Underwater Vehicles

For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties

Control Of Nonh=holonomic Systems

Many real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the chained systems while pursuing inverse optimality and exponential convergence rates, as well as the feed-back stabilization problem under input saturation constraints. These studies are based on global singularity-free state transformations and controls are synthesized from resulting linear systems. Then, the application of optimal motion planning and dynamic tracking control of nonholonomic autonomous underwater vehicles is considered. The obtained trajectories satisfy the boundary conditions and the vehicles\u27 kinematic model, hence it is smooth and feasible. A collision avoidance criteria is set up to handle the dynamic environments. The resulting controls are in closed forms and suitable for real-time implementations. Further, dynamic tracking controls are developed through the Lyapunov second method and back-stepping technique based on a NPS AUV II model. In what follows, the application of cooperative surveillance and formation control of a group of nonholonomic robots is investigated. A designing scheme is proposed to achieves a rigid formation along a circular trajectory or any arbitrary trajectories. The controllers are decentralized and are able to avoid internal and external collisions. Computer simulations are provided to verify the effectiveness of these designs

IMPLEMENTACIÓN EN “HARDWARE IN THE LOOP” DEL SISTEMA CARRO-PÉNDULO INVERTIDO CON BASE EN EL MICROCONTROLADOR HERCULES RM57L843 DE TEXAS INSTRUMENTS

ResumenEn este trabajo se presenta el desarrollo de un simulador “Hardware-In-the-Loop” (HIL) de un sistema carro-péndulo invertido con base en la tarjeta Hercules™ RM57Lx Launchpad de Texas Instruments. Para su implementación se obtiene el modelo dinámico del sistema con las ecuaciones de Euler-Lagrange, posteriormente se programa en el MCU, el cual lo ejecuta en tiempo real con un periodo de muestreo de 1 ms. Desde una interfaz gráfica en LabVIEW se capturan la respuesta del sistema además de que se pueden cambiar los parámetros del sistema. Para incrementar el realismo, en un entorno virtual Unity3D se hizo un modelo gráfico del sistema, en el cual se observan los movimientos del carro péndulo. Para verificar la correcta implementación del sistema se hace una comparación con una simulación desarrollada en Matlab/Simulink.Palabras Claves: Carro-péndulo invertido, microcontrolador, simulador HIL, Unity3D.IMPLEMENTATION IN "HARDWARE IN THE LOOP" OF THE INVERTED CART-PENDULUM SYSTEM BASED ON THE MICROCONTROLLER HERCULES RM57L843 FROM TEXAS INSTRUMENTSAbstractThis paper presents the development of a "Hardware-In-the-Loop" (HIL) simulator of an inverted pendulum-cart system based on the Texas Instruments Hercules ™ RM57Lx Launchpad. For its implementation, the dynamic model of the system is obtained with the Euler-Lagrange equations, later it is programmed in the MCU, which executes it in real time with a sample period of 1 ms. From a graphical interface in LabVIEW, the system response is captured and the system parameters can be changed. To increase the realism, in a virtual environment Unity3D was made a graphic model of the system, in which the movements of the pendulum car are observed. To verify the correct implementation of the system, a comparison is made between a simulation made with Matlab / Simulink.Keywords: HIL simulator, microcontroller, pendulum-cart, Unity3D

Advanced Techniques for Design and Manufacturing in Marine Engineering

Modern engineering design processes are driven by the extensive use of numerical simulations; naval architecture and ocean engineering are no exception. Computational power has been improved over the last few decades; therefore, the integration of different tools such as CAD, FEM, CFD, and CAM has enabled complex modeling and manufacturing problems to be solved in a more feasible way. Classical naval design methodology can take advantage of this integration, giving rise to more robust designs in terms of shape, structural and hydrodynamic performances, and the manufacturing process.This Special Issue invites researchers and engineers from both academia and the industry to publish the latest progress in design and manufacturing techniques in marine engineering and to debate the current issues and future perspectives in this research area. Suitable topics for this issue include, but are not limited to, the following:CAD-based approaches for designing the hull and appendages of sailing and engine-powered boats and comparisons with traditional techniques;Finite element method applications to predict the structural performance of the whole boat or of a portion of it, with particular attention to the modeling of the material used;Embedded measurement systems for structural health monitoring;Determination of hydrodynamic efficiency using experimental, numerical, or semi-empiric methods for displacement and planning hulls;Topology optimization techniques to overcome traditional scantling criteria based on international standards;Applications of additive manufacturing to derive innovative shapes for internal reinforcements or sandwich hull structures

Hardware-in-The-Loop verification for 3D obstacle avoidance algorithm of an underactuated flat-fish type AUV

Hardware-in-The-Loop (HIL) simulations play a major role in the field of testing of Autonomous Underwater Vehicle (AUV) well before the actual vehicle is developed and deployed in the water. This paper discusses the real-Time verification of a 3D obstacle avoidance algorithm of an underactuated flat-fish type AUV using hardware-in-The-loop simulation tool. Software-In-The-Loop (SIL) models are developed in MATLAB/Simulink environment and the HIL simulation is performed using dSPACE environment. The development of HIL test bench and the simulation results are presented in this paper. The results show that the HIL simulation is an effective tool for the verification of control algorithms and the developed obstacle avoidance algorithm can be used in real-Time for the flat-fish type AUV. © 2012 IEEE

Hardware-in-The-Loop verification for 3D obstacle avoidance algorithm of an underactuated flat-fish type AUV

Hardware-in-The-Loop (HIL) simulations play a major role in the field of testing of Autonomous Underwater Vehicle (AUV) well before the actual vehicle is developed and deployed in the water. This paper discusses the real-Time verification of a 3D obstacle avoidance algorithm of an underactuated flat-fish type AUV using hardware-in-The-loop simulation tool. Software-In-The-Loop (SIL) models are developed in MATLAB/Simulink environment and the HIL simulation is performed using dSPACE environment. The development of HIL test bench and the simulation results are presented in this paper. The results show that the HIL simulation is an effective tool for the verification of control algorithms and the developed obstacle avoidance algorithm can be used in real-Time for the flat-fish type AU

Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field

Safe navigation and motion coordination control strategies for unmanned aerial vehicles

Unmanned aerial vehicles (UAVs) have become very popular for many military and civilian applications including in agriculture, construction, mining, environmental monitoring, etc. A desirable feature for UAVs is the ability to navigate and perform tasks autonomously with least human interaction. This is a very challenging problem due to several factors such as the high complexity of UAV applications, operation in harsh environments, limited payload and onboard computing power and highly nonlinear dynamics. Therefore, more research is still needed towards developing advanced reliable control strategies for UAVs to enable safe navigation in unknown and dynamic environments. This problem is even more challenging for multi-UAV systems where it is more efficient to utilize information shared among the networked vehicles. Therefore, the work presented in this thesis contributes towards the state-of-the-art in UAV control for safe autonomous navigation and motion coordination of multi-UAV systems. The first part of this thesis deals with single-UAV systems. Initially, a hybrid navigation framework is developed for autonomous mobile robots using a general 2D nonholonomic unicycle model that can be applied to different types of UAVs, ground vehicles and underwater vehicles considering only lateral motion. Then, the more complex problem of three-dimensional (3D) collision-free navigation in unknown/dynamic environments is addressed. To that end, advanced 3D reactive control strategies are developed adopting the sense-and-avoid paradigm to produce quick reactions around obstacles. A special case of navigation in 3D unknown confined environments (i.e. tunnel-like) is also addressed. General 3D kinematic models are considered in the design which makes these methods applicable to different UAV types in addition to underwater vehicles. Moreover, different implementation methods for these strategies with quadrotor-type UAVs are also investigated considering UAV dynamics in the control design. Practical experiments and simulations were carried out to analyze the performance of the developed methods. The second part of this thesis addresses safe navigation for multi-UAV systems. Distributed motion coordination methods of multi-UAV systems for flocking and 3D area coverage are developed. These methods offer good computational cost for large-scale systems. Simulations were performed to verify the performance of these methods considering systems with different sizes

Control and visual navigation for unmanned underwater vehicles

Ph. D. Thesis.Control and navigation systems are key for any autonomous robot. Due to environmental disturbances, model uncertainties and nonlinear dynamic systems, reliable functional control is essential and improvements in the controller design can significantly benefit the overall performance of Unmanned Underwater Vehicles (UUVs). Analogously, due to electromagnetic attenuation in underwater environments, the navigation of UUVs is always a challenging problem. In this thesis, control and navigation systems for UUVs are investigated. In the control field, four different control strategies have been considered: Proportional-Integral-Derivative Control (PID), Improved Sliding Mode Control (SMC), Backstepping Control (BC) and customised Fuzzy Logic Control (FLC). The performances of these four controllers were initially simulated and subsequently evaluated by practical experiments in different conditions using an underwater vehicle in a tank. The results show that the improved SMC is more robust than the others with small settling time, overshoot, and error. In the navigation field, three underwater visual navigation systems have been developed in the thesis: ArUco Underwater Navigation systems, a novel Integrated Visual Odometry with Monocular camera (IVO-M), and a novel Integrated Visual Odometry with Stereo camera (IVO-S). Compared with conventional underwater navigation, these methods are relatively low-cost solutions and unlike other visual or inertial-visual navigation methods, they are able to work well in an underwater sparse-feature environment. The results show the following: the ArUco underwater navigation system does not suffer from cumulative error, but some segments in the estimated trajectory are not consistent; IVO-M suffers from cumulative error (error ratio is about 3 - 4%) and is limited by the assumption that the “seabed is locally flat”; IVO-S suffers from small cumulative errors (error ratio is less than 2%). Overall, this thesis contributes to the control and navigation systems of UUVs, presenting the comparison between controllers, the improved SMC, and low-cost underwater visual navigation methods