共查询到20条相似文献,搜索用时 15 毫秒
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This paper describes an underwater 3500 m electric manipulator (named Huahai-4E,stands for four functions deep ocean electric manipulator in China),which has been developed at underwater manipulation technology lab in Huazhong University of Science and Technology (HUST) for a test bed of studying of deep ocean manipulation technologies.The manipulator features modular integration joints,and layered architecture control system.The oil-filled,pressure-compensated joint is compactly designed and integrated of a permanent magnet (PM) brushless motor,a drive circuit,a harmonic gear and an angular feedback potentiometer.The underwater control system is based on a network and consisted of three embedded PC/104 computers which are used for servo control,task plan and target sensor respectively.They communicate through User Datagram Protocol (UDP) multicast communication in Vxworks OS.A supervisor PC with a virtual 3D GUI is fiber linked to underwater control system.Furthermore,the manipulator is equipped with a sensor system including a unique ultra-sonic probe array and an underwater camera.Autonomous grasp strategy based multi-sensor is studied.The results of watertight test in 40 MPa,joint’s efficiency test and autonomous grasp experiments in tank are also presented. 相似文献
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As the exploration and exploitation of oil and gas proliferate throughout deepwater area,the requirements on the reliability of dynamic positioning system become increasingly stringent.The control objective ensuring safety operation at deep water will not be met by a single controller for dynamic positioning.In order to increase the availability and reliability of dynamic positioning control system,the triple redundancy hardware and software control architectures were designed and developed according to the safe specifications of DP-3 classification notation for dynamically positioned ships and rigs.The hardware redundant configuration takes the form of triple-redundant hot standby configuration including three identical operator stations and three real-time control computers which connect each other through dual networks.The function of motion control and redundancy management of control computers were implemented by software on the real-time operating system VxWorks.The software realization of task loose synchronization,majority voting and fault detection were presented in details.A hierarchical software architecture was planed during the development of software,consisting of application layer,real-time layer and physical layer.The behavior of the DP-3 dynamic positioning control system was modeled by a Markov model to analyze its reliability.The effects of variation in parameters on the reliability measures were investigated.The time domain dynamic simulation was carried out on a deepwater drilling rig to prove the feasibility of the proposed control architecture. 相似文献
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The formulation of the dynamic coupling between a manipulator and an underwater vehicle is presented. Results from a simulation of a particular manipulator-vehicle configuration illustrate the nature and extent of the dynamic coupling. The modeling processes for the underwater vehicle and the manipulator are described with an evaluation of the simple hydrodynamic effects that can be incorporated in the dynamic equations of the manipulator. The equations are formulated for the combination of a 6-degrees-of-freedom vehicle and a 3-degrees-of-freedom manipulator. The effect of the manipulator motion, assuming perfect manipulator joint angle tracking, on the vehicle's position/orientation and consequently the manipulator end-effector position is investigated assuming no vehicle control. Slotine's sliding mode approach has been used to reduce the effect of the manipulator disturbances. This technique allows the expressions developed for the manipulator disturbances to be incorporated in the control law. Control of the vehicle's yaw angle, in this particular manipulator-vehicle configuration, has been determined to be the single most important factor in reducing the end-effector error variation. This is shown to be beneficial in the regulation of the vehicle's yaw angle and offers improved performance compared to a sliding mode controller that does not incorporate the manipulator disturbances. This technique also demonstrates superior performance and insensitivity to parameter variations compared to a fixed-gain controller 相似文献
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This paper describes the estimation of hydrodynamic coefficients and the control algorithm based on a nonlinear mathematical modeling for a test bed autonomous underwater vehicle (AUV) named by SNUUV I (Seoul National University Underwater Vehicle I).A six degree of freedom mathematical model for SNUUV I is derived with linear and nonlinear hydrodynamic coefficients, which are estimated with the help of a potential code and also the system identification using multi-variable regression.A navigation algorithm is developed using three ranging sonars, pressure sensor and two inclinometers keeping towing tank applications in mind. Based on the mathematical model, a simulation program using a model-based control algorithm is designed for heading control and wall following control of SNUUV I.It is demonstrated numerically that the navigation system together with controller guides the vehicle to follow the desired heading and path with a sufficient accuracy. Therefore the model-based control algorithm can be designed efficiently using the system identification method based on vehicle motion experiments with the appropriate navigation system. 相似文献
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Hyungwon Shim Bong-Huan Jun Pan-Mook Lee Hyuk Baek Jihong Lee 《Ocean Engineering》2010,37(11-12):1036-1047
This paper presents a control technique for structured undersea tasks that require a high degree of precision. The overall efficiency of tele-operated underwater manipulation is improved by reducing the burden on the human operator. A new workspace-control system composed of a computer and input devices in workspace was developed to support the operator. The computer transforms the desired velocity of end-effector in workspaces to desired joint angles by solving the inverse kinematics of the slave manipulators. The desired joint angles are transferred to the slave controller through RS-485 serial communication, and be followed by the slave manipulator. The developed master system provides advantages in conducting structured tasks(coring, drilling, underwater connector mating, etc.) that require precise control of the end-effector’s motion and attitude. The existing master system, however, is more useful for unstructured tasks than newly developed master system. By combining the two master systems, the work efficiency of the underwater tele-operated manipulator system was improved. This paper presents the development of the workspace-control system and a working strategy to alleviate operator’s burden in underwater works. Experimental results are presented to evaluate the effectiveness of the proposed method using underwater manipulators mounted on the KORDI deep-sea ROV Hemire. 相似文献
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A new fault-tolerant redundancy resolution scheme is presented that allows a single six degree of freedom (DOF) command to be distributed over a small remotely operated underwater vehicle–manipulator (ROVM) system. ROVM systems are composed of a remotely operated underwater vehicle (ROV) and serial manipulator. The combined system is often kinematically redundant for the six-DOF end-effector command, and such a ROVM system admits an infinite number of joint-space solutions for a commanded end-effector state. In the current work, the primary objective is to follow the desired end-effector velocities commanded by a human pilot. The primary objective is realized using the right Moore–Penrose pseudoinverse solution that minimizes the two-norm of the collective joint velocities. Secondary objectives considered are: avoiding manipulator joint limits, avoiding singularities and high joint velocities, keeping the end-effector in sight of the on-board camera, minimizing the ROV motion, and minimizing the drag-forces on the ROV. Each criterion is defined within the framework of the gradient projection method (GPM). The hierarchy for the secondary tasks is established by a low-level artificial pilot that determines a weighting factor for each criterion based on if–then-type fuzzy rules that reflect an expert human pilot's knowledge. The resulting weight schedule yields a self-motion (null-space motion) that emulates how a skilled operator would utilize the redundancy of the ROVM to achieve the secondary objectives. In addition, the proposed method has a fault-tolerant property that enforces joint-velocity limits and also redistributes the end-effector velocity command in the case of faulty joints. To demonstrate the efficacy of the proposed scheme, a numerical simulation case study is performed. The results illustrate that complex spatial end-effector manoeuvres that are otherwise not possible with a stationary ROV can be accomplished in real-time via the coordination of the ROV and the manipulator. The on-line nature of the proposed scheme makes it suitable for remote systems where the desired end-effector state is not known a priori. 相似文献
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Underwater Navigation Based on Real-Time Simultaneous Sound Speed Profile Correction 总被引:1,自引:0,他引:1
Precise sound speed profile (SSP) information is critical when using sonar for underwater terrain navigation. Nevertheless, acquiring SSP information in real-time is difficult, especially in underwater navigation environment. To account for this problem, this paper presents an underwater navigation method that applies real-time SSP correction to the terrain measurements. The method uses a probe to measure the surface sound speed simultaneously. Meanwhile, redundancy of topographic measurement data is exploited to derive the equivalent SSP information. The acquired equivalent SSP is updated continuously with particle filter algorithm. The terrain measurements can be corrected in real-time with the equivalent SSP to improve the performance of underwater terrain navigation. By removing the impact of inaccurate SSP from the terrain measurements, the proposed method can achieve precise and robust underwater navigation result without using an underway-profiling instrument. Simulated results confirm the good performance of the proposed method. 相似文献
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A high-resolution underwater acoustic pulse-Doppler navigation system has been developed and tested at sea. The system provides continuous, highly accurate tracking of underwater and ocean-surface platforms in a fixed 50-km2navigation net. Three reference buoys, moored 20 m from the ocean bottom, provide the navigation net used by shipboard processing equipment. Each reference buoy contains an acoustic transponder, used to obtain the acoustic travel times from the transponder to the platform, and a continuous-tone beacon, used to obtain the Doppler shift due to platform motion. The system is capable of determining the position of a platform with respect to the reference net with an error of 2-3 m. The relative position of the platform on a fix-to-fix basis can be determined within several centimeters over short time intervals (approx 10 min). 相似文献
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A neural-network-based learning control scheme for the motion control of autonomous underwater vehicles (AUV) is described. The scheme has a number of advantages over the classical control schemes and conventional adaptive control techniques. The dynamics of the controlled vehicle need not be fully known. The controller with the aid of a gain layer learns the dynamics and adapts fast to give the correct control action. The dynamic response and tracking performance could be accurately controlled by adjusting the network learning rate. A modified direct control scheme using multilayered neural network architecture is used in the studies with backpropagation as the learning algorithm. Results of simulation studies using nonlinear AUV dynamics are described in detail. The robustness of the control system to sudden and slow varying disturbances in the dynamics is studied and the results are presented 相似文献
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Ship hulls, as well as bridges, port dock pilings, dams, and various underwater structures need to be inspected for periodic maintenance. Additionally, there is a critical need to provide protection against sabotage activities, and to establish effective countermeasures against illegal smuggling activities. Unmanned underwater vehicles are suitable platforms for the development of automated inspection systems, but require integration with appropriate sensor technologies. This paper describes a vision system for automated ship-hull inspection, based on computing the necessary information for positioning, navigation, and mapping of the hull from stereo images. Binocular cues are critical in resolving a number of complex visual artifacts that hamper monocular vision in shallow-water conditions. Furthermore, they simplify the estimation of vehicle pose and motion, which is fundamental for successful automatic operation. The system has been implemented on a commercial remotely operated vehicle (ROV), and tested in pool and dock tests. Results from various trials are presented to demonstrate the system capabilities 相似文献
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A novel self-contained navigation system has been devised for underwater vehicles operating in and around offshore installations. This system matches data from a sector-scanning sonar device to a computer model of the installation. The paper begins by highlighting the existing approaches to subsea navigation before outlining the main features of the proposed system. It then concentrates on a key component of this system which is a method for calculating the position and heading of an underwater vehicle navigating in the vincinity of tubular steel structures. An iterative solution method is presented which incorporates six degree of freedom vehicle motions and this is verified in a series of laboratory experiments with various arrangements of structural members and using a commercial sonar device. The key features, applications and performance of this method are discussed. The main conclusion is that the proposed method for calculating the position and heading of an underwater vehicle contributes towards achieving an accurate and reliable subsea navigation capability. 相似文献
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Collision at sea is always a significant issue affecting the safety of ship navigation. The shipborne autonomous collision avoidance system (SACAS) has the great advantage to minimize collision accidents in ship navigation. A parallel trajectory planning architecture is proposed in this paper for SACAS system. The fully-coupled deliberative planner based on the modified RRT algorithm is developed to search for optimal global trajectory in a low re-planning frequency. The fully-coupled reactive planner based on the modified DW algorithm is developed to generate the optimal local trajectory in a high re-planning frequency to counteract the unexpected behavior of dynamic obstacles in the vicinity of the vessel. The obstacle constraints, ship maneuvering constraints, COLREGs rules, trajectory optimality, and real-time requirements are satisfied simultaneously in both global and local planning to ensure the collision-free optimal navigation in compliance with COLREGs rules. The on-water tests of a trimaran model equipped with a model-scale SACAS system are presented to demonstrate the effectiveness and efficiency of the proposed algorithm. The good balance between the computational efficiency and trajectory optimality is achieved in parallel trajectory planning. 相似文献
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Pan-Mook Lee Bong-Huan Jun Kihun Kim Jihong Lee Aoki T. Hyakudome T. 《Oceanic Engineering, IEEE Journal of》2007,32(2):327-345
This paper presents an integrated navigation system for underwater vehicles to improve the performance of a conventional inertial acoustic navigation system by introducing range measurement. The integrated navigation system is based on a strapdown inertial navigation system (SDINS) accompanying range sensor, Doppler velocity log (DVL), magnetic compass, and depth sensor. Two measurement models of the range sensor are derived and augmented to the inertial acoustic navigation system, respectively. A multirate extended Kalman filter (EKF) is adopted to propagate the error covariance with the inertial sensors, where the filter updates the measurement errors and the error covariance and corrects the system states when the external measurements are available. This paper demonstrates the improvement on the robustness and convergence of the integrated navigation system with range aiding (RA). This paper used experimental data obtained from a rotating arm test with a fish model to simulate the navigational performance. Strong points of the navigation system are the elimination of initial position errors and the robustness on the dropout of acoustic signals. The convergence speed and conditions of the initial error removal are examined with Monte Carlo simulation. In addition, numerical simulations are conducted with the six-degrees-of-freedom (6-DOF) equations of motion of an autonomous underwater vehicle (AUV) in a boustrophedon survey mode to illustrate the effectiveness of the integrated navigation system. 相似文献
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