This research aims to address the issue of safe navigation for autonomous vehicles in highly challenging outdoor environments. Indeed, robust navigation of autonomous mobile robots over long distances requires advanced perception means for terrain traversability assessment. Design/methodology/ approach - The use of visual systems may represent an efficient solution. This paper discusses recent findings in terrain traversability analysis from RGB-D images. In this context, the concept of point as described only by its Cartesian coordinates is reinterpreted in terms of local description. As a result, a novel descriptor for inferring the traversability of a terrain through its 3D representation, referred to as the unevenness point descriptor (UPD), is conceived. This descriptor features robustness and simplicity. Findings - The UPD-based algorithm shows robust terrain perception capabilities in both indoor and outdoor environment. The algorithm is able to detect obstacles and terrain irregularities. The system performance is validated in field experiments in both indoor and outdoor environments. Research limitations/implications - The UPD enhances the interpretation of 3D scene to improve the ambient awareness of unmanned vehicles. The larger implications of this method reside in its applicability for path planning purposes. Originality/value - This paper describes a visual algorithm for traversability assessment based on normal vectors analysis. The algorithm is simple and efficient providing fast real-time implementation, since the UPD does not require any data processing or previously generated digital elevation map to classify the scene. Moreover, it defines a local descriptor, which can be of general value for segmentation purposes of 3D point clouds and allows the underlining geometric pattern associated with each single 3D point to be fully captured and difficult scenarios to be correctly handled

An efficient and reliable onboard perception system is critical for a mobile robot to increase its degree of autonomy toward the accomplishment of the assigned task. In this regard, laser range sensors represent a feasible and promising solution that is rapidly gaining interest in the robotics community. This paper describes recent work of the authors in hardware and algorithm development of a 3-D laser scanner for mobile robot applications, which features low-cost, lightweight, compactness, and low power consumption. The sensor allows a vehicle to autonomously scan its environment and to generate an internal hazard representation of the world in the form of digital elevation maps. This suggests a general approach to terrain analysis in structured and unstructured environments for a safe and collision-free path planning. The proposed sensor system along with the algorithms for mapping and planning is validated in indoor laboratory experiments as well as in tests on natural terrain using an all-terrain rover.

In this paper the authors present a new strategy for accurately reconstructing a L-shaped obstacle such as some wooden panels opportunely connect so as to form a right angle. The mechatronics scanning system consists of four inexpensive ultrasonic sensors moved in three dimensional (3D) space by means of a digital motor. The motor rotation is controlled in order to point the sensor array at the target and to obtain distance measurements for each shaft position. Ultrasonic distance sensors propagate large beams and feel the significant effect of multiple reflections. For the sake of excluding all misrepresented distance values at the intersection of the planes, the proposed approach uses powerful mathematical tools together with a physical indicator based on the reflected signal energy. The Fuzzy C-Means (FCM) classification allows partitioning a data set and the introduced physical indicator is able to select the specific cluster corresponding to the spurious distances. Each remaining cluster permits to calculate the equation of a plane because it is referred to the distance values deriving from a direct reflection. These distances are then transformed considering the sensors directivity and the direction of reflection so as to obtain two sets of 3D points. Finally, the reconstruction of each plane is got by the RANdom SAmple Consensus (RANSAC) in such a way as to better fit these points. The details of this strategy and the experimental tests are shown demonstrating the applicability and the good results.

In this paper, the authors present a mechatronics system consisting of an intelligent robotic arm able to sort ball bearings having the same colour and shape drawing advantage from vision. After acquiring and processing an image from a camera, two almost concentric and circular regions are extracted from the image and their areas are calculated as number of pixels belonging to them. The center of these regions provides the point that the end-effector has to reach in order to grip a cylindrical transport structure where the bearing is placed. Since the size measurements of image regions are very repeatable and the depth between the camera and the object is known, the bearing is recognized from the area. For the sake of automatically appreciating the effectiveness of the proposed approach, a RFID (Radio-Frequency Identification) tag is attached to the transport structure that supports the object. The tag contains stored information on the specific bearing for verifying the success in recognition making use of a reader device. Several experimental tests confirmed that the suggested strategy may be applied to track spare parts in assembly lines.

The results of an ambient-vibration based investigation conducted on a historical tower in Italy,to update the 3-D finite element model of the building are presented in this work.The main difficulties are related to the extreme in-homogeneity of the building and the presence of an elevator vain that occupies the posterior part of the tower,forcing to locate the accelerometers only on one facaade of the building. The assessment procedure include full-scale ambient vibration testing,modal identification from ambient vibration responses using three different identification methods,finite element modeling and dynamic-based identification of the uncertain structural parameters of the model.A very good match between theoretical and experimental modal parameters was reached and the model updating has been performed to identify some structural parameters.

In this paper, the authors introduce an innovative and complete tool for the automatic diagnostic and detection of small notches on analyzed components. The tool is based on the analysis of the data of a nanocomposite optical sensor accurately moved by a robotic arm, whose gripper catches and moves the optical sensor, for scanning without contact the external surface of mechanical components. The recent optical sensor is composed of an optical fiber source made up of a nanocomposite material, and it allows detecting the characteristics of the target by monitoring the backscattered light. The innovative tool here presented is based on the analysis of several experiments carried out, considering small notches of different lengths. The proposed algorithm, together with the used device, is able to point out the presence or not of a small notch on the scanned component and also to estimate with a good precision its length and position.

The authors present in this paper some interesting results relating to an innovative device for automatic diagnostic. The system is composed by a robotic arm that accurately moves an optical sensor for automatic diagnostic through the inspection on the presence of notches on a mechanical beam. The optical sensor is composed of an optical fiber source made up of nanocomposite material, a PDMS-Au tip that may enhance the light and a receiver optical fiber sheaf. The new system allows analyzing the characteristics of the target by monitoring the backscattered light. The sensor motion is realized by using a robotic arm whose gripper catches and moves the optical sensor. The device has been evaluated in order to analyze its ability for detecting small notches on a mechanical component.

In this paper the authors present an application of an innovative device consisting in a new optical sensor accurately moved by driving a controlled robotic arm. The new sensor is made up of nanocomposite material and it is composed of an optical fiber source, an optical fiber bundle receiver and a PDMS-Au tip able to enhance the light. The device allows to reconstruct the target characteristics taking advantage of the backscattered light. The motion of the sensor is obtained by means of a robot manipulator which gripper grasps and moves the sensor. The realized device has been tested in order to evaluate its ability to provide useful information on colours, surface opacity and profile of the detected objects.

In this paper, the authors have developed a new method for reconstructing the boundary walls of a room environment by using a mechatronic device consisting of four ultrasonic sensors rotated by a servo modular actuator. This scanning system allows to measure the times of flight in each motor position so as to explore the surrounding space detecting reflections from the boundary walls and from other static obstacles. In addition to undesired reflections, due to non-target obstacles interposed between the sensors and the target surfaces, several spurious times are observed at the corners because of multiple reflections. The Fuzzy C-Means (FCM) algorithm is used for partitioning the obtained dataset in five clusters and some considerations on the output signal energy permit to select the two subsets concerned with multipath echoes. Each remaining cluster is associated to a set of three-dimensional points by considering the directivity of the wide beam propagated. In order to discard the observations that are numerically distant from the confidence data, the three sets are filtered by means of an ellipsoid defined by the Principal Component Analysis (PCA). The best-fit planes are obtained by testing the eigenvalues and relating eigenvectors of the covariance matrix of each filtered set. Several tests are shown and discussed for appreciating the effectiveness of the described approach and they are aimed at making a robot aware of its environment.

Visual Evoked Potentials (VEPs) are referred to electrical potentials due to brief visual stimuli which can be recorded from scalp overlying visual cortex. A way to measure VEPs is through encephalogram (EEG). VEPs are very important because they can quantify functional integrity of the optic pathway. Their study allows to detect abnormalities that affect the visual pathways or visual cortex in the brain, and so methods that permit to identify VEPs components in EEG signals must be defined. However, the background activity measured from EEG hides VEPs components because they have a low voltage. So it is necessary to define a robust method to extract features, which best describe these potentials of interest. In this work Empirical Mode Decomposition (EMD) method is used to separate the EEG components and to detect VEPs. EMD decomposes a signal into components named Intrinsic Mode Functions (IFM). The results, obtained from the study of EEG records of a normal person, suggest that IMFs may be used to determine VEPs in EEG and to obtain important information related to brain activity by a time and frequency analysis of IMF components. It is well comparable with the known Wavelet Transform method, but it is characterized from a greater simplicity of implementation because the basis used in the analysis is generated by the same analyzed signal.

Future mobile robots will have to explore larger and larger areas, performing difficult tasks, while preserving, at the same time, their safety. This will primarily require advanced sensing and perception capabilities. In this respect, laser range sensors represent a feasible and promising solution that is rapidly gaining interest in the robotics community. This paper describes recent work of the authors in hardware and algorithm development of a 3-D laser scanner for mobile robot applications, which features cost effectiveness, lightweight, compactness, and low power consumption. The sensor allows an autonomous vehicle to scan its environment and to generate an internal hazard representation of the world in the form of digital elevation map. Details of the device are presented along with a thorough performance analysis as function of the relevant operational parameters, such as elevation and nodding angular rate. The generation of elevation models is also investigated, addressing the issues connected with the presence of overhanging objects and occluded areas.

Air monitoring plays a key role in measuring atmospheric pollutant concentrations in different locations of the same region or of distinct ones. This paper describes results of processing volatile organic compounds (VOCs) using an interesting genetic algorithm and also processing benzo(a)pyrene(BaP) data. Both pollutants are collected from a network of sensors located in an industrial area and in a city respectively.

Web transport systems for transporting films, textile material, paper, etc., are usually large-scale systems. The velocity and the tension of the web are controlled by dividing the systems into several subsystems in which strong coupling exists between the velocity and tension control. A self-tuning PI (STPI) controller with an estimator based on a novel adaptive particle swarm optimization method is constructed, and it is applied for controlling an actual web transport system. The controllers are designed on the basis of the methodology of the overlapping decentralized control by taking into consideration online executions performed by a general computer. The effectiveness of the constructed control system is verified on the basis of several experimental results obtained by using an actual experimental web transport system

The development of electrical trains has been requiring advances in the construction of components that are usually supervised by smart systems. Safety aspects are given to redundant capabilities of the new equipments to overcome failures. The new components must obey to internationally recognized standards. For that reason, the electrical supply and the mechanical contacts between train and rails are the key issuesto be supervised. The current ISO/IEC/IEEE 1451 is basically helpful for the electrical supply by means of the dedicated transducers. In this paper, a new voltage/current transducer for the train supply is shown and analyzed paying the attention on its reliability, availability, maintainability, and safety approach performed in an innovative way with a specific reference to guidelines of the ISO/IEC/IEEE 1451. At this aim, an extensive theoretical and experimental analysis has been performed using dedicated algorithms developed for the purposes of this research considering reliability aspects according to commercial and defense industry needs.

Mobile robots are increasingly being employed in challenging outdoor applications including search and rescue for disaster recovery, construction, mining, agriculture, military and planetary exploration. In this kind of robotic applications, the accuracy and robustness of the motion control system is greatly affected by the occurrence of undesired dynamics effects such as wheel slippage. In this paper a cross-coupled controller is presented that can be integrated with 4-wheeldrive/ 4-wheel-steer robots to optimize the wheel motors’ control algorithm and reduce synchronization errors that would otherwise result in wheel slip with conventional controllers. Experimental results, obtained with an all-terrain rover operating outdoor, are presented to validate this approach showing its effectiveness in reducing slippage and vehicle posture errors.

This paper proposes an application of industrial interest to assess the capacity of a tank, to measure and to control the contained liquid level and flow by using ultrasonic sensors. A tank is generally characterized by a cylindrical lateral surface which may be generated by rotating a curve around a fixed axis. The rotation of an ultrasonic sensor permits to fit out the generating curve of the surface so that the tank volume may be evaluated. The reconstruction may be then used to measure the quantity of water contained in the tank by means of a second ultrasonic sensor placed above the mouth of the tank and able to give the water level out. Both the ultrasonic sensors have been carefully located for avoiding possible unexpected reflections. Finally, the authors realize an experimental set-up for automatically controlling the water volume by a mechatronics system in which they make use of an electro-valve and an electro-pump. As the water level may be obtained while filling or emptying the tank and the time may be considered in each measurement, the volumetric flow may be estimated. Experimental tests will be shown and technical details will be discussed.

The modelling and the control of web handling systems have been studied for a long time; correct modelling is necessary in order to design a better control system or to identify the plant parameters experimentally. On the web dynamics itself, lumped parameters expressions may be used to designate a web section between two adjacent drive rolls, and there is the necessity of incorporating the property of viscoelasticity to the web. In this paper the lumped model of a new web tension experimental system is updated; the model is based on the conservation mass, torque balance and viscoelasticity (Voigt approach). The experimental system consists of four sections each of which is driven by a servomotor; the speed and tension feedback, by using encoders and tension sensors, drives simultaneously the four servomotors through a real time C programmed D/A board. Usually, as described in the literature, these kinds of models are developed in the Laplace domain and the block scheme gives a graphical interpretation of the interaction between different sections. The transformation of the block scheme in a differential equation system in the time domain is fully described in this paper; it is not a simple step and it requires the introduction of not null initial condition for the derivative of physical variables. Moreover, the problem of validation has been dealt with in detail in this paper, considering simultaneously 2 different combinations of input data in open loop and a multivariable optimization method in order to estimate a certain number of unknown parameters. The results will show the accuracy of this kind of lumped parameters model for the complex experimental systems and useful information for successively designing an efficient control strategy.

The aim of the paper is to describe the non-destructive tests performed on the clock tower of the Castle of Trani (Bari, Italy). The tower is about 9 meters high and has a square plan with a side of about 3.90 meters; moreover it is built on the principal enter of the Castle and supported by a barrel vault reinforced with an arch. The tower, built in 1848, was realized in tufa masonry (Stone of Trani); nevertheless, during the years, it has undergone a series of interventions, in particular in 1979 and 1997 to consolidate the walls cores with armed injections and the vaults extrados with hood in reinforced concrete. The non-destructive monitoring was realized using specific accelerometers placed on the structure for measuring the acceleration in different points. The particular squat structure of the clock tower made the traditional monitoring, with only environmental actions, the so called only-output measurements, not so safe for determining the building modal parameters. For this reason, an electro-hydraulic shaker was ad-hoc designed and realized for applying a controlled dynamic force on the examined old masonry tower. In this paper all the phases and procedures of the experimental monitoring will be described together with a preliminary analysis of the data.

The aim of the paper is to present a structural characterization of the bell tower of the Cathedral of Trani (Bari, Italy) collecting the data of two different non-destructive techniques. The tower, built in 1200, is about 60 meters high and has a square plan with a side of about 7.50 meters; moreover, it is connected to the church through a step supported by a pointed arch. Firstly, an Operational Modal Analysis was performed on the tower by using the data taken by an experimental campaign of measurements of specific accelerometers. The tower vibrations due to ambient actions have been recorded and analyzed by means of two different algorithms in such a way as to estimate the modal parameters of the tower. Moreover, a recent procedure based on the data acquired by means of a ground penetrating radar (GPR) tests for estimating the thicknesses of the internal and external layers at each level of the tower was used. The results of the identification procedure characterized the dynamic behavior of the masonry tower and were utilized also to evaluate the dynamic interaction between the tower and the Cathedral walls. GPR technology has permitted of foreseeing the internal composition of the building walls. Finally, the combination of the results of the two techniques, has allowed realizing a complete 3D finite element model.

Dynamical experimental tests for the structural identification of reinforced cyclopic concrete tower of the Provincial Administration building of Bari, Italy, have been performed for a long period in order to achieve a wide set of data. In this work new experimental data are shown and discussed. Different floors of the tower were simultaneously monitored in such a way to analyse the influence of the external excitation on the tower vibration amplitude. In particular, a very long acquisition (2 hours) during light fires explosions have been carried out Using the acceleration measurements, the modal parameters of the tower are identified consistently by two different output-only procedures: the first, based on the Enhanced Frequency Domain Decomposition, in the frequency domain; the second, based on the Stochastic Subspace Identification Method, works in the time domain. Considerations about the consistency of the results respect to the different methods and to the choice of the identification parameters are carried out.

The paper presents the analysis of an important historical building: the Saint James Theater in the city of Corfù (Greece) actually used as the Municipality House. The building, located in the center of the city, is made of carves stones and is characterized by a stocky shape and by the presence of wooden floors. The study deals with the structural identification of such structure through the analysis of its ambient vibrations recorded by means of accelerometers with high accuracy. A full dynamic testing was developed using ambient vibrations to identify the main modal parameters and to make a non-destructive characterization of this building. The results of these dynamic tests are compared with the modal analysis of a complex finite element (FE) simulation of the structure. This analysis may present several problems and uncertainties for this stocky building. Due to the presence of wooden floors, the local modes can be highly excited and, as a consequence, the evaluation of the structural modal parameters presents some difficulties.