Kil-To Chong

Control-Relevant Discretization of Nonlinear Systems With Time-Delay Using Taylor-Lie Series

A new time-discretization method for the development of a sampled-data representation of a nonlinear continuous-time input-driven system with time delay is proposed. It is based on the Taylor-Lie series expansion method and zero-order hold assumption. The mathematical structure of the new discretization scheme is explored and characterized as useful for establishing concrete connections between numerical and system-theoretic properties. In particular, the effect of the time-discretization method on key properties of nonlinear control systems, such as equilibrium properties and asymptotic stability, is examined. The resulting time-discretization provides a finite-dimensional representation for nonlinear control systems with time-delay enabling the application of existing controller design techniques. The performance of the proposed discretization procedure is evaluated using the case study of a two-degree-of-freedom mechanical system that exhibits nonlinear behavior. Various sampling rates and time-delay values are considered.

Design of Lateral Fuzzy-PI Controller for Unmanned Quadrotor Robot

Quadrotor UAV (Unmanned Aerial Vehicle) is a flying robotic platform which has drawn lots of attention in the recent years. The attraction comes from the fact that it is able to perform agile VTOL (Vertical Take-Off Landing) and hovering functions. In addition, the efficient modular structure composed of four electric rotors makes its design easier compared to other single-rotor type helicopters. In many cases, a quadrotor often utilizes vision systems in order to obtain altitude control and navigation solution in hostile environments where GPS receivers are not working or deniable. For carrying out their successful missions, it is essential for flight control systems to have fast and stable control responses of heading angle outputs. This paper presents a Fuzzy Logic based lateral PI controller to stabilize and control the quadrotor vehicle equipped with vision systems. The advantage of using the fuzzy based PI controller lies in the fact that it could acquire a desired output response of a heading angle even in presence of disturbances and uncertainties. The performance comparison of the newly proposed Fuzzy-PI controller and the conventional PI controller was carried out with various simulation results.

A Lyapunov function approach to longitudinal control of vehicles in a platoon

The Lyapunov stability theorem is used to derive a control law which can be used to control the spacing between vehicles in a platoon. A third order system is adopted to model the vehicle and powertrain dynamics. In addition, the concept of expected spacing error is introduced and used to form a Lyapunov function. Then a control law which always decreases the Lyapunov function is selected. A platoon of four vehicles and various scenarios are used to demonstrate the performance of the proposed control law.

Analysis of dead zone sources in a closed-loop fiber optic gyroscope

Analysis of the dead zone is among the intensive studies in a closed-loop fiber optic gyroscope. In a dead zone, a gyroscope cannot detect any rotation and produces a zero bias. In this study, an analysis of dead zone sources is performed in simulation and experiments. In general, the problem is mainly due to electrical cross coupling and phase modulation drift. Electrical cross coupling is caused by interference between modulation voltage and the photodetector. The cross-coupled signal produces spurious gyro bias and leads to a dead zone if it is larger than the input rate. Phase modulation drift as another dead zone source is due to the electrode contamination, the piezoelectric effect of the LiNbO3 substrate, or to organic fouling. This modulation drift lasts for a short or long period of time like a lead-lag filter response and produces gyro bias error, noise spikes, or dead zone. For a more detailed analysis, the cross-coupling effect and modulation phase drift are modeled as a filter and are simulated in both the open-loop and closed-loop modes. The sources of dead zone are more clearly analyzed in the simulation and experimental results.

Parameter estimation method for coupled tank system using Dual Extended Kalman filter

In this paper, we propose the estimation method for the parameter of dynamic system using Dual Extended Kalman filter. When state is unavailable, the dual extended kalman filter is available. And it is widely used in simultaneously estimating the state and parameter of dynamic systems. The dynamic system in this paper is Coupled Tank. And then the estimating parameters are the orifice coefficients of system. In order to analyze the performance for the parameter estimation, we implemented the computer simulation and compared the results of the dual extended kalman filter and the extended kalman filter. As per the results, the performance of dual kalman filter showed better results than that the performance of extended kalman filter.

Implementation of MariComm bridge for LTE-WLAN maritime heterogeneous relay network

In this study, we shortly introduce MariComm bridge of MariComm (Maritime Broadband Communication) project to provide broadband internet/multimedia services available at a rate of 1 Mbps or more on the sea. MariComm bridge enables MariStations to form the maritime heterogeneous relay networks. Thanks to this bridge function, MariStation can act as a gateway node or a relay node according to the connection possibility of a terrestiral base station. And finally, marine performance tests of this noble maritime communication system on 4 vessels in the Korean southern sea are introduced.

Smart device interface for intelligent control of pipeline type UV Sterilizer

In a pipeline type UV sterilizer, UV lamps are located in the conduit. So it is hard to find out whether the lamp is working or not from the outside of sterilizer. Thus, it is necessary to install a control panel at outside to monitor and control of UV lamp and cleaning wiper. However, setting up the control panel is not only needed the installation cost but also needed another space. In this paper, proposed interface is using smart device to monitor and control of a pipeline type UV sterilizer. It is more convenient and economical than the existing control panel. Also it is extensible to add more sensors and motion for cleaning UV lamp guard to keep sterilizing power.

Research to improve the performance of self localization of mobile robot utilizing video information of CCTV

Abstract The indoor areas for the commercial use of automatic monitoring systems of mobile robot localization improves the cognitive abilities and the needs of the environment with this emerging and existing mobile robot localization, and object recognition methods commonly around its great sensor are leveraged. On the other hand, there is a difficulty with a problem-solving self-location estimation in indoor mobile robots using only the sensors of the robot. Therefore, in this paper, a self-position estimation method for an enhanced and effective mobile robot is proposed using a marker and CCTV video that is already installed in the building. In particular, after recognizing a square mobile robot and the object from the input image, and the vertices were confirmed, the feature points of the marker were found, and marker recognition was then performed. First, a self-position estimation of the mobile robot was performed according to the relationship of the image marker and a coordinate transformation was performed. In particular, the estimation was converted to an absolute coordinate value based on CCTV information, such as robots and obstacles. The study results can be used to make a convenient self-position estimation of the robot in the indoor areas to verify the self-position estimation method of the mobile robot. In addition, experimental operation was performed based on the actual robot system.

The linear model analysis and Fuzzy controller design of the ship using the Nomoto model

Abstract This paper developed the algorithm for improving the performance the auto pilot in the autonomous vehicle system consisting of the Track keeping control, the Automatic steering, and the Automatic mooring control. The automatic steering is the control device that could save the voyage distance and cost of fuel by reducing the unnecessary burden of driving due to the continuous artificial navigation, and avoiding the route deviation. During the step of the ship autonomic navigation control, since the wind power or the tidal force could make the ship deviate from the fixed course, the automatic steering calculates the difference between actual sailing line and the set course to keep the ship sailing in the vicinity of intended course. first, we could get the transfer function for the modeling of ship according to the Nomoto model. Considering the maneuverability, we propose it as linear model with only 4 degree of freedoms to present the heading angle response to the input of rudder angle. In this paper, the model of ship is derived from the simplified Nomoto model. Since the proposed model considers the maximum angle and rudder rate of the ship auto pilot and also designs the Fuzzy controller based on existing PID controller, the performance of the steering machine is well improved.Key Words : Auto-pilot, Nomoto model, Fuzzy, PID, Steering machine

Design of a Cross-obstacle Neural Network Controller using Running Error Calibration

An obstacle avoidance method for a mobile robot is proposed in this paper. Our research was focused on the obstacles that can be found indoors since a robot is usually used within a building. It is necessary that the robot maintain the desired direction after successfully avoiding the obstacles to achieve a good autonomous navigation performance for the specified project mission. Sensors such as laser, ultrasound, and PSD (Position Sensitive Detector) can be used to detect and analyze the obstacles. A PSD sensor was used to detect and measure the height and width of the obstacles on the floor. The PSD sensor was carefully calibrated before measuring the obstacles to achieve better accuracy. Data obtained from the repeated experiments were used to plot an error graph which was fitted to a polynomial curve. The polynomial equation was used to navigate the robot. We also obtained a direction-error model of the robot after avoiding the obstacles. The prototypes for the obstacle and direction-error were modeled using a neural network whose inputs are the obstacle height, robot speed, direction of the wheels, and the error in direction. A mobile robot operated by a notebook computer was setup and the proposed algorithm was used to navigate the robot and avoid the obstacles. The results showed that our algorithm performed very well during the experiments.