Aerial Robotics for Inspection and Maintenance

Aerial robots with perception, navigation, and manipulation capabilities are extending the range of applications of drones, allowing the integration of different sensor devices and robotic manipulators to perform inspection and maintenance operations on infrastructures such as power lines, bridges, viaducts, or walls, involving typically physical interactions on flight. New research and technological challenges arise from applications demanding the benefits of aerial robots, particularly in outdoor environments. This book collects eleven papers from different research groups from Spain, Croatia, Italy, Japan, the USA, the Netherlands, and Denmark, focused on the design, development, and experimental validation of methods and technologies for inspection and maintenance using aerial robots

Towards Tactile Internet in Beyond 5G Era: Recent Advances, Current Issues and Future Directions

Tactile Internet (TI) is envisioned to create a paradigm shift from the content-oriented communications to steer/control-based communications by enabling real-time transmission of haptic information (i.e., touch, actuation, motion, vibration, surface texture) over Internet in addition to the conventional audiovisual and data traffics. This emerging TI technology, also considered as the next evolution phase of Internet of Things (IoT), is expected to create numerous opportunities for technology markets in a wide variety of applications ranging from teleoperation systems and Augmented/Virtual Reality (AR/VR) to automotive safety and eHealthcare towards addressing the complex problems of human society. However, the realization of TI over wireless media in the upcoming Fifth Generation (5G) and beyond networks creates various non-conventional communication challenges and stringent requirements in terms of ultra-low latency, ultra-high reliability, high data-rate connectivity, resource allocation, multiple access and quality-latency-rate tradeoff. To this end, this paper aims to provide a holistic view on wireless TI along with a thorough review of the existing state-of-the-art, to identify and analyze the involved technical issues, to highlight potential solutions and to propose future research directions. First, starting with the vision of TI and recent advances and a review of related survey/overview articles, we present a generalized framework for wireless TI in the Beyond 5G Era including a TI architecture, the main technical requirements, the key application areas and potential enabling technologies. Subsequently, we provide a comprehensive review of the existing TI works by broadly categorizing them into three main paradigms; namely, haptic communications, wireless AR/VR, and autonomous, intelligent and cooperative mobility systems. Next, potential enabling technologies across physical/Medium Access Control (MAC) and network layers are identified and discussed in detail. Also, security and privacy issues of TI applications are discussed along with some promising enablers. Finally, we present some open research challenges and recommend promising future research directions

Steering control for haptic feedback and active safety functions

Steering feedback is an important element that defines driver–vehicle interaction. It strongly affects driving performance and is primarily dependent on the steering actuator\u27s control strategy. Typically, the control method is open loop, that is without any reference tracking; and its drawbacks are hardware dependent steering feedback response and attenuated driver–environment transparency. This thesis investigates a closed-loop control method for electric power assisted steering and steer-by-wire systems. The advantages of this method, compared to open loop, are better hardware impedance compensation, system independent response, explicit transparency control and direct interface to active safety functions.The closed-loop architecture, outlined in this thesis, includes a reference model, a feedback controller and a disturbance observer. The feedback controller forms the inner loop and it ensures: reference tracking, hardware impedance compensation and robustness against the coupling uncertainties. Two different causalities are studied: torque and position control. The two are objectively compared from the perspective of (uncoupled and coupled) stability, tracking performance, robustness, and transparency.The reference model forms the outer loop and defines a torque or position reference variable, depending on the causality. Different haptic feedback functions are implemented to control the following parameters: inertia, damping, Coulomb friction and transparency. Transparency control in this application is particularly novel, which is sequentially achieved. For non-transparent steering feedback, an environment model is developed such that the reference variable is a function of virtual dynamics. Consequently, the driver–steering interaction is independent from the actual environment. Whereas, for the driver–environment transparency, the environment interaction is estimated using an observer; and then the estimated signal is fed back to the reference model. Furthermore, an optimization-based transparency algorithm is proposed. This renders the closed-loop system transparent in case of environmental uncertainty, even if the initial condition is non-transparent.The steering related active safety functions can be directly realized using the closed-loop steering feedback controller. This implies, but is not limited to, an angle overlay from the vehicle motion control functions and a torque overlay from the haptic support functions.Throughout the thesis, both experimental and the theoretical findings are corroborated. This includes a real-time implementation of the torque and position control strategies. In general, it can be concluded that position control lacks performance and robustness due to high and/or varying system inertia. Though the problem is somewhat mitigated by a robust H-infinity controller, the high frequency haptic performance remains compromised. Whereas, the required objectives are simultaneously achieved using a torque controller

Haptic Guidance for Extended Range Telepresence

A novel navigation assistance for extended range telepresence is presented. The haptic information from the target environment is augmented with guidance commands to assist the user in reaching desired goals in the arbitrarily large target environment from the spatially restricted user environment. Furthermore, a semi-mobile haptic interface was developed, one whose lightweight design and setup configuration atop the user provide for an absolutely safe operation and high force display quality

Adaptive assistance-based on decision-making models for telerobotics systems

Esta tesis propone una nueva estrategia de asistencia háptica en la interacción humano-robot. Dado que el humano es el elemento fundamental del sistema, es necesario proponer estrategias que se adapten a su comportamiento, además de garantizar un mejoramiento del desempeño en la tarea. El inconveniente surge cuando se requiere asistir al operador en mejorar el desempeño de la tarea y permitir al usuario total control de la tarea cuando sea necesario, desviándose del plan original con el objetivo de abordar situaciones imprevistas. Desde una perspectiva enfocada en el control, se debe resolver el compromiso existente entre proveer un alto nivel de asistencia para mejorar el desempeño de la tarea y un bajo nivel de asistencia para permitir al operador desviarse del plan pre-programado (original). Se propone entonces incorporar en la asistencia háptica un mecanismo de toma de decisiones usado por los humanos en tareas básicas de decisión entre dos alternativas. Este mecanismo de decisión se incorporar como el método de selección de parámetros en un controlador adaptativo de estructura fija (i.e. un controlador de impedencia/admitancia de parámetros variables). Los resultados experimentales demuestran que el modelo de toma de decisión, i.e. el modelo drift-diffusion modificado, permite asignar el nivel de autonomía de una forma que resulta intuitiva para el usuario y mejora el desempeño en la tarea. Además la estrategia de asistencia basada en modelos de toma de decisión proporciona un mecanismo de sintonizaci ón para resolver diferentes requerimientos de la tarea, lo cual es importante en entornos no estructurados. Dado el número de parámetros configurables presentes en la asistencia, la etapa experimental expone la función de cada uno de estos parámetros. Se realizó un experimento con usuarios en un entorno de teleoperación donde se evalúa estadísticamente el comportamiento de la asistencia en entornos parcialmente estructurados y se compara con la asistencia proporcionada por un experto humano, la cual puede ser considerada como la asistencia adaptativa nominal.Abstract. This thesis proposes a novel haptic assistance method for human-robot interaction. Since the human is the main element of the system, it is necessary to propose strategies that adapt the robot’s dynamics to the human behavior, while guaranteeing an improvement in task performance. The main issue arises when the assistance must chose between assisting the operator to improve task performance or allowing the user to have full authority over the task when necessary, allowing him/her to deviate from the original plan in order to handle unforeseen situations. From a control systems’ perspective, the assistance has to solve the trade-off between high assistance levels to improve task performance and low assistance level to allow the user to deviate from the preprogrammed (original) plan. The main results of this work incorporate into the haptic assistance a human-like decision-making mechanism used in two-alternative force choice tasks. Our experimental results show that the drift-diffusion, which is a decision-making model proposed in the cognitive area, allocates control authority in a way that is intuitive for the user. The the proposed assistance provides a tunable (decision-making) mechanism that is capable of fulfilling different task requirements, which is an important when dealing with unstructured environments. Given the number of configurable parameters in the assistance mechanism, the experimental procedure exposes the effects of changing them. A user study in a telerobotic scenario was performed to evaluate the behavior of the assistance in a partially structured environment; the proposed assistance is compared to the assistance provided by a human expert, which may be considered as the nominal adaptive assistance.Doctorad

Wave impedance selection for passivity-based bilateral teleoperation

When a task must be executed in a remote or dangerous environment, teleoperation systems may be employed to extend the influence of the human operator. In the case of manipulation tasks, haptic feedback of the forces experienced by the remote (slave) system is often highly useful in improving an operator's ability to perform effectively. In many of these cases (especially teleoperation over the internet and ground-to-space teleoperation), substantial communication latency exists in the control loop and has the strong tendency to cause instability of the system. The first viable solution to this problem in the literature was based on a scattering/wave transformation from transmission line theory. This wave transformation requires the designer to select a wave impedance parameter appropriate to the teleoperation system. It is widely recognized that a small value of wave impedance is well suited to free motion and a large value is preferable for contact tasks. Beyond this basic observation, however, very little guidance exists in the literature regarding the selection of an appropriate value. Moreover, prior research on impedance selection generally fails to account for the fact that in any realistic contact task there will simultaneously exist contact considerations (perpendicular to the surface of contact) and quasi-free-motion considerations (parallel to the surface of contact). The primary contribution of the present work is to introduce an approximate linearized optimum for the choice of wave impedance and to apply this quasi-optimal choice to the Cartesian reality of such a contact task, in which it cannot be expected that a given joint will be either perfectly normal to or perfectly parallel to the motion constraint. The proposed scheme selects a wave impedance matrix that is appropriate to the conditions encountered by the manipulator. This choice may be implemented as a static wave impedance value or as a time-varying choice updated according to the instantaneous conditions encountered. A Lyapunov-like analysis is presented demonstrating that time variation in wave impedance will not violate the passivity of the system. Experimental trials, both in simulation and on a haptic feedback device, are presented validating the technique. Consideration is also given to the case of an uncertain environment, in which an a priori impedance choice may not be possible

Novel Haptic Cueing for UAV Tele-Operation.

The use of Unmanned Aerial Vehicles (UAVs) is continuously increasing both for military and civilian operations. The degree of automation inside an UAV has reached the capability of high levels of autonomy, increasing but human participation/action is still a requirement to ensure an ultimate level of safety for the mission. Direct remote piloting is often required for a board range of situations; this is true especially for larger UAVs, where a fault might be dangerous for the platform but even for the other entities of its environment (people, building etc.). Unfortunately the physical separation between pilot/operator and the UAV reduces greatly the situational awareness; this has a negative impact on system performance in the presence of remote and unforeseen environmental constraints and disturbances. This is why this thesis is dedicated to the study of means to increase the level of situational awareness of the UAV operator. The sense of telepresence is very important in teleoperation, and it appears reasonable, and it has already been shown in the literature, that extending the visual feedback with force feedback is able to complement the visual information (when missing or limited). An artificially recreated sense of touch (haptic) may allow the operator to better perceive information from the remote aircraft state, the environment and its constraints, hopefully preventing dangerous situations. This thesis introdues first a novel classification for haptic aid systems in two large classes: Direct Haptic Aid (DHA) and Indirect Haptic Aid (IHA), then, after showing that almost all existing aid concepts belong to the first class, focuses on IHA and tries to show that classical applications (that used a DHA approach) can be revised in a IHA fashion. The novel IHA systems produce different sensations, which in most cases may appear as exactly "opposite in sign" from the corresponding DHA; these sensations can provide valuable cues for the pilot, both in terms of improvement of performance and "level of appreciation". Furthermore, it will be shown that the novel cueing algorithms, which were designed just to appear "natural" to the operator, and not to directly help the pilot in his task (as in the DHA cases), can outperform the corresponding DHA systems. Three case studies were selected: obstacle avoidance, wind gust rejection, and a combination of the two. For all the cases, DHA and IHA systems were designed and compared against baseline performance with no haptic aid. Test results show that a net improvement in terms of performance is provided by employing the IHA cuse instead of both the DHA cues or the visual cues only. Both professional pilots and naïve subjects were used in some of the experiments. The perceived feelings transmitted by the haptic cues, strongly depend by the type of the experiment and the quality of the participants: the professional pilots, for instance, retained the DHA the most helpful force while they preferred IHA because they found it more natural and because they felt a better control authority on the aircraft; different results were obtained with naive participants. In the end, this thesis aim is to show that the IHA philosophy is a valid and promising alternative to the other commonly used, and published in the scientific literature, approaches which fall in the DHA category. Finally the haptic cueing for the obstacle avoidance task was tested in the presence of time delay in the communication link, as in a classical bilateral teleoperation scheme. The Master was provide with an admittance controller and an observer for force exerted by the human on the stick was developed. Experiments have shown that the proposed system is capable of standing substantial communication delays

Output Feedback Bilateral Teleoperation with Force Estimation in the Presence of Time Delays

This thesis presents a novel bilateral teleoperation algorithm for n degree of freedom nonlinear manipulators connected through time delays. Teleoperation has many practical uses, as there are many benefits that come from being able to operate machines from a distance. For instance, the ability to send a remote controlled robotic vehicle into a hazardous environment can be a great asset in many industrial applications. As well, the field of remote medicine can benefit from these technologies. A highly skilled surgeon could perform surgery on a patient who is located in another city, or even country. Earth to space operations and deep sea exploration are other areas where teleoperation is quite useful. Central to the approach presented in this work is the use of second order sliding mode unknown input observers for estimating the external forces acting on the manipulators. The use of these observers removes the need for both velocity and force sensors, leading to a lower cost hardware setup that provides all of the advantages of a position-force teleoperation algorithm. Stability results for this new algorithm are presented for several cases. Stability of each of the master and slave sides of the teleoperation system is demonstrated, showing that the master and slave are both stabilized by their respective controllers when the unknown input observers are used for state and force estimation. Additionally, closed loop stability results for the teleoperation system connected to a variety of slave side environments are presented. Delay-independent stability results for a linear spring-damper environment as well as a general finite-gain stable nonlinear environment are given. Delay-dependent stability results for the case where the slave environment is a liner spring-damper and the delays are commensurate are also presented. As well, stability results for the closed loop under the assumption that the human operator is modeled as a finite-gain stable nonlinear environment are given. Following the theoretical presentation, numerical simulations illustrating the algorithm are presented, and experimental results verifying the practical application of the approach are given

Selected Papers from the 5th International Electronic Conference on Sensors and Applications

This Special Issue comprises selected papers from the proceedings of the 5th International Electronic Conference on Sensors and Applications, held on 15–30 November 2018, on sciforum.net, an online platform for hosting scholarly e-conferences and discussion groups. In this 5th edition of the electronic conference, contributors were invited to provide papers and presentations from the field of sensors and applications at large, resulting in a wide variety of excellent submissions and topic areas. Papers which attracted the most interest on the web or that provided a particularly innovative contribution were selected for publication in this collection. These peer-reviewed papers are published with the aim of rapid and wide dissemination of research results, developments, and applications. We hope this conference series will grow rapidly in the future and become recognized as a new way and venue by which to (electronically) present new developments related to the field of sensors and their applications