Robotic Assembly Cell Research Articles

DEVELOPMENT OF A FUZZY-SIMULATION MODEL OF SCHEDULING ROBOTIC FLEXIBLE ASSEMBLY CELLS

Due to the complexity of scheduling flexible manufacturing systems, the generation of production schedules requires an intelligent technique. Many artificial intelligence techniques such as fuzzy logic, genetic algorithms and neural networks have been successfully applied to the scheduling of advanced manufacturing systems. One such system is Robotic Flexible Assembly Cells (RFACs). Few studies have addressed the problem of scheduling RFACs. The major limitation is that these studies are limited to the assembly of only one product type. The objective of this study is to propose a new intelligent model of scheduling RFACs in a multi-product assembly environment, using fuzzy logic.

Application of Fuzzy Logic to Multi-Objective Scheduling Problems in Robotic Flexible Assembly Cells

This paper is aimed at developing a methodology to solve a multi-objective problem in robotic flexible assembly cells. The proposed methodology is based on three main steps: (1) scheduling of the RFACs using different common rules, (2) normalisation of the scheduling outcomes, and (3) selection of the optimal scheduling rules, using a fuzzy inference system. In this paper, four rules, namely short processing time, long processing time, earlier due date and random, are examined. Four objectives are considered simultaneously: scheduling length, total transportation time, utilisation rate and workload rate. A realistic case study is provided for demonstrating applicability of the suggested methodology. The results show that the methodology is practical and works in RFACs settings.

A Fuzzy Decision Support System for Selecting the Optimal Scheduling Rule in Robotic Flexible Assembly Cells

The aim of this paper is to present a proposed methodology to select optimal scheduling rule for robotic flexible assembly cells based fuzzy decision support system. Six common scheduling rules are considered, and three independent objectives, namely, the minimising of makespan (Cmax), total tardiness (TD) and percentage of tardy jobs (%T) are measured. A fuzzy decision support system is implemented using the Matlab fuzzy toolbox. The final results demonstrate the effectiveness of the proposed methodology to select optimal scheduling rule in a multi-product assembly environment.

Contact-less and Programming-less Human-Robot Collaboration

In today's manufacturing environment, safe human-robot collaboration is of paramount importance, to improve efficiency and flexibility. Targeting the safety issue, this paper presents an approach for human-robot collaboration in a shared workplace in close proximity, where real data driven 3D model of a robot and multiple depth images of the workplace are used for monitoring and decision-making to perform a task. The strategy for robot control depends on the current task and the information about the operator's presence and position. A case study of assembly is carried out in a robotic assembly cell with human collaboration. The results show that this approach can be applied in real-world applications such as human-robot collaborative assembly with human operators safeguarded at all time.

A fuzzy decision support system for selecting the optimal scheduling rule in robotic flexible assembly cells

A fuzzy decision support system for selecting the optimal scheduling rule in robotic flexible assembly cells

Efficient Scheduling Rule for Robotic Flexible Assembly Cells Based on Fuzzy Approach

This study aims to develop an efficient rule for scheduling robotic flexible assembly cells (RFACs). The proposed scheduling rule is called fuzzy sequencing rule (FSR) which is constructed by combining different input variables: processing time, due date, batch size and number of required assembly stations, using the fuzzy logic (FL) technique. Two independent performance measures are considered: makespan and maximum of tardiness. Simulation software named SIMPROCESS is used to examine the performance of FSR compared with existing scheduling rules. Simulation results show that the proposed rule outperforms the common scheduling rules.

Robotic Assembly Planning and Control with Enhanced Adaptability

The dynamic market today requires manufacturing companies to possess high degree of adaptability and flexibility in order to deal with shop-floor uncertainties. Such uncertainties as missing tools, part shortage, job delay, rush-order and unavailability of resources, etc. happen more often in assembly operations. Targeting this problem, this research proposes a function block enabled approach to achieving adaptability and flexibility in assembly planning and control. In particular, this paper presents our latest development using a robotic mini assembly cell for testing and validation of a function block enabled system capable of assembly and robot trajectory planning and control. It is expected that a better adaptability can be achieved by this approach.

A sensor-driven 3D model-based approach to remote real-time monitoring

This paper presents an integrated approach for remote real-time monitoring of manufacturing operations. It is enabled by using virtual 3D models driven by real sensor data. The objectives of this research are twofold: (1) to significantly reduce network traffic for real-time monitoring over the Internet; and (2) to increase the controllability of manufacturing systems from anywhere in a decentralised environment. Particularly, this paper covers the principle of the approach, system architecture, prototype implementation, and a case study of remote control of a robotic assembly cell. Compared with camera-based monitoring systems, our approach only consumes less than 1% of its network bandwidth, feasible and practical as a web-based portable solution.

${\rm M}^{3}$-Deterministic, Multiscale, Multirobot Platform for Microsystems Packaging: Design and Quasi-Static Precision Evaluation

The dawn of next generation robots and systems era which is quietly emerging, requires miniaturized and integrated sensors, actuators, and entire microrobots. One of the defining characteristics of these microsystems is their multiscale nature, e.g., the span of their size, features, and tolerances across multiple dimensional scales, from the meso to the micro and nanoscales. Another defining characteristic is the need to reliably integrate heterogeneous materials via assembly and packaging, in a cost-effective manner, even in low quantities. Thus, it is argued in this paper that cost-effective manufacturing of complex microsystems requires special precision robotic assembly cells with modular and reconfigurable characteristics. This paper presents recent research aimed at developing theoretical underpinnings for how to construct such a manufacturing platform. M3 is a multirobot system spanning across the macro-meso-microscales and specifically configured to package. The M3 robots are systematically characterized in terms of quasi-static precision measures and assembly plans are generated using kinematic identification, inverse kinematics and visual servoing. The advantage of our approach the fact that high assembly yields for our system are a consequence of a set of so-called precision resolution-repeatability-accuracy (RRA) rules introduced in this paper. Experimental results for packaging of a microelectromechanical systems switch are provided to support our findings.

“Plug & Produce” functions for an easily reconfigurable robotic assembly cell

PurposeThis paper aims to develop an easily reconfigurable assembly cell.Design/methodology/approachSome functions are implemented to resolve problems associated with physical reconfiguration of an agent‐based robotic assembly cell, such as position calibration and workspace allocation.FindingsThe implemented prototype assembly cell is composed of industrial manipulators and a belt conveyor. Installation of a new manipulator and assembly execution are successfully demonstrated on the prototype cell.Practical implicationsIn the developed assembly system, installation and removal of assembly devices are easily performed so that it can adapt to changes in the manufacturing environment quickly.Originality/valueThe developed system does not use specially designed hardware. Easy reconfiguration is enabled using conventional devices such as manipulators and belt conveyors.

Modeling a Robotic Assembly Cell with Timed Petri Nets and in Max-Plus Algebra

Modeling a Robotic Assembly Cell with Timed Petri Nets and in Max-Plus Algebra

TOWARDS INTELLIGENT MANUFACTURING

AbstractThis article describes the application of an Artificial Intelligence Planner in a robotized assembly cell that can be integrated to a Flexible Manufacturing System. The objective is to allow different products to be automatically assembled in a single production line with no pre-established assembly plans. The planner function is to generate action plans to the robot, in real time, from two input information: the initial state (disposition of parts of the product in line) and the final state (configuration of the assembled product).

Design of a flexible assembly and remanufacturing cell for advanced SM components: selection of cell design concept based on reflow tools

PurposeTo design a flexible integrated robotic assembly and rework (remanufacturing) cell for assembly, selective assembly and rework of advanced surface mount components (SMCs) using the generic methodology developed in this paper.Design/methodology/approachManual rework procedures are investigated for all advanced SMCs. General and specific component‐related rework considerations are obtained and necessary tooling candidates for automation are determined. This is followed by determination of the specific automated rework procedure and selection of suitable tooling for automated robotic rework and generation and evaluation of design concepts.FindingsThe developed methodology, which considers the reflow tool at the centre of the development process, has worked well in designing a flexible integrated robotic assembly and rework cell.Practical implicationsThis study identified the rework requirements for advanced SMCs, the essential features for rework reflow tools, criteria for comparing reflow tools, and a generic procedure for design and concept selection.Originality/valueIt provides valuable knowledge for designers of flexible integrated robotic assembly and rework cells for assembly, selective assembly and rework of advanced SMCs.

A TOOL FOR ASSESSING RECONFIGURABILITY OF DISTRIBUTED MANUFACTURING SYSTEMS

In recent years, a large number of approaches to developing distributed manufacturing systems has been proposed. One of the principles reasons for these development has been to enhance the reconfigurability of a manufacturing operation; allowing it to readily adapt to changes over time. However, to date, there has only been a limited assessment of the resulting reconfigurability properties and hence it remains inconclusive as to whether a distributed manufacturing system design approach does in fact improve reconfigurability. This paper represents part of a study which investigates this issue. It proposes an assessment tool ***– the so called “Design Structure Matrix” as a means of assessing the modularity of elements in a manufacturing system. (Modularity has been shown to be a key characteristic of a reconfigurable manufacturing system.) The use of the Design Structure Matrix is illustrated in assessing a robot assembly cell designed on distributed manufacturing system principles.

A team-based holonic approach to robotic assembly cell control

Holonic systems are systems that are modelled in terms of components (holons) that have their own unique identity but are part of a larger whole. This larger whole is known as a holarchy. The manufacturing community has recognised the potential benefits of the holonic approach and it has attracted much interest over the past decade. This paper describes elements of a reference model for holonic manufacturing systems in which holons are characterised by the services that they provide and the services that they require other holons to perform on their behalf. In addition, individual holon behaviours are specified in terms of services, providing the ability for behaviours to be specified in a resource independent manner. We expect that this will result in the construction of systems that are easier to understand, extend and modify. An implementation of the model for the control of an industrial strength manufacturing system is described. An interesting feature of the manufacturing system is that the existing controllers are retained, thus demonstrating that holonic control can be implemented using conventional control hardware.

An automated system for the assembly of octree models

This paper presents a novel approach for rapid prototyping based on the octree decomposition of 3D geometric models. The proposed method, referred as OcBlox, integrates an octree modeller, an assembly planning system, and a robotic assembly cell into an integrated system that builds approximate prototypes directly from 3D model data. Given an exact 3D model this system generates an octree decomposition of it, which approximates the shape cubic units referred as “Blox”. These cuboid units are automatically assembled to obtain an approximate physical prototype. This paper details the algorithms used to generate the octree's assembly sequence and demonstrates the feasibility of the OcBlox approach by describing a single resolution example of a prototype built with this automated system. An analysis of the potential of the approach to decrease the manufacturing time of physical components is detailed. Finally, the potential of OcBlox to support complex overhanging geometry is discussed.

RECONFIGURABLE MODULES, PROGRAMMABLE LOGIC CONTROLLER, AND VISION SYSTEM FOR DUAL ROBOT ASSEMBLY WORKCELL DESIGN

Robot workcell system design involves integrating one or more robots with components such as conveyors, pallets, machine tools, and fixtures. Previous work in workcell design has addressed control and operations management issues such as scheduling. There has been relatively little emphasis on overall design, interface, system integration and agility issues. This paper provides a detailed technical description of (1) a cost-effective approach to prototyping a robotic assembly workcell using off-the-shelf modules and sensors; and (2) the process of designing, building, and integrating a dual robot assembly cell using a programmable logic controller. Modules and sensors used include pneumatic devices, solenoids, Hall effect and optical sensors, relays, optical isolators, conveyor, programmable logic controller, and vision system. Ladder diagrams, vision system inspection tools, and an integration interface were developed to synchronize the sequence of operations and communication between hardware devices. A design framework for web-based control of the system is proposed. Future research directions include web-based monitoring, control, and troubleshooting.

2P2-3F-C3 マルチエージェント・アーキテクチャによる柔軟な組立ロボットセル

2P2-3F-C3 マルチエージェント・アーキテクチャによる柔軟な組立ロボットセル

A Cell Management System to Support Robotic Assembly

There is an increasing requirement for the assembly of wider ranges of products in relatively small lot sizes. Consequently, robots are seen as being attractive as an assembly method. There has been much work on developing advanced robot grippers and applying vision systems/artificial intelligence. There has, however, been relatively little work on the overall problem of controlling robotic assembly cells (RACs) and their integration into the wider manufacturing organisation. This paper describes the design of a cell management system (CMS) based on a standard personal computer. The CMS supports RAC operations by managing/presenting data relevant to the cell operator. It also provides an interface between the cell and other organisational computer systems. Furthermore, the CMS allows error checking and recovery functionality to be implemented within an RAC without the need for modifications to the robot controller. Finally, the paper describes a pilot cell developed to test the CMS design.

Petri net supervisors for DES with uncontrollable and unobservable transitions

A supervisor synthesis technique for Petri net plants with uncontrollable and unobservable transitions, that enforces the conjunction of a set of linear inequalities on the reachable markings of the plant, is presented. The approach is based on the concept of Petri net place invariants. Each step of the procedure is illustrated through a running example involving the supervision of a robotic assembly cell. The controller is described by an auxiliary Petri net connected to the plant's transitions, providing a unified Petri net model of the closed-loop system. The synthesis technique is based on the concept of admissible constraints. Procedures are given for identifying all admissible linear constraints for a plant with uncontrollable and unobservable transitions, as well as methods for transforming inadmissible constraints into admissible ones. A technique is described for creating a modified Petri net controller that enforces the union of all of these control laws. The method is practical and computationally inexpensive in terms of size, design time, and implementation complexity.