• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1441-1446
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• 2017

In recent, the studies on the systems have been progressing that count the number of people passing through passageway or count people who exist in specific space. The existing people counting systems count the number of people using ultrared sensors, ultrasonic sensors or camera sensors, which can be installed only on pillar or around wall. Though ultrared sensors and ultrasonic sensors is low cost, they are inadequate to detect incoming/outgoing when several pedestrians pass through passageway concurrently. In this paper, we designed a sensor mat using piezoelectric sensors to complement the above-mentioned disadvantage. Also, we implemented the system that detects direction of progress and counts the number of people. The sensor mat detects direction of progress using pressure given on sensors and timing information and counts the number of people when pedestrians pass through on a sensor mat.

• Tribology and Lubricants
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• v.34 no.4
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• pp.132-137
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• 2018

Ultrasonic waves are used in various applications in multiple devices, sensors, and high-power machinery, such as processing machines, welders, and cleaners, because the acoustic vibration frequencies are above the human audible frequency range. In ultrasonic machining, electrical energy at a high frequency of 20 kHz or more is converted into mechanical vibration by a vibrator and an amplifier. This technique allows instantaneous separation between a tool and a workpiece during machining, machining by pulse impulse force at the time of re-contact and minimizes the minute elastic deformations of the workpiece and machine tools due to the cutting effect. The Al7075 alloy used in this study is a typical aluminum alloy with superior strength that is mainly used in aircrafts, automobiles, and sporting goods. To investigate the optimal conditions for machining aluminum alloy using ultrasonic vibration, the present experiment utilized the Taguchi orthogonal array method, and the coefficient of friction was analyzed using the characteristics of the Taguchi technique. In ultrasonic friction and abrasion tests, the changes in the friction coefficient were measured in the absence of ultrasonic vibrations and at 28 kHz and 40 kHz. As a result, the most considerable influence on the friction coefficient was found to be the normal load, and the frequency of ultrasonic vibrations increases, the coefficient of friction increases. It was thus confirmed that the amount of wear increases when ultrasonic vibration is applied.

• 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 the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.41-47
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• 2012

In this paper, we proposed a new method which analyzes and eliminates errors occurring by multi-reflection of ultrasonic firing in mobile robot application. This new method allows ultrasonic sensors to fire at rates that are three times faster than those customary in conventional applications readings due to ultrasonic noise disturbance. It is possible them to collect and predict sensor data much faster than conventional methods. Furthermore, this method's capability allows mobile robot to navigate in a complex and unknown environment and to collaborate in the same environment with multiple mobile robot, even if their ultrasonic sensors operate. And it's usefulness to avoid moving obstacles by capability of rapid collecting data. Finally, we present experimental results that demonstrate the performances of the new proposed method by experiments in a multi-reflective environment.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.553-557
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• 2005

This paper describes the application results of an ultrasonic detection system for the power transformer. The ultrasonic detection system with 6 sensors was applied to detect partial discharge in a 154kV transformer with a dangerous levels of $C_{2}H_{2},\;C_{2}H_4$ and $CH_{4}$ gases. The ultrasonic detection tests were carried out 2 times, respectively, to confirm the existence and location of the partial discharge in the transformer. As a result of internal inspection, the arc trace between the pressure ring and core due to the partial discharge was found at the estimated position based on the amplitude and arriving time of the ultrasonic signals. Therefore, it was verified that the ultrasonic detection system is effective as a preventive diagnosis method for the power transformer. Also, the reliability of the ultrasonic detection system in detecting partial discharges in the transformer was also confirmed. It is expected, therefore, that the ultrasonic detection system will have beneficial effects on applications and verifications in detecting partial discharges for the power transformer.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.668-671
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• 2004

This paper proposes a new method of sensor fusion of an ultrasonic sensor and a vision sensor at the sensor level. In general vision system, the vision system finds edges of objects. And in general ultrasonic system, the ultrasonic system finds absolute distance between robot and object. So, the method integrates data of two different types. The system makes perfect output for robot control in the end. But this paper does not propose only integrating a different kind of data but also fusion information which receives from different kind of sensors. This method has advantages which can simply embody algorithm and can control robot on real time.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.511-516
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• 1991

A new end-effector has been devised and the problems resulted from using it with SCARA robots are discussed. The end effector has two modules: one composed of two ultrasonic motors and two encoders for controlling each finger, and the other module composed of two ultrasonic motors and two encoders for controlling the wrist. The wrist module adds two degrees of freedom to the SCARA type robot, which generally has four degrees of freedom. With independent finger actuation and touch sensors, the gripper under computer control can feedback information about part size and part presence. Ultrasonic motors with high torque and slow motion characteristics are used. The principle of ultrasonic motors is explained and the servo characteristics of ultrasonic motors are studied. They are controlled by the general motion controller (Hewlett Packard HCTL-1000) which is linked to an IBM-PC AT.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.4
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• pp.315-320
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• 2015

This paper describes the implemenation of localization and visualization scheme to find out an ultrasonic source caused by defects of a power distribution line equipment. To increase the fault detection performance, $2{\times}4$ sensor array is configured with MEMS ultrasonic sensors, and from the sensor signals aquired, the azimuth and elevation angles of the ultrasonic source is estimated based on the delay-sum beam forming method. Also, to visualize the estimated location, it is marked on the background image. Experimental results show applicability of the present technique.

• Journal of Sensor Science and Technology
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• v.26 no.3
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• pp.192-198
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• 2017

In this paper, we newly developed a passive transponder for visible light identification (VLID) using ultrasonic wave. The solar cell in the transponder receives the reader light and generates current for supplying power to the transponder circuit. At the same time the solar cell detects the interrogating signal in the visible light from the reader. The transponder recognizes the interrogating signal and generates the responding signal using ultrasonic wave. In experiments, we used 40 kHz ultrasonic wave for the responding signal from the transponder. The maximum read distance was about 3.4 m when the transponder was exposed to the reader light of 24W LED array.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.62-66
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• 2002

The preliminary results on the application of optical fiber sensor(OFS) for locations of ultrasonic signals in underwater are presented and analyzed. The OFS utilizing the principle of Sagnac interferometry was designed and the hollowed cylindrical mandrel wound by single mode optical fiber was used as sensing component. The ultrasonic signal source was simulated by the PZT actuator operated with function generator. It has been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor and accurate location of ultrasonic signal could be carried out using two OFSs.