Corrective algorithms for measurement improvement in MScMS-II (Mobile Spatial coordinate Measurement System)

This paper presents a set of algorithms for the correction of measurement errors of a prototype system designed for Large Scale Dimensional Metrology (LSDM) applications. The system, developed in the Quality and Industrial Metrology Laboratory of Politecnico di Torino, is based on the principles of photogrammetry and consists of a set of cameras wirelessly connected to a central unit able to track the position of a portable contact probe. Due to its architecture the system is affected by several systematic error sources. This paper addresses some of them: the distortion of the lenses, the dimension of the probe tip and the kinematic of the probe. By means of the implementation of appropriate mathematical correction models, the overall system performance is significantly improved as shown by the conducted test

A novel multi-target modular probe for multiple Large-Volume Metrology systems

Recent studies show that the combined use of Large-Volume Metrology (LVM) systems (e.g., laser trackers, rotary-laser automatic theodolites (R-LATs), photogrammetric cameras, etc.) can lead to a systematic reduction in measurement uncertainty and a better exploitation of the available equipment. Unfortunately, the sensors of a specific LVM system are usually able to localize only specific targets (i.e., active/passive elements positioned in the measurement volume) and not necessarily those related to other systems (e.g., the reflective markers for photogrammetric cameras cannot be used for R-LATs or laser trackers); this represents an obstacle when using combinations of different LVM systems. This paper describes the design of a new modular probe, with different typologies of targets and integrated sensors, which allows to simplify the measurement process. The probe is versatile as the number of targets, their typology and spatial position can be customized depending on the combination of LVM systems in use. A detailed analysis of the technical and functional characteristics of the probe is followed by the presentation of a mathematical/statistical model for the real-time probe localization. Description is supported by realistic application examples

Service gap deployment: a framework to link quality gaps to service activities

This paper presents the service gap deployment (SGD), a new method to prioritise crucial to quality activities of a service that does not completely satisfy customer expectations. In the SGD, service activities (SAs) are related to gaps between customer expectations and perceptions so as to identify SAs that may need a redesign or improvement in order to satisfy customer needs. The method, which expands the gaps model of service quality by Parasuraman et al. (1985), supports the design of evolutionary and sustaining improvements of the service parts that generate customer dissatisfaction. Specifically, the SGD introduces three major contributions: 1) it creates a map relating service dimensions to SAs; 2) it highlights crucial to quality activities; 3) it allows a focused improvement of the analysed service. The description is supported by an excerpt from a real application example, concerning the prioritisation of crucial to quality SAs of an airport luggage delivery service

A proposal of a new paradigm for national quality certification systems

The goal of this paper is to suggest a new incentive model that is capable of creating the conditions for the autonomous growth of diffusion and credibility of the ISO 9000 national quality certification syste

ISO/TS 16949: analysis of the diffusion and current trends

The automotive industry has always shown a particular interest toward quality management systems, which resulted in the development of several different specific standards. As a result of this, by the mid-1980s, automotive suppliers were subject to numerous national and customer specific regulations. The proliferation of these standards and the need to create a single reference model led to Technical Specification (TS) 16949, an ISO technical specification aimed at representing a comprehensive quality management system for the global automotive industry. Since its early introduction, TS 16949 has encountered a certain success thanks to its feature of unifying and harmonizing the already existing standards. This paper studies the global evolution and diffusion of this technical specification, observing its impact on the local economies. The argument is supported by many empirical data

Determining the extrinsic parameters of a network of Large-Volume Metrology sensors of different types

Large-Volume Metrology (LVM) instruments – such as laser trackers, photogrammetric systems, rotary-laser automatic theodolites, etc. – generally include several sensors, which measure the distances and/or angles subtended by some targets. This measurements, combined with the spatial position/orientation of sensors (i.e., the so-called extrinsic parameters), can be used to locate targets in the measurement volume. Extrinsic parameters of sensors are generally determined through dedicated sensor calibration methods, which are based on repeated measurements of specific artefacts. The combined use of multiple LVM instruments enables exploitation of available equipment but may require multiple instrument-dedicated sensor calibrations, which inevitably increase set-up time/cost. This document presents a novel calibration method – called global calibration – which allows the extrinsic parameters of all sensors to be determined in a single process. The proposed method uses a special artefact – i.e., a hand-held probe with assorted types of targets and inertial sensors – and includes a data-acquisition stage, in which the probe is repositioned in different areas of the measurement volume, followed by a data-processing stage, in which an ad hoc mathematical/statistical model is used to determine the extrinsic parameters of sensors. Additionally, the proposed method includes the formulation of a system of linearized equations, which are weighed considering the uncertainty of input variables

Mathematical models for error correction in MScMS-II (Mobile Spatial coordinate Measurement System)

This paper presents three mathematical models for the correction of measurement errors of a prototype system designed for Large Scale Dimensional Metrology (LSDM) applications. The system, developed in the Quality and Industrial Metrology Laboratory of Politecnico di Torino, is based on the principles of photogrammetry and consist of a set of cameras wirelessly connected to a central unit for data elaboration and able to track the position of a hand-held contact probe. Due to its architecture the system is affected by several systematic error sources. This paper addresses some of them: the distortion of the lenses, the dimension of the probe tip and the kinematic of the probe. By means of the implementation of appropriate mathematical correction models, the overall system performance is significantly improved as shown by the proposed tests

A paired-comparison approach for fusing preference orderings from rank-ordered agents

The problem of aggregating multi-agent preference orderings has received considerable attention in many fields of research, such as multi-criteria decision aiding and social choice theory; nevertheless, the case in which the agents’ importance is expressed in the form of a rank-ordering, instead of a set of weights, has not been much debated. The aim of this article is to present a novel algorithm – denominated as ‘‘Ordered Paired-Comparisons Algorithm’’ (OPCA), which addresses this decision-making problem in a relatively simple and practical way. The OPCA is organized into three main phases: (i) turning multi- agent preference orderings into sets of paired comparisons, (ii) synthesizing the paired-comparison sets, and (iii) constructing a fused (or consensus) ordering. Particularly interesting is phase two, which introduces a new aggregation process based on a priority sequence, obtained from the agents’ importance rank-ordering. A detailed description of the new algorithm is supported by practical examples