Analytical Modeling of Human Choice Complexity in a Mixed Model Assembly Line Using Machine Learning-Based Human in the Loop Simulation

Despite the recent advances in manufacturing automation, the role of human involvement in manufacturing systems is still regarded as a key factor in maintaining higher adaptability and flexibility. In general, however, modeling of human operators in manufacturing system design still considers human as a physical resource represented in statistical terms. In this paper, we propose a human in the loop (HIL) approach to investigate the operator???s choice complexity in a mixed model assembly line. The HIL simulation allows humans to become a core component of the simulation, therefore influencing the outcome in a way that is often impossible to reproduce via traditional simulation methods. At the initial stage, we identify the significant features affecting the choice complexity. The selected features are in turn used to build a regression model, in which human reaction time with regard to different degree of choice complexity serves as a response variable used to train and test the model. The proposed method, along with an illustrative case study, not only serves as a tool to quantitatively assess and predict the impact of choice complexity on operator???s effectiveness, but also provides an insight into how complexity can be mitigated without affecting the overall manufacturing throughput

MODELING OF TASK COMPLEXITY IN HUMAN-CENTERED SYSTEMS

Department of System Design & Control EngineeringThroughout the years, technological expansion has been coupled with complex work allocation in Human-Centered System (HCS). In spite of the recent advances in automation, role of humans in the HCS is still regarded a key factor for adaptability and flexibility. Meanwhile, due to advances in computing, computer simulations have been the indispensable tool in the study of complex systems. However, due to the inability to accurately represent human dynamic behavior, the majority of HCS simulations have often failed to meet expectations. The failure of HCS simulations can be traced in poor or inaccurate representation of key aspect of system. Whereas the machine component of HCS is often accurately simulated, research claims that human component is often the cause of a large percentage of the disparity between simulation predictions and real-world performance. This dissertation introduces a novel human behavioral modeling framework that systematically simulates human action behavior in HCS. The proposed modeling framework is demonstrated with a case study using simulation in which a set of feasible human actions are generated from the affordance-effectivity duals in a spatial-temporal dimension. The model employs Markov Decision Process (MDP) in which NASA-TLX (Task Load Index) is used as cost estimates. The action selection process of human agents, i.e., triggering of state transitions, is stochastically modeled in accordance with the action-state cost (load) values. A series of affordance-based numerical values are calculated for predicting prospective actions in the system. Finally, an evacuation simulation example based on the proposed model is illustrated to verify the proposed human behavioral modeling framework. The incorporation of human modeling in HCS simulation offers a wide range of benefits in representing human???s goal directed action. However due to the complexity and the cost of representing every aspect of human behavior in computable terms, the proposed framework is better fit in simplified and controllable environment. Thus, we then propose a human in the loop (HIL) approach to investigate the operator???s performance in HCSparticularly, the mixed model assembly line (MMAL). In HCS such as MMAL, human operators are often required to carry out tasks according to instructions. In the proposed methodology, rather than a mathematical representation of human, a real human plays a core role in system operation for the simulation and consequently influences the outcome in such a way that is difficult if not impossible to reproduce via traditional methods. At the initial stage of the simulation, various features are extracted after which, a stepwise feature selection is used to identify the most relevant features affecting human performance. The selected features are in turn used to build a regression model used to generate human performance parameters in the HCS simulation. Finally, we explore the analytical relationship between the flexibility (variation) and the complexity of human role in HCS. As the number of alternative choices (or actions) available to human increases, the choice process becomes complex, rending human modeling and predictability more difficult. The dissertation will particularly utilize the visual choice complexity to convey the proposed computation of task complexity as a function of flexibility. Thus, we propose a method to quantify task complexity for effective management of the semi-automated systems such a MMAL. Based on the concept of information entropy, our model considers both the variety in the system and the similarity among the varieties. The proposed computational model along with an illustrative case study not only serve as a tool to quantitatively assess the impact of the task complexity on the total system performance, but also provide an insight on how the complexity can be mitigated without worsening the flexibility and throughput of the system.ope

Sequence Based Optimization of Manufacturing Complexity in a Mixed Model Assembly Line

Increasing production variability while maintaining operation efficiency remains a critical issue in many manufacturing industries. While the adoption of mixed-model assembly lines enables the production of high product variety, it also makes the system more complex as variety increases. This paper proposes an information entropy-based methodology that quantifies and then minimizes the complexity through product sequencing. The theory feasibility is demonstrated in a series of simulations to showcase the impact of sequencing in controlling the system predictability and complexity. Hence, the framework not only serves as a tool to quantitatively assess the impact of complexity on total system performance but also provides means and insights into how complexity can be mitigated without affecting the overall manufacturing workload

The relationship between depressive symptoms and cancer risk factors of smoking and physical activity among African-Americans

https://openworks.mdanderson.org/sumexp21/1193/thumbnail.jp

Cattle Identification Using Muzzle Images and Deep Learning Techniques

Traditional animal identification methods such as ear-tagging, ear notching, and branding have been effective but pose risks to the animal and have scalability issues. Electrical methods offer better tracking and monitoring but require specialized equipment and are susceptible to attacks. Biometric identification using time-immutable dermatoglyphic features such as muzzle prints and iris patterns is a promising solution. This project explores cattle identification using 4923 muzzle images collected from 268 beef cattle. Two deep learning classification models are implemented - wide ResNet50 and VGG16\_BN and image compression is done to lower the image quality and adapt the models to work for the African context. From the experiments run, a maximum accuracy of 99.5\% is achieved while using the wide ResNet50 model with a compression retaining 25\% of the original image. From the study, it is noted that the time required by the models to train and converge as well as recognition time are dependent on the machine used to run the model.Comment: 8 pages, 4 figures, 2 table

Forecasting Warping Deformation Using Multivariate Thermal Time Series and K-Nearest Neighbors in Fused Deposition Modeling

Over the past decades, additive manufacturing has rapidly advanced due to its advantages in enabling diverse material usage and complex design production. Nevertheless, the technology has limitations in terms of quality, as printed products are sometimes different from their desired designs or are inconsistent due to defects. Warping deformation, a defect involving layer shrinkage induced by the thermal residual stress generated during manufacturing processes, is a major factor in lowering the quality and raising the cost of printed products. This study utilized a variety of thermal time series data and the K-nearest neighbors (KNN) algorithm with dynamic time warping (DTW) to detect and predict the warping deformation in the printed parts using fused deposition modeling (FDM) printers. Multivariate thermal time series data extracted from thermocouples were trained using DTW-based KNN to classify warping deformation. The results showed that the proposed approach can predict warping deformation with an accuracy of over 80% by only using thermal time series data corresponding to 20% of the whole printing process. Additionally, the classification accuracy exhibited the promising potential of the proposed approach in warping prediction and in actual manufacturing processes, so the additional time and cost resulting from defective processes can be reduced

Method for predicting human behavior based on affordance probability and method for establish training plan using the method thereof

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