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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korea Robotics Society
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Journal DOI :
The Korea Robotics Society
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Volume & Issues
Volume 9, Issue 4 - Nov 2014
Volume 9, Issue 3 - Aug 2014
Volume 9, Issue 2 - May 2014
Volume 9, Issue 1 - Feb 2014
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Graph-based Segmentation for Scene Understanding of an Autonomous Vehicle in Urban Environments
Seo, Bo Gil ; Choe, Yungeun ; Roh, Hyun Chul ; Chung, Myung Jin ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 1~10
DOI : 10.7746/jkros.2014.9.1.001
In recent years, the research of 3D mapping technique in urban environments obtained by mobile robots equipped with multiple sensors for recognizing the robot's surroundings is being studied actively. However, the map generated by simple integration of multiple sensors data only gives spatial information to robots. To get a semantic knowledge to help an autonomous mobile robot from the map, the robot has to convert low-level map representations to higher-level ones containing semantic knowledge of a scene. Given a 3D point cloud of an urban scene, this research proposes a method to recognize the objects effectively using 3D graph model for autonomous mobile robots. The proposed method is decomposed into three steps: sequential range data acquisition, normal vector estimation and incremental graph-based segmentation. This method guarantees the both real-time performance and accuracy of recognizing the objects in real urban environments. Also, it can provide plentiful data for classifying the objects. To evaluate a performance of proposed method, computation time and recognition rate of objects are analyzed. Experimental results show that the proposed method has efficiently in understanding the semantic knowledge of an urban environment.
Exact External Torque Sensing System for Flexible-Joint Robot: Kalman Filter Estimation with Random-Walk Model
Park, Young-Jin ; Chung, Wan-Kyun ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 11~19
DOI : 10.7746/jkros.2014.9.1.011
In this paper, an external torque estimation problem in one-degree-of-freedom (1-DOF) flexible-joint robot equipped with a joint-torque sensor is revisited. Since a sensor torque from the joint-torque sensor is distorted by two dynamics having a spring connection, i.e., motor dynamics and link dynamics of a flexible-joint robot, a model-based estimation, rather than a simple linear spring model, should be required to extract external torques accurately. In this paper, an external torque estimation algorithm for a 1-DOF flexible-joint robot is proposed. This algorithm estimates both an actuating motor torque from the motor dynamics and an external link torque from the link dynamics simultaneously by utilizing the flexible-joint robot model and the Kalman filter estimation based on random-walk model. The basic structure of the proposed algorithm is explained, and the performance is investigated through a custom-designed experimental testbed for a vertical situation under gravity.
Exact Reshaping of Motor Dynamics in Flexible-Joint Robot using Integral Manifold Feedback Control
Park, Young-Jin ; Chung, Wan-Kyun ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 20~27
DOI : 10.7746/jkros.2014.9.1.020
In this paper, an exact reshaping method for the motor dynamics of a flexible-joint robot is proposed using an integral manifold approach. Obtaining the exact model for both motor-side and link-side dynamics of a flexible-joint robot is difficult due to its under-actuated nature and complex dynamics. Despite the simple structure of the motor-side dynamics, they are difficult to model accurately for a flexible-joint robot due to motor disturbances, especially when speed reducers such as harmonic drives are installed. An integral manifold feedback control (IMFC) is proposed to reshape the motor dynamics. Based on the integral manifold approach, it is theoretically proved that the IMFC reshapes motor dynamics exactly even with bounded disturbances such as motor friction. The performance of the proposed IMFC is verified experimentally using a single degree-of-freedom flexible-joint robot under gravity conditions.
Implementation of Bayesian Filter Method and Range Measurement Analysis for Underwater Robot Localization
Noh, Sung Woo ; Ko, Nak Yong ; Kim, Tae Gyun ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 28~38
DOI : 10.7746/jkros.2014.9.1.028
This paper verifies the performance of Extended Kalman Filter(EKF) and MCL(Monte Carlo Localization) approach to localization of an underwater vehicle through experiments. Especially, the experiments use acoustic range sensor whose measurement accuracy and uncertainty is not yet proved. Along with localization, the experiment also discloses the uncertainty features of the range measurement such as bias and variance. The proposed localization method rejects outlier range data and the experiment shows that outlier rejection improves localization performance. It is as expected that the proposed method doesn't yield as precise location as those methods which use high priced DVL(Doppler Velocity Log), IMU(Inertial Measurement Unit), and high accuracy range sensors. However, it is noticeable that the proposed method can achieve the accuracy which is affordable for correction of accumulated dead reckoning error, even though it uses only range data of low reliability and accuracy.
Accurate Calibration of Kinematic Parameters for Two Wheel Differential Drive Robots by Considering the Coupled Effect of Error Sources
Lee, Kooktae ; Jung, Changbae ; Jung, Daun ; Chung, Woojin ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 39~47
DOI : 10.7746/jkros.2014.9.1.039
Odometry using wheel encoders is one of the fundamental techniques for the pose estimation of wheeled mobile robots. However, odometry has a drawback that the position errors are accumulated when the travel distance increases. Therefore, position errors are required to be reduced using appropriate calibration schemes. The UMBmark method is the one of the widely used calibration schemes for two wheel differential drive robots. In UMBmark method, it is assumed that odometry error sources are independent. However, there is coupled effect of odometry error sources. In this paper, a new calibration scheme by considering the coupled effect of error sources is proposed. We also propose the test track design for the proposed calibration scheme. The numerical simulation and experimental results show that the odometry accuracy can be improved by the proposed calibration scheme.
Improvement of surgical haptic master device using cable-conduit and backlash compensation by smooth backlash inverse
Choi, Woo Hyeok ; Yoon, Sung Min ; Lee, Min Cheol ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 48~56
DOI : 10.7746/jkros.2014.9.1.048
In robotic surgery, a surgeon checks only a surgical site of patient in the progress of surgery by vision and sound information. In order to solve this limited information, the haptic function is necessary. And haptic surgical robot is also necessary to design a haptic master device. The master device for laparoscope operation with cable-conduit was developed in previous research to give haptic function. It suggested a possibility of developing a master device by using the cable-conduit. However, it is very inconvenient to use. Therefore, this paper suggests a new mechanism design structure to solve the problems of the previous work by new forming a new master device. And it has proved that it's usability is better than previous one. Furthermore it has also experimented and analyzed that a backlash of new master device is compensated by smooth backlash inverse algorithm.
Bio-inspired Walking and Swimming Underwater Robot Designing Concept and Simulation by an Approximated Model for the robot
Kim, Hee-Joong ; Jun, Bong-Huan ; Lee, Jihong ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 57~66
DOI : 10.7746/jkros.2014.9.1.057
This paper describes the design concept of a bio-inspired legged underwater and estimating its performance by implementing simulations. Especially the leg structure of an underwater organism, diving beetles, is fully adopted to our designing to employ its efficiency for swimming. To make it possible for the robot to both walk and swim, the transformable kinematic model according to applications of the leg is proposed. To aid in the robot development and estimate swimming performance of the robot in advance, an underwater simulator has been constructed and an approximated model based on the developing robot was set up in the simulation. Furthermore, previous work that we have done, the swimming locomotion produced by a swimming patten generator based on the control parameters, is briefly mentioned in the paper and adopted to the simulation for extensive studies such as path planning and control techniques. Through the results, we established the strategy of leg joints which make the robot swim in the three dimensional space to reach effective controls.
Design of a User-Friendly Control System using Least Control Parameters
Heo, Youngjin ; Park, Daegil ; Kim, Jinhyun ;
The Journal of Korea Robotics Society, volume 9, issue 1, 2014, Pages 67~77
DOI : 10.7746/jkros.2014.9.1.067
An electric motor is the one of the most important parts in robot systems, which mainly drives the wheel of mobile robots or the joint of manipulators. According to the requirement of motor performance, the controller type and parameters vary. For the wheel driving motors, a speed tracking controller is used, while a position tracking controller is required for the joint driving motors. Moreover, if the mechanical parameters are changed or a different motor is used, we might have to tune again the controller parameters. However, for the beginners who are not familiar about the controller design, it is hard to design pertinently. In this paper, we develop a nominal robust controller model for the velocity tracking of wheel driving motors and the position tracking of joint driving motors based on the disturbance observer (DOB) which can reject disturbances, modeling errors, and dynamic parameter variations, and propose the methodology for the determining the least control parameters. The proposed control system enables the beginners to easily construct a controller for the newly designed robot system. The purpose of this paper is not to develop a new controller theory, but to increase the user-friendliness. Finally, simulation and experimental verification have performed through the actual wheel and joint driving motors.