scholarly journals Retrofit an 11-meter yacht for autonomous navigation

Author(s):  
X You ◽  
F Ma ◽  
X Wang

Intelligent/autonomous ships form a rising field that brings beneficial changes to waterborne transportation such as relieving labour shortages, avoiding collisions, and providing assistance to humans. Many autonomous navigation attempts have been carried out on ship models rather than real ships. The results of these studies have certain gaps with the results of full-scale ships. Cost and risk of intelligent ships for autonomous navigation are yet unclear, which makes retrofitting existing ships for tests and development appealing. This paper introduces the process of retrofitting a full-scale 11-meter yacht, including mechanical retrofit, hardware redesign, software deployment, and functional testing. The process is proposed as a solution of ship retrofit for autonomous navigation functions like heading control, path following, and collision avoidance. In the end, this paper concludes a plan of hardware and software that could help find more retrofit solutions, providing a reference for academic research and practical applications.

2021 ◽  
Vol 9 (4) ◽  
pp. 405
Author(s):  
Raphael Zaccone

While collisions and groundings still represent the most important source of accidents involving ships, autonomous vessels are a central topic in current research. When dealing with autonomous ships, collision avoidance and compliance with COLREG regulations are major vital points. However, most state-of-the-art literature focuses on offline path optimisation while neglecting many crucial aspects of dealing with real-time applications on vessels. In the framework of the proposed motion-planning, navigation and control architecture, this paper mainly focused on optimal path planning for marine vessels in the perspective of real-time applications. An RRT*-based optimal path-planning algorithm was proposed, and collision avoidance, compliance with COLREG regulations, path feasibility and optimality were discussed in detail. The proposed approach was then implemented and integrated with a guidance and control system. Tests on a high-fidelity simulation platform were carried out to assess the potential benefits brought to autonomous navigation. The tests featured real-time simulation, restricted and open-water navigation and dynamic scenarios with both moving and fixed obstacles.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaojun Zhu ◽  
Yinghao Liang ◽  
Hanxu Sun ◽  
Xueqian Wang ◽  
Bin Ren

Purpose Most manufacturing plants choose the easy way of completely separating human operators from robots to prevent accidents, but as a result, it dramatically affects the overall quality and speed that is expected from human–robot collaboration. It is not an easy task to ensure human safety when he/she has entered a robot’s workspace, and the unstructured nature of those working environments makes it even harder. The purpose of this paper is to propose a real-time robot collision avoidance method to alleviate this problem. Design/methodology/approach In this paper, a model is trained to learn the direct control commands from the raw depth images through self-supervised reinforcement learning algorithm. To reduce the effect of sample inefficiency and safety during initial training, a virtual reality platform is used to simulate a natural working environment and generate obstacle avoidance data for training. To ensure a smooth transfer to a real robot, the automatic domain randomization technique is used to generate randomly distributed environmental parameters through the obstacle avoidance simulation of virtual robots in the virtual environment, contributing to better performance in the natural environment. Findings The method has been tested in both simulations with a real UR3 robot for several practical applications. The results of this paper indicate that the proposed approach can effectively make the robot safety-aware and learn how to divert its trajectory to avoid accidents with humans within the workspace. Research limitations/implications The method has been tested in both simulations with a real UR3 robot in several practical applications. The results indicate that the proposed approach can effectively make the robot be aware of safety and learn how to change its trajectory to avoid accidents with persons within the workspace. Originality/value This paper provides a novel collision avoidance framework that allows robots to work alongside human operators in unstructured and complex environments. The method uses end-to-end policy training to directly extract the optimal path from the visual inputs for the scene.


Author(s):  
Amilton Arruda ◽  
Celso Hartkopf ◽  
Rodrigo Balestra

Over the past decade, one can observe a steady growth in the use of terms such as Place Branding, Nation Branding, Destination Branding and City Branding. Both in academic research and in the practical applications in large cities management and urban spaces, this new paradigm takes shape and, along with it, the need for definitions and concepts, methods and methodologies and the establishment of technical and theoretical standards. This approach was born in the Marketing field, specifically in what was called Place Marketing. In this context the Branding stood out as a development tool solutions to the need for differentiation, generation of solid images and the establishment of symbols and identity signs, in order to leverage economic benefits for countries, cities and regions. In a way, fulfilling, in the first instance, a similar role to the branding of products and services. But it was specifically in Branding corporations that were found the biggest matches to adapt this knowledge to management positions. Ashworth & Kavaratzis (2010) highlight the fact that both present multidisciplinary roots, a multiple number of strategic actors (stakeholders), high degree of intangibility and complexity of social responsibility, the multiplicity of identities and the long-term development needs are strong examples their similarities. The development and management of corporate identities, here expanded to the Branding corporations, it is a prolific field of Design. It great names of the area said their careers and built great legacy. The time of greater proficiency in the area were the 50s and 60s, dominated by modernist thought, and, coincidentally or not, exactly the time that focused efforts to assert the identity of the designer as a professional (STOLARSKI, 2006) . Nationally stand out names like Alexandre Wollner, Ruben Martins, the duo Carlos Cauduro and Ludovico Martino and Aloisio Magalhaes. In contrast, in the literature produced in the marketing field, often the role of design in this context is reduced to merely promotional measures, such as creating logos or advertising campaigns. In other words, defined as a work of low complexity and low social prägnanz. This approach comes at odds with contemporary theories of design, such as MetaDesign, Design Thinking and Design Collaborative, in which are presented motodológicos models of high relevance for the identification, analysis and solution of complex problems involving multiple elements and agents. The proposed article aims to survey the state of the art City Branding / Place Branding focused on publications produced in the disciplinary field of design. The literature review will grant that, before the above presented context, is analyzed as designers and researchers design face the contributions that the field can offer to the practice and theory of Branding places. Finally, Article yearns assess whether the pre-established hypothesis that there are possible and fruitful connections between contemporary theories of design and the City Branding, is being addressed in articles and publications area.DOI: http://dx.doi.org/10.4995/IFDP.2016.3288


Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 954
Author(s):  
Abhijeet Ravankar ◽  
Ankit A. Ravankar ◽  
Arpit Rawankar ◽  
Yohei Hoshino

In recent years, autonomous robots have extensively been used to automate several vineyard tasks. Autonomous navigation is an indispensable component of such field robots. Autonomous and safe navigation has been well studied in indoor environments and many algorithms have been proposed. However, unlike structured indoor environments, vineyards pose special challenges for robot navigation. Particularly, safe robot navigation is crucial to avoid damaging the grapes. In this regard, we propose an algorithm that enables autonomous and safe robot navigation in vineyards. The proposed algorithm relies on data from a Lidar sensor and does not require a GPS. In addition, the proposed algorithm can avoid dynamic obstacles in the vineyard while smoothing the robot’s trajectories. The curvature of the trajectories can be controlled, keeping a safe distance from both the crop and the dynamic obstacles. We have tested the algorithm in both a simulation and with robots in an actual vineyard. The results show that the robot can safely navigate the lanes of the vineyard and smoothly avoid dynamic obstacles such as moving people without abruptly stopping or executing sharp turns. The algorithm performs in real-time and can easily be integrated into robots deployed in vineyards.


Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4412
Author(s):  
Kadeghe Fue ◽  
Wesley Porter ◽  
Edward Barnes ◽  
Changying Li ◽  
Glen Rains

This study proposes an algorithm that controls an autonomous, multi-purpose, center-articulated hydrostatic transmission rover to navigate along crop rows. This multi-purpose rover (MPR) is being developed to harvest undefoliated cotton to expand the harvest window to up to 50 days. The rover would harvest cotton in teams by performing several passes as the bolls become ready to harvest. We propose that a small robot could make cotton production more profitable for farmers and more accessible to owners of smaller plots of land who cannot afford large tractors and harvesting equipment. The rover was localized with a low-cost Real-Time Kinematic Global Navigation Satellite System (RTK-GNSS), encoders, and Inertial Measurement Unit (IMU)s for heading. Robot Operating System (ROS)-based software was developed to harness the sensor information, localize the rover, and execute path following controls. To test the localization and modified pure-pursuit path-following controls, first, GNSS waypoints were obtained by manually steering the rover over the rows followed by the rover autonomously driving over the rows. The results showed that the robot achieved a mean absolute error (MAE) of 0.04 m, 0.06 m, and 0.09 m for the first, second and third passes of the experiment, respectively. The robot achieved an MAE of 0.06 m. When turning at the end of the row, the MAE from the RTK-GNSS-generated path was 0.24 m. The turning errors were acceptable for the open field at the end of the row. Errors while driving down the row did damage the plants by moving close to the plants’ stems, and these errors likely would not impede operations designed for the MPR. Therefore, the designed rover and control algorithms are good and can be used for cotton harvesting operations.


2020 ◽  
Vol 39 (7) ◽  
pp. 856-892 ◽  
Author(s):  
Tingxiang Fan ◽  
Pinxin Long ◽  
Wenxi Liu ◽  
Jia Pan

Developing a safe and efficient collision-avoidance policy for multiple robots is challenging in the decentralized scenarios where each robot generates its paths with limited observation of other robots’ states and intentions. Prior distributed multi-robot collision-avoidance systems often require frequent inter-robot communication or agent-level features to plan a local collision-free action, which is not robust and computationally prohibitive. In addition, the performance of these methods is not comparable with their centralized counterparts in practice. In this article, we present a decentralized sensor-level collision-avoidance policy for multi-robot systems, which shows promising results in practical applications. In particular, our policy directly maps raw sensor measurements to an agent’s steering commands in terms of the movement velocity. As a first step toward reducing the performance gap between decentralized and centralized methods, we present a multi-scenario multi-stage training framework to learn an optimal policy. The policy is trained over a large number of robots in rich, complex environments simultaneously using a policy-gradient-based reinforcement-learning algorithm. The learning algorithm is also integrated into a hybrid control framework to further improve the policy’s robustness and effectiveness. We validate the learned sensor-level collision-3avoidance policy in a variety of simulated and real-world scenarios with thorough performance evaluations for large-scale multi-robot systems. The generalization of the learned policy is verified in a set of unseen scenarios including the navigation of a group of heterogeneous robots and a large-scale scenario with 100 robots. Although the policy is trained using simulation data only, we have successfully deployed it on physical robots with shapes and dynamics characteristics that are different from the simulated agents, in order to demonstrate the controller’s robustness against the simulation-to-real modeling error. Finally, we show that the collision-avoidance policy learned from multi-robot navigation tasks provides an excellent solution for safe and effective autonomous navigation for a single robot working in a dense real human crowd. Our learned policy enables a robot to make effective progress in a crowd without getting stuck. More importantly, the policy has been successfully deployed on different types of physical robot platforms without tedious parameter tuning. Videos are available at https://sites.google.com/view/hybridmrca .


2020 ◽  
pp. 1420326X2092552
Author(s):  
Rui Li ◽  
Dayi Ou ◽  
Sensen Pan

The well-known service quality measurement (SQM) models, Importance-Satisfaction (I-S) model and Improvement index (Ii) model, have been recently proved useful in the analysis of soundscape quality. By combining the concepts of soundscape and quality management, this paper proposes an improved SQM model for soundscape assessment in urban public open spaces. Instead of using the I-S model, the Preference-Satisfaction (P-S) model was developed for soundscape quality evaluation, which can simultaneously assess the importance, satisfaction and improvement direction of soundscape elements and provide more accurate and comprehensive information for guiding the soundscape management and improvement. The proposed methods were subsequently applied to case studies in eight ordinary urban public open spaces in Fujian Province, China, and provided detailed information about the soundscape quality of these surveyed open spaces as well as their improvement strategies. The results have demonstrated the practicality and effectiveness of the proposed method. To the authors' knowledge, practical applications of quality management methods (or its variations) to urban soundscape study are still limited in the literature; therefore, the proposed method and findings of the current study could be valuable for both practical soundscape design and academic research.


2019 ◽  
Vol 16 (2) ◽  
pp. 172988141983158 ◽  
Author(s):  
Yunsheng Fan ◽  
Xiaojie Sun ◽  
Guofeng Wang

There are many unknown obstacles in the sea, so the autonomous navigation of unmanned surface vehicle needs to avoid them as soon as possible even under the condition of low control ability of the controller. To solve the problem, by combining the dynamic collision avoidance algorithm and tracking control, a dynamic collision avoidance control method in the unknown ocean environment is presented. In this article, in consideration of the unknown ocean environment and real-time dynamic obstacle avoidance problem, the collision avoidance controller using a velocity resolution method and backstepping tracking controller based on unmanned surface vehicle maneuvering motion model is designed. Simulation results show that the method is effective and accurate and can provide the reference for the unmanned surface vehicle intelligent collision avoidance control technology.


2000 ◽  
Vol 41 (8) ◽  
pp. 69-76 ◽  
Author(s):  
N. Okuna ◽  
A. Yamada

Tokyo has an experience in operation of full-scale thermal solidification processes for around 10 years. They include artificial lightweight aggregates, slag, brick, and sludge fuel (dried by Carver Greenfield process). Many efforts were concentrated on improving the processes for the years. As a result, the thermal solidification of sewage sludge is no more academic research subject, but is a standardized engineering process. Anyof them are able to be locally implemented depending on specific requests. Among them, the brick seems to be the best choice from the viewpoint of economy. On the other hand, a potential alternative is that the sewage sludge could be served as raw material for Portland cement manufacturing process.


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