Oliver Oberschelp

Modular design and verification of component-based mechatronic systems with online-reconfiguration

The development of complex mechatronic systems requires a careful and ideally verifiable design. In addition, engineers from different disciplines, namely mechanical, electrical and software engineering, have to cooperate. The current technology is to use block diagrams including discrete blocks with statecharts for the design and verification of such systems. This does not adequately support the verification of large systems which improve the system behavior at run-time by means of online reconfiguration of its controllers because the system as whole has to be verified. It also does not support cooperative interdisciplinary work because a white-box view on all blocks involved in the online reconfiguration is required. This paper proposes a rigorous component concept based on the notion of UML component diagrams which enables modular composition and decomposition of complex systems with online reconfiguration given by hierarchical hybrid component specifications. The approach enables compatibility checks between components that are often independently developed (across the different disciplines) and supports compositional model checking based on a rigorously defined semantics.

HYBRID UML COMPONENTS FOR THE DESIGN OF COMPLEX SELF-OPTIMIZING MECHATRONIC SYSTEMS

Language (UML), Real-Time Abstract: Complex technical systems, such as mechatronic systems, can exploit the computational power available to- day to achieve an automatic improvement of the technical system performance at run-time by means of self- optimization. To realize this vision appropriate means for the design of such systems are required. To support self-optimization it is not enough just to permit to alter some free parameters of the controllers. Furthermore, support for the modular reconfiguration of the internal structures of the controllers is required. Thereby it makes sense to find a representation for reconfigurable systems which includes classical, non-reconfigurable block diagrams. We therefore propose hybrid components and a related hybrid Statechart extension for the Unified Modeling Language (UML); it is to support the design of self-optimizing mechatronic systems by al- lowing specification of the necessary flexible reconfiguration of the system as well as of its hybrid subsystems in a modular manner.

Tool support for the design of self-optimizing mechatronic multi-agent systems

Complex technical systems, such as mechatronic systems, can exploit networking as well as the computational power available today to achieve an automatic improvement of the technical system performance at run-time through self-optimization. To realize this vision, appropriate means for the design of such self-optimizing mechatronic systems are required. Well-established techniques and tools for the modeling of cognitive behavior, reflective behavior, and control behavior exist. However, to really enable self-optimization and its full potential, these different aspects have to be safely integrated in a manner that remains comprehensible to the designer. In this article, we present how this required integration has been realized at the semantic level by extending the unified modeling language (UML), and at the tool level by integrating the CAE tool CAMeL and the CASE tool Fujaba real-time tool suite. The presented Mechatronic UML approach supports the design of verifiable, complex, reconfigurable mechatronic systems using the multi-agent system metaphor.

Design and implementation of digital linear control systems on reconfigurable hardware

The implementation of large linear control systems requires a high amount of digital signal processing. Here, we show that reconfigurable hardware allows the design of fast yet flexible control systems. After discussing the basic concepts for the design and implementation of digital controllers for mechatronic systems, a new general and automated design flow starting from a system of differential equations to application-specific hardware implementation is presented. The advances of reconfigurable hardware as a target technology for linear controllers is discussed. In a case study, we compare the new hardware approach for implementing linear controllers with a software implementation.

Multirate simulation of mechatronic systems

In the simulation of mechatronic systems with the help of computers, the use of multirate integration methods allows saving computing time response reaching higher computing precision without higher expense. In the process, however, effects like aliasing and undesirable high frequencies may occur that can result from differing stepsizes. In the following, we present the mechanisms that can compensate for these negative features. Moreover, an exemplary system is used to describe the partitioning into subsystems of varying velocity. Eventually the simulation results of the subsystem in question are presented and discussed. This paper is structured as follows: Section 1 gives an overview of the contents. Section 2 presents a suitable multirate integration method. Section 3 deals with the sequence of evaluations. Section 4 illustrates the realization by software tools and in Section 5 the method described is shown by an example.

Real-Time Support for Online Controller Supervision and Optimisation

This paper presents three methods for the supervision and optimisation of a controller by means of an exemplary application. The supervision is used for error recognition, analysis, and processing. The basic principle comprises the use of different controllers. A robust controller as a fail-safe device and a controller to be tested are implemented In the case of an error during the tests the system automatically switches to the robust controller. This mechanism is implemented by means of a finite-state machine. A precision supervision compares setpoints and measured values. The difference is weighted and transformed into discrete events which affect the switching between the different controllers. Through a spectrum analysis appropriate for real-time use, supervision is effected in the frequency domain. The results of the computation can be used directly for online optimisation. It is shown that in the case of real-time, a synchronous computation of the frequency spectrum is more useful than an asynchronous one. The results are presented with a current application from the domain of railway technology. This is a suspension/tilt-module testbed employed with the research project “Neue Bahntechnik Paderborn”.