• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.145-151
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• 2003

A global ultrasonic sensor system for self-localization of a mobile robot is proposed in this paper. The global ultrasonic sensor system consists of three or more ultrasonic transmitters fixed at some positions in the world coordinate and receivers in the moving coordinate of a mobile robot. In this global sensor system it is easy to get state vector of the mobile robot in the world coordinate from the distance information between each ultrasonic transmitter and receiver. An extended kalman filter algorithm is used to process the noisy ultrasonic signal and to estimate the state vector. In case of using several independent ultrasonic transmitters, it is necessary to avoid the cross talk among the ultrasonic waves and to synchronize between each ultrasonic transmitter and receiver. The small sized radio frequency modules are adopted to solve the cross talk and the synchronization problem Computer simulation and experiments are carried out to verify the effectiveness of the proposed ultrasonic sensor system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.846-851
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• 2004

In this paper, we propose a global ultrasonic system for the self-localization and autonomous navigation of indoor mobile robots. The ultrasonic sensor is regarded as the most cost-effective ranging system among the possible alternatives, and it is widely used for general purpose, since it requires simple electronic drivers and has relatively high accuracy. The global ultrasonic system presented in this paper consists of four or more ultrasonic generators fixed at reference positions in the global coordinates of an indoor environment and two receivers mounted on the mobile robots. By using the RF (Radio Frequency) modules added to the ultrasonic sensors, the robot is able to control the ultrasonic generation and to obtain the critical distances from the reference positions, which are required in order to localize is position in the global coordinates. A kalman filter algorithm designed for the self-localization using the global ultrasonic system and the experimental results of the autonomous navigation are presented in this paper.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.955-961
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• 2006

The global ultrasonic system for the self-localization of a mobile robot consists of several ultrasonic transmitters fixed at some reference positions in the global coordinates of robot environment. By activating the ultrasonic transmitters, the mobile robot is able to get the distance to the ultrasonic transmitters and compute its own position in the global coordinate. Due to the limitation on the ultrasonic signal strength and beam width as well as the environmental obstacles however, the ultrasonic signals from some generator may not be transmitted to the robot. Thus, instead of activating the all ultrasonic transmitters, it is necessary to select some ultrasonic generators to activate based on the current robot position. In this paper, we propose a selective activation algorithm for self-localization with the global ultrasonic system. The selective activation algorithm gets the meaningful ultrasonic data at every sampling instants, which results in the faster and more accurate response of the self-localization than the conventional sequential activation. Through the self-localization and path following control, we verify the effectiveness of the proposed selective activation algorithm.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2421-2423
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• 2002

A global ultrasonic sensor system for self-localization of an indoor mobile robot is proposed in this paper. By the global ultrasonic sensor system, it is meant several ultrasonic transmitters fixed at some positions in the world coordinate and the receiver in the moving coordinate of a mobile robot. In order to achieve the synchronization between an ultrasonic transmitter and receiver and to avoid the crosstalk among the ultrasonic transmitters, simple radio frequency transmitters and receivers are adopted. Experiments are carried out to verify the effectiveness of the proposed ultrasonic sensor system.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.529-536
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• 2004

Autonomous navigation of an indoor mobile robot using the global ultrasonic system is presented in this paper. Since the trajectory error of the dead-reckoning navigation grows with time and distance, the autonomous navigation of a mobile robot requires to localize the current position of the robot, so that to compensate the trajectory error. The global ultrasonic system consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers on the mobile robot has the similar structure with the well-known satellite GPS(Global Positioning System), and it is useful for the self-localization of an indoor mobile robot. The EKF(Extended Kalman Filter) algorithm for the self-localization is proposed and the autonomous navigation based on the self-localization is verified by experiments.

• Journal of Advanced Navigation Technology
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• v.23 no.3
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• pp.228-236
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• 2019

Recently, multi-sensor integration techniques have been actively studied to obtain reliable and accurate navigation solution in GPS (Global Positioning System)-denied harsh environments such as urban canyons, tunnels, and underground roads. In this paper, we propose a low-cost ultrasonic-speedometer utilizing the characteristics of the ultrasonic propagation. An efficient integrated INS (inertial navigation system)/ultrasonic-speedometer navigation system is also proposed to improve the accuracy of positioning in GPS-denied environments. To evaluate the proposed system, car experiments with field-collected measurements were performed. By the experiment results, it was confirmed that the proposed INS/ultrasonic-speedometer system bounds the positioning error growth effectively even though GPS signal is blocked more than 10 seconds and a low-cost MEMS IMU (micro electro mechanical systems inertial measurement unit) is utilized.

• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.487-496
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• 1997

A fuzzy logic controller(FLC) was developed for the autonomous travel of speedsprayer in an orchard. The autonomous travel with the FLC was graphically simulated under the conditions of an ordinary standard orchard. Differential global positioning system(DGPS) was used to find the direction of running and four ultrasonic sensors were used to detect obstacles during the running. The simulation results showed that the speedsprayer, by the FLC combined with DGPS and the ultrasonic sensors. could overcome the turning problem at comers which could not be solved with such a system as machine vision and might be operated autonomously.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.387-395
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• 2020

Accuracy of an integrated Global Positioning System (GPS) / Inertial Navigation System (INS) relies heavily on the visibility of GPS satellites. Especially, its accuracy is dramatically degraded in urban canyon due to signal obstructions due to large structures. In this paper, we propose a new integrated positioning system that effectively combines INS, GPS, ultrasonic sensor, and barometer in GPS-denied environments. In the proposed system, the ultrasonic sensor provides velocity information along the forward direction of moving vehicle. The barometer output provides height information compensated for the pressure variation due to fast vehicle movements. To evaluate the performance of the proposed system, an experiment was carried out by mounting the proposed system on a test car. By the experiment result, it was confirmed that the proposed system bears good potential to maintain positioning accuracy in harsh urban environments.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.571-576
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• 2015

This paper proposes an auto-parking controller for omnidirectional mobile robots. The controller uses the multi-sensor system including ultrasonic sensor and camera. The several ultrasonic sensors of robot detect the distance between robot and each wall of the parking lot. The camera detects the global position of robot by capturing the image of artificial landmarks. To improve the accuracy of position estimation, we applied the extended Kalman filter with adaptive fuzzy controller. Also we developed the fuzzy control system to reduce the settling time of parking. The experimental results are presented to verify the usefulness of the proposed controller.

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.75-82
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• 1998

Autonomous speedsprayer operation was conducted using a fuzzy controller combined with a DGPS. The signal of DGPS receiver and signals of four ultrasonic sensors were processed in real time. The speedsprayer was steered with two levers controlled by two hydraulic cylinders. The fuzzy controller has two inputs; direction of running obtained from the DGPS receiver and distance from trees measured by ultrasonic sensors. The operation times of the hydraulic cylinders were inferred as outputs of the fuzzy controller. Field test results showed that the speedsprayer could be autonomously operated by the developed fuzzy controller including turning operation in the end of the tree row. The ultrasonic sensors contributed a little to performance of the autonomous operation, but the speedsprayer could avoid trees or obstacles in emergent situations with them.