Multi-Laser Displacement Sensor Used in Accurate Digitizing Technique

1994 ◽  
Vol 116 (4) ◽  
pp. 482-490 ◽  
Author(s):  
K. B. Smith ◽  
Y. F. Zheng
Keyword(s):  
Coordinate Measuring Machine ◽  
Displacement Sensor ◽  
Normal Vector ◽  
Laser Displacement Sensor ◽  
Arc Length ◽  
Measuring Machine ◽  
A New Technique ◽  
Six Degree Of Freedom ◽  
The Relationship ◽  
Puma Robot

This paper presents a new technique for digitizing an unknown sculptured surface using a new multi-Laser Displacement Sensor (LDS) and an articulated Coordinate Measuring Machine (CMM). The new multi-LDS measures the tangents, curvatures, and displacement of the surface. This local information is utilized in the technique to extrapolate the surface position and normal vector at the next location to be digitized. In addition, this paper derives the relationship between the digitizing error parameters and the ratio of sampling arc length to the radius of maximum curvature. This technique is illustrated experimentally using a six degree-of-freedom PUMA robot and a Keyence LDS.

scholarly journals Influence of measuring force on CMM accuracy

2018 ◽  
Vol 208 ◽  
pp. 03004
Author(s):  
Bin Wang
Keyword(s):  
Cross Sections ◽  
Measurement Accuracy ◽  
Coordinate Measuring Machine ◽  
Point Of View ◽  
Signal Acquisition ◽  
Force Model ◽  
Thin Part ◽  
Measuring Machine ◽  
The Relationship ◽  
Measuring Force

The measuring accuracy of CMM (Coordinate Measuring Machine) is influenced by many factors, such as temperature, humidity, measuring force and method of signal acquisition. For thin parts, the influence of measuring force is especially obvious. In this paper, the relationship between measuring force and measurement accuracy is studied for a thin part with a U-shaped cross-section. By analyzing the structure of the probe and establishing the force model, the influencing factors of the accuracy of CMM are obtained, and the influence of the contact deformation and the bending deformation on the measurement accuracy is analyzed from the point of view of material mechanics. At the same time, the measurement accuracy of different measuring cross-sections is analyzed. Through the research of this paper, the relationship between measuring force and CMM is established, and an effective method to improve the accuracy of CMM is also found.

A Calibration Method for a Three-Degrees-of-Freedom Parallel Manipulator with a Redundant Passive Chain

2012 ◽  
Vol 162 ◽  
pp. 171-178 ◽  
Author(s):  
Takaaki Oiwa ◽  
Harunaho Daido ◽  
Junichi Asama
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Least Squares Method ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Displacement Sensor ◽  
Measurement Experiment ◽  
Measuring Machine ◽  
Measured Length ◽  
Three Degrees Of Freedom

This paper deals with parameter identification for a three-degrees-of-freedom (3-DOF) parallel manipulator, based on measurement redundancy. A redundant passive chain with a displacement sensor connects the moving stage to the machine frame. The passive chain is sequentially placed in three directions at approximately right angles to one another to reliably detect the motion of the stage. Linear encoders measure changes in lengths of the passive chain and the three actuated chains of the manipulator during traveling of the moving stage. Comparison between the measured length and the length calculated from forward kinematics of the 3-DOF manipulator reveals a length error of the passive chain. The least-squares method using a Jacobian matrix corrects 27 kinematic parameters so that the length errors of the passive chain are minimized. The above calculations were accomplished in both numerical simulations and experiments employing a coordinate measuring machine based on the parallel manipulator. Moreover, a length measurement simulation of gauge block measurement and a measurement experiment using the measuring machine were performed to verify the identified parameters.

Modeling and Simulation of the Engraving Process in Different Life Stages of Small Caliber Guns

2022 ◽  
Author(s):  
Mohamed Dhouibi ◽  
Hamza Ousji ◽  
Oussama Atoui ◽  
Rachid Nasri ◽  
Marc Pirlot
Keyword(s):  
Doppler Radar ◽  
Experimental Studies ◽  
Coordinate Measuring Machine ◽  
Life Stages ◽  
Resistance Evolution ◽  
Chamber Volume ◽  
Gun Barrel ◽  
Measuring Machine ◽  
Bullet Velocity ◽  
The Relationship

Abstract Effects of erosion phenomenon on the performance of a given gun barrel have been analyzed throughout numerical and experimental studies. Mainly, qualitative observations were performed. Theoretical relations between the evolution of the inner barrel profile and the provided interior ballistics are limited. This paper focuses on the development of a numerical model to predict the engraving resistance evolution in terms of the inner barrel profile in the different weapon's life stages. Four test barrels "12.7x99mm NATO" with different chamber volumes were considered. First, a Coordinate Measuring Machine (CMM) with a contact scanning probe was used to measure the inner dimension of the guns. Second, piezoelectric sensors with a special doppler radar were considered to measure the (i) pressure and (ii) the bullet velocity in the test weapons. Finally, based on the obtained experimental results, a Finite Element (FE) analysis using the commercial software LS-DYNA was developed and validated. The obtained numerical results were used as insights to quantify the relationship between the engraving resistance and the chamber volume of small caliber guns.

An exact method for the sphericity measurement of soccer balls

2003 ◽  
Vol 217 (5) ◽  
pp. 715-719 ◽  
Author(s):  
P J Neilson ◽  
R Jones
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Coordinate Measuring Machine ◽  
Current Method ◽  
New Method ◽  
Ball Surface ◽  
Ball Diameter ◽  
Sphere Approximation ◽  
Measuring Machine ◽  
A New Technique

The most popular games in the world are ball sports. Generally, ball properties such as weight, circumference and sphericity are specified in the rules and determine the ball quality. The current method of sphericity measurement employed by the Federation International Football Association (FIFA) is to measure the ball diameter at 16 points and then calculate the mean average. The sphericity of the ball is inferred from the diametric measurements. Unfortunately, diameter measurement does not guarantee sphericity, and a new technique has been developed to measure ball sphericity using a coordinate measuring machine (CMM). In this method a representative sample of the ball surface is probed/measured to give three-dimensional coordinates of defined points, nominally the ball panel centres. Computer software is then used to fit a least-squares sphere approximation to the ball data, giving a unique value for ball sphericity. Measurements were taken of six different brand type balls, with a sample of four balls of each brand; all balls were inflated to the same pressure. The results show that the new method of sphericity measurement suggested here gives a unique assessment of sphericity. The errors obtained from the new method are such that the FIFA error specification may need reconsideration.

scholarly journals Analysis of Motion Errors of Linear Guide Pair Based on Parallel Mechanism

Machines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
Peng-Hao Hu ◽  
Ying-Jun Lei ◽  
Yang-Kai Ou
Keyword(s):  
Parallel Mechanism ◽  
Coordinate Measuring Machine ◽  
Guide Rail ◽  
Motion Error ◽  
Linear Guide ◽  
Measuring Machine ◽  
Moving Platform ◽  
Straightness Error ◽  
The Relationship ◽  
Analysis Of Motion

This paper systematically summarized the technical state of art and research results on the motion error of a linear guideway, corrected some misconceptions, and further clarified the relationship between the straightness error of the guide rail itself and the motion error of the linear stage. Moreover, a new method based on parallel mechanism is provided to study the motion errors of the linear guide pair. The basic idea is to abstract the structural relationship between the stage and the guide rail into a 4-bar parallel mechanism. Thus, the stage can be considered as a moving platform in the parallel mechanism. Its motion error analysis is also transferred to moving platform position analysis in the parallel mechanism. The straightness motion error and angular motion error of the stage can be analyzed simultaneously by using the theory of parallel mechanism. Some experiments were conducted on the linear guideway of a self-developed parallel coordinate measuring machine. The experimental data and analysis verify the feasibility and correctness of this method.

scholarly journals Six-degree-of-freedom pose estimation with µm/µrad accuracy based on laser multilateration

2021 ◽  
Vol 10 (1) ◽  
pp. 19-24
Author(s):  
Jan Nitsche ◽  
Matthias Franke ◽  
Nils Haverkamp ◽  
Daniel Heißelmann
Keyword(s):  
Pose Estimation ◽  
Coordinate Measuring Machine ◽  
Degree Of Freedom ◽  
End Effector ◽  
Data Rates ◽  
Measurement Principle ◽  
Measuring Machine ◽  
Position And Orientation ◽  
Six Degree Of Freedom ◽  
Adequate Measurement

Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm.

Study on Building Digital-Twin of Face-Milled Hypoid Gear From Measured Tooth Surface Topographical Data

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Yi-Hui Lee ◽  
Zhang-Hua Fong
Keyword(s):  
Coordinate Measuring Machine ◽  
Industrial Applications ◽  
Tooth Surface ◽  
Position Vector ◽  
Normal Vector ◽  
Hypoid Gear ◽  
Principal Curvatures ◽  
Digital Twin ◽  
Design Variables ◽  
Measuring Machine

Abstract A highly accurate digital-twin spiral bevel gear or hypoid gear is often required for dynamic analysis or stress analysis for gear transmission. However, a highly accurate digital-twin solid model is not always available because the final hypoid gear is completed by the gear manufacturer. This study constructs a digital-twin from a sample hypoid gear. The tooth surface of sample gear is digitized as topographical grids using a coordinate measuring machine (CMM) or a gear measurement center. The geometric parameters (the surface position vector, the normal vector, the principal curvatures, and the corresponding principal directions) for the measured tooth surface (MTS) are then extracted using numerical differential geometry (NDG). The machine settings and the cutter parameters for the sample hypoid gear are obtained by minimizing the topographical error between the replicated digital-twin and the sample gear using optimization software. The initial estimation for the machine settings and the cutter parameters is calculated using an explicit form of the modified-roll motion (MRM), which decreases numerical divergence and time that is required for calculation. The machine settings, the cutting tool parameters, and the auxiliary flank modification (AFM) motion are used as the design variables. A numerical example is presented to verify the proposed methodology. The numerical results show that the replicated digital-twin that is developed using the proposed method is sufficiently accurate for industrial applications.

A study of the phenomenon of wheel climb derailment: Results of basic experiments using model bogies

2002 ◽  
Vol 216 (4) ◽  
pp. 237-247 ◽  
Author(s):  
K Nagase ◽  
Y Wakabayashi ◽  
H Sakahara
Keyword(s):  
Friction Coefficient ◽  
Vertical Displacement ◽  
Railway Track ◽  
Displacement Sensor ◽  
Major Influence ◽  
Laser Displacement Sensor ◽  
Wheel Slip ◽  
Adhesion Coefficient ◽  
The Relationship ◽  
Basic Experiments

Wheel climb derailment sometimes occurs when a train passes through a steep curve on a railway track at low speeds. The authors conducted experiments on the phenomenon of wheel climb derailment using model bogies and a model track. The Nadal formula (Nadal limit) is used to evaluate the risk of derailment. Because the friction coefficient between the rail and the wheel has a considerable influence on the critical values to be calculated using the Nadal formula, it is inappropriate to evaluate the risk of derailment by using the Nadal formula alone. The risk of derailment can be determined in a straightforward way by measuring the wheel vertical displacement. In this study, to measure the wheel vertical displacement accurately, a high-precision laser displacement sensor was used. The experimental results revealed that a wheel both slips downwards and climbs up simultaneously and that vertical displacement of the wheel occurs when the degree of wheel climb-up exceeds the degree of wheel slip-down. Although the friction coefficient between the rail and the wheel is a primary factor responsible for causing wheel climb derailment, measurement of the friction coefficient is difficult to achieve. Therefore, a model slipping adhesion bogie was used to measure the adhesion coefficient instead of the friction coefficient. The data obtained from the experiments were analysed in order to verify the relationship between the adhesion coefficient and the wheel climb-up behaviour. As a result, it was found that the adhesion coefficient has a major influence on the occurrence of wheel climb derailment.

DIMENSIONAL INSPECTION OF TRANSLATING CAMS BY CNC COORDINATE MEASURING MACHINE

2012 ◽  
Vol 36 (3) ◽  
pp. 259-270
Author(s):  
Jung-Fa Hsieh
Keyword(s):  
Kinematic Model ◽  
Coordinate Measuring Machine ◽  
Least Square ◽  
Normal Vector ◽  
Transformation Theory ◽  
Fitting Method ◽  
Cam Profile ◽  
Measuring Machine ◽  
Normal Vectors ◽  
Nc Data

In this paper, a simple and analytical method is proposed for accomplishing the inspection procedure. In the proposed approach, a kinematic model of the cam profile is derived using homogenous coordinate transformation theory. The normal vectors and principal curvature of the designed translating cam are then derived from the analytical expression for the cam profile. Based on the coordinates and normal vector of each specified point on the cam profile, the NC data required to move the CMM inspection probe to the surface of the cam are then obtained. A least-square fitting method is proposed to minimize the inspection error caused by a misalignment of the actual evaluation frame relative to the ideal frame.

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