Karl-Heinz Wehking

On the Suitability of Different Features for Anomaly Detection in Wire Ropes

Automatic visual inspection of wire ropes is an important but challenging task, as anomalies in the rope are usually unobtrusive. Certainly, a reliable anomaly detection is essential to assure the safety of the ropes. A one-class classification approach for the automatic detection of anomalies in wire ropes is presented. Furthermore, the performance of different well-established features from the field of textural defect detection are compared with respect to this task. The faultless rope structure is thereby modeled by a Gaussian mixture model and outliers are regarded as anomaly. To prove the practical applicability, a careful evaluation of the presented approach is performed on real-life rope data. In doing so, a special interest was put on the robustness of the model with respect to unintentional outliers in the training and on its generalization ability given further data from an identically constructed rope. The results prove good recognition rates accompanied by a high generalization ability and robustness to outliers in the training set.

HMM-Based Defect Localization in Wire Ropes --- A New Approach to Unusual Subsequence Recognition

Automatic visual inspection has become an important application of pattern recognition, as it supports the human in this demanding and often dangerous work. Nevertheless, often missing abnormal or defective samples prohibit a supervised learning of defect models. For this reason, techniques known as one-class classification and novelty- or unusual event detection have arisen in the past years. This paper presents a new strategy to employ Hidden Markov models for defect localization in wire ropes. It is shown, that the Viterbi scores can be used as indicator for unusual subsequences. This prevents a partition of the signal into sufficient small signal windows at cost of the temporal context. Our results outperform recent time-invariant one-class classification approaches and depict a great advance for an automatic visual inspection of wire ropes.

Flexible agent-based planning and adaptation of material handling systems

Todays material handling equipment and industrial automation solutions allow timely adaptation to changing environmental conditions within certain limits. However, in general the planning of material handling systems is a knowledge-driven, non-transparent and time-consuming planning procedure. The aim of the approach presented in this paper is the development of a decentralized methodology for the (rough) design of material handling systems. In this approach the material handling systems are modeled as complex adaptive systems and their planning is modeled as a procedure based on information exchange, formally described and assigned by an agent system. The described planning procedure is based on a bottom-up approach, in which the material handling system is formed by a multiple targeted composition, configuration and adaptation. The planning, based on previously defined rules, leads to an increase in efficiency and transparency.

Use of High Strength Fibre Ropes in Multi-Rope Kinematic Robot Systems

High strength fibre ropes are facing a strongly increasing interest for rope driven applications. Basic characteristics such as strength are already competitive or even outperforming wire ropes; however other limitations still prevent their full reliable industrial use. One particular application where the advantages of high strength fibre ropes do have an extraordinary important effect on the usability of the application is the use in robot systems with multi-rope kinematics. Basic requirements of these systems are (among others) high accuracy paired with a high efficiency, which means high process velocities as well as high accelerations and decelerations. Many tests have already been conducted to simulate a wide range of load settings—however up to date testing of fibre ropes in high speed usage is still mostly missing. This article describes the state of the art of high strength fibre rope usage in material handling, discusses advantages and disadvantages of these ropes and points out the most important challenges for research and improvement of rope driven robot systems.

Agent-based dimensioning to support the planning of Intra-Logistics systems

The increasing cost pressure on Intra-Logistics systems due to the global competition in Intra-Logistics systems motivates planners to decrease planning durations in order to stay cost efficient. Conversely, the rough planning of Intra- Logistics systems is a time consuming, complex task, whose progress is primarily driven by the experience of the planning team. Consequently, the planning is opaque. In order to reduce the planning duration and to systemize the planning this paper presents a rule-based concept for an agent-based assistance system to support the planner during the rough planning of Intra-Logistics systems. The assistance system provides an overview of possible solutions regarding to specified requirements by generating and evaluating all possible solution alternatives.

Linked logistics concepts for future automobile manufacturing using innovative equipment

In this article we present the necessary changes in production logistics of automobile manufacturing for the upcoming years. Based on the higher amount of car models and the continuing growth of variations in the premium car segment, it has become difficult to produce vehicles economically using Henry Ford’s idea conveyor-based techniques. While this method has advantages regarding the high amount of output, changes will be necessary in order to cope with high variant productions tending to lot size one. Therefore the research project ARENA2036 (Active Research Environment for the Next Generation of Automobiles) and specifically the members of the “research factory” is focuses on developing new concepts for assembly and logistics including technologies such as human-robot interaction (HRI), virtual security fences and transparent information.

Changes in production logistics for automobile manufacturing

Changes in the production of automobile will be needed in the next years. This observation is based not only on the higher amount of variations and car models but also on the different power unit alternatives. These transformations can take place only if production logistics changes their processes and workflows. In the context of the research environment ARENA2036, new concepts are being developed at the Institute for logistics and material handling (IFT) in Stuttgart. In this paper we give an overview of these new concepts, their specific operating resources and the results of initial simulation studies.

Bending Fatigue Strength and Lifetime of Fiber Ropes

Modern fiber ropes have several distinctive properties which predestine them amongst others for high dynamic applications in robotics. Beside their great breaking load due to their high tensile streghth, the extremely low density and weight are the most important advantages over steel wire ropes. For steel wire ropes, it is generally known that their lifetime drops when raising the dynamic stress on running or static ropes. The long-time behavior of high-dynamically stressed fiber ropes is totally unexplored up to now. This lack impedes the breakthrough of fiber ropes and causes a safety gap, which has to be closed. This paper describes the research on modern fiber ropes regarding their lifetime in normal and high dynamic applications. The derived results are interpretered with respect to application in robotics.

Challenges of a safe value-added production logistics of the future

In this article, we present challenges of a safe value-added production logistics for the future. Challenges have been tracked down in the area of collaboration with AGVs, sensors, position detection and real-time decision making. Different concepts and technologies may help to find solutions for these challenges. Pick-by-Voice systems or novel sensors can improve AGV collaboration. Monitoring systems and safety sensors that measures the distance to obstacles reliably and identifies specific objects at the same time are needed to enable autonomous and changeable production logistics systems. In addition, technologies such as Ultra-Wideband-systems (UWB) support safe position detection. Progress in the field of information systems like smart contracts helps utilize real-time decision making. Elaborated safety concepts are required for the implementation of a value-added production logistics.

Aufzüge und Schachtförderanlagen

In den Geltungsbereich der Personenfordertechnik fallen die Aufzuge, die Seilbahnen und Aufstiegshilfen, die Fahrtreppen und Fahrsteige und die Schachtforderanlagen. Bei den Aufzugen wird zwischen Seil‑, Hydraulik‑, Spindel‑, Trommel‑ und Zahnstangenaufzugen unterschieden. Seil- und Hydraulikaufzuge haben einen Anteil von 98 %. Unter Seilbahnen fallen die Seilschwebebahnen im Pendel- und im Umlaufbetrieb mit Tragseil (meist vollverschlossenes Spiralseil) und Zugseil (Rundlitzenseil). Bei Einseilumlaufbahnen sind die Funktionen von Zug- und Tragseil im Forderseil zusammengefuhrt.