaded position control structure is state of the art in modern production machines and machine tools. Since an adequate controller performance of the electromechanical axes is still a key aspect for a resource efficient and high-quality production, this topic is addressed by the paper. An overall approach/framework to monitor and ensure an improved controller performance over time, comprising five tangible approaches is presented. All methodologies were developed in the department for control and feedback control technologies of the Technische Universitaet Chemnitz. They will be demonstrated and also be discussed based on experimental results.

Similarity Estimation for Assessing the Accuracy of a Non-Invasive Identification Method

In the paper, an approach for parameter identification during regular movements of servo axes is discussed. In contrast to the usual case, where test signals are applied to the process, there is no deterministic excitation present in this manner. Consequently, the accuracy of the identified parameter depends on the available excitation and needs to be assessed after the identification is completed. Considering that, several methods of error calculation and similarity measurement are presented in the paper and discussed for the specific use case of non-invasive parameter identification.

Das Presswerk auf dem Weg in das Cyber-physische Zeitalter

Kurzfassung Bereits heute sind Presswerke mit Sensorik, Aktorik, Datenspeichern, Datenverarbeitungs- sowie Kommunikationseinheiten ausgestattet und besitzen damit Merkmale eines Cyber-physischen Systems. Konkrete Beispiele im Beitrag zur Sensorik, Datenanalyse und Aktorik zeigen dies auf. Ein Anwendungsbeispiel in Form eines digitalen Zwillings demonstriert die Adaption der Ziehkissen-Zylinderkräfte, basierend auf Ergebnissen der Werkstoffprüfung. Nach Meinung der Autoren wird das Presswerk zukünftig als autonomes System in Echtzeit auf Parameterschwankungen reagieren und Korrekturmaßnahmen selbstständig einleiten können.

Assessing the accuracy of a non-invasive identification method

The paper discusses an approach for parameter identification during regular movement of servo axes. In contrast to the usual case, where test signals are applied the accuracy of the identified parameter can depend on the available excitation and needs to be assessed after the identification has run. Considering that, methods of error calculation and similarity measurement are presented in the paper and discussed for the specific use case.

Assessment of optimization criteria in the time domain used for simulation based controller parametrization

Controller parameterization is commonly performed by applying basic tuning rules or by carrying out not comprehensible design automatisms, which are integrated in the control system. As an alternative, a relatively new and promising approach is the application of the so-called “simulation-based optimization”. This method allows a flexible definition of different optimization criteria. Therefore, in this work, different criteria in the time domain are investigated and evaluated according to their application for the simulation-based optimization.

Identification of Parametric Models and Controller Design for Cascaded Position Control

Abstract The standard in industrial motion controllers comprises today a cascaded system of position loop, velocity loop and current loop. Each controller has to be designed according to its subordinated system behavior. The paper presents a method for the identification of plant parameters in the time domain. The approach is based on the auto relay feedback experiment by Astrom/ Hagglund and a modified technique of gradual pole compensation. In addition to a theoretical description, the implementation as an automatic application in the motion control system SIMOTION is shown. Finally, the velocity controller and the position controller are adjusted according to the identified systems. Furthermore, the identification results as well as the achievable controller performance on a test rig will be presented.

Identification of Parametric Models for Commissioning Servo Drives

Modern production machines contain up to 100 position controlled servo drives. The setting-up operation of these servo drives is a time-consuming and cost-intensive process. The paper presents a new method, which supports the user by justifying the position controller automatically. Based on the auto relay feedback experiment by Astrom and Hagglund, the introduced technique is applied to identify a parametric model of the position controlled system by means of gradual pole compensation. Therefor, a mechanism has been developed, which automatically adjusts the model parameters according to the time behaviour of the controlled system. The presented algorithm has successfully been implemented in the motion control system SIMOTION. In addition, it has been evaluated concerning the achievable identification accuracy. Furthermore, examples for the identification procedure and the parametrization of the position controller are given.