Moon G. Joo

A class of hierarchical fuzzy systems with constraints on the fuzzy rules

This paper presents a class of hierarchical fuzzy systems where previous layer outputs are used not in IF-parts, but only in THEN-parts of the fuzzy rules of the current layer. The proposed scheme is shown to be a universal approximator to any real continuous function on a compact set if complete fuzzy sets are used in the IF-parts of the fuzzy rules with singleton fuzzifier and center average defuzzifier. From the example of ball-and-beam control system simulation, it is demonstrated that the proposed scheme approximates with high accuracy a model nonlinear controller with fewer fuzzy rules than a centralized fuzzy system, and its control performance is comparable to that of a nonlinear controller.

A Method of Converting a Fuzzy System to a Two-Layered Hierarchical Fuzzy System and Its Run-Time Efficiency

In classical single-layer fuzzy systems (FSs), the number of rules and the run-time computational requirements increase exponentially with the number of input domains. In this paper, we present a method for converting a multidimensional FS to a two-layer hierarchical FS that reduces the number of rules and improves the run-time efficiency. The first layer of the two-layer system consists of FSs whose rule bases can be represented as linearly independent vectors. The second layer constructs linear combinations of the rule base vectors. The effectiveness of the hierarchical conversion in reducing the number of rules and improving efficiency is demonstrated on a classic control problem and a simulated higher dimensional FS.

A tactics for robot soccer with fuzzy logic mediator

This paper presents a tactics using fuzzy logic mediator that selects proper robot action depending on the positions and the roles of adjacent two robots. Conventional Q-learning algorithm, where the number of states increases exponentially with the number of robots, is not suitable for a robot soccer system, because it needs so much calculation that processing cannot be accomplished in real time. A modular Q-learning algorithm reduces a number of states by partitioning the concerned area, where mediator algorithm for cooperation of robots is used additionally. The proposed scheme not only reduces a number of a calculation but also combines a robot action selection with robot cooperation by means of fuzzy logic system.

A Study on an Integral State Feedback Controller for Way-point Tracking of an AUV

A state feedback controller with integration of output error is proposed for way-point tracking of an AUV (Autonomous Underwater Vehicle). For the steering control on the XY plane, the proposed controller uses three state variables (sway velocity, yaw rate, heading angle) and the integral of the steering error, and for the depth control on the XZ plane, it uses four state variables (pitch rate, depth, pitch angle) and the integral of the depth error. From the simulation using Matlab/Simulink, we verify that the performance of the proposed controller is satisfactory within an error range of 1m from the target way-point for arbitrarily chosen sets of consecutive way-points.

Implementation of AUV Test-Bed

This study deals with the hardware architecture of developing autonomous underwater vehicle and an application software to test its test bed. Overall hardware consists of a main control processor, a sensor data gathering processor to give an accurate position and posture from IMU, GPS, depth sensor by using extended Kalman filter, and a actuator control processor to control a thruster and four rudder motors. An application program was also designed to test communication with a host computer and to test functions of each processor.

Identification and Distance Detection for Ultrasonic Sensor by Correlation Method

Abstract This paper presents a method for identification and distance detection for ultrasonic sensors of indoor mobile robot by using correlation scheme. The transmitted signal is identified by correlation between known model patterns and the patterned signal from transmitters and this scheme is useful when multiple sensors are involved. Distance detection by correlation is shown to be more accurate than conventional threshold method.

Way-point tracking for a hovering AUV by PID controller

In this paper, we suggest a PID controller for tracking the way-points of hovering autonomous underwater vehicle(HAUV). The PID controller is aimed at tracking arbitrary way-points and the way-points are established as the surveillance pathway for an offshore plant construction. Controllers are composed of a vertical plane controller and a horizontal plane controller. To verify the performance of the suggested controller, we designed a simulator using Matlab/Simulink, and the parameters of HAUV are those of developing HAUV. As the result of simulation, the PID controller chased all the way-points within error range of 1 meter, and therefore shows durability of suggested controller.

Design and Implementation of A Hovering AUV with A Rotatable-Arm Thruster

In this paper, we propose the hardware and software of a test-bed of a hovering AUV (autonomous underwater vehicle). Test-bed to develop as the underwater robot for the hovering -type is planning to apply for marine resource development and exploration for deep sea. The RTU that controls a azimuth thruster and a vertical thruster of test-bed is a intergrated-type thruster. The main control unit that collects sensor`s data and performs high-speed processing and controls a movement of test-bed is a underwater hybrid navigation system. Also it transfers position, posture, state information of test-bed to the host PC of user using a wireless communication. The host PC checks a test-bed in real time by using a realtime monitoring system that is implemented by LabVIEW.

An LQR Controller for Autonomous Underwater Vehicle

In this paper, An LQR controller is proposed for way-point tracking of AUV (Autonomous Underwater Vehicle). The LQR controller aims at tracking a series of way-points which operator registers arbitrarily in advance. It consists of a depth controller and a steering controller and AUVs surge speed is assumed varying to consider the dynamic environment of the underwater. In order to show the performance, a conventional state feedback controller is compared with the proposed controller by the simulation using Matlab/Simulink. The parameters of AUV developed by the authors laboratory are used. In the simulation, we verify that the LQR controller can track all the way-points within 1 m error range under the varying surge speed, which proves the robustness of the LQR controller.

Development of HAUV's Test-Bed using the Azimuth Thruster

In this paper, we discuss the development of test-bed prior to the development of HAUV (hovering autonomous underwater vehicle). The test-bed under development is comprised of RTU (rotating thruster unit), the main control unit, and the power unit. The RTU, consisting of azimuth thruster and motor control board, is an integratedtype thruster to operate the test-best by controlling the direction and the propulsion of the azimuth thruster. The main control unit consists of IMU, depth sensor, main PC, and navigation control & sensor processing board. The navigation control and sensor processing board collects data transmitted from the IMU and the depth sensor and performs high-speed calculations to apply the navigation system. The main PC transmits commands to the navigation control and sensor processing board as well as the motor control board, and engages in communication with the outside. The user performs real-time monitoring through communication with main PC. In the power unit, the power system considering emergency situations is applied. The power unit supplies power to RTU and the main control unit.