Tactile Scanning Research Articles

Tactile, Orientation, and Optical Sensor Fusion for Tactile Breast Image Mosaicking

Breast cancer screening using tactile imaging (TI) is an advancing field of low-cost noninvasive medical imaging. Utilizing arrays of capacitive pressure transducers to perform a differential stress measurement of suspicious tissue, TI has been shown to be effective in measuring lesion size and stiffness, and subsequent differentiation of malignant and benign conditions, in repeated clinical studies. In order to further improve the lesion classification accuracy of clinical TI, this article presents a novel method of mosaicking tactile images to form a large composite tactile map using the vein structure within the breast to spatially register tactile data. This article demonstrates practical nonrigid tactile image mosaicking, using probe contact force and relative orientation sensor fusion to correct for the tissue deformation during tactile scanning, miniaturized and applied to a pre-clinical TI prototype. Testing of the proposed TI prototype on representative, tissue-mimicking, and silicone breast phantoms, with varying baseline elasticity and internal vein structure, yields typical image registration accuracies of 0.33% ± 0.15%. In similar testing, the proposed system measures the background elasticity of the samples with worst case error < 4.5% over the range of 9–60 kPa, required for accurate lesion characterization. This work will lead into further clinical validation of TI for measurement and classification of in situ phantom and breast lesions, utilizing the delivered metrics from this work to improve differentiation accuracy.

Filtering effects on involute gear form measurement

Traditional gear measurement results are used to classify a gear tolerance grade in accordance with ISO 1328-1:2013 but as more stringent requirements are placed on gear performance it is important to also characterise performance related features properly on the gear flank surface. However, the measurement uncertainty of the measurement machines is not improving at the same rate as the tolerance requirements, and it is not uncommon to have less than 10 μm tolerances to be measured with a 1–3 μm measurement uncertainty capability. This breaks the ‘rule of thumb’ that the uncertainty should be smaller than one tenth of the value you are trying to measure. It is therefore important to review the measurement and evaluation process to identify if there are any areas for improvement within our current methods. Additionally, the measurements are being used to refine gear tooth contact analysis performance models and the development of optical and high speed tactile scanning measurement methods is allowing the full 3D gear flank surface measurement a feasible option on the shop floor. Greater understanding of the involute flank beyond the standard evaluation limits is thus required. These additional requirements have prompted this review of the effect that the Gaussian filters specified in ISO 1328-1:2013 have and that their characteristics are fully understood by those who must perform and interpret the measurement results. This paper examines the effect that these filters have on measurements where micro geometry corrections, such as tip relief, or tooth tip and end face chamfers are present. Methods of minimising these effects are reviewed with specific reference to strategies defined in ISO 16610-28:2016. Recommendations are offered to minimise the effects when evaluating the gear tolerance class and quantifying gear flank micro geometry.

Fabrication of soft x-ray monolithic Wolter mirror based on surface scanning measurement using touch probe.

The monolithic Wolter mirror is an ideal optical device for focusing soft x rays to a submicron-sized spot, with the advantages of high efficiency, large acceptance, achromaticity, and robustness to alignment error. The fabrication process for this type of mirror has not been established because of the difficulty in highly accurate figure measurement of free-form surfaces with small radii of curvature and steep profiles. In this study, we employed tactile scanning measurement for surface characterization to fabricate a high-precision Wolter mirror. First, it was demonstrated that the touch probe measurement did not leave scratches on the raw surface of the mirror substrate. Next, the measurement capability of the surface profiler was assessed, and the data analysis conditions were determined. Finally, the Wolter mirror was fabricated through repeated figure correction based on the tactile measurement, and the figure error of the final surface was evaluated. Wave-optical simulations that used this error as reference suggested that the size of the beam focused by the mirror was equivalent to the theoretical value at 1000 eV. The reflected image with uniform intensity distribution obtained at SPring-8 also revealed the effectiveness of the present fabrication approach based on tactile measurement.

Intraoperative analysis of patellofemoral joint morphology before and after total knee arthroplasty : Afeasibility study.

BackgroundPatellofemoral problems after total knee arthroplast (TKA) are frequent and often associated with a change in the geometry of the trochlear groove.ObjectiveThe present study aimed to analyze the feasibility of intraoperative examination of the patellofemoral joint geometry before and after the implantation of bicondylar total knee replacements without exposing the patient to radiation.Material and methodsThe patellofemoral joint morphology geometries of 33 patients before and after implantation of a bicondylar total knee replacement was intraoperatively analyzed using a digital scanning method. Femoral surface geometries were extracted from intraoperatively recorded tactile scanning data using an in-house algorithm. The geometries were then characterized by sulcus height, medial femoral condyle height and lateral femoral condyle height.ResultsOur preliminary results show that these key geometric parameters are only partially restored after TKA leading to a distinctly different shaped profile of the anterior distal femur. Maximum and minimum mean differences in sulcus height, medial femoral condyle height, and lateral femoral condyle height before and after surgery were 2.00 mm/−3.06 mm, 2.51 mm/−6.25 mm and 2.74 mm/−3.58 mm, respectively.ConclusionA new method for intraoperative analysis of the patellofemoral joint morphology before and after TKA without radiation exposure was developed and utilized. Even with the use of modern total knee designs, the patellofemoral articulation is considerably changed postoperatively as quantified by the key parameters of sulcus height, medial femoral condyle height, and lateral femoral condyle height. This may result in altered knee biomechanics and might explain persistent patellofemoral disorders, which are often reported by patients after TKA.

Effects of Different Hard Finishing Processes on Gear Excitation

Gearboxes are essential in mechanical drive trains for power transmission. A low noise emission and thus an optimized excitation behavior is a substantial design objective for many applications in terms of comfort and operational safety. There exist numerous processes for manufacturing gears, which all show different properties in relation to the process variables and, therefore, differences in the resulting accuracy and quality of the gear flank. In this paper, the influence of three different manufacturing processes for hard finishing—continuous generating grinding, polish grinding and gear skiving—on the surface structure of gear flanks and the excitation behavior is investigated experimentally and analyzed by the application force level. A tactile scanning of the gear flanks determines the flank surface structure and the deviations from the desired geometry. A torsional acceleration measurement during speed ramp-ups at different load levels is used to analyze the excitation of the gears. The results show only a minor influence of the surface structure on the application force level. The excitation behavior is dominated by the influence of the flank modification and its deviation from the design values.

APPLICATION OF RULED SURFACES IN FREEFORM AND GEAR METROLOGY

An application of two ruled surfaces (i.e., surfaces generated by a motion of a straight line), a surface of hyperbolic paraboloid and a tangent surface of a cylindrical helix in freeform and gear metrology is introduced in this paper. Both surfaces have been implemented as the main functional figures in several artefacts – metrological calibration standards intended for testing the freeform capabilities of various measuring technologies (e.g., tactile point-to-point measurement and tactile scanning on coordinate measuring machine, optical scanning, computer tomography). Geometrical and mathematical properties of the surface used are summarised, CAD models of all the developed standards are presented and photos of the manufactured standards are shown.

COMPLEX-SHAPED PARTS GRINDING TECHNOLOGY INFORMATION ENSURING

A method of computer-aided design and manufacture of complex-shaped parts of machines and implants from difficult-to-machine materials (titanium, cobalt-chromium alloys, zirconium dioxide, etc.) has been developed, based on the principles of building an integrated CAD/CAM/CAE system of computer-aided designing and a hierarchical intelligent numerical control system. It is shown that kinematical mechanisms created over the past several centuries do not allow reproducing with the required accuracy the joints movement of living organisms for their use in biomedical implantation technologies. Therefore, the worn out joints of living organisms are reconstructed by adding complex-shaped parts from these difficult-to-machine materials. Information about the geometric shape of these parts (3D model) at the pre-production stage is obtained using modern methods of computed tomography and magnetic resonance imaging, and at the production stage the actual location of the stock grinding allowance is measured by laser (or tactile) scanning. To reduce the unevenness of the position of the grinding stock allowance, the workpiece of a complex-shaped part before grinding is oriented in the coordinate system of a CNC machine based on the established criterion for minimizing the allowance. An example of such orientation of the gear workpiece is given. This workpiece is measured with a Renishaw tactile probe on the left and right sides of the gear valleys before gear grinding. Both the minimum allowance on the left and right sides of the valleys and the difference between them are determined, and then additionally the gear wheel blank is rotated in the appropriate direction to align these minimum values detected. In turn, the aligned minimum allowances, should be sufficient to compensate for the influence of technological factors from the previous operation and the error in setting the workpiece for this operation. For complex-shaped implants, such an additional orientation is performed, for example, according to algorithms for ensuring the minimax value of the allowance.

A region segmentation method to measure multiple features using a tactile scanning probe

ABSTRACT Coordinate measuring machines (CMMs) have been widely used in industry to precisely measure parts for inspection or quality control. One of the main barriers to using a CMM touch-trigger probe is the cumbersome programming work required to identify the probing points and for scan path planning. In this paper, we propose a practical data-segmentation method to continuously measure multiple features of the workpiece using a scanning probe. This approach takes advantage of the fast data-capture capability of the scanning probe and, subsequently, the point dataset is segmented using the information extracted from the CAD model of the part. This methodology does not require tedious programming and all desired measurement results can be obtained from a single scan. The principle of the method is presented, and the feasibility of the method is experimentally verified on a bridge-type Hexagon DEA Global CMM equipped with a Leitz LSP-X1 probe. The proposed method avoids manual operation errors and generates more sampling points than traditional methods; therefore, theoretically providing lower measurement uncertainty. The test results also indicate that the new method using a scanning probe is easy to implement and can save more than 90% measurement time in comparison with a conventional touch-trigger method.

Research regarding tactile scanning versus optical scanning

In today’s fast-moving world, the manufacturing industry must keep up with evolving trends. One such trend that has greatly impacted the manufacturing industry is called Industry 4.0 and is regarded as the fourth industrial revolution. In this revolution one important aspect is that of quality. This paper makes a comparative study between tactile and optical measuring machines in the context of Industry 4.0. As the manufacturing industry must be more flexible and solve problems in a timelier manner, it is important to identify the right technologies appropriate for quality control.

Novel measurement standard for internal involute microgears with modules down to 0.1 mm

Involute microgears are important components used in industrial applications. Quality control benefits from enhanced, monitored measurement processes. Workpiece-like measurement standards help to verify measurements and estimate measurement uncertainties by comparing the geometrical values measured with the calibration values. To address the need for reliable, traceable gear standards on the microscale, Germany’s national metrology institute, the Physikalisch-Technische Bundesanstalt, has developed the first internal involute microgear measurement standard with modules between 0.1 and 1 mm. We manufactured two versions with different materials (titanium and carbide) by means of wire electrical discharge machining. Profile and flank deviations were calibrated with sub-micrometer uncertainty by means of tactile scanning measurements using a micro coordinate measuring machine. This paper features information on the design, manufacturing, and calibration processes, including a detailed measurement uncertainty budget.

Cross-Modal Correspondences Enhance Performance on a Colour-to-Sound Sensory Substitution Device.

Visual sensory substitution devices (SSDs) can represent visual characteristics through distinct patterns of sound, allowing a visually impaired user access to visual information. Previous SSDs have avoided colour and when they do encode colour, have assigned sounds to colour in a largely unprincipled way. This study introduces a new tablet-based SSD termed the ‘Creole’ (so called because it combines tactile scanning with image sonification) and a new algorithm for converting colour to sound that is based on established cross-modal correspondences (intuitive mappings between different sensory dimensions). To test the utility of correspondences, we examined the colour–sound associative memory and object recognition abilities of sighted users who had their device either coded in line with or opposite to sound–colour correspondences. Improved colour memory and reduced colour-errors were made by users who had the correspondence-based mappings. Interestingly, the colour–sound mappings that provided the highest improvements during the associative memory task also saw the greatest gains for recognising realistic objects that also featured these colours, indicating a transfer of abilities from memory to recognition. These users were also marginally better at matching sounds to images varying in luminance, even though luminance was coded identically across the different versions of the device. These findings are discussed with relevance for both colour and correspondences for sensory substitution use.

Setup of a high-precision profilometer and comparison of tactile and optical measurements of standards

Both optical and tactile probes are often used in dimensional metrology applications, especially for roughness, form, thickness and surface profile measurements. To perform such kinds of measurements with a nanometre-level of accuracy (∼30 nm), Laboratoire National de Métrologie et d’Essais (LNE) has developed a new high-precision machine. The architecture of the machine contains a short and stable metrology frame dissociated from the supporting frame. It perfectly respects the Abbe principle. The metrology loop supports reference laser interferometers and is equipped either with an optical probe or a tactile probe of nanometric resolution and linear residuals. The machine allows in situ calibration of the measuring optical and tactile probes by comparison to the laser interferometer measurements, considered as a reference. In this paper, both architecture and operation of the LNE's high-precision profilometer are detailed. A brief comparison of the behaviour (linear residuals) of the confocal chromatic and tactile probes is presented. Optical and tactile scanning of V-grooves artefacts with 75, 24, 7.5, 2.4, 0.75 and 0.24 µm depths are illustrated and discussed. In addition, a comparison between optical, tactile and atomic force microscopy measurements on a VLSI SHS 880-QC is also performed. Finally, a comparison of an optical and tactile scanning of optical aspherical lens with a polymer coating is presented and discussed.

Towards quantitative modelling of surface deformation of polymer micro-structures under tactile scanning measurement

Contact stylus-based surface profilometry is capable of topography measurement whilst being independent of the physical, electrical and optical properties of the materials under test, and has therefore become an indispensable tool for dimensional measurement of transparent specimens. However, large measurement deviations will appear when soft specimens, especially specimens made of polymers, are measured by contact stylus profilometry. In this paper the surface deformation behaviour of two polymers for molding and one photoresist, i.e. Ormocomp, Ormoclad and SU-8, under different tactile measurement conditions have been experimentally investigated. An empirical analytical model is hereby proposed for the prediction of surface deformation of soft specimens under tactile (sliding) contact. Preliminary experimental results demonstrate that the proposed five-parameter model is applicable for describing the deformation behaviour of these thermoplastic materials under the scanning speed ranging from 2 to 200 μm s−1 and the probing force varying from 5 to 500 μN. In addition, thanks to quantitative topographical measurements of the layer thickness of the aforementioned photoresists, the scratch behaviour and the time-dependent mechanical properties of these materials have also been experimentally determined.

Non-linear dynamic compensation and re-sampling for tactile scanning measurement of curved surface topography based on GPS standards

Tactile scanning method is widely used for curved surface topography measurement. Owing to the non-linear transformation process from the vertical translational displacement of the measured point (the coordinates of stylus tip) to the angular displacement of the stylus tip (measured by the cylindrical diffraction grating), the non-linear error exists within the horizontal and vertical coordinates of the obtained sampling data. And the non-linear error normally rises with the increasing of the measurement range.To solve the non-linear problem, a tactile scanning measurement system based on cylindrical grating interference principle is constructed for curved surface topography; the originations of the non-linear error in this system are analyzed, the error compensation model is established, through which the non-linear error of the collected data is dynamically compensated. Subsequently, for the non-uniform distribution of the sampling points, data analysis method is investigated, in which non-uniform interpolation and re-sampling techniques are investigated to obtain accurate data with uniform interval, so that the analysis and evaluation of surface profile can be conducted based on GPS (Geometrical Product Specifications) standards. Experimental results prove the improvements.

Comparison of the Spatial Landmark Scatter of Various 3D Digitalization Methods

The aim of this study was to compare four different three-dimensional digitalization methods on the basis of the complex anatomical surface of a cleft lip and palate plaster cast, and to ascertain their accuracy when positioning 3D landmarks. A cleft lip and palate plaster cast was digitalized with the SCAN3D photo-optical scanner, the OPTIX 400S laser-optical scanner, the Somatom Sensation 64 computed tomography system and the MicroScribe MLX 3-axis articulated-arm digitizer. First, four examiners appraised by individual visual inspection the surface detail reproduction of the three non-tactile digitalization methods in comparison to the reference plaster cast. The four examiners then localized the landmarks five times at intervals of 2 weeks. This involved simply copying, or spatially tracing, the landmarks from a reference plaster cast to each model digitally reproduced by each digitalization method. Statistical analysis of the landmark distribution specific to each method was performed based on the 3D coordinates of the positioned landmarks. Visual evaluation of surface detail conformity assigned the photo-optical digitalization method an average score of 1.5, the highest subjectively-determined conformity (surpassing computer tomographic and laser-optical methods). The tactile scanning method revealed the lowest degree of 3D landmark scatter, 0.12 mm, and at 1.01 mm the lowest maximum 3D landmark scatter; this was followed by the computer tomographic, photo-optical and laser-optical methods (in that order). This study demonstrates that the landmarks' precision and reproducibility are determined by the complexity of the reference-model surface as well as the digital surface quality and individual ability of each evaluator to capture 3D spatial relationships. The differences in the 3D-landmark scatter values and lowest maximum 3D-landmark scatter between the best and the worst methods showed minor differences. The measurement results in this study reveal that it is not the method's precision but rather the complexity of the object analysis being planned that should determine which method is ultimately employed.

Involvement of NO-synthase and nicotinic receptors in learning in the honey bee

Restrained worker honey bees ( Apis mellifera) are one of the main models for the comparative study of learning and memory processes. Bees easily learn to associate a sucrose reward to antennal tactile scanning of a small metal plate (associative learning). Their proboscis extension response can also be habituated through repeated sucrose stimulations (non-associative learning). We studied the role of nitric oxide synthase and nicotinic acetylcholine receptors in these two forms of learning. The nicotinic antagonist MLA or the nitric oxide synthase inhibitor l-NAME impaired the formation of tactile associative long-term memory that specifically occurs during multiple-trial training; however these drugs had no effect on single-trial training. None of the drugs affected retrieval processes. These pharmacological results are consistent with data previously obtained with olfactory conditioning and indicate that MLA-sensitive nicotinic receptors and NO-synthase are specifically involved in long-term memory. MLA and l-NAME both reduced the number of trials required for habituation to occur. This result suggests that a reduction of cholinergic nicotinic neurotransmission promotes PER habituation in the honey bee.

Tactile Speed Scaling: Contributions of Time and Space

A major challenge for the brain is to extract precise information about the attributes of tactile stimuli from signals that co-vary with multiple parameters, e.g., speed and texture in the case of scanning movements. We determined the ability of humans to estimate the tangential speed of surfaces moved under the stationary fingertip and the extent to which the physical characteristics of the surfaces modify speed perception. Scanning speed ranged from 33 to 110 mm/s (duration of motion constant). Subjects could scale tactile scanning speed, but surface structure was essential because the subjects were poor at scaling the speed of a moving smooth surface. For textured surfaces, subjective magnitude estimates increased linearly across the range of speeds tested. The spatial characteristics of the surfaces influenced speed perception, with the roughest surface (8 mm spatial period, SP) being perceived as moving 15% slower than the smoother, textured surfaces (2-3 mm SP). Neither dot disposition (periodic, non periodic) nor dot density contributed to the results, suggesting that the critical factor was dot spacing in the direction of the scan. A single monotonic relation between subjective speed and temporal frequency (speed/SP) was obtained when the ratings were normalized for SP. This provides clear predictions for identifying those cortical neurons that play a critical role in tactile motion perception and the underlying neuronal code. Finally, the results were consistent with observations in the visual system (decreased subjective speed with a decrease in spatial frequency, 1/SP), suggesting that stimulus motion is processed similarly in both sensory systems.

Nanometrology – Nanopositioning- and Nanomeasuring Machine with Integrated Nanopobes

The paper describes the operation of a high-precision wide scale three-dimensional nanopositioning and nanomeasuring machine (NPM-Machine) having a resolution of 0,1 nm over the positioning and measuring range of 25 mm x 25 mm x 5 mm. The NPM-Machine has been developed by the Technische Universität Ilmenau and manufactured by the SIOS Meßtechnik GmbH Ilmenau. The machines are operating successfully in several German and foreign research institutes including the Physikalisch-Technische Bundesanstalt (PTB). The integration of several, optical and tactile probe systems and scanning force microscopes makes the NPM-Machine suitable for various tasks, such as large-area scanning probe microscopy, mask and water inspection, circuit testing as well as measuring optical and mechanical precision work pieces such as micro lens arrays, concave lenses, mm-step height standards.

Judgment of rectangular areas in children blind from birth

Many studies in the framework of information integration theory have been dedicated to the judgment of rectangular areas in young sighted individuals. Many integration rules have been proposed (e.g., multiplicative, additive, maximum extent, relative centration, length only, width only) and tested, but uncertainties persist concerning the fine integration process. In order to shed light on this process, we turned to a population of young children blind from birth, 6 to 8 years of age, and examined in detail their gestural strategies when placed in an area evaluation situation. The following prudent conclusions appear justified: (a) that the strategy of acquisition and integration of information was a very markedly dimensional strategy; (b) that this strategy could be accompanied by attempted tactile scanning of the two dimensions; and (c) that the integration process obeyed an additive type rule, with greater weight attributed to the larger dimension (relative centration rule).

Pseudoneglect and reversed pseudoneglect among left-handers and right-handers

Two experiments were carried out to examine specific hand contribution to pseudoneglect and reversed pseudoneglect phenomena in dextrals and sinistrals when bisection tasks were conducted exclusively in the midline spatial condition. Both dextrals and sinistrals showed the same overall pattern deviation: in the tactile scanning task, both right and left hands deviated to the left of the midpoint and in the kinesthetic scanning tasks, the right hand deviated to the left and the left hand to the right of the midpoint. However, when these deviations were tested against zero (i.e. the objective midpoint) clear differences appeared related to hand, task and handedness. These results were discussed with respect to “enhancement theory”.