Research Project History

Click to expand the following past research projects of the Production & Logistics Networks Workgroup.

Motivation

Due to the increasing dynamic and structural complexity of internal and external business processes in logistics systems, it is often not possible to provide all decision-relevant information to a central authority and to deduce control measures according to a defined target system. By establishing autonomous logistics processes a fast and flexible adaptation to changing conditions shall be achieved. In this project, the following underlying questions about autonomously controlled logistics processes were examined:

  • Identification problem: What are autonomous logistic processes and how do they differ from central controlled processes?
  • Description problem: How does processing of orders change by implementing autonomous processes?
  • Modeling problem: How can autonomous logistic processes be modeled and which methods are suitable?
  • Evaluation problem: How to measure and evaluate autonomously controlled processes?

 

Results

Among the findings of this project is the definition of the term autonomous control from an engineering point of view. The constituent features of this definition form the basis for the list of criteria to describe autonomous logistic processes. Concerning the modeling of autonomous processes, requirements for modeling methods were developed. To validate the research results a production logistics scenario of a job shop production and a practical scenario with the order processing of an automotive terminal in the company EH Harms Automobile-Logistics developed. Simulation studies show extensive improvement for autonomous space allocation. Furthermore the changes needed for autonomous processes were investigated in the form of process and simulation studies and an evaluation system for autonomous logistic systems was developed.

Contact:

Dipl.-Wi.-Ing. Oliver Jeken
Jacobs University Bremen gGmbH
Campus Ring 1 | 28725 Bremen | Germany
Office: South Hall, Room 122
phone: +49 421 200 3475
e-mail: o.jeken@jacobs-university.de

Collaborative Research Centre 637

Prof. Dr.-Ing. Katja Windt is subproject leader in the Collaborative Research Centre 637 Autonomous Cooperating Logistics Processes – A Paradigm Shift and its Limitations” of the projects A7 Autonomous Product Construction Cycle and T1 Automobile Logistics.

Motivation

The different approaches regarding autonomous control in logistics have in common that a higher achievement of the logistic targets should be realized by coping with complexity and dividing the planning task. This leads to a shift of the decision process to the autonomous acting logistic objects. To be able to perform a well-founded investigation an evaluation system is needed which fulfills the following requirements:

1. To determine the degree of complexity of a logistic system.
2. To determine the degree of autonomous control of a logistic system.
3. To measure the achievement of the logistic targets of a logistic system.

Only by matching these requirements an evaluation system will be able to conclude whether central control or autonomous control is the better choice or not.

Objectives

The transfer project T1 is about investigating and evaluating methods of autonomous control in automobile logistics based on the concepts and methods for modeling, control and evaluation of logistic processes developed by the CRC 637. We focus on the comparison of rule-based and bounded rationality methods of autonomous control for a selected area in automobile logistics, which is represented by a car terminal. The evaluation of the single methods of autonomous control is conducted using the evaluation system for autonomous controlled logistic systems. This evaluation system offers the determination of the achievement of the logistic targets by taking into account the degree of complexity and the degree of autonomous control of the observed logistic system.

Approach

  • Application of different rule-based and bounded rationality methods of autonomous control using the example of automobile logistics,
  • evaluation of single methods of autonomous control by means of the evaluation system for autonomous controlled logistic processes,
  • derivation of application areas of single methods of autonomous control for different degrees of complexity and autonomous control using the example of automobile logistics,
  • validation and adaption of existing results in research regarding autonomous control methods (rule-based and bounded rationality) and the evaluation system (catalogue of criteria, complexity cube, measurement and control system).

 

Contact:

Dr. Till Becker
Jacobs University Bremen gGmbH
Campus Ring 1 | 28725 Bremen | Germany
Office: South Hall, Room 123
phone: +49 421 200 3074
e-mail: t.becker@jacobs-university.de

Collaborative Research Center 637

Prof. Dr.-Ing. Katja Windt was subproject leader in the Collaborative Research Center 637 Autonomous Cooperating Logistics Processes – A Paradigm Shift and its Limitations” of the projects A7 Autonomous Product Construction Cycle and T1 Automobile Logistics.

Grooving Factory is an interdisciplinary research project that uses auditory display – the acoustic presentation of information – for the analysis of production planning and feedback data. The project was initiated by Prof. Dr.-Ing. Katja Windt and Julian Klein at the the workgroup “Rhythm”of the Junge Akademie at the Berlin-Brandenburg Academy of Sciences and Humanities and the National Academy of Sciences Leopoldina.

Motivation

In order to accomplish a better achievement of their logistic objectives, companies collect data at an increasing level of detail for the adjustment of production planning and control (PPC). Statistical methods, as they are conventionally used in logistic analysis, are only insufficiently suitable to cope with this increased amount of information, since they mostly rely on averaging. Not only that they monitor the flow of production merely rudimental, they are also not capable to distinguish between the large amounts of product variants, provided by companies for competitive reasons, and interrelated process restrictions. Therefore, actual analyses of logistic planning and feedback data more and more include computer-aided data analysis methods, such as knowledge discovery in databases (KDD). In this context, explorative data analysis (EDA) has become increasingly important. Introduced by John W. Tukey in the 70s, this recursive analysis approach between testing and evaluating generates new hypotheses about structural qualities of data samples rather than confirming existing ones. As counterpart to graphical statistics, the scientific discipline of auditory display, i.e. the acoustic representation of information, has been successfully established in the field of EDA. This method is particularly suitable for detailed analyses of chronological sequences of events within the production workflow.

Objectives

The project aims to develop a method to identify order- and process-related bottlenecks as well as their impact on schedule adherence of the overall production work flow for the analysis of manufacturing data. The novel approach focuses on the identification of systematic sequences of order patterns (order attributes, prioritization, process-related restrictions) within the data structure that have impact on the schedule adherence of the overall production workflow.

Intermediate Results

Additionally to the established perspectives ( order-oriented and resource-oriented view) used for logistic analysis, a third one called “synchronous view” has been introduced for auditory analysis. In this perspective, all sequential processes of an order are simultaneously displayed in a sound (spatially distributed according to the processing workflow) providing a characteristic acoustic profile (“fingerprint”) of each order. That way, orders with symptomatically prolonged throughput times could be identified.

Contact

Dr. Michael Iber
Jacobs University Bremen gGmbH
Campus Ring 1 | 28759 Bremen | Germany
Office: South Hall, Room 108
phone: +49 421 200 3031
e-mail: m.iber@jacobs-university.de

 

Research Motivation

uncertainties, fluctuations, and inappropriate high work in process levels are only a few reasons for a low proportion of orders that are produced on time, thus resulting in a low due date reliability.
in order to improve the logistic target achievement, some 80% of all production planners use ‘safety lead-time’ to absorb uncertainty in time.
with fixed customer due dates and backwards scheduling of orders, this reaction implies
that orders have to be released earlier, which increases the workload in the processes.
in case of inflexible capacities, the work in process level rises and actual lead times get longer with an increased standard deviation.
finally, this vicious cycle leads to a lower due date reliability than previous to the taken improvement measure and makes further measures necessary

Figure 1: Measures in Scope of the Lead Time Syndrome
Fig. 1 shows that the effectiveness of measures to improve the logistic performance strongly depends on the question, if the chain reaction of the LTS will be triggered (worsened logistic performance) or not (improved logistic performance)
even today’s manufacturing facilities deal with interactions and effects of the LTS without knowing the syndrome itself
investigating the LTS line of argumentation by the use of logistic equations can enable understanding the interactions of the affected logistic variables the LTS was merely logically questioned, but not fundamentally investigated towards the logistic effects in networked production systems

Research Objectives

mathematical consolidation of the Lead Time Syndrome line of argumentation influence of the Lead Time Syndrome on the logistic target achievement
Quantification of different LTS triggers in manufacturing
stepwise investigation of possible triggers (acc. to LTS steps)
cause-effect relations of LTS variables and the logistic targets
influence of the transient response of production systems

Figure 3: Discrete Event Simulation
Composition of measures to improve the logistic performance
advancement and mathematical evaluation of measures
method to determine planned values (e.g., initial lead times & time interval)
derivation of potentials and strategies in logistic target achievement
development of a controlling tool for a continuous improvement

Figure 4: From Theory into Practice – Control Loop of PPC [1]

First Results

Figure 5: Mathematical Investigation of the Lead Time Syndrome [2]
the formal derivation and evaluation of the LTS line of argumentation has been partly completed (see Fig. 5)
it revealed the different assumptions of the LTS line of argumentation in the logistic equations, i.e., fixed values (e.g., capacities), the backward scheduling as scheduling technique, etc.
the occurrence of lead time standard deviation is both a consequence and a trigger of the LTS, thus a key figure which directly influences the due date reliability of a production process
not only the LTS line of argumentation, but rather other triggers such as statistical correlations, disturbances and reaction times strongly influence the resulting lead time standard deviation in the last step of the LTS
Fig. 6 shows the investigation of variables and effects that influence the lead time standard deviation (these effects are overlapping and influencing each other)

Figure 6: Standard Deviation Influencing Effects Within the Scope of the Lead Time Syndrome [3]

Contact

Dr. Mathias Knollmann
Research Associate & PhD Student
Production & Logistics Networks Workgroup
Department of Mathematics and Logistics
Phone: 0421 200 3475
Fax: 0421 200 3078
Email: m.knollmann@jacobs-university.de
pln-workgroup.user.jacobs-university.de

References

1. Wiendahl, H.-P., 1997. Fertigungsregelung: Logistische Beherrschung von Fertigungsabläufen auf Basis des Trichtermodells, Hanser Verlag
2. Knollmann, M. & Windt, K., 2013. Exploitation of Due Date Reliability Potentials – Mathematical Investigation of the Lead Time Syndrome. In H.-J. Kreowski, B. Scholz-Reiter, & K.-D. Thoben, eds. Lecture Notes in Logistics: Dynamics in Logistics, Third International Conference, LDIC 2012, Bremen, Germany. Springer, pp. 313–326
3. Knollmann, M. & Windt, K., 2013. Evaluating Lead Time Standard Deviation With Regard To The Lead Time Syndrome. In K. Windt, ed. Lecture Notes in Production Engineering: Robust Manufacturing Control; Proceedings of the CIRP Sponsored Conference RoMaC 2012, Germany. Springer, pp. 469–480.

 

Motivation

The network of public transport brings people and goods to their destinations in a highly organized fashion. Similarly, the network of metabolic reactions in a cell is responsible for providing a wide range of substances at the right time in the right proportions for a specific location of consumption. These parallels let us assume that the logistics targets are comparable. The key challenge for both systems is very general: How do logistics systems ensure robustness with respect to perturbations? Within this project we want to explore possible forms of knowledge transfer between the two disciplines, systems biology and logistics. We here focus on a comparison of metabolism and industrial production.
This is a collaborative project by Prof. Dr.-Ing. Windt and Prof. Dr. Hütt from Jacobs University and Prof. Dr. Helbing from ETH Zurich.

Objectives

The project aims at comparing design principles and formal relations between systems properties and functions of metabolism and to exploit them in the context of transportation and industrial production.

Approach

 

  • Establishment of the agent‐based modeling of metabolism
  • Establishment of a suitable process classification scheme of modeling elements of production logistics processes and the related data
  • Derivation of metabolism‐inspired optimization strategies for industrial production

 

Contact

Dr. Till Becker
Jacobs University Bremen gGmbH
Campus Ring 1 | 28725 Bremen | Germany
Office: South Hall, Room 123
phone: +49 421 200 3074
e-mail: t.becker@jacobs-university.de