Adaptive Production Control with Negotiating Agents in Modular Assembly Systems

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.

One of the major challenges in commercializable micro-nano systems development is the high cost and turnaround that are incurred through multiple product-optimization iterations and expensive fabrication processes for specific systems. Development of complex and heterogeneous micro-nano systems, that are only possible through assembly and not by conventional surface machining approaches, are further impeded by lack of standard design rules and off-the-shelf robotic manipulation systems. Dedicated hardware and system specific component designs, although possible, are not commercially viable for addressing the wide range of opportunities that exists in the prevailing micro-nano domain. In this paper, we present an alternative and holistic top-down approach for micro-nano manufacturing using modular part designs and flexible assembly systems. We incorporate, seamlessly, multiple novel algorithms related to microrobotics and scaling of physics, obtained both analytically as well as experimentally; in order to predict, track and control the uncertainty propagation in a typical manufacturing process, in micro-nano scale, throughout production steps including design, machining, setup, assembly, testing etc. We demonstrate, through multiple examples, the implementation of the proposed framework in micro-nano scale manufacturing.

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/

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.

Car Latch (CL) has very complex mechanical structure, requiring strict technological process, and it is difficult to realize automatic manufacturing. In allusion to above problem, a kind of embedded flexible assembly system (FAS) for CL based on laser identification (LAI) has been put forward according to wide investigation and analysis for current CL assembly technology. In this paper, FAS idea is firstly brought into CL manufacturing. So kinds of CL can be assembled according to different production demands and flexibility of this system can be fully presented. CL structure and its technological processes are analyzed. By the introduction of LAI, Latch piece location and key outline identification problems are resolved in process of its assembly. Embedded micro process unit (EMPU) acts as a main controller, and closed loop control system, which has abundant control functions is implemented to realize control task for the whole assembly process. The idea of modularization is adopted, and that makes this system have strong augmentability and multiplexing ability to meet different assembly demands. A number of industry field experiments proved that this system locates exactly, runs stably, and increases the production efficiency of CL.

We present a decision-support framework for speeding up the ramp-up of modular assembly systems by learning from past experience. Bringing an assembly system to the expected level of productivity requires engineers performing mechanical adjustments and changes to the assembly process to improve the performance. This activity is time-consuming, knowledge-intensive and highly dependent on the skills of the engineers. Learning the ramp-up process has shown to be effective for making progress faster. Our approach consists of automatically capturing information about the changes made by an operator dealing with disturbances, relating them to the modular structure of the machine and evaluating the resulting system state by analysing sensor data. The feedback thus obtained on applied adaptations is used to derive recommendations in similar contexts. Recommendations are generated with a variant of the k-nearest neighbour algorithm through searching in a multidimensional space containing previous system states. Applications of the framework include knowledge transfer among operators and machines with overlapping structure and functionality. The application of our method in a case study is discussed.

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.

Operational flexibility is an important property of electric power systems. The term flexibility is widely used in the context of power systems although at times without a proper definition. The role of operational flexibility for the transition of existing power systems, many of them based on fossil fuels, towards power systems effectively accommodating high shares of variable Renewable Energy Sources (RES) has been widely recognized. Availability of sufficient operational flexibility is a necessary precondition for the grid integration of large shares of power in-feed from variable RES, for example wind power and photovoltaics (PV). The paper analyzes the role of operational flexibility in power systems. Necessary flexibility metrics for categorizing different types of operational flexibility are discussed. A new methodology for assessing the technically available operational flexibility is presented. Qualitative insights are derived, notably regarding the limits of RES integration for a given power system with its specific flexibility properties. An extensive simulation study is performed, assessing the role that operational flexibility has for the mitigation of challenges, namely curtailment, arising from high shares of variable RES in-feed.

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

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.

In order to complete the robot axle hole assembly task in an unstructured environment, an adaptive impedance control algorithm based on joint space force and position double feedback is proposed, and the assembly process adjustment strategy is designed to complete the assembly task. By installing a torque sensor on the joint of the six-axis cooperative robot, the control model of joint force position with double feedback is formed. By combining the model reference adaptive control (MRAC), operational force planning, and operational space motion planning, an assembly system based on joint space flexibility control is finally designed. According to the task of axle hole assembly, the geometric constraint analysis and force analysis are carried out in the axle hole assembly process, and the corresponding adjustment strategy is designed. The assembly experiments were carried out for holes with different gaps, and the pose parameters, contact force, and control adaptability parameters during assembly were analyzed experimentally. The experimental results show that the flexible assembly system can complete the shaft hole assembly well, and the assembly torque is controlled in a small range, which meets the assembly requirements.

Mass customization is one of competitive strategies in modern manufacturing (Blecker & Friedrich, 2006), the objective of which is to maximize customer satisfaction by producing highly customized products with high production efficiency. There are two starting points moving towards mass customization, mass production and one-of-a-kind production (OKP). The production volume of mass production is normally large, whereas that of OKP is usually small or extremely even just one. Mass production can achieve high production efficiency but relatively low customization, because products are designed in terms of standard product families, and produced repetitively in large volume. Comparatively, OKP can achieve high customization but relatively low production efficiency, because product design in OKP is highly customer involved, and each customer has different requirements. Therefore, the variation of customer requirements causes differences on each product. To improve production efficiency, OKP companies use mixed-product production on a flow line (Dean et al., 2008, 2009). Moreover, the production scheduling and control on OKP shop floors is severely challenged by the variation of customer requirements, whereas that in mass production is comparatively simple. Therefore, we focus on the adaptive production scheduling and control for OKP.

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.