Optimal Tracker For Unreliable Manufacturing Systems

This paper deals with the inventory-production control problem where the produced items are assumed to deteriorate at a rate that depends on the demand rate of the production system. The state of this production system is assumed to be described by a continuous-time Markov process taking values in a finite discrete space. The inventory-production control problem is formulated as a stochastic optimal control problem. The optimal policy that solves the optimal control problem is obtained in terms of a set of coupled Riccati equations. The guaranteed cost problem is also treated. A numerical example is provided to show the usefulness of the proposed model

Image Segmentation with Human-in-the-loop in Automated De-caking Process for Powder Bed Additive Manufacturing

Additive manufacturing (AM) becomes a critical technology that increases the speed and flexibility of production and reduces the lead time for high-mix, low-volume manufacturing. One of the major bottlenecks in further increasing its productivity lies around its post-processing procedures. This work focuses on tackling a critical and inevitable step in powder-bed additive manufacturing processes, i.e., powder cleaning or de-caking. Pressing concerns can be raised with human involvement when performing this task manually. Therefore, a robot-driven automatic powder cleaning system could be an alternative to reducing time consumption and increasing safety for AM operators. However, since the color and surface texture of the powder residuals and the sintered parts are similar from a computer vision perspective, it can be challenging for robots to plan their cleaning path. This study proposes a machine learning framework incorporating image segmentation and eye tracking to de-cake the parts printed by a powder bed additive manufacturing process. The proposed framework intends to partially incorporate human biological behaviors to increase the performance of an image segmentation algorithm to assist the path planning for the robot de-caking system. The proposed framework is verified and evaluated by comparing it with the state-of-the-art image segmentation algorithms. Case studies were utilized to validate and verify the proposed human-in-the-loop algorithms. With a mean accuracy, f1-score, precision, and IoU score of 81.2%, 82.3%, 85.8%, and 66.9%, respectively, the suggested HITL eye tracking plus segmentation framework produced the best performance out of all the algorithms evaluated and compared. Regarding computational time, the suggested HITL framework matches the running times of the other test existing models, with a mean time of 0.510655 seconds and a standard deviation of 0.008387. Finally, future works and directions are presented and discussed. A significant portion of this work can be found in (Asare-Manu et al., 2023

Controlled switching in Kalman filtering and iterative learning controls

“Switching is not an uncommon phenomenon in practical systems and processes, for examples, power switches opening and closing, transmissions lifting from low gear to high gear, and air planes crossing different layers in air. Switching can be a disaster to a system since frequent switching between two asymptotically stable subsystems may result in unstable dynamics. On the contrary, switching can be a benefit to a system since controlled switching is sometimes imposed by the designers to achieve desired performance. This encourages the study of system dynamics and performance when undesired switching occurs or controlled switching is imposed. In this research, the controlled switching is applied to an estimation process and a multivariable Iterative Learning Control (ILC) system, and system stability as well as system performance under switching are investigated. The first article develops a controlled switching strategy for the estimation of a temporal shift in a Laser Tracker (LT). For some reason, the shift cannot be measured at all time. Therefore, a model-based predictor is adopted for estimation when the measurement is not available, and a Kalman Filter (KF) is used to update the estimate when the measurement is available. With the proposed method, the estimation uncertainty is always bounded within two predefined boundaries. The second article develops a controlled switching method for multivariable ILC systems where only partial outputs are measured at a time. Zero tracking error cannot be achieved for such systems using standard ILC due to incomplete knowledge of the outputs. With the developed controlled switching, all the outputs are measured in a sequential order, and, with each currently-measured output, the standard ILC is executed. Conditions under which zero convergent tracking error is accomplished with the proposed method are investigated. The proposed method is finally applied to solving a multi-agent coordination problem”--Abstract, page iv

PV systems design optimization as function of the climatic conditions

The present work evaluates some of the weaknesses affecting the solar photovoltaic energy deployment in the frame of the Sustainable Developing Goals (SDG) of the UN. As one of the most promising renewable energy sources due to its resource availability, modularity and competitive costs, the rapid growth of the PV in terms of new designs and module technologies needs to be assessed. An adequate analysis of these developments requires not only the energy production to be evaluated, also technologic lifecycle, including economic and environmental costs, must be considered. To that end, an analysis of the photovoltaic systems designs, adequate technology selection and sizing methods is done as function of the climatic conditions. The suitability of installing solar trackers compared to fixed tilt racking designs is assessed as function of the diffuse fraction including the economic and energetic costs. This analysis is extrapolated to a worldwide extent as function of the Köppen climate classification. Besides, the behaviour of the different PV modules commercial technologies is evaluated as function of the climate. Finally, the limitations of the most frequent sizing methods for stand-alone PV systems are evaluated in terms of user consumption regimes and the climatic conditions. A simple algorithm allows to optimize the PV system sizing in terms of the economic and energetic costs

Technical Approaches toComputer-Assisted Orthopedic Surgery

Abstract : Surgical navigation systems and medical robotic devices are increasingly being used during trauma and orthopedic surgery. This article tries to present the underlying technology of these devices and to describe different approaches to the various aspects of the methods. To structure the variety of available products and presented research modules, a new categorization for these approaches is proposed. Examples of pre- or intraoperative imaging modalities, of trackers for navigation systems, of different surgical robots, and of methods for registration as well as referencing are discussed. Many applications that have been realized for numerous surgical procedures will be presented and their advantages, disadvantages, and possible implications will be elucidate

Pictures in Your Mind: Using Interactive Gesture-Controlled Reliefs to Explore Art

Tactile reliefs offer many benefits over the more classic raised line drawings or tactile diagrams, as depth, 3D shape, and surface textures are directly perceivable. Although often created for blind and visually impaired (BVI) people, a wider range of people may benefit from such multimodal material. However, some reliefs are still difficult to understand without proper guidance or accompanying verbal descriptions, hindering autonomous exploration. In this work, we present a gesture-controlled interactive audio guide (IAG) based on recent low-cost depth cameras that can be operated directly with the hands on relief surfaces during tactile exploration. The interactively explorable, location-dependent verbal and captioned descriptions promise rapid tactile accessibility to 2.5D spatial information in a home or education setting, to online resources, or as a kiosk installation at public places. We present a working prototype, discuss design decisions, and present the results of two evaluation studies: the first with 13 BVI test users and the second follow-up study with 14 test users across a wide range of people with differences and difficulties associated with perception, memory, cognition, and communication. The participant-led research method of this latter study prompted new, significant and innovative developments