A Normalized Measurement Vector Model for Enhancing Localization Performance of 6-DoF Bearing-only SLAM

International Journal of Control, Automation and Systems - This study proposes a novel bearing measurement model in order to improve the localization performance of 6-DoF SLAM (six...     

INS/vSLAM system using distributed particle filter

In implementing an INS/SLAM integrated navigation system based on the vision sensor, a suboptimal nonlinear filter is used to figure out the nonlinear characteristics in measurement and noise model. When a conventional centralized filter is used, however, the entire state vectors need to be reconfigured in every necessary cycle as the number of feature points changes, which is hard to isolate potential faults. Furthermore, any change in the number of feature points and a subsequent increase in the dimension of state variables may result in an exponential growth in computation quantities. In order to address these issues, this paper presents a distributed particle filter approach for implementing a vision sensor based INS/SLAM system. The proposed system has several local filters which are subject to change flexibly by the number of feature points, and separates state vectors into sub-states for vehicle dynamics and feature points so that minimum state vectors can be estimated in the master filter. Simulation results show that the distributed particle filter performs competitively as with the centralized particle filter and is capable of improving computation quantities.     

Geometrical distortion integrated performance index for vision-based navigation system

This paper proposes weighted dilution of precision (WDOP) as an indicator of the accuracy of position and attitude in vision-based navigation. WDOP accurately represents the tendencies of navigational errors. It is obtained by weighted least squares. The weight is determined by the deployment of feature points and the geometrical distortion of the vision sensor. The performance of WDOP was verified by simulation. The values of the dilution of precision (DOP) and WDOP were computed and analyzed by comparison with the navigational errors. Additionally, a correlation test was used to determine how well they reflect the trends of the navigational errors. Simulation results showed that WDOP was strongly correlated with navigational errors, which makes it a parameter that can be used to determine the quality of a vision-based navigation system. The proposed WDOP can be used as a practical indicator of navigation performance.     

Fast and accurate analyses of spacecraft dynamics using implicit time integration techniques

This paper deals with the implementation techniques of an implicit integrator to achieve fast and accurate analyses of spacecraft dynamics. For this purpose, the pseudospectral method is adopted to directly integrate the second-order system of equations for both the spacecraft dynamics and corresponding state transition matrix. Various implementation techniques are proposed to enhance the numerical efficiency and integration accuracy, which include a moving horizon approach, the decoupled integration of the second-order dynamics for the state transition matrix, and the grid adaptation method. The numerical features of the proposed techniques are investigated through their applications to a spacecraft’s motion around highly eccentric elliptic orbits, and the resultant numerical errors and computing times are compared with those from the Runge-Kutta method to show the relative efficiency and accuracy of the presented methods. In addition, an optimal two-impulse orbit transfer from the Earth to the Moon is analyzed by implementing the proposed methods using a multiple-shooting framework. The results show that the proposed techniques are extremely effective for dynamical problems requiring intensive and accurate time integrations, and can provide much better accuracy and efficiency than the explicit Runge-Kutta integrator.     

Oscillation amplitude-controlled resonant accelerometer design using a reference tracking automatic gain control

In this paper, it is presented a novel approach for the self-sustained resonant accelerometer design, which takes advantages of an automatic gain control in achieving stabilized oscillation dynamics. Through the proposed system modeling and loop transformation, the feedback controller is designed to maintain uniform oscillation amplitude under dynamic input accelerations. The fabrication process for the mechanical structure is illustrated in brief. Computer simulation and experimental results show the feasibility of the proposed accelerometer design, which is applicable to a control grade inertial sense system. Recommended by Editorial Board member Dong Hwan Kim under the direction of Editor Hyun Seok Yang. This work was supported by the BK21 Project ST·IT Fusion Engineering program in Konkuk University, 2008. This work was supported by the Korea Foundation for International Cooperation of Science & Technology(KICOS) through a grant provided by the Korean Ministry of Education, Science & Technology(MEST) in 2008 (No. K20601000001). Authors also thank to Dr. B.-L. Lee for the help in structure manufacturing. Sangkyung Sung is an Assistant Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the M.S and Ph.D. degrees in Electrical Engineering from Seoul National University in 1998 and 2003, respectively. His research interests include inertial sensors, avionic system hardware, navigation filter, and intelligent vehicle systems. Chang-Joo Kim is an Assistant Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the Ph.D. degree in Aeronautical Engineering from Seoul National University in 1991. His research interests include nonlinear optimal control, helicopter flight mechanics, and helicopter system design. Young Jae Lee is a Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the Ph.D. degree in Aerospace Engineering from the University of Texas at Austin in 1990. His research interests include integrity monitoring of GNSS signal, GBAS, RTK, attitude determination, orbit determination, and GNSS related engineering problems. Jungkeun Park is an Assistant Professor of the Department of Aerospace Engineering at Konkuk University. Dr. Park received the Ph.D. in Electrical Engineering and Computer Science from the Seoul National University in 2004. His current research interests include embedded real-time systems design, real-time operating systems, distributed embedded real-time systems and multimedia systems. Joon Goo Park is an Assistant Professor of the Department of Electronic Engineering at Gyung Book National University, Korea. He received the Ph.D. degree in School of Electrical Engineering from Seoul National University in 2001. His research interests include mobile navigation and adaptive control.     

A novel control loop design and its application to the force balance of vibratory rate sensor

This paper investigates a new loop design approach of force balance control for the vibratory rate sensor application. The proposed force balance control design takes advantages of the modified automatic gain control configuration in controlling the system’s oscillating dynamics at the sense mode. The adapted automatic gain control scheme and force balance strategy, which maintains a constant oscillation magnitude in the sense mode, have several advantages. First it is possible to analyze a complicated nonlinear feedback system using a linear control theory, which resulted in straightforward prediction of closed loop performance. Moreover the control system to achieve the design goals can be implemented using a relatively simple feedback configuration. An application to the vibratory rate sensor using the proposed automatic gain control configuration witnessed that the force balance control can be validated in a practical design process. Experiments using an actual micromachined rate sensor verified the feasibility of the proposed control scheme with demonstration of enhanced performance. Recommended by Editorial Board member Dong Hwan Kim under the direction of Editor Hyun Seok Yang. This work was supported by the BK21 Project, ST-IT Fusion Engineering program in Konkuk University, 2008. This work was supported by the KICOS through a grant provided by the Korean Ministry of Education, Science & Technology in 2008 (No. K20601000001). Sangkyung Sung is an Assistant Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the M.S. and Ph.D. degrees in Electrical Engineering from Seoul National University in 1998 and 2003, respectively. His research interests include inertial sensors, avionic system hardware, integrated navigation, and intelligent vehicle technologies. Sukchang Yun is a Ph.D. course student of the Department of Aerospace Information Engineering at Konkuk University, Korea. He received the M.S. degree in Aerospace Engineering from Konkuk University in 2009. His research interests include MEMS mechatronics and control, INS/GPS integration, and instrumentation. Woon-Tahk Sung is an Senior Engineer of the Communication Reserarch Center, Samsung Electronics Co. Ltd. He received the Ph.D. degree in School of Electrical Engineering from Seoul National University in 2007. His research interests include analog and digital control algorithm, MEMS piezo actuator, circuit design for microsystems using VCM. Chang Joo Kim is an Assistant Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the Ph.D. degree in Aeronautical Engineering from Seoul National University in 1991. His research interests include nonlinear optimal control, helicopter flight mechanics, and helicopter system design. Young Jae Lee is a Professor of the Department of Aerospace Engineering at Konkuk University, Korea. He received the Ph.D. degree in Aerospace Engineering from the University of Texas at Austin in 1990. His research interests include integrity monitoring of GNSS signal, GBAS, RTK, attitude determination, orbit determination, and GNSS related engineering problems.     

An Efficient Integrated Attitude Determination Method Using Partially Available Doppler Measurement Under Weak GPS Environment

International Journal of Control, Automation and Systems - In this paper, we propose a new and efficient method to achieve a three dimensional attitude determination through combining the Doppler...     

Estimation of leakage through radial clearance during compression process of a rolling piston rotary compressor

The leakage characteristics during the compression process in a rolling piston rotary compressor were investigated in this research. The thermodynamic conditions and geometric features during the compression process were determined from the results of a numerical compressor simulation. Refrigerant R410a and lubricant oil PVE-68 were used as working fluids. Leakage models with and without consideration of the lubricant oil effect were used to examine leakage characteristics through the radial clearance. A model for pure refrigerant that included the operating conditions and geometric characteristics of a compressor was developed using the verified results of a CFD (Computational fluid dynamics) simulation. The area ratios for both the refrigerant and lubricant oil at the radial clearance was obtained by numerical analysis during the compression process of the rolling piston rotary compressor. The results showed that the cross sectional area at the radial clearance would be charged with the pure refrigerant up to a maximum of 81.2 % during the compression process.

     

Design and Performance Validation of Integrated Navigation System Based on Geometric Range Measurements and GIS Map for Urban Aerial Navigation

International Journal of Control, Automation and Systems - This article proposes an efficient integrated navigation algorithm to secure reliable navigation solutions in urban flight environments...     

Synthetic Deep Neural Network Design for Lidar-inertial Odometry Based on CNN and LSTM

International Journal of Control, Automation and Systems - This paper proposes an integrated navigation algorithm based on the deep learning method using lidar and inertial measurements. The...