Johannes Cottyn

A method to align a manufacturing execution system with Lean objectives

The application of information technology and Lean principles have long been seen as mutually exclusive, but both approaches are more and more claimed to be interdependent and complementary. Real-time production information is crucial to make important business decisions. A manufacturing execution system (MES) can provide the necessary support during the Lean journey. MES can trigger, feed or validate the Lean decision-making process by providing useful information. In addition, MES can maintain the process improvements by enforcing the standardised way of working. However, this is only possible when MES is aligned and is kept aligned to the Lean objectives. The MES processes must be included in the continuous improvement cycle to prevent them from becoming obsolete. In this work, a method is proposed to analyse this alignment between Lean and MES. The manufacturing operations management framework provided by ISA 95 is believed to deliver the necessary components to identify and structure this alignment. Mapping MES and Lean activities onto the same framework brings valuable insights about their dependency. The analysis is explored through a case example. Preventing the system from becoming obsolete, by proposing standard model changes, is an important direction for further research.

The Efficiency of Hybrid Stepping Motors: Analyzing the Impact of Control Algorithms

Stepping motors are used in numerous applications because of their low manufacturing cost and simple open-loop position control capabilities. It is well known that their energy efficiency is low, although the actual efficiency values are generally not available. Moreover, the bulk of the stepping motors are driven in a non-optimal way, e.g., in an open loop with a maximum current to avoid step loss and, thus, with low efficiency. In this article, the impact of the control algorithm on the efficiency of the motor is analyzed, measured, and discussed. The basic open-loop full-, half-, and microstepping algorithms are considered together with a more advanced vector control algorithm. For each algorithm, the torque/current optimization is discussed.

ISO Efficiency Curves of a -Two-Phase Hybrid Stepping Motor

Stepping motors are used in numerous applications because of their low manufacturing cost and simple speed control. It is well known that their energetic efficiency is low but actual values are typically not available. In this paper the influence of the control algorithm on the efficiency of the stepping motor is analyzed, measured and discussed. For a good comparison of the efficiency for the different analyzed algorithms, ISO efficiency curves are used. As the number of stepping motors installed worldwide is enormous, a few percents energy saving per stepping motor can mean a big difference in global energy use.

The combined adoption of production it and strategic initiatives - Initial considerations for a Lean MES analysis

Todays economic environment drives the adoption of strategic intitiatives. At one hand there is the interest in different management philosophies, such as Lean manufacturing. On the other hand manufacturers see a greater need to adopt, upgrade or expand their enterprise IT solutions. As real-time information is crucial, the support for the companys strategic initiatives must be considered in the requirements analysis for and selection procedure of the new or modified production IT. To justify the IT and integration investments, the featured benefits of the companys strategic initiatives can be used. As both items are so interrelated, it seems obvious to seek methods to combine the adoption of production IT and strategic initiatives. The combination of Lean manufacturing and Manufacturing Execution System adoption is presented as an example. Both items are described and their mutual support possibilities are outlined. First, the ability of the ISA 95 standard to add the Lean support in the requirements analysis is studied. Second, the justification of the MES investment through the featured Lean improvements is analysed. The corresponding steps for a Lean MES analysis are listed. To conclude, further research on the Lean MES adoption and specifically the implementation of an automated Value Stream Mapping tool is mentioned.

The evaluation of an elementary virtual training system for manual assembly

Due to the low volume high variety strategies of manufacturing companies, manual assembly operators have a much larger cognitive load than before. The expertise of the operators must be kept up to date at any time. Since the high investment and low flexibility of a real setting to perform a manual assembly training, a virtual replica is introduced in many cases. The aim of this paper is to study the effect of an elementary virtual training for manual assembly tasks. In literature, different studies on the topic can be found; nevertheless, a comparison between the different studies is not possible due to diverse evaluation methods and descriptions. A benchmark for a uniform evaluation of virtual training systems is presented and applied to this experiment. Two groups were submitted to a number of manual assembly tasks. The test group got a virtual training period in advance. A significant learning transfer during that training period was observed. When the first assembly of the reference group is counted as a real training, no significant difference can be found between the virtual and real training. The outcomes of this experiment will be used in future work to compare different virtual training systems and influential factors such as the assembly complexity. Furthermore, the application of virtual training to manual assembly in a mixed-model environment and its industrial usability are topics that still need to be studied.

Sensitivity analysis of a linear model for a vector controlled hybrid stepping motor

Recent research on stepping motors concerns intelligent motion control algorithms such as sensorless vector control. Sensorless control is commonly based on a motor model. For stepping motors, this model is highly nonlinear, resulting in a high computational cost. When the motor is controlled by a vector-controlled algorithm, the position dependence of certain model parameters can be eliminated. If saturation and reluctance effects are neglected, the motor model can be transformed into a linear model. In this paper, the linear model is verified by simulations and measurements. A profound sensitivity analysis proves the robustness of the model. Due to the hybrid motor construction reluctance effects occur. These effects are also measured and discussed.

Abnormal work cycle detection based on dissimilarity measurement of trajectories

This paper proposes a method for detecting the abnormalities of the executed work cycles for the factory workers using their tracks obtained in a multi-camera network. The method allows analyzing both spatial and temporal dissimilarity between the pairwise tracks. The main novelty of the methods is calculating spatial dissimilarity between pair-wise tracks by aligning them using Dynamic Time Warping (DTW) based on coordinate distance, and specially the velocity and dwell time dissimilarity using a different track alignment based on velocity difference. These dissimilarity measurements are used to cluster the executed work cycles and detect abnormalities. The experimental results show that our algorithm outperforms other methods on clustering the tracks because of the use of temporal dissimilarity.