PhD Projects

• Flexible Task-oriented Robot Controls on the basis of the SES/MB and DEVS formalism
  M.Eng. Tobias Schwatinski
  in cooperation with University of Rostock
  since September 2009
  
  Task-oriented programming methods for offline robot control development are subject of many research activities. In this context task-oriented is understood as only specifying what task a robot should process and not how this task is being executed. In general simple task-based controls have several limitations e.g. that control structures and parameterisation of basic tasks are time invariant. The whole flexibility has to be implemented inside these basic tasks. This project focuses on the development of a time variant control system. Therefore any control strategy has to be specified in a declarative way. During real-time execution temporary controls are synthesised reiteratively and generated depending on actual process states and objectives. The SES/MB framework is used for this purpose. In future this approach will be generalised for cooperate robot controls.
  
  
  
• Predictive Simulation in Complex Control Problems
  M.Eng. Tobias Pingel
  in cooperation with University of Rostock
  since September 2009
  
  In complex control problems often multiple control variants exist. To find the optimum control strategy variant simulation is being applied. In a given amount of time -- at best in real-time -- the variant simulation should predict the best strategy for the current state. With a limited amount of time, normally just a subset of all variants can be evaluated on-line. Thus, an all-variant simulation, e.g. with the help of genetic algorithms, has to be performed off-line and parallel in time to find the global optimum subsequently. This PhD project focuses on analysing realizability of real-time predictive simulation using parallel and distributed computing methods on the basis of commodity HPC hardware, such as (clustered) multicore workstations.
  
  
  
• Control of processes with deadzone characteristics
  M.Eng. Michael Tomforde
  in cooperation with University of Rostock and IAV GmbH
  since October 2006
  
  In practical control systems, deadzone characteristics are encountered in a wide range of mechanical and electrical components, such as valves or DC servo motors. Another process that exhibits a deadzone characteristic is the three-way catalyst. Due to its oxygen storage ability, the normalized air-fuel ratio post catalyst remains at one despite air-fuel mixture variations pre catalyst, as long as certain levels of the oxygen storage state are not exceeded.
  The aim of this project is to reduce the exhaust emissions produced by cars equipped with a three-way catalyst by improving the control of the air-fuel mixture. Low emissions are reached if post-catalyst air-fuel ratio remains at one despite large air-fuel mixture variations and a biased measurement of pre-catalyst air-fuel ratio. Typically, the aim of a controller for deadband processes is to overcome the deadzone in an optimal way, commonly by employing the deadzone inverse to cancel it. For this project, however, the aim of the controller is to keep the oxygen storage state within the deadzone.
  In order to control the oxygen storage state (and pre-catalyst air-fuel ratio which is connected to the storage state via the deadzone), a model-based approach is proposed, since the storage state cannot be measured directly by a sensor. Thus, the project includes i) the development of a control-oriented model of a three-way catalyst, which has to be both accurate and simple enough to be calculated on the vehicles electronic control unit, and ii) the design of a suitable control strategy.
  
  
  
• Torque Coordination of Spark Ignition Engine - Control of Processes with Auxiliary Actuating and Control Variables
  Dipl.-Ing (FH) Christian Fritzsche
  in cooperation with University of Rostock and IAV GmbH
  since July 2006
  
  Due to increasing demands on driving comfort, consumption and emission of modern combustion engines new combustion processes came to introduction of series production in the last years. The potential of these combustion processes in general can only be utilized by introduction of additional actuating and measure variables. Thereby an increasing complexity from control viewpoint is almost unavoidable. The choice of particular actuating variables has decisive influence on efficiency, comfort and waste gas emission. Besides the main manipulated variables, as e.g. the throttle position, there are some more different actuating variables that are in many cases only effective for limited operating ranges of the engine with different effects.
  The cooperative graduation project deals with the general problem of control with auxiliary actuating and control variables. Application emphasis of the procedures to be developed is located in the field of combustion engine controllers.
  One aim is to find the best compromise between efficiency, driving comfort and waste gas emission. This is achieved by an optimized choice, according to several criteria, of available actuating variables for the realization of the driving torque.
  
  
  
• Application of sophisticated algorithms for spark ignition engine control
  M.Eng. Stefan Behrendt
  in cooperation with University of Rostock and IAV GmbH
  since March 2006
  
  The coordination of available actuators in modern engine control units (ECUs) is a challenging task. The broad variety of signals (e.g. throttle, advance angle, exhaust gas recirculation, injection, etc.) to influence the momentum and engine speed are coupled. Therefore a multi-variable control should manage these actuators to fulfill the control aim in an efficient manner. A compromise respecting further aims like comfort issues and exhaust gas emissions must be found. An available scheme to cope with these requirements is model predictive control (MPC). The incorporated optimization ensures the optimal selection of actuator signals under their constraints.
  The cooperative graduation project is concerned with the development of a suitable quadratic program that solves the optimization within the MPC algorithm. It needs to fulfill the real-time requirements when run on high-potential micro-controllers (e.g. Infineon Tricore) that are incorporated in modern ECUs.
  
  
  
• Parallel and Distributed Simulation of Discrete-Event Systems within Engineering Applications
  M.Eng. Christian Stenzel
  in cooperation with University of Rostock and MTG Marinetechnik GmbH
  since March 2006
  
  Parallel and distributed simulation techniques of discrete-event systems evolved since the end of the 70s. Sophisticated synchronization algorithms mainly developed in the High Performance Computing (HPC) commmunity help to reduce the execution time of complex discrete-event simulation within a parallel execution. On the other hand, distributed simulation techniques, mainly developed within the military domain, allow the concurrent execution of interconnected simulation components in heterogeneous soft- and hardware environments. The union of these both historically and technically very different developments succeeded through the introduction of the standard High Level Architecture through the American Department of Defense since the mid-90s.
  From the vantage point of the engineering domain only a few application fields can benefit from parallel and distributed simulation techniques of discrete-event systems. Especially for automation engineering a systematic analysis of the pros and cons of such techniques can not be found througout the literature. Due to this fact the project pursues three objectives:
  (i) Evaluation of parallel discrete-event simulation methods in the field of automation engineering and related domains, (ii) evaluation of the standard HLA as military innovation in the field of automation engineering and related domais and (iii) statements to the practical relevance of parallel and distributed simulation methods and HLA.
  Therefore, this project introduces basics in parallel and distributed simulation techniques. As a second step concepts and implementations to realize parallel and distributed simulations within often-used engineering tools, namely so-called Scientific and Technical Computing Environments (SCEs), are proposed. Upon this basis, the value of such simulation methods can be examined in detail at typical applications of automation engineering and related domains.
  
  
  
• Simulation model-based Rapid Control Prototyping of Complex Robot Controls
  M.Eng. Gunnar Maletzki
  in cooperation with University of Rostock
  since March 2005
  
  Progressive robotics research opens up new application fields incessantly. Hence, demands on the development of robot controls are increasing. Easy programming and integration of different external hardware are of particular importance. The aim of every control implementation is to realise easy, safe, fast and cost-effective design and commissioning of robot applications. Therefore, it is essential to avoid re-implementations in the entire development process.
  An approach for integrated modeling, simulation and operation, named "simulation model-based rapid control prototyping", is introduced and illustrated by the example of a sensor based robot control. It is discussed how simulation models have to be structured in the early system design stage in order to extend them to model-based control programs for the operation stage stepwise.
  Objects of this research are (i) the prevention of re-implementations, (ii) the development of a task oriented programming approach, (iii) methods for an easy integration of different hardware and (iv) a concept for specification of high flexible and re-configurable controls.
  
  
  
• Simulation Based Parameter and Structure Optimisation of Discrete Event Systems
  Dr. (PhD) Olaf Hagendorf
  in cooperation with Liverpool John Moores University and Syntax Software GbR
  July 2005 - July 2009
  (Thesis submitted 05/2009, PhD examination 07/2009)
  
  The research reported in this thesis details a new simulation based approach providing automatic reconfiguration and optimisation of both model structure and model parameters.This is achieved through a combination of simulation, optimisation and model management methods. Simulation is used to determine current model performance and an optimisation method, assistet by model management, searches for an optimal solution with repeated model parameter and model structure changes. The approach employs a meta-modeling method to define a set of model structure variants and includes a model base with pre-defined basic components. With the meta-modeling method the model management can determine specific model structures and create executeable models.
  thesis
  
  
  
  
• DEVS-Based Modeling and Simulation in Scientific and Technical Computing Environments
  Dipl.-Ing (FH) Christina Deatcu
  in cooperation with University of Rostock
  since January 2005
  
  Discrete Event System Simulation (DEVS) in our days is not widely accepted by engineers. This is mainly caused by the fact that engineers usually are rather familar with Scientific and technical Computing Environments (SCEs) than with the use of high level programming language simulation libraries. Furthermore, most of those comercial off-the-shelf tools are just suitable for specific application areas.
  One more aspect is that SCEs offer good opportunies to integrate DEVS modeling and simulation with other advanced techniques such as e.g. optimisation, ode solvers, data aquisition and analysis and integration of hardware.
  In this project main focus is put on modeling and simulation of hybrid system dynamic by utilisation of the features for solving ordinary differential equations within the most popular SCE Matlab. The approach includes modeling of structure variable systems, as well.
  A prototype for DEVS modeling and simulation without hybrid and structure variable parts is available here.
  
  
  
• Model Based Control for Automotive Applications
  M.Eng. Jacky Ölscher
  in cooperation with University of Rostock and IAV GmbH
  September 2004 - August 2008
  
  The aim of the project is the modelling of the SI-engine combustion process in order to get useful combustion parameters, e.g. the angle of 50 per cent mass fraction burned, for the interpretation of the combustion quality. These information are helpful for engine closed loop control purposes and will be modelled with respect to the existing measuring signals of a common car.
  
  
  
• Investigations on SCE Based Parallel Computing
  Dr.-Ing. René Fink
  in cooperation with University of Rostock and IAV GmbH
  March 2004 - December 2007
  (Thesis submitted 07/2007, PhD examination 12/2007, honored with summa cum laude)
  
  Scientific and technical Computing Environments (SCEs) like Matlab are powerful tools for todays engineers, especially for desing problems. But the increasing complexity of calculations often lead to bottlenecks in interactive design processes. Parallel processing offers one possibility to bypass those bottlenecks. Within this research project, approaches for combining SCEs and parallel processing are investigated and classified. Several tools are examined with respect to their programming model, abstraction level and communication performance. Furthermore, several example programs are parallelized for runtime measurements and implementation effort investigations.
  poster, thesis
  
  
  
• An Integrated Simulation-Model-Based Approach for Process Planning and Process Control of Discontinuous Production Processes
  Dipl.-Ing (FH) Martin Kremp
  in cooperation with Liverpool John Moores University
  October 2002 - August 2007
  
  In complex, cost-intensive and automated discontinuous production processes discrete event simulation is widely known in system design and production planning and scheduling. It is used to analyse systems performance, to compare different system structures, layouts and control strategies, to optimise systems parameters etc. But there is a gap of using the outcomes of a simulation project for process control development.
  This research proposes a novel holistic approach using a simulation model directly for process control after the simulation model has been used to design the process. The simulation-model-based process control approach is the basis to integrate further simulation-based modules. Here an optimisation module is integrated to react immediately to process disturbances within the scope of online-coupled short term planning.
  The entire integrated simulation-model-based approach for process planning and process control is applied and validated by means of a miniaturised laboratory plant, reflecting a real manufacturing and material flow application.
  poster
  
  
  
  
• The Development of a Genetic Programming Method for Kinematic Robot Calibration
  Dr. (PhD) Jens-Uwe Dolinsky
  in cooperation with Liverpool John Moores University
  finished March 2001
  thesis