• ETRI Journal
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• v.38 no.2
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• pp.337-346
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• 2016

We propose a data-driven kinematic control method for a robotic spatial augmented reality (RSAR) system. We assume a scenario where a robotic device and a projector-camera unit (PCU) are assembled in an ad hoc manner with loose kinematic specifications, which hinders the application of a conventional kinematic control method based on the exact link and joint specifications. In the proposed method, the kinematic relation between a PCU and joints is represented as a set of B-spline surfaces based on sample data rather than analytic or differential equations. The sampling process, which automatically records the values of joint angles and the corresponding external parameters of a PCU, is performed as an off-line process when an RSAR system is installed. In an on-line process, an external parameter of a PCU at a certain joint configuration, which is directly readable from motors, can be computed by evaluating the pre-built B-spline surfaces. We provide details of the proposed method and validate the model through a comparison with an analytic RSAR model with synthetic noises to simulate assembly errors.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.3
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• pp.259-267
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• 2020

For real-time precise positioning, N-RTK (Network Real-Time Kinematic) technology is widely used these days. However, the currently operating N-RTK system has a limitation in terms of the number of users. Therefore, if reference points generate correction messages with no limit on the number of users are developed later, it is determined that an appropriate reference point installation interval is required, so that the accuracy of the N-RTK system according to the baseline distance was analyzed. This experiment utilized receivers with varying performance that estimated the rover position, and RTKLIB, an open-source software, is used for processing data. As a result, the rover position was estimated accurately with a high rate of fixed ambiguity for all the receivers. When the reference station with a baseline length of 40 km was used, the vertical RMSE (Root Mean Squared Error) was quite similar to the short baseline case, but only half of the ambiguity fixing rate was achieved. The outlier in the estimated rover position was not observed for the longer baselines in the case of a high-end receiver. It is necessary to analyze the ambiguity fixing and the accuracy of the kinematic positioning with scientific GNSS processing software.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.181-182
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• 2010

For real-time displacement monitoring of large-scale structures, the high-rate (>1 Hz) GPS data processing is necessary, which is not possible even for the scientific GPS data processing softwares. Since the baseline is generally very short in this case, most of the atmospheric effects are removed, resulting in the unknowns of position and integer ambiguity. The number of unknowns in real-time kinematic GPS positioning makes the positioning impossible with usual approach, thus two-step approach is tested in this study.

• Journal of Positioning, Navigation, and Timing
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• v.2 no.1
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• pp.19-31
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• 2013

It is well known that the accident of vehicles carrying hazardous materials incurs huge losses economically and socially. To detect and respond rapidly against the accident of a vehicle carrying hazardous materials, it is essential to estimate the relative navigation information between the forward tractor module and the backward trailer module of the vehicle reliably and accurately. In this paper, a precise relative positioning system based on GPS is designed, implemented, and evaluated as a prerequisite to design an effective relative navigation system for the vehicle carrying hazardous materials. An experiment using field-collected 10 Hz real GPS measurements showed that the designed relative positioning system achieves 22 cm accuracy within 15 epochs by float solutions. Also, it was found that cm-level integer solutions can be generated reliably after the quick convergence of float solutions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.5
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• pp.493-504
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• 2008

Space-Based Augmentation System (SBAS), which is one of the GPS augmentation systems, is a Wide-Area Differential GPS that provides differential GPS corrections and integrity data. In this study, we did performance analysis of kinematic SBAS surveying by conducting Real-Time Kinematic (RTK), DGPS, standalone, and SBAS surveys. Considering static survey results as truth, 2-D Root Mean Square (RMS) error and 3-D RMS error were computed to evaluate the positioning accuracy of each survey method. As a result, the 3-D positioning error of RTK was 13.1cm, DGPS 126.0cm, standalone (L1/L2) 135.7cm, standalone (C/A) 428.9cm, and SBAS 109.2cm. The results showed that the positioning accuracy of SBAS was comparable to that of DGPS.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.86-93
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• 2017

The Expanded Guide Circle (EGC) method has been originally proposed as the guidance navigation method for improving the efficiency of the remote operation using the sensory information. The previous algorithm is, however, concerned only for the omni-directional mobile robot, so it needs to suggest a suitable one for a mobile robot with non-holonomic constraints. The ego-kinematic transform is a method to map points of $R^2$ into the ego-kinematic space which implicitly represents non-holonomic constraints for admissible paths. Thus, robots with non-holonomic constraints in the ego-kinematic space can be considered as "free-flying object". In this paper, we propose an effective obstacle avoidance method for mobile robots with non-holonomic constraints by applying EGC method in the ego-kinematic space using the ego-kinematic transformation. This proposed method shows that it works better for non-holonomic mobile robots such as differential-drive robot than the original one. The simulation results show its effectiveness of performance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.271-279
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• 1998

This paper discusses the development of compaction management system using Real Time Kinematic (RTK) GPS technology for the efficient management or compaction. The use or RTK provides the land surveyors with a graphical display of his/her corrected position on the ground at that moment in time. In this work, we intended to improve the efficiency of compaction management showing the route of rollers and the total number of compaction obtained from management software (GPSROLL v.1.0) developed in this study. The RTK GPS system installed on the roller. To improve the efficiency of field management, GPSROLL software provides also data processing module for the field soil test and the field surveying data. GPSROLL system is based on the Korean GUI for user-friendly data input and output.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.565-567
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• 2018

The rover acquires its own position information using satellites signals provided by several satellites(at least four or more). For the present, GNSS systems are widely used in various fields. However, there are many factors that cause accuracy errors in positioning between rovers and GNSS satellites. Due to satellite time error, orbit error, ionospheric & convective refraction, multipath, etc., rover can't acquire precise position. Differential GPS(DGPS) and Real-Time Kinematic(RTK) have been developed as compensation techniques to reduce such errors. In this paper, we intend to develop a terminal with RTK technique to acquire precise position information of mobile station.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.27-40
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• 1996

This paper proposed a kinematic modeling methodlogy and feedback control system based on kinematics for 2 degrees of freedom of 4-wheeled mobile robot. We assigned coordinate systems to specify the transformation matirx and write the kinematic equation of motion. We derived the actuated inverse and sensed forwared solution for the calculation of actual robot orientation and the desired robot orientation. It is the most significant error and has the largest impact on the motion accuracy. To calculate the WMR position in real time, we introduced the dead-reckoning algorithm and composed two feedback control system that is based on kinematics. Through the simulation result, we compare with the ffedback control system for position control.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.19-29
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• 1997

This paper presents stable kinematic modeling and path planning and path tracking algorithms for the poisition control of 4-wheeled 2-d.o.f(degree of freedom) mobile robot. We drived the actuated inverse and sensed forward solution for the calculation of actuator velocity and robot velocities. the deal-reckoning algorithm is introduced to calculate the position of WMR in real time. The gaussian functions are applied to control and to design the smooth orientation angle of WMR and the path planning algorithm for obstacle avoidance is prosed. We composed feedback control system to compensate for error because of uncertainty kinematic modeling and measurement noise. The simulation resutls show that the proposed kinematkc modeling and path planning and feedback control algorithms are useful.