간행물
로봇학회논문지 KCI 등재 The Journal of Korea Robotics Society
- 발행기관 한국로봇학회
- 자료유형 학술지
- 간기 계간
- ISSN 1975-6291 (Print)2287-3961 (Online)
- 수록기간 2006 ~ 2020
- 주제분류 공학 > 제어계측공학 공학 분류의 다른 간행물
- 십진분류KDC 559DDC 629
권호리스트/논문검색
제13권 제2호 (통권 제48호) (2018년 6월) 9건
1.
2018.06
서비스 종료(열람 제한)
This study focuses on autonomous exploration based on map expansion for an underwater robot equipped with acoustic sonars. Map expansion is applicable to large-area mapping, but it may affect localization accuracy. Thus, as the key contribution of this paper, we propose a method for underwater autonomous exploration wherein the robot determines the trade-off between map expansion ratio and position accuracy, selects which of the two has higher priority, and then moves to a mission step. An occupancy grid map is synthesized by utilizing the measurements of an acoustic range sonar that determines the probability of occupancy. This information is then used to determine a path to the frontier, which becomes the new search point. During area searching and map building, the robot revisits artificial landmarks to improve its position accuracy as based on imaging sonar-based recognition and EKF-SLAM if the position accuracy is above the predetermined threshold. Additionally, real-time experiments were conducted by using an underwater robot, yShark, to validate the proposed method, and the analysis of the results is discussed herein.
2.
2018.06
서비스 종료(열람 제한)
This paper presents about design efforts of a human-sized quadruped robot leg for high energy efficiency, and verifications. One of the representative index of the energy efficiency is the Cost of Transport (COT), but increased in the energy or work done is not calculated in COT. In this reason, the input to the output energy efficiency should be also considered as a very important term. By designing the robot with customized motor housing, small rotational inertia, and low gear ratio to reduce friction, high energy efficiency was achieved. Squatting motion of one leg was performed and simulation results were compared to the experimental results for validation. The developed 50 kg robot can lift the weight up to 200 kg, and during squatting, it showed high energy efficiency. The robot showed 71% input to output energy efficiency in positive work. Peak current during squatting only appears to be 0.3 A.
3.
2018.06
서비스 종료(열람 제한)
In this paper, a soft robotic arm which can prevent impact injury during human-robot interaction is introduced. Two degrees of freedom joint are required to realize free movement of the robotic arm. A robotic joint concept with a single degree of freedom is presented using simple inflatable elements, and then extended to form a robotic joint with two degrees of freedom joint using similar manufacturing methods. The robotic joint with a single degree of freedom has a joint angle of 0° bending angle when both chamber are inflated at equal pressures and maximum bending angles of 28.4° and 27.1° when a single chamber if inflated. The robotic joint with two degrees of freedom also has a bending angle of 0° in both direction when all three chambers are inflated at equal pressures. When either one or two chambers were pressurized, the robotic joint performed bending towards the uninflated chambers.
4.
2018.06
서비스 종료(열람 제한)
A small and lightweight crawling robots have been actively studied thanks to their outstanding mobility and maneuverability. Those robots can navigate into more confined spaces that larger robots are unable to reach or enter such as debris and caves. In this paper, we propose a milli-scale hexapedal robot based on planar linkage design. To make this possible, two necessary conditions for successful crawling are satisfied: thrust force from the ground and aerial phase while running. These conditions are achieved through a newly developed leg design. The robot has a pair of legs and each leg has three feet. Those feet alternatively moves based on 1DOF planar linkage. This linkage is installed at each side of the robot and finally the robot shows the alternating gait and aerial phase during running. As a result, the robot runs with the crawling speed of 0.9 m/s.
5.
2018.06
서비스 종료(열람 제한)
In this paper, a high performance underwater vehicle which can be manufactured at low cost is designed and fabricated, and its performance is verified through experiments. To improve efficiency, the Myring equation is used to design the appearance and the duct structure including the thruster is planned to increase the propulsion efficiency while reducing the drag force. Through various methods, it is secured stable waterproof performance, and also is devised to have high speed movement and turning performance. The developed underwater vehicle is equipped with a high output BLDC motor to achieve a linear speed of up to 2 m/s and can change direction rapidly with stability through four rudders. The rudders are driven by coupling a timing belt and a pulley by extending the axis of a servo motor, and are equipped at the end of the body to turn heading. In addition, for stable posture control, the roll keeps its internal center of gravity low and maintains its stability due to restoring force. By controlling the four rudders, pitch and yaw are handled by the PID controller and show stable performance. To investigate the horizontal turning performance, it is confirmed that the yaw rate controller is designed and stable yaw rate control is performed.
6.
2018.06
서비스 종료(열람 제한)
To fly a drone or unmanned aerial vechicle(UAV) safely, its pilot needs to maintain high situation awareness of its flight space. One of the important ways to improve the flight space awareness is to integrate both the global and the local navigation map a drone provides. However, the drone pilot often has to use the inconsistent reference frames or perspectives between the two maps. In specific, the global navigation map tends to display space information in the third-person perspective, whereas the local map tends to use the first-person perspective through the drone camera. This inconsistent perspective problem makes the pilot use mental rotation to align the different perspectives. In addition, integrating different dimensionalities (2D vs. 3D) of the two maps may aggravate the pilot’s cognitive load of mental rotation. Therefore, this study aims to investigate the relation between perspective difference (0°, 90°, 180°, 270°) and the map dimensionality matches (3D-3D vs. 3D-2D) to improve the way of integrating the two maps. The results show that the pilot’s flight space awareness improves when the perspective differences are smaller and also when the dimensionalities between the two maps are matched.
7.
2018.06
서비스 종료(열람 제한)
Obstacle avoidance is one of the most important parts of autonomous mobile robot. In this study, we proposed safe and efficient local path planning of robot for obstacle avoidance. The proposed method detects and tracks obstacles using the 3D depth information of an RGB-D sensor for path prediction. Based on the tracked information of obstacles, the paths of the obstacles are predicted with probability circle-based spatial search (PCSS) method and Gaussian modeling is performed to reduce uncertainty and to create the cost function of caution. The possibility of collision with the robot is considered through the predicted path of the obstacles, and a local path is generated. This enables safe and efficient navigation of the robot. The results in various experiments show that the proposed method enables robots to navigate safely and effectively.
8.
2018.06
서비스 종료(열람 제한)
This paper proposes a unified framework that overcomes four motion constraints including joint limit, kinematic singularity, algorithmic singularity and obstacles. The proposed framework is based on our previous works which can insert or remove tasks continuously using activation parameters and be applied to avoid joint limit and singularity. Additionally, we develop a method for avoiding obstacles and combine it into the framework to consider four motion constraints simultaneously. The performance of the proposed framework was demonstrated by simulation tests with considering four motion constraints. Results of the simulations verified the framework’s effectiveness near joint limit, kinematic singularity, algorithmic singularity and obstacles. We also analyzed sensitivity of our algorithm near singularity when using closed loop inverse kinematics depending on magnitude of gain matrix.
9.
2018.06
서비스 종료(열람 제한)
RRT* (Rapidly exploring Random Tree*) based algorithms are widely used for path planning. Informed RRT* uses RRT* for generating an initial path and optimizes the path by limiting sampling regions to the area around the initial path. RRT* algorithms have several limitations such as slow convergence speed, large memory requirements, and difficulties in finding paths when narrow aisles or doors exist. In this paper, we propose an algorithm to deal with these problems. The proposed algorithm applies the image skeletonization to the gridmap image for generating an initial path. Because this initial path is close to the optimal cost path even in the complex environments, the cost can converge to the optimum more quickly in the proposed algorithm than in the conventional Informed RRT*. Also, we can reduce the number of nodes and memory requirement. The performance of the proposed algorithm is verified by comparison with the conventional Informed RRT* and Informed RRT* using initial path generated by A*.
