Search results

The purpose of this paper is to give a novel sensor‐less manipulation strategy for the high‐precision assembly of an eccentric peg into a hole.

Based on the authors' previous work on the attractive region, this paper proposes the sensorless eccentric peg‐hole insertion strategy. The analysis is based on the visible strategic behaviors by decomposing the high‐dimensional configuration space of the eccentric peg‐hole into two low dimensional configuration subspaces. Then, the robotic manipulations can be designed in the configuration subspaces. Finally, a typical industry application, fitting an eccentric crankshaft into a bearing hole of the automotive air‐conditioners, is used to validate the presented strategy.

The attractive region constructed in the configuration space has been applied to guide the robotic manipulations, such as, the locating and the insertion.

The designed robotic assembly system without using force sensor or flexible wrist has an advantage in terms of expense and durability for the automotive air‐conditioners manufacturing industry.

Most previous work on sensorless manipulation strategy has concentrated on inserting a symmetric peg into a hole. However, for the assembly of an eccentric peg into a hole, the robotic manipulations should be explored in a high‐dimensional configuration space as the six‐DOFs of the eccentric peg. In this paper, the decomposition method of the high‐dimensional configuration space would make the system analysis visible; then, the assembly strategy can be easily designed in the two subspaces.

This paper presents a spectral multidomain method for solving the Navier‐Stokes equations in the vorticity‐stream function formulation. The algorithm is based on an extensive use of the influence matrix technique and so leads to a direct method without any iterative process. Numerical results concerning the Czochralski melt configuration are reported and compared with spectral monodomain solutions to show the advantage of the domain decomposition for such a problem which solution presents a singular behaviour.

The purpose of this paper is twofold. In view of the importance of process platform‐based production configuration (PPbPC) in sustaining product family production efficiency, it is to study the underlying logic for configuring production processes for a product family based on a process platform. Second, it is to apply the Petri nets (PNs) techniques to model PPbPC, in attempting to shed light on the underlying logic.

The authors first identify the fundamental issues in PPbPC, including variety handling, process variation accommodation, configuration at different abstraction levels, and constraint satisfaction. To accommodate the corresponding modelling difficulties, the authors develop a formalism of hierarchical colored timed PNs (HCTPNs) based on the principles of hierarchical PNs, timed PNs, and colored PNs. In the formalism, three types of nets together with a system of HCTPNs are defined to address the modelling of PPbPC.

Applying HCTPNs to vibration motors' case has revealed the logic of specifying complete production processes of final products at different levels of abstraction to achieve production configuration. The preliminary results also further demonstrate the feasibility of modelling PPbPC based on HCTPNs.

Traditional approaches to planning production processes for individual products may limit production performance improvement when companies need to timely produce a high variety of customized products. Systematic methods should be developed to plan production processes for product families so as to achieve production efficiency while utilizing the existing manufacturing resources.

By integrating the advantages of existing PN techniques, the HCTPNs formalism is developed to shed light on planning production processes for product families. The resulting production configuration model can facilitate practitioners to achieve production efficiency in producing large numbers of customized products.

The development of reconfigurable modular production systems is one of the crucial factors for manufacturers to sustain their competitive advantage in areas such as precision assembly. To ensure the effective and cost efficient configuration and successive reconfigurations it is of critical importance to involve all stakeholders in the decision‐making process. The reported research is targeting the development of an integrated Web‐enabled decision‐making environment that supports some of the key assembly system engineering stages from user requirement specification to system implementation. The focus is on the design of assembly workstations based on detailed process requirements with a target of developing highly efficient and cost‐effective solutions. The paper presents an application framework for collaborative distributed design supported by domain ontologies and is illustrated using an industrial case study.

The functionality and reliability of an overhauled aero-engine is determined by all configuration changes in the overhaul process. Identifying, recording, auditing, tracking and tracing of configuration modifications are significant and meaningful. Considering the barriers to these goals, this paper aims to put forward an approach to configuration management in the aero-engine overhaul process.

The overhaul configuration management model is proposed to describe an aero-engine’s configuration evolution trajectory in the overhaul process. The controlling and auditing procedures are put forward to control and audit parts’ return-to-zero statuses and overproof statuses. And some searching algorithms are also designed to enable tracking and tracing of the configuration status along the time coordinate, or get a snapshot of an aero-engine’s configuration at a certain time. The above model, procedures and algorithms have been implemented and adopted to fulfill the configuration management requirements in the aero-engine overhaul process.

The approach is effective in identifying, recording, controlling, auditing, tracking and tracing configuration changes in the overhaul process.

The approach’s implementation and adoption present a practical example for aero-engines’ configuration management issue in the overhaul process.

The work proposes an original aero-engine configuration management solution for the overhaul process and enables a reliable and accurate configuration management mode.

Under restriction of an isotropic elastic response of deformed lattice, develops a covariant theory of finite elastoplasticity in principal axes of a pair of deformation tensors. In material description, the tensor pair consists of the plastic deformation tensor and the total deformation Cauchy‐Green tensor. Applies the proposed theory to elastoplastic membrane shells, whose references and current configurations can be arbitrary space‐curved surfaces. Pressure‐insensitive von Mises yield criterion with isotropic hardening and a quadratic form of the strain energy function given in terms of elastic principal stretches are considered as a model problem. Through an explicit enforcement of the plane stress condition we arrive at a reduced two‐dimensional problem representation, which is set in the membrane tangent plane. Numerical implementation of the presented theory relies crucially on the operator split methodology to simplify the state update computation. Presents a set of numerical examples in order to illustrate the performance of the presented methodology and indicate possible applications in the area of sheet metal forming.

This paper aims to explore the use of the knowledge management (KM) perspective for configuration projects. Configuration projects implement configurators as information technology systems that help companies manage the specification process of customised products. An effective method of retrieving and formalising knowledge for configurators is essential, because it can reduce the risk of unsuccessful implementation and the time and effort required for development. Unfortunately, no standard KM frameworks are available specifically for configuration projects. This study identifies the knowledge necessary for different phases of a configuration project (which knowledge, for what purpose and from what sources), examines how it is transformed during a configuration project (what KM activities and tools are used) and establishes how the knowledge can be documented for future maintenance and updates.

This paper proposes a four-step framework for making the KM process more efficient in configuration projects. The framework is based on the literature, developed in collaboration with industrial partners and tested on four configuration projects in two engineering companies. The framework is a structured KM approach designed to save time for both domain experts and the configuration team. The authors have used a qualitative exploratory design based on multiple data sources: documentation, workshops and participant observation.

The proposed framework comprises four steps: determination of the system’s scope, to establish the project’s goal based on stakeholders’ requirements and prioritise the required products and processes; knowledge acquisition, to classify the knowledge according to the desired output and identify different knowledge sources; modelling and knowledge validation; and documentation and maintenance, to ensure that the KM system can be maintained and updated in the future.

Because the framework is tested on a limited number of cases, its generalisability may be limited. However, focusing on a few case applications allows us to assess the effectiveness of the framework in detail and in depth to identify the practical challenges of applying it. The results of the tests support the framework’s validity. Although the framework is designed mainly for engineering companies, other industries could benefit from using it as well.

The individual steps of the framework create a structured approach for the KM process. Thus, the approach can save both time and resources for companies, without the need for additional investment.

A standard framework is lacking in the literature on KM for configuration projects. This study fills that gap by developing a KM framework for configuration projects, based on KM frameworks developed for IT projects, and KM tools.

The paper aims to propose a method to build environmental constraint region online in complex-shaped peg-in-hole assembly tasks.

Compared with conventional way which using computer-aided design (CAD) models of assembly parts to construct the environmental constraint region offline, the paper provides an online approach that consists of three aspects: modeling assembly parts through visual recognition, decomposing complex shapes into multiple primitive convex shapes and a numerical algorithm to simulate the peg-in-hole insertion contact. Besides, a contrast experiment is performed to validate the feasibility and effectiveness of the method.

The experiment result indicates that online construction takes less time than the offline way under the same task conditions. Furthermore, due to the CAD models of the parts are not required to be known, the method proposed in the paper has a broader application in most assembly scenarios.

With the improvement of customization and complexity of manufactured parts, the assembly of complex-shaped parts has drawn greater attention of many researchers. The assembly methods based on attractive region in environment (ARIE) have shown great performance to achieve high-precision manipulation with low-precision systems. The construction of environmental constraint region serves as an essential part of ARIE-based theory, directly affect the formulation and application of assembly strategies.

The purpose of this paper is to explore, through a case study, and using Pawson and Tilley's notion of context-mechanism-outcome configurations, how a sectoral innovation system (SIS) for health technologies has developed.

The case study data were collected as part of a large study that looked at technology innovation and adoption in the UK's National Health Service and were collected using an interpretive case study methodology. Primary data came from interviews and secondary data from published sources, including articles authored by members of the innovation team.

The paper identifies three specific configurations of context, mechanism and outcome that were important in the case and discusses how these contribute to a broader understanding of a healthcare services SIS.

Research conducted through a single case study is open to the criticism that its findings are not generalisable but it has offered an economical way of gaining a deep description of a situation and an understanding of the contextual factors affecting a phenomenon. The paper presents a refined model for understanding SISs that though primarily rooted within the healthcare care sector has potential for application in other sectors, especially those that encompass a significant public-sector component.

The paper's findings and conclusions have relevance to healthcare service innovation policy development. The findings will also be useful to professionals responsible for innovation projects and their support within the sector.

The paper makes an important contribution to the understanding of a SIS for healthcare services as well as refining a general model of SISs.