Virtual distances methodology as verification technique for AACMMs with a capacitive sensor based indexed metrology platform

This paper presents a new verification procedure for articulated arm coordinate measuring machines (AACMMs) together with a capacitive sensor-based indexed metrology platform (IMP) based on the generation of virtual reference distances. The novelty of this procedure lays on the possibility of creating virtual points, virtual gauges and virtual distances through the indexed metrology platform’s mathematical model taking as a reference the measurements of a ball bar gauge located in a fixed position of the instrument’s working volume. The measurements are carried out with the AACMM assembled on the IMP from the six rotating positions of the platform. In this way, an unlimited number and types of reference distances could be created without the need of using a physical gauge, therefore optimizing the testing time, the number of gauge positions and the space needed in the calibration and verification procedures. Four evaluation methods are presented to assess the volumetric performance of the AACMM. The results obtained proved the suitability of the virtual distances methodology as an alternative procedure for verification of AACMMs using the indexed metrology platform

A review of tangential composite and radial composite gear inspection

This paper presents an overview of the literature on tangential composite and radial composite gear inspection. It demonstrates – by dealing with their origins and key milestones in their history and development – the important role that inspections play in terms of the functional nature of the gears concerned. This comprehensive consideration of the subject also attempts to demonstrate how the lack of clear guidelines and standards designed to unify the criteria applied to testing, the interpretation of results and calibration of equipment, along with the number of simultaneous variables involved in trials of this type, leads to doubts (including with respect to the actual standards concerned) as to whether these tests are valid, or instead accepted only has partial validations. Even so, the repeatability of the experimental data demonstrates not only their metrological potential, with respect to functionality, but also the fact that they are both effective and origina

A new calibration guideline for worm and worm-gear rolling testers

The evaluation and calibration of gear testers are considered as a key point to ensure the obtained results in gear metrology. Although ISO TC 60 working group has developed standards in this regard, the fact is that for the time being, there are not specific international standards for gear rolling tests. In this work, a periodical calibration guideline for gear rolling testers, particularly for worm gear transmission, is proposed, allowing the reduction of possible error sources in the measurement process. A series of tasks distributed over time are suggested in this work to maintain the accuracy of the gear rolling test machines

Influence of décollement-cover thickness variations in fold-and-thrust belts: Insights from centrifuge analog modeling

Centrifuge analog modeling incorporating thickness variations of décollement and overlying sedimentary cover is used to study thrust-wedge evolution on salt-detached contractional systems involving tapered sedimentary cover. From simpler, layer-cake to 3D tapered décollement-cover sequences, our models constrain wedge evolution: a more advanced front, where the cover is thicker, promotes differential frontal translation and triggers vertical axis rotation of several hinterland anticlines which appear towards the thinner cover area. In all cases, the décollement level is strongly sheared and tends to migrate laterally toward the thinner cover areas. Models are compared with previous analog models under normal gravity and the natural example of the South Pyrenean Central salient. All in all, we conclude that a 3D tapered décollement-cover basin architecture, as a sole factor, can determine the formation of a thrust salient formed by increasing structural curvature (progressive arc)

Application of virtual distances methodology to laser tracker verification with an indexed metrology platform

High-range measuring equipment like laser trackers need large dimension calibrated reference artifacts in their calibration and verification procedures. In this paper, a new verification procedure for portable coordinate measuring instruments based on the generation and evaluation of virtual distances with an indexed metrology platform is developed. This methodology enables the definition of an unlimited number of reference distances without materializing them in a physical gauge to be used as a reference. The generation of the virtual points and reference lengths derived is linked to the concept of the indexed metrology platform and the knowledge of the relative position and orientation of its upper and lower platforms with high accuracy. It is the measuring instrument together with the indexed metrology platform one that remains still, rotating the virtual mesh around them. As a first step, the virtual distances technique is applied to a laser tracker in this work. The experimental verification procedure of the laser tracker with virtual distances is simulated and further compared with the conventional verification procedure of the laser tracker with the indexed metrology platform. The results obtained in terms of volumetric performance of the laser tracker proved the suitability of the virtual distances methodology in calibration and verification procedures for portable coordinate measuring instruments, broadening and expanding the possibilities for the definition of reference distances in these procedures

Coupling far and near tectonic signals in syn-orogenic sediments : the Olvena growth strata (Sierras Marginales, southern Pyrenees)

The Olvena area (Sierras Marginales, southern Pyrenees) provides an outstanding example for studying the relationships between tectonics and sedimentation related to fold-and-thrust systems having shallow décollements. Stratigraphic and sedimentological features allow infer i) the relationship between Oligocene-Miocene locallysourced alluvial fans and a far-sourced wider fluvial system, and ii) the control exerted by tectonics on the stratigraphic architecture. Initially, uplift resulting from folding and thrusting in the Sierras Marginales precluded the entrance through this area into the Ebro basin of a wide fluvial system sourced in internal zones of the Pyrenean chain (including the Axial Zone). A subsiding area was created in the southern front of the Sierras where west-flowing alluvial fans generated, having their source areas in the rejuvenated reliefs. The subsequent cessation of movement of the tectonic structures permitted these reliefs to be subdued and the overpassing of the north-coming fluvial system that progressively covered a wider area. Sequential evolution and stratigraphic architecture evidence thrust emplacement geometry and chronology, including out-of-sequence reactivation of structures and the influence of evaporite flow along the décollement. Although these syn-tectonic deposits belong to the Ebro basin succession, its megasequential evolution differs from the general sequence established for the basin fill, highlighting the importance of differentiating the influence of near-coming sedimentary systems when interpreting basin-scale sequence stratigraphy

Design of a multi-point kinematic coupling for a high precision telescopic simultaneous measurement system

This paper covers the design of a new multi-point kinematic coupling specially developed for a high precision multi-telescopic arm measurement system for the volumetric verification of machine tools with linear and/or rotary axes. The multipoint kinematic coupling allows the simultaneous operation of the three telescopic arms that are registered at the same time to a sphere fixed on the machine tool spindle nose. Every coupling provides an accurate multi-point contact to the sphere, avoiding collisions and interferences with the other two multi-point kinematic couplings, and generating repulsion forces among them to ensure the coupling’s fingers interlacing along the machine tool x/y/z travels in the verification process. Simulation presents minimal deformation of the kinematic coupling under load, assuring the precision of the sphere-to-sphere distance meas-urement. Experimental results are provided to show that the multi-point kinematic coupling developed has repeatability values below ±1.2 µm in the application. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Influence of high precision telescopic instrument characterization on multilateration points accuracy

Currently accuracy of manufacturing machines is a must. Verification is the main way to obtain it; highlighting the volumetric verification as the best technique to improve machine tool position accuracy along all its workspace in the shortest time possible. In this way, different measurements based on multilateration techniques like laser tracker and laser tracer are used. This paper studies how characteristics of a new high precision telescopic system consisting in three lines, with measuring principle based on simultaneous laser affect multilateration accuracy to obtain 3D coordinates. The paper analyses instrument characterising both the design, the components and their operation. Moreover, tests carried out study how instruments behavior affect to the accuracy of data capture using analytical and optimization techniques, proving an error estimation depending on the technique used

Vía de abordaje posterior en cuatro transaquílea en el síndrome doloroso del retropié: Haglund, pump bump y tendinitis calcificante del tendón de Aquiles

Actualmente existe la tendencia a utilizar técnicas mínimamente invasivas en el tratamiento del síndrome doloroso del retropié. En nuestro servicio, preferimos utilizar la vía de abordaje posterior abierta en cuatro transaquílea, dado que permite una mejor visualización de las lesiones presentes a este nivel. Este tipo de abordaje concede al cirujano poder realizar con mayor facilidad y precisión la técnica quirúrgica con una tasa muy baja de complicaciones.Currently, there is a trend towards the use of minimally invasive techniques for the treatment of posterior heel pain. In our hospital, we prefer to use the tendon splitting approach through a four-shaped cutaneous incision. It provides a better visualization of retrocalcaneal space. This type of surgical approach allows an easier and complete surgery with a very low complication rate

Matrix architecture plays a pivotal role in 3D osteoblast migration: The effect of interstitial fluid flow

Osteoblast migration is a crucial process in bone regeneration, which is strongly regulated by interstitial fluid flow. However, the exact role that such flow exerts on osteoblast migration is still unclear. To deepen the understanding of this phenomenon, we cultured human osteoblasts on 3D microfluidic devices under different fluid flow regimes. Our results show that a slow fluid flow rate by itself is not able to alter the 3D migratory patterns of osteoblasts in collagen-based gels but that at higher fluid flow rates (increased flow velocity) may indirectly influence cell movement by altering the collagen microstructure. In fact, we observed that high fluid flow rates (1 µl/min) are able to alter the collagen matrix architecture and to indirectly modulate the migration pattern. However, when these collagen scaffolds were crosslinked with a chemical crosslinker, specifically, transglutaminase II, we did not find significant alterations in the scaffold architecture or in osteoblast movement. Therefore, our data suggest that high interstitial fluid flow rates can regulate osteoblast migration by means of modifying the orientation of collagen fibers. Together, these results highlight the crucial role of the matrix architecture in 3D osteoblast migration. In addition, we show that interstitial fluid flow in conjunction with the matrix architecture regulates the osteoblast morphology in 3D