scholarly journals EXAMINATION METHOD OF THE EFFECT OF THE INCIDENCE ANGLE OF LASER BEAM ON DISTANCE MEASUREMENT ACCURACY TO SURFACES WITH DIFFERENT COLOUR AND ROUGHNESS

2016 ◽  
Vol 22 (3) ◽  
pp. 420-436 ◽  
Author(s):  
Karol Daliga ◽  
Zygmunt Kurałowicz
Keyword(s):  
Laser Beam ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Incidence Angle ◽  
Distance Measurement ◽  
Distance Measurements ◽  
Total Station ◽  
Examination Method ◽  
Critical Incidence ◽  
Reflective Foil

Interest in the influence of the incidence angle of a laser beam to distance measurements can be seen in many areas of science and technology: geodesy, glaciology, archaeology, machine automation, and others. This paper presents results of measurements of the effect of the incidence angle of a laser beam to distance measurements to the surfaces of different colour and roughness by Topcon's electro-optical total station with an accuracy of 3 mm. Measurement method and the method of elimination of test stand errors are presented. The results of measurements have been analysed and the influence of selected factors (surface colour and roughness, lack of instrument rectification) on the distance measurement have been discussed. It is also shown the critical incidence angle above which it can be impossible to measure distances to reflective foil with tested total station

scholarly journals A Parallel-Phase Demodulation-Based Distance-Measurement Method Using Dual-Frequency Modulation

2019 ◽  
Vol 10 (1) ◽  
pp. 293
Author(s):  
In-Gyu Jang ◽  
Sung-Hyun Lee ◽  
Yong-Hwa Park
Keyword(s):  
Frequency Modulation ◽  
Measurement Method ◽  
Continuous Wave ◽  
Measurement Range ◽  
Distance Measurement ◽  
Measurement Technology ◽  
Dual Frequency ◽  
Distance Measurements ◽  
Time Required ◽  
Phase Demodulation

Time-of-flight (ToF) measurement technology based on the amplitude-modulated continuous-wave (AMCW) model has emerged as a state-of-the-art distance-measurement method for various engineering applications. However, many of the ToF cameras employing the AMCW process phase demodulation sequentially, which requires time latency for a single distance measurement. This can result in significant distance errors, especially in non-static environments (e.g., robots and vehicles) such as those containing objects moving relatively to the sensors. To reduce the measurement time required for a distance measurement, this paper proposes a novel, parallel-phase demodulation method. The proposed method processes phase demodulation of signal in parallel rather than sequentially. Based on the parallel phase demodulation, 2π ambiguity problem is also solved in this work by adopting dual frequency modulation to increase the maximum range while maintaining the accuracy. The performance of proposed method was verified through distance measurements under various conditions. The improved distance measurement accuracy was demonstrated throughout an extended measurement range (1–10 m).

scholarly journals LAND UNMANNED COMPLEX WITH PASSIVE RANGE MEASUREMENT

2021 ◽  
pp. 11-16
Author(s):  
Volodymyr I. Mikitenko ◽  
Volodymyr M. Senatorov ◽  
Anatolii Gurnovych
Keyword(s):  
Measurement Method ◽  
Measurement Accuracy ◽  
Vision System ◽  
Distance Measurement ◽  
Measuring Channel ◽  
Wide Field ◽  
Range Finder ◽  
Fixed Base ◽  
Movement Parameters ◽  
Base Range

The automatic robotic complex will obviously become one of the main subjects in the conduct of military actions in the near future. To control movement parameters, as well as search, target detection and aiming, the complex includes a technical vision system. The minimum sufficient configuration of such a system includes a television search camera with a wide field of view, television and thermal imaging sights, and a rangefinder. The use of laser rangefinders ensures high accuracy of aiming weapons, but generates a powerful unmasking feature. To ensure the secrecy of the functioning of the robotic complex, range finders can operate in a passive mode using information from on-board television cameras. But at the same time, the metrological characteristics of the information measuring channel are significantly deteriorated. Accuracy of five methods of passive distance measurement with application of TV-systems of land unmanned complex is assessed in paper. Classic method of TV-sight external-base range-finder with scale, designed on human height 1,65 m, is ensuring measurement accuracy 135 m on distance 1000 m. External base method, when a range finger scale is forming on remote display as variable length vertical line in process of target framing, is ensuring measurement accuracy 100,3 m on dis-tance 1000 m. Fixed-base range-finder method, when distance between entrance pupils of TV-sight and wide viewing field camera using as base, is ensuring measurement accuracy 76 m on distance 1000 m.  Distance measurement method due to displacement of land unmanned complex ensures a measurement accuracy up to 168 m on distance 1000 m. Measurement method due to using zoom-objective is not suitable for land unmanned complex. Proposals have been formulated for the spatial layout of the computer vision system, in which the method of the fixed-base rangefinder is implemented, which ensures the highest measurement accuracy.

scholarly journals A Novel Three-Head Ultrasonic System for Distance Measurements Based on the Correlation Method

2014 ◽  
Vol 14 (6) ◽  
pp. 331-336 ◽  
Author(s):  
Krzysztof Gądek ◽  
Marek Dudzik ◽  
Anna Stręk
Keyword(s):  
Standard Deviation ◽  
Present Article ◽  
Experimental Research ◽  
Measurement Method ◽  
Correlation Method ◽  
Distance Measurement ◽  
Distance Measurements ◽  
Mechanical Interference ◽  
Measurement Signal

Abstract A novel double-emitter ultrasonic system for distance measurements based on the correlation method is presented. The proposed distance measurement method may be particularly useful in difficult conditions, e.g. for media parameters undergoing fast changes or in cases when obstacles and mechanical interference produce false reflections. The system is a development of a previously studied single-head idea. The present article covers a comparison of the two systems in terms of efficiency and precision. Experimental research described in this paper indicated that adding the second head improved the measurement exactness – standard deviation decreased by 40%. The correlation method is also described in detail, also giving the criterion for the quality of the measurement signal.

scholarly journals The Improvement and application of elevation measurement method with total station

2020 ◽  
Vol 165 ◽  
pp. 03018
Author(s):  
Yiteng Xu ◽  
Xin Zhao ◽  
Hewen Liu ◽  
Feng Xu ◽  
Xiaoqiang Wang
Keyword(s):  
Mathematical Model ◽  
Measurement Error ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Accuracy Analysis ◽  
Error Sources ◽  
Total Station ◽  
Elevation Measurement ◽  
Measurement Efficiency

In this paper, by analyzing the limitations of the traditional trigonometric elevation method, and on the basis of establishing a mathematical model of trigonometric elevation, a convenient and fast trigonometric elevation method without instrument height and prism height is improved, and the operation steps of the method are introduced in detail. The accuracy analysis was evaluated and the method was applied to actual engineering. The results show that under the premise of ensuring the measurement accuracy, this method not only reduces the range of measurement error sources, but also improves the measurement efficiency.

scholarly journals An Offset Laser Measurement Method for the Deviation Analysis of Cylindrical Gear

2021 ◽  
Author(s):  
Ning Mei ◽  
Aiping Song ◽  
Chenwei Yu ◽  
Jianzhou Pan
Keyword(s):  
Laser Beam ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Measurement Data ◽  
Displacement Sensor ◽  
Spatial Distance ◽  
Tooth Surface ◽  
Normal Vector ◽  
Laser Displacement Sensor ◽  
Laser Measurement

Abstract Generally, in the laser measurement of gears, the laser beam passes through the center of the gear, and the laser displacement sensor reads the spatial distance from the gear involute tooth surface to the laser displacement sensor. However, in this method, the angle between the laser beam and the normal vector of the measured tooth surface is too large, which affects the accuracy of the measurement and the stability of the data. This paper proposes an offset laser measurement method. The laser beam is offset from the center of the gear by a certain distance to form a larger incident angle with the tooth surface, which can effectively improve the problem and increase the measurement accuracy. Through the discussion of selecting the optimal offset distance, the range of optimal offset measurement position is obtained and clarified by experiments. We solved the data conversion problem caused by the change of measuring position, and measured the pitch deviation and helix angle of the gear to confirm the feasibility of this method. Based on theoretical calculation and experimental verification, it is found that this method has the advantages of better measurement accuracy and less measurement data fluctuations. It is suitable for precision gear measurement.

scholarly journals An Offset Laser Measurement Method for the Deviation Analysis of Cylindrical Gears

Machines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 111
Author(s):  
Ning Mei ◽  
Aiping Song ◽  
Chenwei Yu ◽  
Jianzhou Pan
Keyword(s):  
Laser Beam ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Measurement Data ◽  
Displacement Sensor ◽  
Spatial Distance ◽  
Tooth Surface ◽  
Normal Vector ◽  
Laser Displacement Sensor ◽  
Laser Measurement

Generally, in the laser measurement of gears, the laser beam passes through the center of the gear, and the laser displacement sensor reads the spatial distance from the gear involute tooth surface to the laser displacement sensor. However, in this method, the angle between the laser beam and the normal vector of the measured tooth surface is too large, which affects the accuracy of the measurement and the stability of the data. This paper proposes an offset laser measurement method. The laser beam is offset from the center of the gear by a certain distance to form a larger incident angle with the tooth surface, which can effectively address the problem and increase the measurement accuracy. Through a selection of the optimal offset distance, the range of optimal offset measurement positions was obtained and clarified by experiments. We solved the data conversion problem caused by the change in measuring position, and we measured the pitch deviation and helix angle of the gear to confirm the feasibility of this method. According to the theoretical calculation and experimental verification, it was found that this method has the advantages of better measurement accuracy and less fluctuation in measurement data. It is, thus, suitable for precision gear measurement.

Acoustic Distance Measurement Method Using 2ch Microphones Measurable from 0m Based on Phase Interference and Removal of DC Component

2015 ◽  
Vol 135 (11) ◽  
pp. 1349-1350
Author(s):  
Kazuhiro Suzuki ◽  
Noboru Nakasako ◽  
Masato Nakayama ◽  
Toshihiro Shinohara ◽  
Tetsuji Uebo
Keyword(s):  
Measurement Method ◽  
Distance Measurement ◽  
Phase Interference ◽  
Dc Component

Detection and Analysis of Rats’ Bioelectromagnetic Signal

2014 ◽  
Vol 536-537 ◽  
pp. 13-17
Author(s):  
Hong Long Cao ◽  
Fen Ju Qin ◽  
Xue Guan Liu ◽  
He Ming Zhao
Keyword(s):  
Standard Deviation ◽  
Automatic System ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Biological Activities ◽  
Measurement Data ◽  
Measured Data ◽  
The Mean ◽  
Frequency Window ◽  
Window Effects

In this paper, we designed an automatic system and automatic test software, and they can carry out Kunming rats bioelectromagnetic measurement in standard status and anesthesia automatically in anechoic chamber where the electromagnetic field outside is shielded, the reflection wave is absorbed, and the measurement accuracy will be improved. We get a great number of measurement data with frequency-sweep measurement method. The mean and standard deviation of amplitudes vs. frequencies is calculated and analyzed. The results show the measurement method is feasible. We have plotted the means of measured data as multiple sets of Y values in a series of bars with standard deviations bars included and distributed in the frequency axis of X. It is found that the fluctuation of the mean and standard deviation in some frequencies is not evident which may explain frequency window effects, while in other frequencies, such a fluctuation can be obviously observed, which may suggest that bioelectromagnetic signal is influenced by biological activities (standard and anaesthesia status) in these frequency points.

Evaluation and defense of light commands attacks against voice controllable systems in smart cars

2021 ◽  
pp. 095745652110015
Author(s):  
Zhijian Xu ◽  
Guoming Zhang ◽  
Xiaoyu Ji ◽  
Wenyuan Xu
Keyword(s):  
Laser Beam ◽  
Success Rate ◽  
Incidence Angle ◽  
Attack Angle ◽  
Light Transmittance ◽  
Controllable System ◽  
Lower Light ◽  
Controllable Systems ◽  
Smart Cars ◽  
The Impact

The in-car voice controllable system has become an almost standard feature in smart cars. Prior work shows that the voice controllable system is vulnerable to light commands attack which uses the laser as the medium to inject voice commands. In this article, we first reproduced the light commands attack on acoustic isolated in-car voice controllable system under several scenarios with a lightweight solution. We validate the feasibility of injecting the malicious voice command through a window into the microphone by modulating a laser beam. Then, we tested a variety of mainstream countermeasures such as placing sunscreen film on the glass panel to see whether it can protect the microphone from being attacked. Surprisingly, we find that the lower light transmittance of sunscreen film is the lower the success rate of the attack. Experiment results also show that when the transmittance rate of sun film is 50% which is the darkest sunscreen film that can be applied, the attacking success rate decreased by up to 0.4. We also explore the impact of attack angle by changing the incidence angle of the laser beam and the results demonstrate that light commands is sensitive to attack angle and the successful angle range is ± 15°. Finally, we propose a series of hardware-based protection schemes against light commands attacks.

Sign in / Sign up

Export Citation Format

Share Document