Prof. Dr.

Wrobel, Stefan

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  • Publication
    Explainable production planning under partial observability in high-precision manufacturing
    ( 2023-10)
    Weichert, Dorina
    ;
    Kister, Alexander
    ;
    Volbach, Peter
    ;
    Houben, Sebastian
    ;
    Trost, Marcus
    ;
    Wrobel, Stefan
    Conceptually, high-precision manufacturing is a sequence of production and measurement steps, where both kinds of steps require to use non-deterministic models to represent production and measurement tolerances. This paper demonstrates how to effectively represent these manufacturing processes as Partially Observable Markov Decision Processes (POMDP) and derive an offline strategy with state-of-the-art Monte Carlo Tree Search (MCTS) approaches. In doing so, we face two challenges: a continuous observation space and explainability requirements from the side of the process engineers. As a result, we find that a tradeoff between the quantitative performance of the solution and its explainability is required. In a nutshell, the paper elucidates the entire process of explainable production planning: We design and validate a white-box simulation from expert knowledge, examine state-of-the-art POMDP solvers, and discuss our results from both the perspective of machine learning research and as an illustration for high-precision manufacturing practitioners.
  • Publication
    Robustness in Fatigue Strength Estimation
    ( 2022-12-02)
    Weichert, Dorina
    ;
    Kister, Alexander
    ;
    Houben, Sebastian
    ;
    Ernis, Gunar
    ;
    Wrobel, Stefan
    Fatigue strength estimation is a costly manual material characterization process in which state-of-the-art approaches follow a standardized experiment and analysis procedure. In this paper, we examine a modular, Machine Learning-based approach for fatigue strength estimation that is likely to reduce the number of experiments and, thus, the overall experimental costs. Despite its high potential, deployment of a new approach in a real-life lab requires more than the theoretical definition and simulation. Therefore, we study the robustness of the approach against misspecification of the prior and discretization of the specified loads. We identify its applicability and its advantageous behavior over the state-of-the-art methods, potentially reducing the number of costly experiments.