Engineering methods and tools for cyber–physical automation systems

Much has been published about potential benefits of the adoption of cyber–physical systems (CPSs) in manufacturing industry. However, less has been said about how such automation systems might be effectively configured and supported through their lifecycles and how application modeling, visualization, and reuse of such systems might be best achieved. It is vitally important to be able to incorporate support for engineering best practice while at the same time exploiting the potential that CPS has to offer in an automation systems setting. This paper considers the industrial context for the engineering of CPS. It reviews engineering approaches that have been proposed or adopted to date including Industry 4.0 and provides examples of engineering methods and tools that are currently available. The paper then focuses on the CPS engineering toolset being developed by the Automation Systems Group (ASG) in the Warwick Manufacturing Group (WMG), University of Warwick, Coventry, U.K. and explains via an industrial case study how such a component-based engineering toolset can support an integrated approach to the virtual and physical engineering of automation systems through their lifecycle via a method that enables multiple vendors' equipment to be effectively integrated and provides support for the specification, validation, and use of such systems across the supply chain, e.g., between end users and system integrators

Ontology based semantic-predictive model for reconfigurable automation systems

Due to increasing product variety and complexity, capability to support reconfiguration is a key competitiveness indicator for current automation system within large enterprises. Reconfigurable manufacturing systems could efficiently reuse existing knowledge in order to decrease the required skills and design time to launch new products. However, most of the software tools developed to support design of reconfigurable manufacturing system lack integration of product, process and resource knowledge, and the design data is not transferred from domain-specific engineering tools to a collaborative and intelligent platform to capture and reuse design knowledge. The focus of this research study is to enable integrated automation systems design to support a knowledge reuse approach to predict process and resource changes when product requirements change. The proposed methodology is based on a robust semantic-predictive model supported by ontology representations and predictive algorithms for the integration of Product, Process, Resource and Requirement (PPRR) data, so that future automation system changes can be identified at early design stages

A method to assess assembly complexity of industrial products in early design phase

Complexity is one of the factors, inducing high cost, operational issues, and increased lead time for product realization and continues to pose challenges to manufacturing systems. One solution to reduce the negative impacts of complexity is its assessment, which can help designers to compare and rationalize various designs that meet the functional requirements. In this paper, a systemic approach is proposed to assess complexity of a product's assembly. The approach is based on Hückel's molecular orbital theory and defines complexity as a combination of both the complexity of product entities and their topological connections. In this model, the complexity of product entities (i.e., components and liaisons) is defined as the degree to which the entity comprises structural characteristics that lead to challenges during handling or fitting operations. The characterization of entity complexities is carried out based on the widely used DFA principles. Moreover, the proposed approach is tested on two case studies from electronics industry for its validity. The results showed that the approach can be used at initial design stages to improve both the quality and assemblability of products by reducing their complexity and accompanying risks

Innovative mechanism to identify robot alignment in an automation system

Robotic applications are commonly used in industrial automation systems. Such systems are often comprised of a series of equipment, including robotic arms, conveyors, a workspace, and fixtures. While each piece of equipment may be calibrated with the highest precision, their alignment in relation to each other is an important issue in defining the accuracy of the system. Currently, a variety of complex automated and manual methods are used to align a robotic arm to a workspace. These methods often use either expensive equipment or are slow and skill-dependent. This paper presents a novel low-cost method for aligning an industrial robot to its workcell at 6 degrees of freedom (DoF). The solution is new, simple and easy to use and intended for the SMEs dealing with low volume, high complexity automated systems. The proposed method uses three dial indicators mounted to a robot end effector and a fixed measurement cube, positioned on a workcell. The robot is pre-programmed for a procedure around the cube. The changes on the dial indicators are used to calculate the misalignment between the robot and the workcell. Despite simplicity of the design, the solution is supported with complex real-time mathematical calculations and proven to identify and eliminate misalignment up to 3mm and 5 degrees to an accuracy of 0.003mm and 0.002 degrees: much higher than the precision required for a conventional industrial robot. In this article, the authors describe a proposed solution, validate the computation both theoretically and through a laboratory test rig and simulation

Plant descriptions for engineering tool interoperability

The emergence and deployment of connected devices in many domains of application (e.g. industrial production, buildings and facilities, urban environment, etc.) have resulted in the need to achieve integration of multiple and more complex systems. This new environment is stressing the intrinsic limits imposed by monolithic standards, data models and integration methods that focus on specific domains of application, types of systems, or specific aspects of a system. This paper describes the Plant Description Service developed as part of the Arrowhead Interoperability framework (EU ECSEL funded project). The manuscript contains a description of the abstract system descriptive model based on which the Plant Description service was implemented, and describes how the service can be used to achieve integration of several industry standards and data models. Case studies are provided that illustrates how the service was practically implemented to support engineering scenarios in the domain of industrial production. The paper concludes with a critical review of the approach and suggestion for future work and developments

Design evaluation of automated manufacturing processes based on complexity of control logic

Complexity continues to be a challenge in manufacturing systems, resulting in ever-inflating costs, operational issues and increased lead times to product realisation. Assessing complexity realizes the reduction and management of complexity sources which contributes to lowering associated engineering costs and time, improves productivity and increases profitability. This paper proposes an approach for evaluating the design of automated manufacturing processes based on the structural complexity of the control logic. Six complexity indices are introduced and formulated: Coupling, Restrictiveness, Diameter, Branching, Centralization, and Uncertainty. An overall Logical Complexity Index (CL) which combines all of these indices is developed and demonstrated using a simple pick and place automation process. The results indicate that the proposed approach can help design automation logics with the least complexity and compare alternatives that meet the requirements during initial design stages

A model for complexity assessment in manual assembly operations through predetermined motion time systems

Manual assembly processes are favoured for supporting low volume production systems, high product variety, assembly operations that are difficult to automate and manufacturing in low-wage countries. However, manual operations can dramatically impact assembly cycle times, quality and cost when the complexity of the manual operation increases. This paper proposes a method for assessing the process complexity of manual assembly operations, using a representation of manual operations based on predetermined motion time systems. The purpose of this framework is to provide a tool that can be used practically to assess, and therefore control, the complexity of manual operations during their design

Porosidad del cuero para capellada

Se determinó la porosidad de cueros para capellada curtidos al cromo, recurtidos y semiterminados, mediante el método de intrusión de mercurio. Las presiones absolutas variando de 5 a l0000 psi; esto es, involucrando radio de poros de 50 a 0,01 micrones. Se estudiaron dos métodos de secado previo de la muestra estufa y liofilización - comparados con el secado efectuado directamente en el porosímetro por vacío. Además, se investigó la incidencia del desengrasado del cuero con éter de petróleo. La porosidad de las nuestras secadas en estufa, fue un 25 % menor que la exhibida por aquellas secadas por vacío o liofilización. Esta merma es muy similar a la contracción volumétrica experimentada por el cuero cuando se lo secó en estufa y esta circunstancia pone limitaciones al uso de este método de secado, antes utilizado por Stromberg (l955) y Kanagy (1963).A study was made of the semifinished upper leather porosity with the mercury porosimeter (Aminco) at absolute pressures vary from 50 to 0,01 microns. Two methods - oven drying and freeze drying - were compared with another made by vacuum in the porosimeter. Leather samples were previously degrease or not with petroleum ether. Porosity of the oven dried samples was 25 % less than those samples dried by vacuum or freezing. This porosity reduction is very similar to the volume reduction observed in leather samples dried in an oven. According with the results obtained the oven drying method used by Stromberg (1955) and by Kanagy (1963) affects considerably the leather porosity data and this problem can be avoided by the use of the other methods of drying

A lightweight approach for human factor assessment in virtual assembly designs : an evaluation model for postural risk and metabolic workload

The assessment and optimisation of postural stress and physical fatigue can be challenging and is typically conducted only after the design of manual operations has been finalised. However early assessment of manual operations and identification of critical factors that are deemed outside of an appropriate envelope can avoid the time and costs often associated with re-designing machines and layout for operator work processes. This research presents a low cost software solution based on a simplified skeleton model that uses operator position and workload data extracted from a simulation model used for virtual manufacturing process planning. The developed approach aims to assess postural stress and physical fatigue scores of assembly operations, as they are being designed and simulated virtually. The model is based on the Automotive Assembly Worksheet and the Garg’s metabolic rate prediction model. The proposed research focuses on the integration of virtual process planning, ergonomic and metabolic analysis tools, and on automating human factor assessment to enable optimisation of assembly operations and workload capabilities at early design stage