• 센서학회지
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• 제23권4호
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• pp.251-258
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• 2014

While the feasibility of vertical velocity as a threshold parameter for pre-impact fall detection has been verified, effects of sensor attachment locations and methods calculating vertical acceleration and velocity on the detection performance have not been studied yet. Regarding the vertical velocity-based pre-impact fall detection, this paper investigates detection accuracies of eight different cases depending on sensor locations (waist vs. sternum), vertical accelerations (accurate acceleration based on both accelerometer and gyroscope vs. approximated acceleration based on only accelerometer), and vertical velocities (velocity with attenuation vs. velocity difference). Test results show that the selection of waist-attached sensor, accurate acceleration, and velocity with attenuation based on accelerometer and gyroscope signals is the best in overall in terms of sensitivity and specificity of the detection as well as lead time.

• 제어로봇시스템학회논문지
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• 제15권1호
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• pp.82-88
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• 2009

The output of the encoder is a digital pulse, which is also easy to be connected to a digital controller. There are various angular velocity detecting methods of M, T, and M/T. Each of them has its own properties. There is a common limitation that the angular velocity detection period is strongly dependent on the destination velocity magnitude in case of ultimate low range. They have ultimately long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a zero velocity detectable sensor algorithm with the dual encoder system. The sensor algorithm is able to keep detection period moderately at near zero velocity and even detect zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the algorithm validity.

• 한국정밀공학회지
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• 제24권9호
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• pp.76-85
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• 2007

An optical rotary encoder is easy to implement for automatic control applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using the encoder, there are various angular velocity detecting methods, M-, T-, and M/T-method. Each of them has a property of its own. They have common limitation that the angular velocity detection period is strongly subject to the destination velocity magnitude in case of ultimate low range. They have ultimate long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a dual encoder system with two encoders of normal resolution. The dual encoder system is able to keep detection period moderately at near zero velocity and even detects zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the dual encoder system validity.

• Journal of Positioning, Navigation, and Timing
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• 제9권1호
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• pp.33-42
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• 2020

In Integration Approach (IA)-based Pedestrian Dead Reckoning (PDR), it is important to detect the exact zero-velocity of the foot with an Inertial Measurement Unit (IMU). By detecting zero-velocity during the stance phase of the foot touching the ground and executing Zero-velocity UPdaTe (ZUPT) at the exact time, stable navigation information can be provided by the PDR. When the pace is fast, however, it is not easy to accurately detect the zero-velocity because of the small stance phase interval and the large signal variance of the corresponding interval. Incorrect zero-velcity detection greatly causes navigation errors of IA-based PDR. In this paper, we propose a method to detect the zero-velocity stably even at high speed by novel buffering of IMU's output data and signal processing of the buffer. And we design a PDR based on this. By analyzing the performance of the proposed Zero-Velocity Detection (ZVD) algorithm and ZVD-based PDR through experiemnts, we confirm that the proposed method can provide accurate navigation information of pedestrians such as firefighters in the indoor space.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.494-497
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• 1994

We propose a novel velocity detection method of moving object based on a speckle pattern on the target surface using a self-mixing laser diode (SMLD). By this measurement, it was confirmed that the speckle signal has its waveform independent of the target velocity, and has its averaged frequency directly proportional to the target velocity. So it will be possible to detect the velocity of the target transversely translating against the laser light beam using a compact measuring system.

• 한국정밀공학회지
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• 제25권8호
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• pp.29-36
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• 2008

An optical rotary encoder is easy to implement for automation system applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using an incremental encoder and a counting device, it is easy to measure angular displacement, as the number of the output pulses is proportional to the rotational displacement. This method can only detect the angular placement once a pulse signal comes out of the encoder. The angular displacement detection period is strongly subject to the change of the angular displacement in case of ultimate low velocity range. They have ultimate long detection period or cannot even detect angular displacement at near zero velocity. This paper proposes an algorithm for detecting angular displacement by using a dual encoder system with two encoders of normal resolution. The angular displacement detecting algorithm is able to keep detection period moderately at near zero velocity and even detect constant angular displacement within nominal period. It is useful for motion control applications in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the angular displacement detection algorithm.

• 대한기계학회논문집B
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• 제21권3호
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• pp.427-435
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• 1997

Conditional sampling techniques are utilized to investigate the relation between the wall skin-friction and stream wise velocity fluctuations in a turbulent boundary layer. Conditionally averaged results using a peak detection and the VITA (variable-interval time-averaging) technique show that a high skin friction is associated with high frequency components of the wall skin-friction fluctuations. The conditionally averaged wall skin-friction fluctuations obtained by using the VITA technique have a positively-skewed characteristics compared with the conditionally averaged stream wise velocity fluctuations. It is confirmed that there exists a phase shift between the wall skin-friction and stream wise velocity fluctuations, which was also found from the long-time averaged space-time correlations. The amount of phase shift between the wall skin-friction and stream wise velocity fluctuations is the same as that from the long-time averaged space-time correlations and does not change despite the variation of the detection threshold.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1108-1114
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• 2011

In general, railway system uses wheels so detecting speed by tachometer. However, LRT(Light Rail Transits) stands out recently as alternatives transportation, and besides of that Maglev trains are emerged as an alternative means of transportation. Maglev operates above certain heights caused inability of the measurement by tachometer which used to detect speed of wheels. Velocity Detection Signal Device of Train Control System applied in "Train Control System Project of Pilot Line Construction for Urban MAGLEV Train" which is prepared ahead of opening in 2013. This paper, therefore, explains the function and operation principal of Velocity Detection Signal Device, and suggests installation method of velocity detection loop installed around the track.

• 전기학회논문지
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• 제67권8호
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• pp.1113-1118
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• 2018

Protection in HVDC(High Voltage Direct Current) have the very fast velocity of fault detection. Because Fault in HVDC has the fast propagation, large currents, high interruption cost. The focus to velocity caused possibility of errors like a detection error like a high impedance fault. In this paper, Proposed complex composition for get the reliability and velocity. That used SFCL(Super Conducting Fault Current Limiter), Protection Zone and DTS(Distributed Temperature Sensing). The SFCL was detect the fault by quench and DTS&Protection Zone were perceive the detect by variation too. To examine the proposed method, PSCAD/EMTDC simulated. The results of simulation, proposed methods could the detect of fault to whole HVDC line. And that improved the reliability of fault clearing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2962-2964
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• 1999

We know the traffic information about the velocity and position of vehicle by extraction and tracking vehicle from continuosly obtained road image of camera. The conventional method of vehicle detection indicate increment of error due to headlight and taillight in night road image. This paper show such as vehicle detection of binary, Edge detection. amalgamation of image are applied to extract the vehicle, and Kalman filter is adaptive methods for tracking position and velocity of vehicle.