Application of intelligent instruments for the monitoring of thrust reverse noise at airports

Peer Reviewe

METROLOGICAL CHARACTERIZATION OF A LASER-CAMERA 3D VISION SYSTEM THROUGH PERSPECTIVE-N-POINT POSE COMPUTATION AND MONTE CARLO SIMULATIONS

Abstract. This study focuses on the metrological characterization of a 3D vision system consisting in the fusion of a CMOS camera sensor with a 2D laser scanner for contactless dimensional measurements. The purpose is to obtain an enhanced measurement information as a result of the combination of two different data sources. On one side, we can estimate the pose of the target measurand by solving the well-known Perspective-n-Point (PnP) problem from the calibrated camera. On the other side, the 2D laser scanner generates a discrete point cloud which describes the profile of the intercepted surface of the same target object. This solution allows to estimate the target's geometrical parameters through the application of fit-to-purpose algorithms that see the data acquired by the overall system as their input. The measurement uncertainty is evaluated by applying the Monte Carlo Method (MCM) to estimate the uncertainty deriving from the Probability Distribution Functions (PDF) of the input variables. Through a Design of Experiments (DOE) model the effects of different influence factors were evaluated

Incidents and injuries in foot launched flying extreme sports: a snap shot from the UK

Background. Participation rates in extreme sports have grown exponentially in the last 40 years,often surpassing traditional sporting activities. The purpose of this study was to examine injury rates in foot launched flying sports, i.e. sports in which a pilot foot-launches into flight with a wing already deployed. Method. This paper is based on a retrospective analysis of the reports of incidents that occurred between 2000 and 2014 among the British Hang Gliding and Paragliding Association members. Results. The majority of the 1411 reported injuries were in the lower limb, followed by the upper limb. The most common lower limb injury was to the ankle and included fractures sprains and dislocations. The distribution of injures was different in each discipline. The calculated yearly fatality rate (fatalities /100,000 participants) was 40.4 in hang gliding, 47.1 in paragliding, 61.9 in powered hang gliding and 83.4 in powered paragliding; the overall value for foot launched flight sports was 43.9. Discussion. Significant differences in injury rates and injury patterns were found among different sport disciplines that can be useful to steer research on safety, and adopt specific safety rules about flying, protective clothing and safety systems in each of these sports

A non-contact optical technique for vehicle tracking along bounded trajectories

This paper presents a method for measuring the non-controlled trajectory of a cart along a bounded rectilinear path. The method uses non-contact measurement devices to identify the position of a movable laser scanner working in helical mode in order to reconstruct the 3D model of bridges. The main idea of the proposed method is to use vision systems in order to identify the coordinates of the laser scanner placed on the cart with respect to the global reference system. A fit-to-purpose vision system has been implemented: the system uses three CCD's cameras mounted on the cart to identify the relative rotations with respect to the environment. Two lasers pointers and a laser distance meter are fixed at the starting point of the trajectory and pointing in the direction of motion of the cart, creating three dots on a plane placed on the cart. One of the camera detects the cart displacements and rotations in the plane using a blob analysis procedure. The method described in this paper has a constant uncertainty and the measurement range only depends on the lasers power. The theoretical accuracy of the measurement system is close to 1 mm for the translation along the motion direction and around 0.5 mm along the other two directions. Orientations measurement have a theoretical accuracy of less than 0.1 °. The solution has been implemented for the 3D reconstruction of concrete bridge; preliminary experimental results are presented and discussed

Measurement method for quality control of cylinders in roll-to-roll printing machines

This paper describes a measurement method for the quality control of cylinders for printing machines based on roll-to-roll presses. If the surface finishing of the cylinders is not adequate, the printing is unacceptable, and the defective cylinders must be reworked. The performed quality check of the cylinder surface roughness by means of contact methods was unable to identify the cylinder defects, and acceptance of the manufactured cylinders before integration was demanded to the visual inspection performed by trained operators. In this work a contactless measurement method based on the eddy current displacement sensor was proposed and validated as a tool for quality check as an alternative to optical roughness measurements. A test bench for the characterization of printer cylinders was designed and manufactured, allowing for the validation of the proposed method on different batches of cylinders and the identification of a threshold to guide the acceptance of tested cylinders prior to mounting on the roll-to-roll press

Automatic measurement of hand dimensions using consumer 3D cameras

This article describes the metrological characterisation of two prototypes that use the point clouds acquired by consumer 3D cameras for the measurement of the human hand geometrical parameters. The initial part of the work is focused on the general description of algorithms that allow for the derivation of dimensional parameters of the hand. Algorithms were tested on data acquired using Microsoft Kinect v2 and Intel RealSense D400 series sensors. The accuracy of the proposed measurement methods has been evaluated in different tests aiming to identify bias errors deriving from point-cloud inaccuracy and at the identification of the effect of the hand pressure and the wrist flexion/extension. Results evidenced an accuracy better than 1 mm in the identification of the hand’s linear dimension and better than 20 cm3 for hand volume measurements. The relative uncertainty of linear dimensions, areas, and volumes was in the range of 1-10 %. Measurements performed with the Intel RealSense D400 were, on average, more repeatable than those performed with Microsoft Kinect. The uncertainty values limit the use of these devices to applications where the requested accuracy is larger than 5 % (volume measurements), 3 % (area measurements), and 1 mm (hands’ linear dimensions and thickness)

METROLOGICAL CHARACTERIZATION OF OPTICAL 3D COORDINATE MEASUREMENT SYSTEMS – COMPARISON OF ALTERNATIVE HARDWARE DESIGNS AS PER ISO 10360

Abstract. This research focuses on the characterization of the metrology of Optical 3D Coordinate Measurement Systems (O3DCMS). The focus is set on the identification and execution of the procedure indicated by the currently active technical standards related to industrial O3DCMS, for their metrological assessment, objective comparison, and performance tracking. This work leads to the implementation of an ad hoc software for the execution of the standard tests by the ISO 10360-13 standard. The implemented software application is employed in a real-case scenario for evaluating the performances of an industrial 3D scanner based on structured light. The specific hardware components to be assessed are two light sources of the active stereoscopic vision system, named Digital Light Projectors (DLP). The case study applies the procedures and metrics indicated by the active standards to objectively compare two alternative hardware design of the system under test. This results in the identification of the most performing hardware configuration, allowing the selection of the best system design, basing on objective metrological parameters

Hand-arm vibration in motocross: measurement and mitigation actions

SUMMARY Objective. This study focused on the quantification of vibration which reaches the hands of motocross riders and on the reduction of such vibration thanks to the handlebar and handlebar mounts. Background. Vibration transmitted through the hand and arm can lead to vascular and musculo- skeletal problems that are well documented in the scientific literature. Controlled studies identi- fying plate-handlebar characteristics effects on the vibration attenuation in motocross are lacking. Methods. We measured the vibration exposure of professional and recreational motocross riders on a motocross track and replicated the vibration patterns on a LDS V930 shaker in the laboratory, to analyze the effectiveness of various components in reducing the rider vibration exposure. Labo- ratory tests were performed with ten subjects randomly gripping different combinations of handle- bars and steering plates, and questionnaires were used to evaluate the comfort. Objective measure- ments of vibration reduction were then compared to the subjective values of perceived comfort. Results. According to the current EU legislation, the measured vibration levels reach the expo- sure limit in less than 1h. The mechanical characteristics of the handlebars and steering plates have a limited effect on the vibration transmitted to the rider’s hands. The rubber elements that many manufacturers use to reduce the vibration have limited effects at frequencies that are harmful for the musculoskeletal system. Questionnaires results have no correlation with the measured plate and handlebar performances. Conclusions. Most of the techniques used to reduce the hand-arm vibration exposure of moto- cross drivers are ineffective

Use of Machine Learning and Wearable Sensors to Predict Energetics and Kinematics of Cutting Maneuvers

Changes of directions and cutting maneuvers, including 180-degree turns, are common locomotor actions in team sports, implying high mechanical load. While the mechanics and neurophysiology of turns have been extensively studied in laboratory conditions, modern inertial measurement units allow us to monitor athletes directly on the field. In this study, we applied four supervised machine learning techniques (linear regression, support vector regression/machine, boosted decision trees and artificial neural networks) to predict turn direction, speed (before/after turn) and the related positive/negative mechanical work. Reference values were computed using an optical motion capture system. We collected data from 13 elite female soccer players performing a shuttle run test, wearing a six-axes inertial sensor at the pelvis level. A set of 18 features (predictors) were obtained from accelerometers, gyroscopes and barometer readings. Turn direction classification returned good results (accuracy > 98.4%) with all methods. Support vector regression and neural networks obtained the best performance in the estimation of positive/negative mechanical work (coefficient of determination R-2 = 0.42-0.43, mean absolute error = 1.14-1.41 J) and running speed before/after the turns (R-2 = 0.66-0.69, mean absolute error = 0.15-018 m/s). Although models can be extended to different angles, we showed that meaningful information on turn kinematics and energetics can be obtained from inertial units with a data-driven approach

Development of a two-dimensional dynamic model of the foot-ankle system exposed to vibration

Workers in mining, mills, construction and some types of manufacturing are exposed to vibration that enters the body through the feet. Exposure to foot-transmitted vibration (FTV) is associated with an increased risk of developing vibration-induced white foot (VIWFt). VIWFt is a vascular and neurological condition of the lower limb, leading to blanching in the toes and numbness and tingling in the feet, which can be disabling for the worker. This paper presents a two-dimensional dynamic model describing the response of the foot-ankle system to vibration using four segments and eight Kelvin-Voigt models. The parameters of the model have been obtained by minimizing the quadratic reconstruction error between the experimental and numerical curves of the transmissibility and the apparent mass of participants standing in a neutral position. The average transmissibility at five locations on the foot has been optimized by minimizing the difference between experimental data and the model prediction between 10 and 100 Hz. The same procedure has been repeated to fit the apparent mass measured at the driving point in a frequency range between 2 and 20 Hz. Monte Carlo simulations were used to assess how the variability of the mass, stiffness and damping matrices affect the overall data dispersion. Results showed that the 7 degree-of-freedom model correctly described the transmissibility: the average transmissibility modulus error was 0.1. The error increased when fitting the transmissibility and apparent mass curves: the average modulus error was 0.3. However, the obtained values were reasonable with respect to the average inter-participant variability experimentally estimated at 0.52 for the modulus. Study results can contribute to the development of materials and equipment to attenuate FTV and, consequently, lower the risk of developing VIWFt.INAI