Monocular vision-based calibration method for the axial and transverse sensitivities of low-frequency tri-axial vibration sensors with the elliptical orbit excitation

Purpose The welding areas of the workpiece must be consistent with high precision to ensure the welding success during the welding of automobile parts. The purpose of this paper is to design an automatic high-precision locating and grasping system for robotic arm guided by 2D monocular vision to meet the requirements of automatic operation and high-precision welding. Design/methodology/approach A nonlinear multi-parallel surface calibration method based on adaptive k-segment master curve algorithm is proposed, which improves the efficiency of the traditional single camera calibration algorithm and accuracy of calibration. At the same time, the multi-dimension feature of target based on k-mean clustering constraint is proposed to improve the robustness and precision of registration. Findings A method of automatic locating and grasping based on 2D monocular vision is provided for robot arm, which includes camera calibration method and target locating method. Practical implications The system has been integrated into the welding robot of an automobile company in China. Originality/value A method of automatic locating and grasping based on 2D monocular vision is proposed, which makes the robot arm have automatic grasping function, and improves the efficiency and precision of automatic grasp of robot arm.

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Analysis of the ground vibration generated by debris flows and other torrential processes at the Rebaixader monitoring site (Central Pyrenees, Spain)

Natural Hazards and Earth System Science ◽

10.5194/nhess-14-929-2014 ◽

2014 ◽

Vol 14 (4) ◽

pp. 929-943 ◽

Cited By ~ 20

Author(s):

C. Abancó ◽

M. Hürlimann ◽

J. Moya

Keyword(s):

High Frequency ◽

Debris Flows ◽

Low Frequency ◽

Ground Vibration ◽

Monitoring Site ◽

Velocity Signal ◽

Vibration Sensors ◽

Definition Of ◽

Flow Detection ◽

Central Pyrenees

Abstract. Monitoring of debris flows using ground vibration sensors has increased in the last two decades. However, the correct interpretation of the signals still presents ambiguity. In the Rebaixader monitoring site (Central Pyrenees, Spain) two different ground vibration stations are installed. At the first station the ground velocity signal is transformed into an impulses-per-second signal (low frequency, 1 Hz). The analysis of the data recorded at this station show that the shape of the impulses signal is one of the key parameters to describe the evolution of the event. At the second station the ground velocity signal is directly recorded at high frequency (250 Hz). The results achieved at this station show that the differences in time series and spectral analysis are helpful to describe the temporal evolution of the events. In addition, some general outcomes were obtained: the attenuation of the signal with the distance has been identified as linear to exponential; and the assembly of the geophones to the terrain has an important effect on the amplification of the signal. All these results highlight that the definition of ground vibration thresholds for debris-flow detection or warning purposes is a difficult task; and that influence of site-specific conditions is notable.

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Low-frequency axial vibration drilling of Al2O3/GFRP laminated composite plate by diamond trepanning bit

Composite Structures ◽

10.1016/j.compstruct.2020.112374 ◽

2020 ◽

Vol 245 ◽

pp. 112374

Author(s):

Lei Zheng ◽

Peng Qin ◽

Dongming Lv ◽

Wendong Wei ◽

Xianglong Dong ◽

...

Keyword(s):

Composite Plate ◽

Low Frequency ◽

Laminated Composite ◽

Axial Vibration ◽

Laminated Composite Plate ◽

Vibration Drilling

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A Simple Calibration Method of Anti-Stokes–Stokes Raman Intensity Ratios Using the Water Spectrum for Intracellular Temperature Measurements

Applied Spectroscopy ◽

10.1177/0003702820933908 ◽

2020 ◽

Vol 74 (10) ◽

pp. 1295-1296

Author(s):

Yuki Yoshikawa ◽

Shinsuke Shigeto

Keyword(s):

Raman Spectrum ◽

Low Frequency ◽

Practical Method ◽

Calibration Method ◽

Temperature Measurements ◽

Raman Shift ◽

Acquisition Time ◽

Boltzmann Factor ◽

Intensity Ratios ◽

Anti Stokes

Presented here is a facile and practical method for calibrating anti-Stokes–Stokes intensity ratios in low-frequency Raman spectra that is devised specifically for temperature measurements inside cells. The proposed method uses as an intensity standard the low-frequency Raman spectrum of liquid water, a major molecular component of cells, whose temperature is independently measured with a thermocouple. Rather than calibrating pixel intensities themselves, we obtain a correction factor at each Raman shift in the 20–200 cm−1 region by dividing the anti-Stokes–Stokes intensity ratio calculated theoretically from the Boltzmann factor at the known temperature by that obtained experimentally. The validity of the correction curve so obtained is confirmed by measuring water at other temperatures. The anti-Stokes–Stokes intensity ratios that have been subjected to our calibration are well fitted with the Boltzmann factor within ∼1% errors and yield water temperatures in fairly good agreement with the thermocouple temperature (an average difference ∼1 ℃). The present method requires only 15 min of spectral acquisition time for calibration, which is 50 times shorter than that in a recently reported calibration method using the pure rotational Raman spectrum of N2. We envision that it will be an effective asset in Raman thermometry and its applications to cellular thermogenesis and thermoregulation.

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Calibration method for small circular loop antennas using a standard loop antenna and vector network analyzer in low-frequency band

10.1109/emceurope.2008.4786877 ◽

2008 ◽

Cited By ~ 1

Author(s):

Masanori Ishii ◽

Yozo Shimada

Keyword(s):

Frequency Band ◽

Low Frequency ◽

Calibration Method ◽

Vector Network Analyzer ◽

Loop Antenna ◽

Network Analyzer ◽

Circular Loop ◽

Loop Antennas

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Major Breakthrough in Multi Material Drilling, Using Low Frequency Axial Vibration Assistance

SAE International Journal of Materials and Manufacturing ◽

10.4271/2012-01-1866 ◽

2012 ◽

Vol 6 (1) ◽

pp. 11-18 ◽

Cited By ~ 8

Author(s):

Sylvain Laporte ◽

Côme De Castelbajac

Keyword(s):

Low Frequency ◽

Axial Vibration ◽

Vibration Assistance

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Viscoelastic nanoscale properties of cuticle contribute to the high-pass properties of spider vibration receptor ( Cupiennius salei Keys)

Journal of The Royal Society Interface ◽

10.1098/rsif.2007.1000 ◽

2007 ◽

Vol 4 (17) ◽

pp. 1135-1143 ◽

Cited By ~ 37

Author(s):

Michael E McConney ◽

Clemens F Schaber ◽

Michael D Julian ◽

Friedrich G Barth ◽

Vladimir V Tsukruk

Keyword(s):

Low Frequency ◽

Young Modulus ◽

Surface Force ◽

Mechanical Stimuli ◽

Low Frequencies ◽

Cupiennius Salei ◽

Vibration Sensors ◽

Force Curves ◽

Epicuticular Layer ◽

High Pass

Atomic force microscopy (AFM) and surface force spectroscopy were applied in live spiders to their joint pad material located distal of the metatarsal lyriform organs, which are highly sensitive vibration sensors. The surface topography of the material is sufficiently smooth to probe the local nanomechanical properties with nanometre elastic deflections. Nanoscale loads were applied in the proximad direction on the distal joint region simulating the natural stimulus situation. The force curves obtained indicate the presence of a soft, liquid-like epicuticular layer (20–40 nm thick) above the pad material, which has much higher stiffness. The Young modulus of the pad material is close to 15 MPa at low frequencies, but increases rapidly with increasing frequencies approximately above 30 Hz to approximately 70 MPa at 112 Hz. The adhesive forces drop sharply by about 40% in the same frequency range. The strong frequency dependence of the elastic modulus indicates the viscoelastic nature of the pad material, its glass transition temperature being close to room temperature (25±2 °C) and, therefore, to its maximized energy absorption from low-frequency mechanical stimuli. These viscoelastic properties of the cuticular pad are suggested to be at least partly responsible for the high-pass characteristics of the vibration sensor's physiological properties demonstrated earlier.

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Monocular Vision Ranging and Camera Focal Length Calibration

Scientific Programming ◽

10.1155/2021/9979111 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Lixia Xue ◽

Meian Li ◽

Liang Fan ◽

Aixia Sun ◽

Tian Gao

Keyword(s):

Camera Calibration ◽

Polynomial Regression ◽

Focal Length ◽

Three Dimensional ◽

Calibration Method ◽

Monocular Vision ◽

Field Of Vision ◽

Average Accuracy ◽

Ground Object ◽

The Relationship

The camera calibration in monocular vision represents the relationship between the pixels’ units which is obtained from a camera and the object in the real world. As an essential procedure, camera calibration calculates the three-dimensional geometric information from the captured two-dimensional images. Therefore, a modified camera calibration method based on polynomial regression is proposed to simplify. In this method, a parameter vector is obtained by pixel coordinates of obstacles and corresponding distance values using polynomial regression. The set of parameter’s vectors can measure the distance between the camera and the ground object in the field of vision under the camera’s posture and position. The experimental results show that the lowest accuracy of this focal length calibration method for measurement is 97.09%, and the average accuracy was 99.02%.

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