• 융합신호처리학회논문지
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• 제11권1호
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• pp.63-73
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• 2010

본 논문에서는 위치 불확실성이 최소화되도록 중첩 초음파 센서 링을 최적 설계하는 방법과 이를 향상된 해상도의 장애물 탐지에 응용하는 방안에 대해 기술하도록 한다. 기본적으로 일군의 초음파 센서들이 일정 간격으로 상호 빔 폭이 중첩되도록 원형으로 배치된다고 가정한다. 첫째, 빔 폭 중첩 상태를 활용함으로써 초음파 센서 고유의 위치 불확실성을 현저히 감소시킬 수 있음을 보인다. 둘째, 반경이 영인 이상적인 중첩 초음파 센서 링에 대해, 위치 불확실성을 나타낼 수 있도록 유효 빔 폭의 개념을 도입하고, 유효 빔 폭을 최소화하기 위해 필요한 초음파 센서의 최적 개수를 구한다. 셋째, 일정 반경의 실제 중첩 초음파 센서 링을 대상으로, 위치 불확실성 정도를 표현하는 설계 지수를 정의하고, 상용 저지향성 초음파 센서를 구성되는 중첩 초음파 센서 링의 최적 설계 예를 제시한다. 넷째, 초음파 센서의 측정 거리로부터 이동로봇 중심 기준 장애물의 위치를 산정하기 위한 기하학적 방법을 기술한다. 마지막으로, 한 쪽이 열린 평면 장애물 탐지 실험을 통해, 자체 제작된 초음파 센서 링의 장애물 탐지 해상도가 향상됨을 입증한다.

• 제어로봇시스템학회논문지
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• 제19권7호
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• pp.614-619
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• 2013

In multi-robot systems, ultrasonic sensors are widely used for localization and/or obstacle detection. However, conventional ultrasonic sensors have a drawback, that is, the interference problem among ultrasonic transmitters. There are some previous studies to avoid interferences, such as TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access). In multiple autonomous mobile robots systems, the Doppler-effect has to be considered because ultrasonic transceivers are attached to the moving robots. To overcome this problem, we find out the ASK (Amplitude Shift Keying)-CDMA technique is more robust to the Doppler-effect than the BPSK (Binary Phase Shift Keying)-CDMA technique. In this paper, we propose a new code-expression method and a Monte-Carlo based algorithm that optimizes the ultrasonic code combination in the ASK-CDMA ultrasonic system. The experimental results show that the proposed algorithm improves the performance of the ultrasonic multiple accessing capacity in the ASK-CDMA ultrasonic system.

• Journal of Advanced Marine Engineering and Technology
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• 제30권8호
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• pp.919-926
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• 2006

To move in unknown or uncertain environment, a mobile robot must collect informations from various sensors and use it to construct a representation of the external world. Ultrasonic sensor can provide range data for this purpose in a simple cost-effective way. However conventional ultrasonic sensor system for a mobile robot are not sufficient for environment recognition because of their large beam opening angle, specular reflection. This paper describe on environmental perception algorithm which can solve these problems in case using ultrasonic sensor. The algorithm consist of two parts. One is to solve beam opening angle problem by fusion from multiple ultrasonic sensors. The other is to cope with specular reflection problem in wall line extract, which is based on Hough Transform. Experiments to verify the validity of the proposed algorithm are carried out, and the results are provided at last part in this paper.

• 대한기계학회논문집B
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• 제23권7호
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• pp.893-900
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• 1999

Measuring temperature with ultrasonic wave apparatus is desirable in the cue of gas below $300^{\circ}$ because of the fact that the temperature of gas is the function of only sound velocity. In this study, being used a heatable wind channel and a blower. the variation of temperature is observed in accordance with flow rate(air velocity). The frequency modulation method is used to measure the temperature which is varying in hot air flow up to $100^{\circ}$. The length changed in the position of ultrasonic sensors is considered. Also. the effects of air velocity at the same temperature and various facing angles of ultrasonic sensors are considered. As a result of this study. it has been found that the temperature in gas flow is correctly measured regardless of both the distance of ultrasonic sensors and the variation of air velocity. and that there is just a little influence of facing angles.

• 한국산업융합학회 논문집
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• 제17권3호
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• pp.151-169
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• 2014

We propose a new technique for autonomous navigation and travelling of mobile robot based on ultrasonic sensors through the narrow labyrinth that leave only distance of a few centimeters on each side between the guides and the robot. In our current implementation the ultrasonic sensor system fires at a rate of 100 ms, that is, each of the 8 sensors fires once during each 100 ms interval. This is a very good firing rate, implemented here for optimal performance. This paper presents an extensively tested and verified solution to the problem of obstacle avoidance. Our solution is based on the optimal placement of ultrasonic sensors at strategic locations around the robot. Both the sensor location and the associated navigation algorithm are defined in such a way that only the accurate radial sonar data is used for accurate travelling.

• 한국항공우주학회지
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• 제45권2호
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• pp.124-132
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• 2017

무인기에 대한 관심이 급증하면서 무인기 충돌회피에 대한 많은 연구가 진행 중이다. 충돌회피를 위해서는 무인기 주변에 대한 상황인식이 이루어져야하며 이를 위해 라이더, 영상 카메라, 레이저 센서, 그리고 초음파센서 등이 활용되고 있다. 본 논문에서는 MB 1230 초음파 센서를 이용하여 초음파 센서의 특성을 분석하였다. 또한, 동시에 다수 초음파 센서를 사용할 경우 센서간의 간섭영향으로 정확한 거리 측정값을 획득하지 못함을 확인하였다. 이러한 초음파 센서 신호 간섭을 해결하기 위해 다수의 초음파 센서를 동시에 작동시키는 것이 아니라 초음파 센서의 Enable 신호 입력단을 이용하여 각 초음파 센서를 순차적으로 활성화시킴으로써 초음파 센서간의 간섭을 해결하는 방안을 제안하였으며 실험을 통해 제안한 방안의 효과를 확인하였다.

• 조명전기설비학회논문지
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• 제27권12호
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• pp.38-43
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• 2013

In this paper, the location measurement method for the reliable location data using ultrasonic sensors is proposed for the dimming control of the LED flat lamp. The measurement errors depending on the reflection angle of the object have to be considered to obtain the reliable location data in the ultrasonic sensors. In the experiment, the cause of the measurement errors depending on reflection angle is analyzed and velocity change of ultrasonic wave depending on reflection angle is measured. And the location measurement method depending on velocity change of ultrasonic wave is proposed. From the results, the average absolute deviation of the x-coordinates was 1.47cm when the location measurement method was considered, and it was closer to the true values than the average absolute deviation of the x-coordinates which was 5.89cm without regard to the reflection angle.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.1028-1036
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• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments by virtue that they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a comer, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding of ultrasonic signals, which allows multi-sensors to be emitted simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented. A micro-controller unit is implemented using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances fur each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.132-145
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• 2008

We propose a new technique for autonomous navigation and travelling of mobile robot based on ultrasonic sensors through the narrow labyrinth that leave only distance of a few centimeters on each side between the guides and the robot. In our current implementation the ultrasonic sensor system fires at a rate of 100 ms, that is, each of the 8 sensors fires once during each 100 ms interval. This is a very good firing rate, implemented here for optimal performance. This paper presents an extensively tested and verified solution to the problem of obstacle avoidance. Our solution is based on the optimal placement of ultrasonic sensors at strategic locations around the robot. Both the sensor location and the associated navigation algorithm are defined in such a way that only the accurate radial sonar data is used for accurate travelling.

• 센서학회지
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• 제14권2호
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• pp.101-108
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• 2005

The research on the avoidance of the large-obstacles such as a wall, a large box, etc. using ultrasonic sensors has been generally progressed up to now. But the mobile robot could meet a small-obstacle such as a small plastic bottle, a small sphere, and so on in its designated path, and could be disturbed by them in the locomotion of the mobile robot. So, it is necessary to research on the avoidance of a small-obstacle. In this paper, a robot's small-obstacle perceiving system was designed and fabricated by arranging four ultrasonic sensors on the plastic plate to avoid small-obstacles. The system was installed on the upper part of the mobile robot with the slope angles between $40.7^{\circ}$ and $23.3^{\circ}$ to a horizontal line and the dynamic characteristic test of the robot was performed. As the result, it was confirmed that the mobile robot with the system could avoid small-obstacles in indoor environment safely.