A methodological approach to fully automated highly accelerated life tests

Microsystem Technologies - Highly accelerated life test (HALT) is a test methodology to evaluate reliability of mechanical and electromechanical devices. HALT is often used on devices that must be...     

Modified QFD and problem‐solving techniques integrated approach implementing corrective actions: a case study in an Italian manufacturing plant

The ISO 9001:2000 and Total Quality Management models impose that organizations adopt structured procedures to implement corrective and preventive actions. In this paper, a structured framework to solve a non‐conformity in a product or in a process, selecting the best corrective actions, is proposed. Some problem‐solving techniques are applied in a structural method (i) to find the problem (product or process non‐conform), (ii) setting the problem (using data‐collecting instruments), (iii) analyzing the problem (with techniques such as Pareto charts, histograms, stratification analysis) and (iv) searching possible alternative solutions. Then, a modified quality function deployment technique is applied to evaluate and to classify the alternative solutions with respect to three different parameters (benefit, cost and impact). The framework has been developed to select and implement corrective actions in an Italian manufacturing plant. The case study is presented in this paper. However, the proposed approach is applicable in many other contexts. Copyright © 2008 John Wiley & Sons, Ltd.     

A Smart Lighting System for Visual Comfort and Energy Savings in Industrial and Domestic Use

The goal of this work is to develop a smart light-emitting diode lighting system for industrial and domestic use with several advantages over conventional systems, namely energy saving, high reliability, and visual comfort of interior lighting. This is achieved by integrating a smart control module and a fault diagnosis and prognosis module within a conventional lighting system. The first module controls the lighting level in an energy-efficient way, keeping a desired light level where it is needed while regulating it to a minimum where not required; this is achieved by fully exploiting fuzzy logic and proportional-integrative-derivative controllers. The second module performs fault diagnosis on the light-emitting diode system and predicts when light-emitting diode maintenance should be performed; this is achieved by employing both hardware redundancy and signal-based approaches. Interaction between the two modules permits maintenance of a desired level of light even in the case of failures on one or more light-emitting diodes. The overall system has been experimentally validated in three different scenarios.     

An integrated structural framework to cost-based FMECA: The priority-cost FMECA

The Failure Mode, Effects and Criticality Analysis (FMECA) methodology is a widely recognized tool for the study and reliability analysis of a design or process. Many authors in the field have emphasized the usefulness of this particular method as well as its limitations. In particular, there are two main criticisms regarding the Risk Priority Number (RPN) method of calculation and the extreme difficulty in considering the variable of the corrective action cost in the analysis. The main scope of this work is to present a new integrated approach, named priority-cost FMECA (PC-FMECA), in order to exceed these limits. Making reference to a paper by Braglia [MAFMA: multi-attribute failure modes analysis. Int J Qual Reliab Manage 2000; 17(9)], this study proposes a method which allows for the calculation of a new RPN and the introduction of the concept of Profitability taking into consideration the corrective action cost. The study is divided in three fundamental phases: critical analysis of the FMECA model, proposal and development of the PC-FMECA and presentation of an implemented case study in the automotive field.     

Correction scheme for close-range lidar returns

Because of the effect of defocusing and incomplete overlap between the laser beam and the receiver field of view, elastic lidar systems are unable to fully capture the close-range backscatter signal. Here we propose a method to empirically estimate and correct such effects, allowing to retrieve the lidar signal in the region of incomplete overlap. The technique is straightforward to implement. It produces an optimized numerical correction by the use of a simple geometrical model of the optical apparatus and the analysis of two lidar acquisitions taken at different elevation angles. Examples of synthetic and experimental data are shown to demonstrate the validity of the technique.     

Mechatronic designs for a robotic hand to explore human body experience and sensory-motor skills: a Delphi study

To bridge the gap between users' expectations and technological solutions, a better understanding of human body experience and sensory-motor skills is mandatory. This could pave the way towards a novel generation of robotic hands, which can be successfully employed in everyday life e.g. in prosthetics and assistive robotics. Available robotic hands are still far from matching the requirements of the corresponding experimental and real-world applications, e.g. fast motions might be achieved at the expense of accuracy. Knowledge of the users' sensory-motor skills can guide technical developments, e.g. prosthetic design processes. This paper presents design solutions developed in a Delphi study. Explorative questionnaires are prepared to acquire and elaborate expert opinions to improve the design of previously developed robotic anthropomorphic hands. By gathering and fusing expert opinions, novel robotic hand and wrist concepts specifically optimized regarding body experience and sensory-motor skill research are developed. In three rounds, experts with experience in robotic hand design and/or control analyze, develop, and rank solutions for mechanisms, actuators, and control , which result in overall design concepts. The technical concepts and implications resulting from the study are discussed considering psychological and biomechanical aspects.     

Scrap value stream mapping (S-VSM): a new approach to improve the supply scrap management process

In this work, an innovative methodology to improve the Supply Scrap Management Process (SSMP), based on Value Stream Mapping (VSM), is presented. VSM is one of the best tools to map a process and eliminate its critical issues, that produces good results if applied to production processes, but can be ineffective for management processes as the SSMP. Therefore, the main objective of this work is to overcome this limitation. The proposed approach taking the name Scrap Value Stream Mapping (S-VSM) and integrates concepts from VSM and other Lean Production (LP) and World Class Manufacturing tools. It is structured in five steps. The definition of the process borders and the identification of categories of loss through the first four steps of Cost Deployment is the first step. Then, the SSMP is subdivided in its Accounting and Physical Streams and the current state is drawn. Next, wastes and critical issues are analysed and their root causes are determined using some of LP tools. In step four, improvements are proposed and the future state is drawn. Furthermore, potential savings, in terms of €, are estimated. In the last step, a methodology to monitor the effects of implemented improvements is defined. A case study taken from the application of the S-VSM within automotive company is presented.     

A Rapid Prototyping Scenario for Power Factor Control in Permanent Magnet Synchronous Motor Drives: Control Solutions for Interleaved Boost Converters

Rapid prototyping of control is one of the most important technologies for designers and researchers to shorten design and testing of control algorithms. This article presents power electronics opportunities provided by PSIM software and a high performance digital signal processing. The field of application examined is motor control and switching mode power supplies. In particular, more emphasis to the theoretical treatment of linear and non-linear power factor controllers has been given, and the performances of examined algorithms in both the simulated and real world have been verified. Finally, good matching between the results of these two configurations has been documented.