Total Cost of Ownership Driven Methodology for Predictive Maintenance Implementation in Industrial Plants

Part 4: Product and Asset Life Cycle Management in Smart Factories of Industry 4.0International audienceThis paper proposes a methodology to drive from a strategic point of view the implementation of a predictive maintenance policy within an industrial plant. The methodology integrates the evaluation of system performances, used to identify the critical components, with simulation and cost analysis. The goal is to evaluate predictive maintenance implementation scenarios based on alternative condition monitoring (CM) solutions, under the lenses of Total Cost of Ownership (TCO). This allows guiding the decision on where in the industrial system to install diagnostic solutions for monitoring of asset health, by keeping a systemic and life cycle-oriented perspective. Technical systemic performances are evaluated through Monte Carlo simulation based on the Reliability Block Diagram (RBD) model of the system. To validate the methodology, an application case study focused on a production line of a relevant Italian company in the food sector is presented

An Overview of Kinematic and Calibration Models Using Internal/External Sensors or Constraints to Improve the Behavior of Spatial Parallel Mechanisms

This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify geometric and non-geometric parameters in the calibration of parallel robots are discussed, examining the advantages and disadvantages of each method, presenting new trends and identifying unsolved problems. This overview tries to answer and show the solutions developed by the most up-to-date research to some of the most frequent questions that appear in the modelling of a parallel mechanism, such as how to measure, the number of sensors and necessary configurations, the type and influence of errors or the number of necessary parameters

Aquifer Vulnerability and Contamination Risk

Water supply systems must be designed in such a way to ensure groundwater extraction sustainability. In addition, the quality of pumped water must also be guaranteed, and this entails protecting the groundwater source from contamination. To do so, it is necessary to identify the physical and hydraulic characteristics of the soil, the unsaturated medium and the aquifer itself that influence the migration of contaminants spilled at the surface towards the aquifer, and hence potentially towards sensitive targets (i.e., drinking water pumping wells). The susceptibility of an aquifer to become polluted following a contaminant spill is called vulnerability, and its assessment is the focus of this chapter. Of the four categories of vulnerability assessment methods, i.e., overlay, index and statistical methods, and process-based simulation models, this chapter presents examples of the former two, which are of easier implementation and are widely used. Overlay methods define aquifer vulnerability on the basis of groundwater circulation and rely on the superposition of maps of the hydrogeologic, structural and morphologic setting. Index methods, instead, are based on the assignment of scores (sometimes weighed) to sets of parameters that are likely to affect the degree of vulnerability. Specific methods of these two categories described in detail in this chapter are the one developed by the Bureau de Recherches Géologiques et Minières in France, the Italian CNR-GNDCI and SINTACS methods, the US-EPA DRASTIC method and the British GOD method. The suitability of different methods is discussed, and how vulnerability assessment can be used to determine the risk of contamination is presented. On this basis, an example of contamination risk reduction strategies is illustrated

Redundant singularities versus constraint singularities in parallel mechanisms

The paper discusses the redundant singularities versus constraint singularities in relation to the main structural parameters of parallel mechanisms. The formulae of mobility, connectivity, overconstraint and redundancy of parallel mechanisms, recently proposed by the second author of this paper, are used to characterise these singularities and the transition phase between them. By using these formulae, the main properties of three types of singularity are identified. A new combined constraint-redundant singularity is defined and characterised, in connection with constraint and redundant singularities. A reconfigurable eight-bar single-loop mechanism is used to illustrate the three types of singularities. This mechanism has an interesting property to continually transit from one type of singularity to another by remaining always in a singular configuration. The properties of the redundant and constraint-redundant singularities are defined in this paper in relation to the four main structural parameters of a mechanism. </jats:p