New Instrumented Trolleys and A Procedure for Automatic 3D Optical Inspection of Railways.

This paper focuses on new instrumented trolleys, allowing automated 3D inspection of railway infrastructures, using optical scanning principles and devices for defects and damage evaluation. Inspection of rolling components is crucial for wear evaluation and to schedule maintenance interventions to assure safety. Currently, inspection trolleys are mainly instrumented with 2D contact or optical sensors. The application of 3D non-contact digitizers proposed in this paper allows for a quick and more complete monitoring of the health conditions of railways, also in combination with a proper procedure for automatic 3D inspection. The results of the experimental tests using 3D portable optical scanners on railways are compared with results obtained by a trolley instrumented with 2D contact sensors. The results demonstrate the effectiveness of the trolleys mounting 3D handheld optical digitizers with proper automated software inspection procedures.

A methodology to evaluate contact areas and indentations of human fingertips based on 3D techniques for haptic purposes.

This paper presents a methodology to study the contact of human fingers with surfaces based on 3D techniques. This method helps to investigate the fingertip mechanical properties which are crucial for designing haptic interfaces. The dependence of the fingertip deformation on the applied forces is obtained both with theoretical and experimental approaches. The experimental procedure is based on digital measurements by 3D optical scanners to reconstruct the geometry of the fingertip impression and on force measurements by an instrumented plate. Results highlight the force-displacement trend and can be validated with a Finite Element Model (FEM), with data from literature or with measurements at a force-strain gauge. Gross contact areas, radii and work of adhesion are also detected, and results are compared with contact models available in literature. • A sensorized plate with a thin force sensitive resistor and a dough material layer is used to measure the contact force corresponding to a specific digital imprint. • 3D indentation maps are obtained and evaluated by comparing the 3D scan model of fingertips during imprinting with the digital model of the undeformed fingers and of the imprints. • Force-displacement results can be validated by comparison with a developed FEM, a force-displacement gauge or literature outcomes.

Modeling and Simulation of Robotic Grasping in Simulink Through Simscape Multibody.

Grasping and dexterous manipulation remain fundamental challenges in robotics, above all when performed with multifingered robotic hands. Having simulation tools to design and test grasp and manipulation control strategies is paramount to get functional robotic manipulation systems. In this paper, we present a framework for modeling and simulating grasps in the Simulink environment, by connecting SynGrasp, a well established MATLAB toolbox for grasp simulation and analysis, and Simscape Multibody, a Simulink Library allowing the simulation of physical systems. The proposed approach can be used to simulate the grasp dynamics in Simscape, and then analyse the obtained grasps in SynGrasp. The devised functions and blocks can be easily customized to simulate different hands and objects.

Knee Wear Assessment: 3D Scanners Used as a Consolidated Procedure.

It is well known that wear occurring in polyethylene menisci is a significant clinical problem. At this regard, wear tests on biomaterials medical devices are performed in order to assess their pre-clinical performance in terms of wear, durability, resistance to fatigue, etc. The objective of this study was to assess the wear of mobile total knee polyethylene inserts after an in vitro wear test. In particular, the wear behavior of mobile bearing polyethylene knee configurations was investigated using a knee joint wear simulator. After the completion of the wear test, the polyethylene mobile menisci were analyzed through a consolidated procedure by using 3D optical scanners, in order to evaluate the 3D wear distribution on the prosthesis surface, wear depths, wear rates, amount of material loss and contact areas. The results in terms of wear rates and wear volumes were compared with results of gravimetric tests, finding equivalent achievements.

Wear Distribution Detection of Knee Joint Prostheses by Means of 3D Optical Scanners.

The objective of this study was to examine total knee polyethylene inserts from in vitro simulation to evaluate and display-using a 3D optical scanner-wear patterns and wear rates of inserts exposed to wear by means of simulators. Various sets of tibial inserts have been reconstructed by using optical scanners. With this in mind, the wear behavior of fixed and mobile bearing polyethylene knee configurations was investigated using a knee wear joint simulator. After the completion of the wear test, the polyethylene menisci were analyzed by an innovative 3D optical scanners in order to evaluate the 3D wear distribution on the prosthesis surface. This study implemented a new procedure for evaluating polyethylene bearings of joint prostheses obtained after in vitro wear tests and the proposed new approach allowed quantification of the contact zone on the geometry of total knee prostheses. The results of the present study showed that mobile TKPs (total knee prosthesis) have lower wear resistance with respect to fixed TKPs.

New Challenges in Tribology: Wear Assessment Using 3D Optical Scanners.

Wear is a significant mechanical and clinical problem. To acquire further knowledge on the tribological phenomena that involve freeform mechanical components or medical prostheses, wear tests are performed on biomedical and industrial materials in order to solve or reduce failures or malfunctions due to material loss. Scientific and technological advances in the field of optical scanning allow the application of innovative devices for wear measurements, leading to improvements that were unimaginable until a few years ago. It is therefore important to develop techniques, based on new instrumentations, for more accurate and reproducible measurements of wear. The aim of this work is to discuss the use of innovative 3D optical scanners and an experimental procedure to detect and evaluate wear, comparing this technique with other wear evaluation methods for industrial components and biomedical devices.