Multi-Camera-Based Universal Measurement Method for 6-DOF of Rigid Bodies in World Coordinate System

Zhao, Zuoxi; Zhu, Yuchang; Li, Yuanhong; Zhi, Qiu; Luo, Yangfan; Xie, Chaoshi; Zhang, Zhuangzhuang

doi:10.3390/s20195547

Cited by 8 publications

(2 citation statements)

References 47 publications

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“…In the equation, U 0 represents the object distance, and u 0 , v 0 represents the coordinate position of the origin of the image plane coordinate system in the pixel coordinate system. These parameters can be calibrated using Zhang’s calibration method [ 35 ]. f x is the normalized focal length in the U-axis direction, f x = f /d x , f y is the normalized focal length in the V-axis direction, with f y = f /d y , where f is the focal length of the lens, and d x and d y are the sizes of the image pixels in the two directions.…”

Section: Principle Of Recording Torsion Pendulum Curve Based On Monoc...mentioning

confidence: 99%

Research on the Measurement Technology of Rotational Inertia of Rigid Body Based on the Principles of Monocular Vision and Torsion Pendulum

Chen

Zeng

et al. 2023

Sensors

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Damping is an important factor contributing to errors in the measurement of rotational inertia using the torsion pendulum method. Identifying the system damping allows for minimizing the measurement errors of rotational inertia, and accurate continuous sampling of torsional vibration angular displacement is the key to realizing system damping identification. To address this issue, this paper proposes a novel method for measuring the rotational inertia of rigid bodies based on monocular vision and the torsion pendulum method. In this study, a mathematical model of torsional oscillation under a linear damping condition is established, and an analytical relationship between the damping coefficient, torsional period, and measured rotational inertia is obtained. A high-speed industrial camera is used to continuously photograph the markers on a torsion vibration motion test bench. After several data processing steps, including image preprocessing, edge detection, and feature extraction, with the aid of a geometric model of the imaging system, the angular displacement of each frame of the image corresponding to the torsion vibration motion is calculated. From the characteristic points on the angular displacement curve, the period and amplitude modulation parameters of the torsion vibration motion can be obtained, and finally the rotational inertia of the load can be derived. The experimental results demonstrate that the proposed method and system described in this paper can achieve accurate measurements of the rotational inertia of objects. Within the range of 0–100 × 10−3 kg·m2, the standard deviation of the measurements is better than 0.90 × 10−4 kg·m2, and the absolute value of the measurement error is less than 2.00 × 10−4 kg·m2. Compared to conventional torsion pendulum methods, the proposed method effectively identifies damping using machine vision, thereby significantly reducing measurement errors caused by damping. The system has a simple structure, low cost, and promising prospects for practical applications.

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Section: Principle Of Recording Torsion Pendulum Curve Based On Monoc...mentioning

confidence: 99%

Research on the Measurement Technology of Rotational Inertia of Rigid Body Based on the Principles of Monocular Vision and Torsion Pendulum

Chen

Zeng

et al. 2023

Sensors

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show abstract

“…The multi‐camera systems (MCSs) provide a solution for high‐precision estimation of 6‐DOF motion. MCS reported in the existing literature generally fix multiple cameras with overlapping FOV on a stable platform to measure the 3D displacement (Park et al., 2015) or 6‐DOF pose changes (Z. Zhao et al., 2020) of rigid body structures. However, using multiple cameras without overlapping FOV to solve the problem of 6‐DOF ego‐motion of the observation platform has not been reported hitherto.…”

Section: Introductionmentioning

confidence: 99%

Displacement measurement of large structures using nonoverlapping field of view multi‐camera systems under six degrees of freedom ego‐motion

Yin

Zhang

et al. 2022

Computer aided Civil Eng

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In this work, a non-overlapping field of view (FOV) multi-camera system (MCS) has been proposed to realize the motion self-compensation, which can be flexibly arranged according to the field situation. The challenges of ensuring a complete fixed measurement platform owing to the self-weight, unexpected collisions, and adjacent engineering constructions have been addressed in this study. MCS can be fixed on an unstable platform and employ two or more correcting cameras, without an overlapping FOV, to measure and compensate the six degrees of freedom (6-DOF) ego-motion of the platform, with high accuracy. The numerical simulation results show that, under the same configuration conditions, the 6-DOF motion estimation accuracy of the proposed method is better than that of the Perspective-n-Points methods, especially for the estimation accuracy of the out-of-plane motion and the roll motion of the camera. The field demonstration has been performed on a suspension bridge, and the results demonstrate that the deflection measurements provided by the proposed MCS are consistent with those provided by the Robotic Total Station. The proposed MCS, which is not restrained by a strictly stable platform, proves to be an effective method to compensate for the errors induced by the platform ego-motion, and it can meet the requirements of the displacement measurement of large structures needing high precision.

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A four parallel laser-based simultaneous measurement method for 6-degrees-of-freedom errors of rigid body with translational motion

Zheng

Zhu

et al. 2022

Review of Scientific Instruments

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The measurement of six-degrees-of-freedom (6-DOF) errors of rigid bodies can show the real and accurate spatial pose of those rigid bodies. It plays a major role in precision calibration, spacecraft docking, machining, assembly, etc. In this paper, a four parallel laser-based simultaneous measurement (FPL-SM) method is proposed for measuring 6-DOF errors of rigid bodies with translational motion. First, a FPL-SM device is introduced. Its four laser heads form a rectangle, which is perpendicular to the movement direction of the measured linear displacement. Second, identification formulas for all geometrical errors in rigid bodies with translational motion are presented based on the relative positions of the four lasers. Based on the readings of the four lasers, angular errors and corresponding straightness errors are calculated for the direction of motion around the other two linear motions. As the two parallel sides of the rectangle are in different planes, the straightness errors of the two planes are different. The rolling angular error in the direction is expressed as the difference between the straightness errors of the two planes divided by the distance between the two planes. Six fundamental errors for rigid bodies with translational motion are obtained by four lasers in a single setting of the device. For multiple rigid bodies with mutually perpendicular translational motion, the squareness error is calculated by fitting to the actual direction of motion. Finally, experiments were carried out on the SmartCNC_DRDT five-axis machine tool and 21 geometric errors were determined for three translational axes. Error compensation was carried out using the generated machine tool geometric error data to verify the effectiveness of the proposed FPL-SM method. In addition, geometric errors and thermal errors of the Z axis of the GTI-2740 machine tool are measured based on the FPL-SM method.

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Multi-Camera-Based Universal Measurement Method for 6-DOF of Rigid Bodies in World Coordinate System

Cited by 8 publications

References 47 publications

Research on the Measurement Technology of Rotational Inertia of Rigid Body Based on the Principles of Monocular Vision and Torsion Pendulum

Research on the Measurement Technology of Rotational Inertia of Rigid Body Based on the Principles of Monocular Vision and Torsion Pendulum

Displacement measurement of large structures using nonoverlapping field of view multi‐camera systems under six degrees of freedom ego‐motion

A four parallel laser-based simultaneous measurement method for 6-degrees-of-freedom errors of rigid body with translational motion

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