• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.298-311
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• 2015

Nowadays, automatic digging operation of an excavator is a big challenge due to the complexity of digging environment, the hardness of soil and buried obstacles into the ground. In order to achieve the maximum soil bucket volume, this paper introduces a novel engineering model that was developed as a virtual excavator in the design phase. Through this model, the designs of mechanical and control systems for autonomous excavator are executed and modified easily before developing in real testbed. Based on a concept of an autonomous excavation, a mechanical system of excavator was first designed in SOLIDWORKS, and a soil model also was modeled by finite-element analysis in ANSYS, both modeled models were then exported to ADAMS environment to investigate the digging behavior through virtual simulation. An intelligent control strategy was generated in MATLAB/Simulink to control the excavator operation. The simulation results were demonstrated by effectiveness of the proposed excavator robot in testing scenarios with many soil types and obstacles.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.19-25
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• 2008

This paper proposes a hierarchically structured navigation algorithm for autonomous mobile robot under unknown environment based on fuzzy-neal network. The proposed algorithm consists of two basic layers as follows. The lower layer consists of two parts such as fuzzy algorithm for goal approach and fuzzy-neural algorithm for obstacle avoidance. The upper layer which is basically fuzzy algorithm adjusts the magnitude of the weighting factor depending on the environmental situation. The proposed algorithm provides an efficient method to escape local mimimum points as shown in the simulation result. Most simulation results show that this algorithm is very effective for autonomous mobile robots' traveling in unknown field.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.1
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• pp.18-23
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• 2003

This paper presents new algorithms of path planning and obstacle avoidance for an autonomous mobile robot to navigate under unknown environments in the real time. Temporary targets are set up by distance variation method and then the algorithms of trajectory planning and obstacle avoidance are designed using fuzzy rules. It is shown by computer simulation that these algorithms are working well. Furthermore, an autonomous mobile robot was constructed to implement and test these algorithms in the real field. The experimental results are also satisfactory just like those of computer simulation.

• Journal of Auto-vehicle Safety Association
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• v.15 no.3
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• pp.53-58
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• 2023

Defects in the vehicle itself were considered the biggest risk factor for traffic accidents as the electrical and electronic components of vehicles, which were not there before, increase. Therefore, the vehicles have been developed based on ISO 26262 (an international functional safety standard) which is focusing on functional defect safety evaluation of electrical and electronic component systems. However, in the future, as autonomous driving technology is applied, even vehicles without functional defects must be prepared for the dangerous traffic situation that may arise from exceptional or external factors. SOTIF (Safety Of The Intended Functionality) is a concept to prevent exceptional or external factors. The main objective of SOTIF is to decrease Unknown & Unsafe factors as much as possible by finding Known factors and Unsafe factors. In this study, Prescan provided SIEMENS, one of the autonomous driving simulators, is used to make scenarios of IGLAD traffic accident cases. From the simulation results, Unsafe & Safe cases were classified and analyzed to derive unsafe factors.

• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.6-12
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• 2023

For the commercialization and standardization of autonomous vehicles, demand for rigorous safety criteria has been increased over the world. In Korea, the number of extraordinary service permission for automated vehicles has risen since Hyundai Motor Company got its initial license in March 2016. Nevertheless, licensing standards and evaluation factors are still insufficient for operating on public roadways. To assure driving safety, it is significant to verify whether or not the vehicle's decision is similar to human driving. This paper validates the safety of the autonomous vehicle by drawing scenario-based comparisons between manual driving and autonomous driving. In consideration of real traffic situations and safety priority, seven scenarios were chosen and classified into basic and advanced scenarios. All scenarios and safety factors are constructed based on existing ADAS requirements and investigated via a computer simulation and actual experiment. The input data was collected by an experimental vehicle test on the SNU FMTC test track located at Siheung. Then the offline simulation was conducted to verify the output was appropriate and comparable to the manual driving data.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.406-415
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• 2023

In this study, we focused on developing and verifying ship collision avoidance algorithms using Unity simulator and ROS(Robot Operating System). ROS is used to establish an environment where communication between different operating systems is possible, and a dynamic model of a ship is constructed within Unity simulator. The Lidar data collected in Unity environment is passed to the system based on python through ROS. In the system based on python, control command values were created through the logic of the collision avoidance algorithm using data, and the values were transferred back to Unity to control the movement of the virtual ship. Through the developed simulation system, the reliability of the collision avoidance algorithm of ships with two different forms in an environment similar to the actual physical world was confirmed. As a result, it was confirmed on the simulator that it could be avoided without collision even in an environment with various types of obstacles, and that the avoidance characteristics according to the dynamics of the ship could be analyzed.

• Journal of Auto-vehicle Safety Association
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• v.15 no.4
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• pp.39-47
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• 2023

Research on the safety of autonomous vehicle is being conducted in various countries, including the European Union, and computer simulation techniques so called 'Virtual Tool Chain' are mainly used. As part of the crash safety study of autonomous vehicle, 25 car to car collision scenarios were provided as a result of a real accident-based accident reproduction analysis study conducted by a domestic research institution, and a vehicle crash analysis was performed using the FE car to car model of the Honda Accord. In order to analyze the results of the car to car simulation and to construct a database, major crash parameters were selected as impact speed, angle, location, and overlap, and a method of defining them in an indexed form was presented. In order to compare the crash severity of each scenario, a value obtained by integrating the resultant acceleration measured by the ACU of the vehicle was applied. The equivalent collision test mode was derived by comparing the crash severity of the regulation test mode, 30 deg rigid barrier mode, in the same way.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.3
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• pp.131-139
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• 2024

Crew Transfer Vessels (CTVs) are primarily used for the maintenance of offshore wind farms. Despite being manually operated by professional captains and crew, collisions with other ships and marine structures still occur. To prevent this, the introduction of autonomous navigation systems to CTVs is necessary. In this study, research on the obstacle avoidance system of the autonomous navigation system for CTVs was conducted. In particular, research on obstacle avoidance simulation for CTVs using deep reinforcement learning was carried out, taking into account the currents and wind loads in offshore wind farms. For this purpose, 3 degrees of freedom ship maneuvering modeling for CTVs considering the currents and wind loads in offshore wind farms was performed, and a simulation environment for offshore wind farms was implemented to train and test the deep reinforcement learning agent. Specifically, this study conducted research on obstacle avoidance maneuvers using MATD3 within deep reinforcement learning, and as a result, it was confirmed that the model, which underwent training over 10,000 episodes, could successfully avoid both static and moving obstacles. This confirms the conclusion that the application of the methods proposed in this study can successfully facilitate obstacle avoidance for autonomous navigation CTVs within offshore wind farms.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.403-410
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• 2003

ANS (autonomous navigation system) is an expert system which builds navigation plans, understands the current environment, and controls a surface ship. The most ideal way to test ANS is available after it is installed into a real surface ship. however, it is impossible to implement into a real ship. since it costs too much to develop the hardware interfaces just for testing. The most appropriate way for testing is to develop a simulation system for a surface ship and apply it. A simulation system for a surface ship consists of two sub-systems : one is a ship movement simulation system to imitate the physical movement characteristics of the ship, and the other is an environmental objects simulation system to build up surroundings of the ship. In this paper, we design and develop a surface ship movement simulation system which imitates its physical movement characteristics by using a motion equation for surface ship.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.29
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• pp.63-78
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• 1994

Today, the problem of interrational competition has been strongly appeared and as the deflation is deep occasionally, it is sure that granting autonomous motivation of businessman or importance of self development is proposed especially. Then, which subject is included in granting autonomous motivation as that\ulcorner We must study about that subject first. First, we should study about essence of granting autonomous motivation. Granting autonomous motivation is the course of accompli¬shment of ideal human individually. Secondly, we will divide that into goal, desire and positive attitude subjectly and will study about those respectively. Contents of this theory are as below. 1. Proposal of problem 2. Basic structure of granting autonomous motivation and ability 2-1 Consideration of granting autonomous motivation 2-2 Basic structure of ability 3. The method of granting autonomous motivation 3-1 Simulation of granting autonomous motivation 3-2 Establishment of subject on granting autonomous motivation 4. Granting autonomous motivation by utilization of opportunity 4-1 Utilization of opportunity 4-2 Self-development by reading 4-3 Self development by writing 4-4 Self-development by discussion 4-5 Self development by control of health 4-6 Self-development by making the time 5. Conclusion This theory will be developed by classification as above. Reflecting many times and experiencing a skill for himself, he should teach his men the skill. There are some men not to be able to talk with, but a businessman should make his surroundings cheerful with granting autonomous motivation. If he understands the men of his surroundings with his positive attitude, all tasks of him will be achieved. Formation of question consciousness that he can study always, is needed on which is the important task in himself.