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.

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.

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Performance optimization of a concrete mixer is fundamental in many industrial technologies. Wear is one of the main phenomena to be forecast and tested during the design and service of mechanical components. In all the concrete mixers types, blades suffer the wear more than other components. Two different blade shapes have been tested in order to evaluate the wear rates and which of them has the best performance in terms of wear resistance. One of the two shapes has been designed in order to minimize wear rates and to allow longer durability, on the basis of a theoretical approach. To guarantee the consistence of the comparison, the two different blades have been tested in a dedicated planetary concrete mixer, with the same operating conditions (time-period, same mixture and mixer). The purpose of this paper is to show optical non-contact measurements of worn blades operating in a planetary concrete mixer in order to evaluate wear rates and to validate the efficiency of the new blade design.

Underactuated, modular and compliant hands and grippers are interesting solutions in grasping and manipulation tasks due to their robustness, versatility, and adaptability to uncertainties. However, this type of robotic hand does not usually have enough dexterity in grasping. The implementation of some specific features that can be represented as “embedded constraints” allows to reduce uncertainty and to exploit the role of the environment during the grasp. An example that has these characteristics is the Soft ScoopGripper a gripper that has a rigid flat surface in addition to a pair of modular fingers. In this paper, we propose an upgraded version of the Soft ScoopGripper, developed starting from the limits shown by the starting device. The new design exploits a modular structure to increase the adaptability to the shape of the objects that have to be grasped. In the proposed device the embedded constraint is no rigid neither unactuated and is composed of an alternation of rigid and soft modules, which increase versatility. Moreover, the use of soft material such as thermoplastic polyurethane (TPU) reduces the risk of damage to the object being grasped. In the paper, the main design choices have been exploited and a finite element method (FEM) analysis through static simulation supports a characterization of the proposed solution. A complete prototype and some preliminary tests have been presented.

3D vision systems are more and more required in a large variety of applications and mostly for mechanical and medical purposes. This paper presents the study and realization of a prototype of a structured light automated tilt-rotational 3D vision system for high-quality reconstructions of components of various sizes and in cases of freeform and complex surfaces. The main goal of this research work was to develop an instrument with the following main novelties: configurability for different object sizes, high precision and resolution levels and ability to automatically generate the mesh representing the full scanned objects without any intervention of the operator by means of a 2 degrees of freedom automated tilt-rotational mechanical positioning system. A detailed analysis of the instrument and the procedures and results of the performance tests are presented, together with the examination of possible strategies to obtain a better performance, especially by the calibration and the synchronization between the optical and the mechanical systems. As a result, the prototype and the performance parameters resulting from the experimental campaigns, are reported.