Development of a novel cloud-based multi-tenant model creation service for automatic virtual metrology

摘要

AVM (Automatic Virtual Metrology) is the highest-level technology for VM (Virtual Metrology) applications from the perspective of automation. Its various automatic capabilities could facilitate fast factory-wide deployment and operations of VM systems. AVM systems have been successfully applied to the semiconductor, TFT-LCD, solar-cell, and machining industries for on-line monitoring the production quality of workpieces. However, in its past industrial applications, the model creation (MC) functionality of the existing AVM system encountered several limitations, such as being a standalone application and confined to be used in situ in a factory, no support for multiuser model creation, wasting computing resources, etc., which could diminish the applicability of the existing AVM system in current global and distributed manufacturing environments. Thus, this paper is dedicated to tackling the problem of how to systematically and effectively overcome MC-related limitations of the existing AVM system so that it can robustly support multiple users across factories to create their VM models simultaneously in distributed manufacturing settings. By leveraging the advantages of cloud computing and several IT technologies (including virtualization software, XML, Web Service, Multi-tenancy technique, and HTML5), this paper proposes a novel cloud-based multi-tenant model creation service (i.e., CMMCS) for AVM. The proposed CMMCS contains a cloud-based system architecture, functional frameworks of its key components, several functional mechanisms, and HTML5-based Web GUIs. Testing results in an industrial case study that creates VM models using the CMMCS for CNC machine tools in machining wheel rims of automobiles in a factory in Taiwan demonstrate that the CMMCS can allow multiple users from different tenants to simultaneously create their VM models, while enabling the MC cloud services to be more robust for processing MC requests, having higher CPU-usage rates in the underlying virtual machines, and achieving better cross-platform usage, compared to the original MC functionality. This paper has provided a feasible solution to systematically and effectively remedying the MC-related limitations of the existing AVM system. The existing VM-related literature mainly focused on the development of VM models. To our knowledge, no papers have coped with issues addressed in this paper by leveraging cloud computing. The results of this paper can be a useful reference for industrial practitioners to construct AVM systems which support multi-tenant or multiuser model creation.