• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2397-2399
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• 2004

This paper deals with the messages scheduling of a CAN (Controller Area Network), based on the distributed control scheme to integrate actuators and sensors in a humanoid robot. In order to supply the distributed processing for a humanoid robot, each control unit should have the efficient control method, fast calculation and valid data exchange. The preliminary study has concluded that the performance of CAN is better and easier to implement than other network such as FIP (Factory Instrumentation Protocol), VAN (Vehicle Area Network), etc. Since humanoid robot has to treat the significant control signals from many actuators and sensors, the communication time limitation could be critical according to the transmission speed and data length of CAN specification. In this paper, the CAN message scheduling in humanoid robot was suggested under the presence of Jitter in the message group, the existence of high load of messages over the network and the presence of transmission errors. In addition, the response time under the worst case is compared with the simulation by using the simulation algorithm. As a result, the suggested messages scheduling can guarantee our CAN limitation, and utilized to generate the walking patterns for the humanoid.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.464-467
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• 1995

Autonomous Mobile Robot(AMR) is a field of study which is under active research along with rapid development of the engineering technology. The main reasons for the high interest in AMR are because of its ability to change work space freely and its capability to replace human being for difficult and dangerous jobs. Also the fact that AMR provides a variety of research fields, such as path planning, navigation algorithm, sensor fusion, image processing, and controller design is part of the reason for its popularity. But relatively few researches are concerned with controller. So in this paper, a control strategy of mobile robot with nonholonomic constraint for tracking ordered discontinuous motion is proposed. The proposed control strategy has been designed as a state feedback shape to allow the AMR to obtain continuous velocity and track the path which is composed of discontinuous motions. In order to design such controller, 3 states have been reduced to 2 states through coordinate projection. These ideas are tested for validity through simulation and simulation result is compared with experiments result.

• 한국CDE학회논문집
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• 제10권3호
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• pp.210-216
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• 2005

Digital manufacturing could be very effective in shipbuilding in order to estimate the process time, to improve the operation efficiency, and to prevent bottleneck processes in advance. The subassembly process having done research consists of piece arrangement, tack welding, robot welding, manual welding and so on. The robot welding of them was the focus of the simulation. The analysis and modeling were carried out by using UML (Unified Modeling Language) as well as $IDEF\phi$ (Integration DEFinition). The characteristics of the process resources were analyzed using the shipyard data, and the layout of the subassembly line was designed with the resources. Using the constructed resource and process model, the productivity and efficiency of changed robot welding stage were investigated. It was simulated how much the variations in the resource performance have influence on improvement of productivity. One of the important outputs in this simulation was the cycle time during a certain period's work. The cycle time prediction was also undertaken for the different torch and the different piece arrangement. The proposed model was established three-dimensionally in a digital environment so that interferences among objects and space allocations for the resources could be easily investigated.

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.69-74
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• 2008

Robotics and artificial intelligence are components of IT that involve networks, electrical and electronic engineering, and wireless communication. We consider an algorithm for efficient navigation by building a precise map in a multi-robot system under conditions of limited and unlimited communications. The basis of the navigation algorithm described in this paper is a wave algorithm, which is effective in obtaining an accurate map. Each robot in a multi-robot system has its own task such as building a map for its local position. By combining their data into a shared map, the robots can actively seek to verify their relative locations. Using shared maps, they coordinate their exploration strategies to maximize exploration efficiency. To prove the efficiency of the proposed technique, we compared the final results with the results in $Burgard^{8}$ and $Stachniss.^{9-10}$ All of the simulation comparisons, which are shown as graphs, were made in four different environments.

• 한국해양공학회지
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• 제27권2호
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• pp.100-106
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• 2013

This paper deals with the design method for a small waterproof 4-axis robot arm. An extensive analysis was performed on the torque applied to the robot joint as a result of the payload, as well as the design of the joint actuator capacity. In addition, a study was undertaken on the design of a waterproof joint actuator that works at depths greater than 10 m and the wiring design for a small waterproof connector to avoid obstructing the robot motion. Finally, a finite element method simulation was carried out to analyze the strength of the designed robot arm link, and its stability was verified through a simulation test.

• 사물인터넷융복합논문지
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• 제7권4호
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• pp.29-34
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• 2021

실 환경에서 로봇에 강화학습을 적용하기 위해서는 수많은 반복 학습이 필요하므로 가상 환경에서의 시뮬레이션을 사용할 수밖에 없다. 또한 실제 사용하는 로봇이 저사양의 하드웨어를 가지고 있는 경우 계산량이 많은 학습 알고리즘을 적용하는 것은 어려운 일이다. 본 연구에서는 저사양의 하드웨어를 가지고 있는 모바일 로봇의 장애물 충돌 회피 문제에 강화학습을 적용하기 위하여 가상의 시뮬레이션 환경으로서 Unity에서 제공하는 강화학습 프레임인 ML-Agent를 활용하였다. 강화학습 알고리즘으로서 ML-Agent에서 제공하는 DQN을 사용하였으며, 이를 활용하여 학습한 결과를 실제 로봇에 적용해 본 결과 1분간 충돌 횟수가 2회 이하로 발생하는 결과를 얻을 수 있었다.

• 로봇학회논문지
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• 제18권2호
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• pp.172-181
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• 2023

This paper presents research on the stability of control for a quadruped robot with two different leg structure designs. The focus of the research is on the design and analysis of the leg structures in terms of their impact on the stability and robustness of the robot's motion. First, a static analysis was performed in the simulation to compare the structural strength of the legs when the same force was applied. Secondly, two quadruped robots were built, each equipped with differently designed legs, and performed trot gait walking in the real world. And the states of the robots and the torques of each joint were analyzed and compared. In conclusion, based on the results of structural analysis in simulation and the actual walking experiments with the robots, it was demonstrated that the legs designed to be structurally robust improved the control stability of the quadruped robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.523-525
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• 2004

Over the last few years, the control of bipedal robot has been considered a promising research field in the community of robotics. But the problems we encounter make the control of a bipedal robot a hard task. The complicated link connection of the bipedal robot makes it impossible to achieve its exact model. In addition, the joint velocity is needed to accomplish good control performance. In this paper a control method using ANFIS as an system approximator is purposed. First a model biped robot of a biped robot with switching leg influence is presented. Unlike classical method, ANFIS approximation error estimator is inserted in the system for tuning the ANFIS. In the entire system, only ANFIS is used to approximate the uncertain system. ANFIS tuning rule is given combining the observation error, control error and ANFIS approximation error. But this needs velocity information which is not available. So a practical method is newly presented. Finally, computer simulation results is presented to show this control method has good position tracking performance and robustness without need for leg switching acknowledgement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.490-492
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• 2004

This paper presents an obstacle avoidance of a mobile robot by the subgoal generation using infrared sensors. When an obstacle appears on the path which the robot is moving forward the robot has to get information, such as distance between the robot and the obstacle and the shape of the obstacle for avoidance behavior. Our collision avoidance algorithm needs the only distance between the robot and the obstacles. The distances are used for subgoal generation. Simulation results show that a robot can go to the goal, carrying out subgoal generation and avoiding obstacles.

• 제어로봇시스템학회논문지
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• 제9권6호
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• pp.466-472
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• 2003

This paper describes a tracking control for the mobile robot based on fuzzy systems. Since the mobile robot has the nonholonomic constraints, these constraints should be considered to design a tracking controller for the mobile robot. One of the well-known tracking controllers for the mobile robot is the back-stepping controller. The conventional back-stepping controller includes the dynamics and kinematics of the mobile robot. The conventional back-stepping controller is affected by the derived velocity reference by a kinematic controller. To improve the performance of the conventional back-stepping controller, this paper uses the fuzzy systems known as the nonlinear controller. The new velocity reference for the back-stepping controller is derived through the fuzzy inference. Fuzzy rules are selected for gains of the kinematic controller. The produced velocity reference has properly considered the varying reference trajectories. Simulation results show that the proposed controller is more robust than the conventional back-stepping controller.