scholarly journals On AUV Control with the Aid of Position Estimation Algorithms Based on Acoustic Seabed Sensing and DOA Measurements

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5520 ◽  
Author(s):  
Alexander Miller ◽  
Boris Miller ◽  
Gregory Miller
Keyword(s):  
Nonlinear Filtering ◽  
Control Algorithm ◽  
Autonomous Underwater Vehicles ◽  
Position Estimation ◽  
Velocity Estimation ◽  
Estimation Algorithms ◽  
Underwater Navigation ◽  
High Level ◽  
Nonlinear Observation ◽  
Available Information

This article discusses various approaches to the control of autonomous underwater vehicles (AUVs) with the aid of different velocity-position estimation algorithms. Traditionally this field is considered as the area of the extended Kalman filter (EKF) application: It became a universal tool for nonlinear observation models and its use is ubiquitous. Meanwhile, the specific characteristics of underwater navigation, such as an incomplete sets of measurements, constraints on the range metering or even impossibility of range measurements, observations provided by rather specific acoustic beacons, sonar observations, and other features seriously narrow the applicability of common instruments due to a high level of uncertainty and nonlinearity. The AUV navigation system, not being able to rely on a single source of position estimation, has to take into account all available information. This leads to the necessity of various complex estimation and data fusion algorithms, which are the matter of the present article. Here we discuss some approaches to the AUV position estimation such as conditionally minimax nonlinear filtering (CMNF) and unbiased pseudo-measurement filters (UPMFs) in conjunction with velocity estimation based on the seabed profile acoustic sensing. The presented estimation algorithms serve as a basis for a locally optimal AUV motion control algorithm, which is also presented.

scholarly journals Sensor Modeling for Underwater Localization Using a Particle Filter

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1549
Author(s):  
Humberto Martínez-Barberá ◽  
Pablo Bernal-Polo ◽  
David Herrero-Pérez
Keyword(s):  
Sequential Monte Carlo ◽  
Sensory Information ◽  
Dead Reckoning ◽  
Underwater Vehicle ◽  
Position Estimation ◽  
Sources Of Uncertainty ◽  
Sensor Signals ◽  
Underwater Navigation ◽  
Underwater Localization ◽  
Sensor Modeling

This paper presents a framework for processing, modeling, and fusing underwater sensor signals to provide a reliable perception for underwater localization in structured environments. Submerged sensory information is often affected by diverse sources of uncertainty that can deteriorate the positioning and tracking. By adopting uncertain modeling and multi-sensor fusion techniques, the framework can maintain a coherent representation of the environment, filtering outliers, inconsistencies in sequential observations, and useless information for positioning purposes. We evaluate the framework using cameras and range sensors for modeling uncertain features that represent the environment around the vehicle. We locate the underwater vehicle using a Sequential Monte Carlo (SMC) method initialized from the GPS location obtained on the surface. The experimental results show that the framework provides a reliable environment representation during the underwater navigation to the localization system in real-world scenarios. Besides, they evaluate the improvement of localization compared to the position estimation using reliable dead-reckoning systems.

Rehabilitation in Tehri Dam: An evaluation

Social Change ◽  
2001 ◽  
Vol 31 (1-2) ◽  
pp. 110-143 ◽  
Author(s):  
B. K. Sinha ◽  
H. C. Pokhriyal
Keyword(s):  
Common Property ◽  
Rehabilitation Process ◽  
Common Property Resources ◽  
Urban Households ◽  
Positive Externalities ◽  
Rural And Urban ◽  
Tehri Dam ◽  
High Level ◽  
Available Information ◽  
Ownership Rights

In the whole debate of ecological suitability of Tehri Dam, the rehabilitation aspect has been found ignored. Keeping in view of the significance of complete rehabilitation and resettlement of the oustees, the overall rehabilitation process including rural and urban population is analysed in the present paper. In total, 125 villages will be fully or partially submerged affecting more than one lakh population. More than twenty thousand urban populations will also be rehabilitated. It is expected that around 6000 cores of rupees (at 1993 price level) will be spent. Out of which 13% will be spent on the rehabilitation of the oustees. On the basis of the available information, it is found that only 33% of the rural families and 66% of the urban households have actually received the compensation or taken the possession of the land in the new sites. Non availability of land to the rest of the oustee households has been identified as the peculiar dimension of the rehabilitation process. The resettled households in Dehradun and Haridwar districts are facing the problem of geographic continuity, land owner shiprights and absence of institutional mechanism like panchayati raj institutions in the new settlements. The absence of non-farm employment and non-accessibility to the common property resources are the critical problems, including the availability of drinking water, irrigation, primary health and education, which can be observed seen in the rehabilitation sites. The resettlers are unable to adjust with the new environment including a high level of dependency on the market forces for each and every requirement. The partially submerged population is also facing peculiar problems. They will only be given cash compensation without any other compensatory measures. The ‘upstream cost and down stream benefits syndrome’ is strikingly visible in the rehabilitation process. In the urban resettlement process various issues Iike-the validity of survey, classification of urban households and cut off dates are relevant to mention. The positive externalities of the old Tehri town were completely missing in the new urban rehabilitation site. As a whole it can be tentatively said that the process of rehabilitation has been loosely coordinated and badly implemented. The issues of upstream cost, accessibility to common property resources and customary rights are the neglected aspects in the process. The re-organisation of the institutional frame work and granting land ownership rights to the resettlers and quality of the basic amenities are the other inevitable requirements need proper assessment and implementation. The present process of rehabilitation is largely non-participatory and non transparent, which can only be solved through radical measures. These measures are unlikely to be initiated in the present set of Tehri dam administration.

scholarly journals An Autonomous Human Following Caddie Robot with High-Level Driving Functions

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1516
Author(s):  
Jung Hyun Choi ◽  
Kangwagye Samuel ◽  
Kanghyun Nam ◽  
Sehoon Oh
Keyword(s):  
Control Algorithm ◽  
Ground Surface ◽  
Golf Course ◽  
Driving Mode ◽  
Operating Modes ◽  
Advanced Control ◽  
Heading Angle ◽  
High Level ◽  
Trajectory Generator ◽  
Manual Mode

Nowadays, mobile robot platforms are utilized in various fields not only for transportation but also for other diverse services such as industrial, medical and, sports, etc. Mobile robots are also an emerging application as sports field robots, where they can help serve players or even play the games. In this paper, a novel caddie robot which can autonomously follow the golfer as well as provide useful information such as golf course navigation system and weather updates, is introduced. The locomotion of the caddie robot is designed with two modes: autonomous human following mode and manual driving mode. The transition between each mode can be achieved manually or by an algorithm based on the velocity, heading angle, and inclination of the ground surface. Moreover, the transition to manual mode is activated after a caddie robot has recognized the human intention input by hand. In addition, the advanced control algorithm along with a trajectory generator for the caddie robot are developed taking into consideration the locomotion modes. Experimental results show that the proposed strategies to drive various operating modes are efficient and the robot is verified to be utilized in the golf course.

scholarly journals A Framework for Multiple Ground Target Finding and Inspection Using a Multirotor UAS

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 272 ◽  
Author(s):  
Ajmal Hinas ◽  
Roshan Ragel ◽  
Jonathan Roberts ◽  
Felipe Gonzalez
Keyword(s):  
Target Detection ◽  
Low Cost ◽  
Target Position ◽  
Position Estimation ◽  
Quality Data ◽  
Unmanned Aerial Systems ◽  
Modular Software ◽  
Ground Target ◽  
High Level ◽  
Aerial Systems

Small unmanned aerial systems (UASs) now have advanced waypoint-based navigation capabilities, which enable them to collect surveillance, wildlife ecology and air quality data in new ways. The ability to remotely sense and find a set of targets and descend and hover close to each target for an action is desirable in many applications, including inspection, search and rescue and spot spraying in agriculture. This paper proposes a robust framework for vision-based ground target finding and action using the high-level decision-making approach of Observe, Orient, Decide and Act (OODA). The proposed framework was implemented as a modular software system using the robotic operating system (ROS). The framework can be effectively deployed in different applications where single or multiple target detection and action is needed. The accuracy and precision of camera-based target position estimation from a low-cost UAS is not adequate for the task due to errors and uncertainties in low-cost sensors, sensor drift and target detection errors. External disturbances such as wind also pose further challenges. The implemented framework was tested using two different test cases. Overall, the results show that the proposed framework is robust to localization and target detection errors and able to perform the task.

scholarly journals An Underwater Vector Propulsion Device Based on the RS+2PRS Parallel Mechanism and Its Attitude Control Algorithm

2019 ◽  
Vol 9 (23) ◽  
pp. 5210 ◽  
Author(s):  
Wang ◽  
Guo ◽  
Zhong
Keyword(s):  
Attitude Control ◽  
Parallel Mechanism ◽  
Control Algorithm ◽  
Simulation Analysis ◽  
Autonomous Underwater Vehicles ◽  
Propulsion System ◽  
Precession Angle ◽  
Nutation Angle ◽  
Prismatic Joints ◽  
Spherical Parallel Mechanism

In order to overcome the disadvantages of some existing autonomous underwater vehicles (AUVs), such as actuator extraposition and degree-of-freedom (DOF) redundancy, a 2-DOF vector propeller propulsion system with built-in actuator based on the deficient DOF parallel mechanism is proposed. The RS+2PRS (Revolute-Spherical+ Prismatic-Revolute-Spherical) parallel mechanism is used as the main structure, and the driving parts are placed in the interior of the AUV cabin, which is beneficial to the sealing and protection of the propulsion system. In addition, the motion parameters decoupling shows that the two independent parameters are the precession angle and the nutation angle of the propeller installation platform. Therefore, the attitude control algorithm uses two prismatic joints as driving units to establish the nonlinear mapping model with the two Euler attitude angles. In the end, the simulation analysis and the real device are used to verify the feasibility of the attitude control algorithm and the in situ adjustment function of the propeller, which lays the theoretical foundation for engineering applications in the future.

An Innovative Navigation Strategy for Autonomous Underwater Vehicles: An Unscented Kalman Filter Based Approach

2015 ◽  
Author(s):  
Benedetto Allotta ◽  
Riccardo Costanzi ◽  
Enrico Meli ◽  
Alessandro Ridolfi ◽  
Luigi Chisci ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Unscented Kalman Filter ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Measurement Unit ◽  
Doppler Velocity ◽  
Underwater Robotics ◽  
Filtering Algorithm ◽  
Navigation Algorithms ◽  
Underwater Navigation

Developing reliable navigation strategies is mandatory in the field of Underwater Robotics and in particular for Autonomous Underwater Vehicles (AUVs) to ensure the correct achievement of a mission. Underwater navigation is still nowadays critical, e.g. due to lack of access to satellite navigation systems (e.g. the Global Positioning System, GPS): an AUV typically proceeds for long time intervals only relying on the measurements of its on-board sensors, without any communication with the outside environment. In this context, the filtering algorithm for the estimation of the AUV state is a key factor for the performance of the system; i.e. the filtering algorithm used to estimate the state of the AUV has to guarantee a satisfactory underwater navigation accuracy. In this paper, the authors present an underwater navigation system which exploits measurements from an Inertial Measurement Unit (IMU), Doppler Velocity Log (DVL) and a Pressure Sensor (PS) for the depth, and relies on either an Extended Kalman Filter (EKF) or an Unscented Kalman Filter (UKF) for state estimation. A comparison between the EKF approach, classically adopted in the field of underwater robotics and the UKF is given. These navigation algorithms have been experimentally validated through the data related to some sea tests with the Typhoon class AUVs, designed and assembled by the Department of Industrial Engineering of the Florence University (DIEF) for exploration and surveillance of underwater archaeological sites in the framework of the THESAURUS and European ARROWS projects. The comparison results are significant as the two filtering strategies are based on the same process and sensors models. At this initial stage of the research activity, the navigation algorithms have been tested offline. The presented results rely on the experimental navigation data acquired during two different sea missions: in the first one, Typhoon AUV #1 navigated in a Remotely Operated Vehicle (ROV) mode near Livorno, Italy, during the final demo of THESAURUS project (held in August 2013); in the latter Typhoon AUV #2 autonomously navigated near La Spezia in the framework of the NATO CommsNet13 experiment, Italy (held in September 2013). The achieved results demonstrate the effectiveness of both navigation algorithms and the superiority of the UKF without increasing the computational load. The algorithms are both affordable for online on-board AUV implementation and new tests at sea are planned for spring 2015.

Robust Autopilot Design for Unmanned Underwater Vehicle Based on H∞ Mixed Sensitivity

2012 ◽  
Vol 457-458 ◽  
pp. 764-772 ◽  
Author(s):  
Fang Rong Wang ◽  
Ru Wen Kan ◽  
Shu Nan Liu ◽  
Xu Bin Dong ◽  
Tao Shang ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
System Modeling ◽  
Nonlinear Problems ◽  
Underwater Vehicle ◽  
Unmanned Underwater Vehicle ◽  
Navigation Simulation ◽  
Underwater Navigation ◽  
Three Degrees Of Freedom

As the complexity of marine environment and the existence of uncertain factors along with Unmanned Underwater Vehicle (UUV) dynamics itself bringing many nonlinear problems, it is difficult to control the navigation in accordance with a predetermined trajectory. Based on the UUV dynamics analysis and system modeling, this paper decoupled its control system into three sub-control systems, designed robust autopilot using H∞ mixed sensitivity control algorithm to generate the low-order controller to achieve independent control of three degrees of freedom. Eventually, the underwater navigation simulation results show that the proposed method can provide better control performance and the method is feasible and high efficiency in actual applications.

HIGH-LEVEL AUTONOMY FOR AUTONOMOUS UNDERWATER VEHICLES

2007 ◽  
Vol 40 (17) ◽  
pp. 38-43
Author(s):  
Hans-Ulrich Kobialka ◽  
Walter Nowak
Keyword(s):  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
High Level
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