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Fuzzy Logic Based Navigation for Multiple Mobile Robots in Indoor Environments
Zhao, Ran,Lee, Dong Hwan,Lee, Hong Kyu Korean Institute of Intelligent Systems 2015 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.15 No.4
The work presented in this paper deals with a navigation problem for multiple mobile robot system in unknown indoor environments. The environment is completely unknown for all the robots and the surrounding information should be detected by the proximity sensors installed on the robots' bodies. In order to guide all the robots to move along collision-free paths and reach the goal positions, a navigation method based on the combination of a set of primary strategies has been developed. The indoor environments usually contain convex and concave obstacles. In this work, a danger judgment strategy in accordance with the sensors' data is used for avoiding small convex obstacles or moving objects which include both dynamic obstacles and other robots. For big convex obstacles or concave ones, a wall following strategy is designed for dealing with these special situations. In this paper, a state memorizing strategy is also proposed for the "infinite repetition" or "dead cycle" situations. Finally, when there is no collision risk, the robots will be guided towards the targets according to a target positioning strategy. Most of these strategies are achieved by the means of fuzzy logic controllers and uniformly applied for every robot. The simulation experiments verified that the proposed method has a positive effectiveness for the navigation problem.
Fuzzy-based Path Planning for Multiple Mobile Robots in Unknown Dynamic Environment
Zhao, Ran,Lee, Hong-Kyu The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2
This paper presents a path planning problem for multi-robot system in the environment with dynamic obstacles. In order to guide the robots move along a collision-free path efficiently and reach the goal position quickly, a navigation method based on fuzzy logic controllers has been developed by using proximity sensors. There are two kinds of fuzzy controllers developed in this work, one is used for obstacle avoidance and the other is used for orientation to the target. Both static and dynamic obstacles are included in the environment and the dynamic obstacles are defined with no type of restriction of direction and velocity. Here, the environment is unknown for all the robots and the robots should detect the surrounding information only by the sensors installed on their bodies. The simulation results show that the proposed method has a positive effectiveness for the path planning problem.
Mobile Robot Navigation using Optimized Fuzzy Controller by Genetic Algorithm
Zhao, Ran,Lee, Dong Hwan,Lee, Hong Kyu Korean Institute of Intelligent Systems 2015 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.15 No.1
In order to guide the robots move along a collision-free path efficiently and reach the goal position quickly in the unknown multi-obstacle environment, this paper presented the navigation problem of a wheel mobile robot based on proximity sensors by fuzzy logic controller. Then a genetic algorithm was applied to optimize the membership function of input and output variables and the rule base of the fuzzy controller. Here the environment is unknown for the robot and contains various types of obstacles. The robot should detect the surrounding information by its own sensors only. For the special condition of path deadlock problem, a wall following method named angle compensation method was also developed here. The simulation results showed a good performance for navigation problem of mobile robots.
Zhaoran Wang,Huilong Dong,Xiaohui Yu,Yujin Ji,Tingjun Hou,Youyong Li 한국물리학회 2017 Current Applied Physics Vol.17 No.12
Porous monolayer materials have been proven potential for gas separation and purification, because of their natural pathways of controllable sizes and well-ordered distribution. In this work, a novel material, two-dimensional (2D) porous polyphthalocyanine (PPc) is investigated by density functional theory (DFT) simulations for separating NH3 from H2 and N2 during ammonia synthesis process. Based on the calculated diffusion barriers through transition state search, we demonstrate that 2D PPc is able to offer high selectivity (107) of (H2, N2)/NH3 at room temperature. Further molecular dynamics (MD) simulation also indicates that the 2D PPc can effectively separate NH3 from H2 and N2. Thus the 2D PPc is promising for the practical applications of synthetic ammonia process.
Jin Xianjian,Wang Zhaoran,Yang Junpeng,Xu Liwei,Yin Guodong 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.5
Lightweight electric vehicles (LEVs) possess great advantages in the viewpoint of fuel consumption, environment protection and traffic mobility. However, due to the drastic reduction of vehicle weights and body size, the effects of payload parameter variation in LEV control and estimation system become much more pronounced and have to be systematically analysed. This paper proposes a novel payload parameter sensitivity analysis to provide quantitative insight into the sensitivity of payload parameter on the LEV system responses and state estimation. The analysis-oriented LEV dynamic model considering payload parameter variations is developed. Then, the trajectory sensitivity index of the influential parameters is defined and derived with the perturbation approach, the median method is used to improve the calculation accuracy for the trajectory sensitivity of payload parameter. Finally, the extended Kalman filter is designed to show the effect and importance of the sensitive payload parameters on the observation accuracy, the payload parameter variations along with fundamental state estimation such as vehicle sideslip angle, longitudinal velocity and vehicle roll angle are analysed. Simulation results with Matlab/Simulink-Carsim® show that the proposed method can accurately describe the relationship between the vehicle payload parameters and system state estimation, which is helpful to design and evaluate LEV controller and observer performances.
Restricting CEO Pay Backfires : Evidence from China
Kee-Hong Bae,Zhaoran Gong,Wilson H.S. Tong 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05
Using the pay restriction imposed on CEOs of centrally administered state-owned enterprises (CSOEs) in China in 2009, we study the effects of limiting CEO pay. Compared with firms not subject to the restriction, the CEOs of CSOEs experience a significant pay cut. Pay-performance sensitivity for these firms also significantly decreases. In response to the pay cut, CEOs increase their consumption of perks and siphon off firm resources for their own benefit. Ultimately, the performance of these firms drops significantly following the pay restriction. Our findings suggest that restricting CEO pay distorts CEO incentives and brings unintended consequences. Our findings caution against limiting the pay of CEOs.
박지영,이장연,권대길,Zhaoran Huang 한국인터넷방송통신학회 2008 한국인터넷방송통신학회 논문지 Vol.8 No.5
Recently an efficiently transmit maximum information messages are important issue in ubiquitous network. Traditionally when forwarding information packet destined to some other node, it simply repeats by turns. On the other side in using network coding, we allow the node to combine a number of packets it has received or created into one or several outgoing packets. However, wireless network environment, one of the network coding problem is overhearing problem. In most network coding paper, assume that overhearing is perfect or researches solve without overhearing problem. We solve overhearing problem from optimal power control and improve network coding capacity. 유비쿼터스 네트워크(Ubiquitous Network) 상에서 최대한 많은 정보를 효율적으로 전달하는 것이 중요한 이슈로 떠오르고 있다. 네트워크 코딩(Network Coding)은 네트워크의 노드에서 입력정보를 단순하게 전달하는데 준하는 것이 아니라 받은 정보를 결합하여 정보를 전달하는 새로운 패러다임이다. 그러나 네트워크 코딩이 실제 무선 환경에서 사용되기 위해서는 네트워크 코딩이 갖고 있는 단점들을 좀 더 보완하여야 한다. 그 단점중 하나가 오버히어링 문제(overhearing problem)인데 많은 논문들은 오버히어링이 된다고 가정을 하거나 오버히어링 문제없이 문제를 풀어 나가고 있다. 이와 같은 문제를 적절한 전력 제어로 오버히어링 문제를 해결하고 더 좋은 성능을 증진시키는 것을 검증하였다.