Integrated Heterogeneous Micro-Nano Systems via Modular Designing and Flexible Assembly

Flexible Assembly Systems - Hardware Components and Features: Basic components of a FAS.- Classification of flexible assembly systems.- Examples of industrial installations.- Issues in Design, Planning and Scheduling of Flexible Assembly: FAS design issues.- Network design for material flow systems.- Design for assembly.- Assembly planning.- Planning and scheduling.- Loading and Routing Decisions in Flexible Assembly Systems: Description of a flexible assembly system.- Optimization of station workloads and product movements.- Design and balancing of flexible assembly lines.- Numerical examples.- Simultaneous loading and routing.- Sequential loading and routing.- Loading and Routing Decisions with Assembly Plan Selection: Simultaneous loading, routing and assembly plan selection in a general flexible assembly system.- Simultaneous loading, routing and assembly plan selection in a flexible assembly line.- Loading and Scheduling in Flexible Assembly Cells: Loading and scheduling in a robot assembly cell.- Loading and sequencing in printed circuit board assembly.- Production Scheduling in Flexible Assembly Lines: Flexible assembly line with limited intermediate buffers.- Flexible assembly line with no in-process buffers.- Global lower bounds for flexible flow lines with unlimited buffers.- Just-in-time scheduling of flexible assembly lines.- Multilevel scheduling of flexible assembly lines with limited intermediate buffers.- Machine and Vehicle Scheduling in Flexible Assembly Systems: Dispatching scheduling.- Machine and vehicle scheduling - a multi-level approach.- Machine and vehicle scheduling - a single-level approach.

Modular fixtures are one of the important aspects of manufacturing. This paper presents a desktop VR system for modular fixture design. The virtual environment is designed and the design procedure is proposed. It assists the designer to make the feasible design decisions effectively and efficiently. A hierarchical data model is proposed to represent the modular fixture assembly. Based on this structure, the user can manipulate the virtual models precisely in VE during the design and assembly processes. Moreover, the machining simulation for manufacturing interaction checking is discussed and implemented. Finally, the case study has demonstrated the functionality of the proposed system. Compared with the immersive VR system, the proposed system has offered an affordable and portable solution for modular fixtures design

Modular production system concept for a water tap assembly

During the early 1980s, the concept of a flexible assembly machine was first suggested by Hounsfield (1983). Following this, a variety of research projects have been conducted in an attempt to develop a flexible assembly system that is functional and economically viable. The most significant contribution has been made by the EURICA EU 321 - FAMOS - INFACT* project. However, despite the developments made during these projects, no industrial based system exists today. This paper presents a simulation model of a novel concept for a multi-station flexible automatic assembly machine, and examines the application of a rule based control strategy for the control of a materials handling system used in such a system. * http://www.3.eureka.be/home/

An increasing number of product variants caused by individualization drives industry to develop flexible modular assembly systems. In such systems, automated guided vehicles handle the material transport between decoupled workstations. This enables jobs to be flexibly routed through production, utilizing order and operation flexibility. Order flexibility denotes a partially flexible order of a job's operations, whereas operation flexibility is given, if at least one operation of a job is allocatable to more than one workstation. Managing the given flexibility and coordinating the automated guided vehicles in real production environments requires robust control algorithms. Exploiting the potential of Industry 4.0, this work presents a negotiation-based agent approach by decentralizing the problem: A job release agent defines the points in time and the product types of released jobs. Job routing agents negotiate with workstation agents to schedule their operations by minimizing makespan. Finally, a vehicle agent organizes the transports from workstation to workstation. The agent system has been successfully evaluated and achieved better results than earlier implementations.

Recently a major trend in flexible and precision assembly automation, and in automation in general, has been in robots that can safely work next to people. Increasingly, as part of collaborative automation, such robots are also designed to collaborate as teams with other robots. These intelligent machines are called cobots, or collaborative robots, and are reducing the cost and time to install robots in many applications. Flexible and precision assembly refers to an assembly system that can build multiple similar products with little or no reconfiguration of the assembly system. It can serve as a model for some of the emerging applications in flexible and precision automation. Precision assembly implies assembly with precise motions and operations. Recently, machine learning interacting with the robots’ sensors enables robots to assemble parts and components with precision that exceeds their own motion precision. A truly flexible assembly system would enable precision assembly, include flexible part feeding, grasping, and fixturing, as well as a variety of mating and fastening processes that can be quickly added or deleted without costly engineering. There is a limited science base for how to design flexible assembly systems in a manner that will yield predictable and reliable throughputs. The emergence of geometric modeling systems (as part of CAD) has enabled work in geometric reasoning in the past few years. Geometric models have been applied in areas such as machine vision for object recognition, design, and throughput analysis of flexible part feeders, dynamic simulation of assembly stations and assembly lines. Still lacking are useful techniques for automatic model generation, planning, error representation, error prevention (avoidance), and error recovery. Future software architectures for flexible and precision automation should include geometric modeling and reasoning capabilities to support autonomous, sensor-driven systems.

Global competition and the rapid pace of technological change now require the almost continual introduction of product upgrades by any manufacturer. Thus, such a manufacturer is likely to market older and newer versions of a product simultaneously, not to mention niche-specific editions of any product upgrade. An increasingly successful response to this product proliferation is the implementation of flexible assembly systems. In the context of a flexible assembly system (FAS), the ability to estimate the impact of various product and process options on the maximal level of system output becomes crucial to managing the ever-changing product mix. This paper presents a tool for such impact estimation that can facilitate concurrent development and engineering. Experience with an actual FAS is the basis for the reported results. The tool is a specialized combination of discreteevent computer simulation, experimental design, and regression analysis. Application of the tool assumes FAS use with a cellular manufacturing philosophy. Thus, uncluttered process flow for a family of products in the sense of group technology places the focus on potential bottlenecks. The new tool here models the impact of process and product options on bottleneck and, hence, FAS behavior.

As manufacturing trends shift towards customized production, the demand for agile automation systems capable of efficient adaptation to rapidly changing task requirements is rising. This work presents a flexible robotic assembly system that combines CAD based component localization, compliance control, and a multi-modal gripper to enable robust and efficient programming of complex tasks. The process can be easily configured for novel assemblies through a dedicated Graphical User Interface (GUI), which facilitates component identification and task sequencing. Component poses are extracted from 3D CAD models in reference to the assembly origin, while the active compliance scheme compensates for minor positioning errors. The gripper incorporates a parallel jaw element, a rotating module, and an electromagnet to minimize retooling delays. The first iteration of the proposed system placed first in the manufacturing track of the Robotic Grasping and Manipulation Competition of the 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), experimentally validating its efficiency.

Components of the Design Process of Flexible and Reconfigurable Assembly Systems

Diminishing fossil fuel reserves and a growing collective environmental awareness has led to the development of alternative methods of power generation such as Concentrated Solar Power (CSP). Although almost all existing CSP plants currently use water-cooled condensers, limited water supplies in the designated desert regions for such power plants, the high costs associated with providing cooling water and environmental considerations will all restrict the future use of water-cooled condensers. Air-cooled condensers (ACCs) are therefore proposed, despite evidence to suggest that they suffer from significant inefficiencies [1]. It has been suggested that a modular design, addressed in this paper, could offer solutions to issues with current ACC technologies. To fully characterise the modular ACC design it is necessary to quantify the steam-side characteristics. A series of tests were performed under vacuum conditions representative of an operational condenser. The condenser vacuum was measured for a series of incremental fan rotational speeds, to determine both the qualitative and quantitative relationship between fan speed and condenser pressure. Results indicate that for a given steam mass flow rate, the condenser pressure decreases with increasing fan rotational speed. Furthermore, the choice of vacuum pump, used to displace air leakages, was shown to have a significant influence on the steam-side response. Larger displacement-capacity vacuum pumps permit lower condenser pressures. The steam condensation pressure drop through the condenser tubes was also measured. Results for the measured pressure drop revealed a large level of momentum recovery, which is not uncommon in steam condensation processes. Experimental frictional pressure drops were determined and these compared favourably with certain two-phase frictional pressure drop correlations. In particular, the Lockhart & Martinelli correlation was found to be most capable of predicting the frictional pressure drop trends encountered during testing. The large level of agreement between the measurements and predictions provide confidence in future use of the Lockhart & Martinelli correlation to predict frictional pressure losses.

To date, holonic manufacturing system (HMS), one of the novel concepts to meet the increasing globalization and customization of the manufacturing processes, has been conceptually constructed, and prototyping systems, holonic fixturing station (HOLOFIX), holonic autonomous guided vehicles (H-AGVs) etc. were developed with enhanced performances in their specific processes. This work presented an object oriented technology (OOT)-supported migration approach to holonic robot assembly cell. Based on the analysis of activities in the flexible assembly cell, an architecture of workstation for holonic robot assembly cell was proposed. The holonic robot workstation was established by incorporating a control computer that performs production planning, shop floor control and local operations into each of robot systems in the flexible assembly cell, workstations of this kind functions as the building blocks of holonic robot assembly cell. The holonic robot assembly cell employs a dynamic holarchy evolution mechanism to carry out assembly tasks. The entire implementation was conducted on the flexible assembly system in PMA/Leuven.

Flexible Assembly Systems through Workplace-Sharing and Time-Sharing Human-Machine Cooperation (PISA)

The successful implementation of a Flexible Manufacturing/Assembly System can be an effective means of reducing labor, resources and work-in-process inventory. It can increase equipment utilizations, improve quality and result in increased throughput. Simulation is an effective tool for analyzing critical system components and their inter-relationships; consequently, ensuring systems design meets throughput requirements at reduced costs. This paper presents an approach to the design, specification and implementation of a Flexible Assembly System (FAS) using simulation. It presents a practical approach for designing manufacturing systems involving uncertainties. Two simulation models are discussed:(1) a GPSS/H model and(2) a PCMODEL model.The GPSS/H model was used during the early FAS design and specification stage. The PCMODEL model was used to sell the proposed FAS configuration to management. The FAS has been successfully implemented.

Modular design and assembly of automotive and architectural structures - product integration through adhesive bonding

Introduction: The use of robotic systems for surgical procedures has increased rapidly over the past two decades. Although robotic-assisted surgery (RAS) has several advantages over conventional laparoscopic surgery, its costs and prolonged operative times remain a subject of debate. High costs are not only ascribed to high purchase and maintenance costs of the robot but also to longer operating times as well. Prolonged overall operating room times are partially due to extra time needed for preparing the robot (draping the robot, positioning the robot, and calibrating and docking the robotic arms). Hence, a study of the draping time and docking time of da Vinci Xi and three newer “multi-arm” robotic surgical systems, namely Cambridge Medical Robotics (CMR) Versius, Sudhir Srivastava Innovations International Inc. (SSI) Mantra, and Hugo RAS was planned. Review Methodology: This observational study was conducted in six centers of excellence which have conducted more than 100 RAS in the particular robotic platform during the past 1 year. The setup times, from the moment a patient entered the operating room until the surgeon started at the console, were documented by the observing researcher who had no other obligations during the surgery. Time points of different steps were recorded in HH: mm format. The data were entered into a spreadsheet, and descriptive and multivariate analyses of the draping time and docking time were done using statistical tools. Results: The mean draping time was 04:50.40, 05:00.00, 04:29.99, and 05:20.00 for da Vinci Xi, CMR Versius, SSI Mantra, and Hugo RAS, respectively. The mean docking time was 08:07.20, 09:26.67, 10:59.99, and 16:00.00 for da Vinci Xi, CMR Versius, SSI Mantra, and Hugo RAS, respectively. Discussion: There is no significant difference in the draping time of the four robotic platforms studied. However, the docking time of da Vinci Xi and Hugo RAS showed a significant difference with da Vinci Xi having a shorter docking time than Hugo RAS (P = 0.045). However, CMR Versius and SSI Mantra did not show any significant difference in docking time among themselves or in comparison to da Vinci Xi. Conclusions: The newer multi-arm robotic systems are comparable to da Vinci Xi with respect to draping time and docking time.