Scan Matching Online Cell Decomposition for Coverage Path Planning in an Unknown Environment

Dugarjav, Batsaikhan,Lee, Soon-Geul,Kim, Donghan,Kim, Jong Hyeong,Chong, Nak Young Korean Society for Precision Engineering 2013 International Journal of Precision Engineering and Vol.14 No.9

This paper presents a novel sensor-based online coverage path-planning algorithm that guarantees the complete coverage of an unknown rectilinear workspace for the task of a mobile robot. The proposed algorithm divides the workspace of the robot into cells at each scan sample. This division can be classified as an exact cell decomposition method, which incrementally constructs cell decomposition while the robot covers an unknown workspace. To guarantee complete coverage, a closed map representation based on a feature extraction that consists of a set of line segments called critical edges is proposed. In this algorithm, cell boundaries are formed by extended critical edges, which are the sensed partial contours of walls and objects in the workspace. The robot uses a laser scanner to sense the critical edges. Sensor measurement is sampled twice in each cell. Scan matching is performed to merge map information between the reference scan and the current scan. At each scan sample, a two-direction oriented rectilinear decomposition is achieved in the workspace and presented by a closed map representation. The construction order of the cells is very important in this incremental cell decomposition algorithm. To choose the next target cell from candidate cells, the robot checks for redundancy in the planned path and for possible positions of the ending points of the current cell. The key point of the algorithm is memorizing the covered space to define the next target cell from possible cells. The path generation within the defined cell is determined to minimize the number of turns, which is the main factor in saving time during the coverage. Therefore, the cell's long boundary should be chosen as the main path of the robot. This algorithm is verified by an experiment under the LABVIEW environment.

A Study on Variable Speed Generation System with Energy Saving Function

Dugarjav, Bayasgalan,Lee, Sang-Ho,Han, Dong-Hwa,Lee, Young-Jin,Choe, Gyu-Ha The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.1

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

Scan Matching Online Cell Decomposition for Coverage Path Planning in an Unknown Environment

Batsaikhan Dugarjav,이순걸,김동한,김종형,정낙영 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

This paper presents a novel sensor-based online coverage path-planning algorithm that guarantees the complete coverage of an unknown rectilinear workspace for the task of a mobile robot. The proposed algorithm divides the workspace of the robot into cells at each scan sample. This division can be classified as an exact cell decomposition method, which incrementally constructs cell decomposition while the robot covers an unknown workspace. To guarantee complete coverage, a closed map representation based on a feature extraction that consists of a set of line segments called critical edges is proposed. In this algorithm, cell boundaries are formed by extended critical edges, which are the sensed partial contours of walls and objects in the workspace. The robot uses a laser scanner to sense the critical edges. Sensor measurement is sampled twice in each cell. Scan matching is performed to merge map information between the reference scan and the current scan. At each scan sample, a two-direction oriented rectilinear decomposition is achieved in the workspace and presented by a closed map representation. The construction order of the cells is very important in this incremental cell decomposition algorithm. To choose the next target cell from candidate cells, the robot checks for redundancy in the planned path and for possible positions of the ending points of the current cell. The key point of the algorithm is memorizing the covered space to define the next target cell from possible cells. The path generation within the defined cell is determined to minimize the number of turns, which is the main factor in saving time during the coverage. Therefore, the cell’s long boundary should be chosen as the main path of the robot. This algorithm is verified by an experiment under the LABVIEW environment.

Current State of Distributed Solar Power System Development and Challenges in Mongolia

Bayasgalan Dugarjav,Turmandakh Bat-Orgil,Gansukh Myagmar 한국신재생에너지학회 2022 AFORE Vol.2022 No.9

Friction and wear properties of rice husk ceramics under dry condition

Tuvshin Dugarjav,Takeshi Yamaguchi,Kei Shibata,Kazuo Hokkirigawa 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1

The friction and wear behaviors of rice husk (RH) ceramics, prepared by carbonizing the mixture of rice husk and phenol resin at 900 °C in N2 gas environment, sliding against high carbon chromium steel (JIS SUJ2), austenitic stainless steel (JIS SUS304), and Al2O3under dry condition were investigated using a ball-on-disk tribometer. The test results show that the friction coefficient of RH ceramics takes very low values 0.05-0.08 and 0.06-0.11 sliding against SUJ2 and SUS304, respectively, and much higher values around 0.14-0.23against Al2O3. It was also shown that SUJ2 provides the lowest specific wear rate values below 10-9 mm2/N, while, those of SUS304 and Al2O3 mostly stayed between 10-9 to 10-8 mm2/N range. The worn surfaces of counterparts were observed with optical microscopy and analyzed using cross-sectional transmission electron microscopy with energy dispersive X-ray spectroscopy and electron diffraction. It was suggested that the tribological behaviors of RH ceramics are closely related with the formation of a transferred film, consisted of amorphous silica and carbon particles, on a counterpart surface. The transferred film was formed readily on SUJ2 balls, whereas for SUS304 the presence of the film was subject of the sliding conditions. Moreover, formation of the transferred film could not be detected on Al2O3 counterparts.

THE STUDY ON STRUCTURE OPTIMIZATION OF RESIDENTIAL PV SYSTEM FOR MONGOLIAN HOUSEHOLD

Bayasgalan Dugarjav,Young-Ho Lee,Jinsoo Song 한국신재생에너지학회 2015 AFORE Vol.2015 No.11

Adaptive Online Cell Decomposition with a Laser Range Finder in Unknown Non-Rectilinear Environments

Batsaikhan Dugarjav,이순걸,Tan Bui Quang,곽관웅,이범주 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.4

Although the use of autonomous mobile robots in a known workspace has become increasingly popular, their application in an unknown workspace remains a challenge. This paper presents a sensor-based online cell decomposition method that is supported by online coverage; it allows a robot to simultaneously explore an unknown workspace and achieve adaptive cell decomposition to ensure the coverage of a non-rectilinear environment. Assumptions on the proposed method are established to obtain a viable solution. First, map building and position correction are simplified under the following assumptions. The workspace of the robot is nonrectilinear and structured, in which several convex obstacles are distributed. The orthogonality assumption follows the previous assumption. The orthogonality assumption posits that major structures of the indoor environment can be modeled by sets of lines and curves. Second, the decomposed cell must be as large as possible. Lastly, cells are composed by considering their adaptability to an explored map, that is, each cell is composed and updated until it is unchanged. The main process to construct cells is performed after a visibility map is built to guarantee that all visible maps have been seen by a mobile robot previously. The performance evolution of the proposed method is verified through an experiment.

Time-Efficient and Complete Coverage Path Planning Based on Flow Networks for Multi-Robots

Adiyabaatar Janchiv,Dugarjav Batsaikhan,김병수,이원구,이순걸 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.2

Complete coverage path planning (CCPP), specifically, the efficiency and completeness of coverage of robots, is one of the major problems in autonomous mobile robotics. This study proposes a path planning technique to solve global time optimization. Conventional algorithms related to template-based coverage can minimize the time required to cover particular cells. The minimal turning path is mostly based on the shape and size of the cell. Conventional algorithms can determine the optimum time path inside a cell; however, these algorithms cannot ensure that the total time determined for the coverage path is the global optimum. This study presents an algorithm that can convert a CCPP problem into a flow network by exact cell decomposition. The total time cost to reach the edge of a flow network is the sum of the time to cover the current cell and the time to shift in adjacent cells. The time cost determines a minimum-cost path from the start node to the final node through the flow network, which is capable of visiting each node exactly once through the network search algorithm. Search results show that the time-efficient coverage can obtain the global optimum. Simulation and experimental results demonstrate that the proposed algorithm operates in a time-efficient manner.

Complete Coverage Path Planning for Multi-Robots Based on

Adiyabaatar Janchiv,Dugarjav Batsaikhan,Gook hwan Kim,Soon-Geul Lee 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

Complete coverage path planning is major problem for autonomous mobile robot, which concerns both efficiency and completeness of coverage. In this paper, a complete coverage path planning algorithm is proposed for two indoor floor-caring robots, such as cleaning or inspecting industrial and public floor areas, to have the minimal turning path based on the shape and size of the cell covering the whole working area. The proposed algorithm divides the whole cleaning area into cells by cellular decomposition method, and then provides efficient covering order over the cells based on distance among centroids of cells. It also provides more optimal coverage path and reduces the rate of energy consumption and working time. Both simulation and experimental results demonstrate the effectiveness of the algorithm. As compared performance indices between experiment and simulation, the total number of turns and the working time show the practical efficiency and robustness of the proposed algorithm.

Cell equalizer for recycling batteries from hybrid electric vehicles

Bat-Orgil, Turmandakh,Dugarjav, Bayasgalan,Shimizu, Toshihisa The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3

The rise of electric vehicles (EVs) and hybrid electric vehicles (HEVs) has resulted in increases in battery toxic waste. Although the powering and capacity characteristics of batteries deteriorate after use in EVs and HEVs, they usually retain enough potential for reuse as power sources in home energy systems, whose power requirements are much lower than those of EVs and HEVs. This study proposes an active cell equalizer that balances the state of charge (SOC) of nickel-metal hybrid (NiMH) batteries recycled from HEVs. In the proposed cell equalizer, two different circuits, e.g., a generation control circuit (GCC) and a power-decoupling circuit are integrated. Excessive energy is automatically transferred from a high-SOC cell to a low-SOC cell through the GCC. The power-decoupling circuit lowers the power pulsation caused by the single-phase DC/AC inverter. This reduces the low-frequency ripple current flowing into the battery pack, ensures safe operation and prolongs the lifecycle of the batteries. A prototype circuit with a three-stage battery pack is implemented in the discharging state and the obtained experimental results are analyzed to verify the equalizer functionality.