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1.
In this paper, we propose a new procedure for the extended calibration of charge-mode accelerometers. This procedure covers two main stages. The first one follows the general guidelines of international guides that relate to calibrating accelerometers in the frequency domain and are implemented using a weighted-least-squares method. These guidelines are modified herein for the advanced modelling of the charge-mode accelerometer. The second stage provides a new solution which is an extension of the standard calibration using the upper bound of the dynamic error (UBDE) according to the integer-square criterion and a fixed-point algorithm that enables this error to be determined. Additionally, the special functions, representing the values of the dynamic error for the predetermined ranges of the parameters associated with the mathematical model of the charge-mode accelerometer, are determined. Such functions ensure an easy and rapid execution of the second stage of calibration without conducting complicated procedures to determine the value of the UBDE.The extended procedure proposed here enables the comparison of accelerometers with similar technical parameters, but produced by different manufacturers of measuring sensors that frequently compete with each other. In this way, we can select the accelerometer that will produce the lower value of UBDE. 相似文献
2.
《Measurement》2016
The paper presents an application of the continuous wavelet transform (CWT) to analyse the energy density of signals which maximize the integral-square error (ISE) at the output of two different accelerometers. These accelerometers were chosen as being examples of a large class of measuring instrument intended for the measurement of nondetermined input signals. Input signals constrained in magnitude only and simultaneously in magnitude and rate of change are considered in this paper.Scalogram analysis which provides a graphical representation of the signal energy density over the time-scale plane is discussed in detail in the second section of this paper. In the third, the results for the two accelerometers modelling are presented, while the fourth section presents methods for determining signals maximizing the ISE by using the genetic algorithm (GA).The final sections is devoted to a discussion of the results and analysis of the energy density based on the scalogram and corresponding conclusions with respect to properly determined signals maximizing ISE.For modelling the sensors MathCad15 was applied, while the maximizing signals and CWT analysis were executed using MATLAB2011.The methods presented in this paper constitute a novel approach for the estimation of the correctness of the signals maximizing the ISE by means of energy density analysis. 相似文献
3.
《Measurement》2015
The paper presents the way of determining the time dependent characteristics of maximum error generated by an accelerometer in case it measures dynamically changing signals of vibrations. For that purpose, a domain has been specified, which may contain the class of signals maximizing the error criterion assumed. Indispensable constraints have been imposed on signals, which result from the dynamic properties of the accelerometer examined. These constraints concern amplitude and rate of change. Constraint values have been determined using a mathematical model of an accelerometer obtained from concurrent measurements of its amplitude and phase characteristics. The error has been calculated in relation to a standard, having the form of an ideal low-pass filter. The characteristics of the error as a function of measurement time have been provided. The numerical solutions presented in the article refer to a popular accelerometer of the PCB type, and error in the form of integral square-error. 相似文献
4.
A two-dimensional test body having cross-aligned hollow cones has been developed for automatic calibration of coordinate measuring machines (CMMs). Two hours are sufficient for the measurement of translatory and rectangularity errors of a CMM by means of the test body. In this paper the principles of measurement of such erros using the test body are described These principles can be utilized on the assumption that one knows the exact values of the test body, so the calibration procedures for the test body are also described. 相似文献
5.
H. Yagishita 《Precision Engineering》1990,12(3)
A new method for measuring the dynamic transmission error between a hob and worktable in large gear hobbing machines is described in which a pair of small, highly sensitive servo-accelerometers are mounted tangentially, 180° (arc degree) apart, on the periphery of a large worktable, in order to detect rotational fluctuations of the worktable. Two acceleration signals from the servo-accelerometers mounted on the worktable are summed in order to determine the circumferential acceleration. The resulting sum will nullify the rectilinear acceleration of the worktable. After the circumferential acceleration signal transmitted by a telemeter is processed by a pulse signal from a rotary encoder attached to the hob shaft in this apparatus, the dynamic transmission error can be obtained. In tests using a large gear hobbing machine (3.3 m worktable diameter), the dynamic transmission error has been measured and recorded. By processing the recorded analogue signal with an FFT (Fast Fourier Transformation) analyser and by consulting the schematic drawing of the rotational transmission mechanism, specific parts in the mechanism causing the transmission error can be identified. Also, by processing the circumferential acceleration signal of the worktable from a standing start with an FFT analyser, the rotational natural frequency of the worktable can be easily obtained. 相似文献
6.
列车动态包络线是评定列车安全运行的一项重要指标,基于双目立体视觉的方法是目前能够实现速度超过200 km/h列车动态包络线测量的唯一方法.因受到大视场和标定时间的严格限制,便携的标定设备、易于搭建的靶标和快速的标定算法便成为标定过程需要满足的三个条件.本文提出一种新的基于双目立体视觉的大视场现场快速标定方法,设计轻型便携靶标,靶标上40个反光标记点表示铁轨坐标系,并用于计算双相机内外参数.并且,双相机仅需同时拍摄一张靶标图像,就能实现双相机内外参数快速一体化标定.实验结果表明,该方法测量精度可达±1 mm,能够满足高速列车动态包络线测量现场标定要求. 相似文献
7.
为提高6-PSS并联机构的运动精度,需对其进行误差分析和标定研究。利用矢量法构建并联6自由度机构的误差模型,根据MATLAB计算得到机构的误差源对动平台末端位姿影响的灵敏度。对机构进行误差综合分析,结合运动学正解和逆解,提出一种新的基于机构坐标轴姿态约束的运动学标定方法。根据测量初始值,利用标定算法解算得到机构的标定值。借助外部检测设备测量得机构标定前和标定后的位移和角度误差,标定后位移误差由10mm减小到1mm,角度误差由0.3°减小到0.1°。以实际测量数据验证了该标定方法的有效性和正确性,并最终提高了并联机构的运动精度。 相似文献
8.
提出一种改进的柔性视觉测量系统标定方法。建立了包含手眼关系误差与机器人运动学参数误差的系统误差模型。在机器人末端安装结构光传感器构建了机器人柔性视觉测量系统,并在机器人工作空间中固定一个标准球作为标定参考物。标定时,机器人被控制在不同位姿下测量球心坐标。首先,应用机器人的理论模型初步标定手眼关系;然后,基于球心约束,通过迭代算法同时得到准确的手眼关系和实际的机器人运动学参数。基于ABB IRB2400工业机器人进行了系统标定实验,并利用激光跟踪仪进行精度验证。结果表明:标定前后机器人柔性视觉测量系统的距离测量标准差由0.566mm降低到0.173mm,充分验证了改进方法的有效性和实用性。该方法提高了手眼关系的精度;不需要采用任何昂贵的外部设备,适合工业现场使用。 相似文献
9.
为了提高1P3R型柔性测量臂的检测精度,提出了一种自适应误差标定方法来完成它的参数标定和误差补偿。首先,基于RPY理论建立柔性测量臂的运动学模型并应用微分法推导了误差模型。然后,基于马尔柯夫链收敛性理论进行实数编码;在遗传算法(GA)中引入自适应控制算子,提高了父代种群的多样性和最优个体变异数量;最后,对比分析了归一化GA、一般GA和最小二乘法等3种算法的误差标定精度及其收敛性,验证了所提出方法的有效性和可行性。结果显示:归一化GA仅用328代寻优计算,其精度达到5.2μm,收敛速度是一般GA的2.3倍且精度提高了3.1μm;最小二乘法经20次迭代计算后停止收敛,精度仅为18.4μm。实验结果表明:归一化GA具有收敛速度快、标定精度高和收敛稳定性好等明显优势,更易于实现该类测量机的高精度检测。 相似文献
10.
11.
Methods of analytic determination of calibration intervals for off-line measuring facilities and means of determining the calibration intervals by simulation for redundant measuring systems are discussed. 相似文献
12.
Juan Carlos JáUREGUI Eusebio E. HERNáNDEZ Marco CECCARELLI Carlos LóPEZ-CAJúN Alejandro GARCíA 《Frontiers of Mechanical Engineering》2013,8(3):252
The pose accuracy of a parallel robot is a function of the mobile platform posture. Thus, there is no a single value of the robot’s accuracy. In this paper, two novel methods for estimating the accuracy of parallel robots are presented. In the first method, the pose accuracy estimation is calculated by considering the propagation of each error, i.e., error variations are considered as a function of the actuator’s stroke. In the second method, it is considered that each actuator has a constant error at any stroke. Both methods can predict pose accuracy of precise robots at design stages, and/or can reduce calibration time of existing robots. An example of a six degree-of-freedom parallel manipulator is included to show the application of the proposed methods. 相似文献
13.
关节臂式坐标测量机(AACMM)是一种便携式高精度测量设备,由于测量机末端探头中心坐标的关系且关节的旋转角度非常复杂,有必要建立准确的数学模型以达到所需的精度。其经典的数学模型是Denavit-Hartenberg(D-H)模型,但它在相邻关节轴平行时存在缺陷且忽略了静态柔性误差。为了消除D-H模型的不足,研究了一种基于广义几何误差理论的数学模型,并采用非常快速模拟退火算法对广义几何误差参数进行标定。对比实验结果表明,广义几何误差模型进行算法标定后平均误差减小了0.500 1 mm,标准偏差减小了0.337 3 mm;基于广义几何误差模型的长度测量的平均误差为0.045 4 mm,标准偏差为0.032 3 mm,均优于采用MDH模型测量的平均误差和标准偏差,验证了方法的有效性。 相似文献
14.
The present study outlines the efforts made to improve national primary water flow standards and calibration systems through design and development. The facility has been designed and developed in accordance with ISO 4185 standard in the flow range 0.03 m3/h to 650 m3/h to calibrate various types of flow meters up to DN200 (Nominal diameter) using 12 kg, 300 kg, 3000 kg, and 6000 kg weighing systems. In the flow range up to 530 m3/h, the expanded uncertainty in flow meter calibration in totalized mode is found to be ±0.01% to ±0.025% (k = 2), whereas it is ±(0.03–0.05) % (k = 2) up to DN200 size (test rigs) for mass flow rate (MFR) and volume flow rate (VFR) in the flow range 0.1 m3/h to 650 m3/h. The measurement uncertainty achieved is comparable to that of state-of-the-art water flow measurement capabilities available at numerous National Metrology Institutes (NMIs). Thus, the present designed and developed system at CSIR-National Physical Laboratory (CSIR-NPL) is a solution to maintain traceability to the users and industries. 相似文献
15.
A new calibration method is proposed to improve the circular plane kinematic accuracy of industrial robot by using dynamic measurement of double ball bar (DBB). The kinematic model of robot is established by the MDH (Modified Denavit-Hartenberg) method. The error mapping relationship between the motion error of end-effector and the kinematic parameter error of each axis is calculated through the Jacobian iterative method. In order to identify the validity of the MDH parameter errors, distance errors and angle errors of each joint axis were simulated by three orders of magnitude respectively. After multiple iterations, the average value of kinematic error modulus of end-effector was reduced to nanometer range. Experiments were conducted on an industrial robot (EPSON C4 A901) in the working space of 180 mm × 490 mm. Due to the measuring radius of DBB, the working space was divided into 30 sub-planes to measure the roundness error before and after compensation. The average roundness error calibrated by the proposed method at multi-planes decreased about 21.4%, from 0.4637 mm to 0.3644 mm, while the standard deviation of roundness error was reduced from 0.0720 mm to 0.0656 mm. In addition, by comparing the results of positioning error measured by the laser interferometer before and after calibration, the range values of motion errors of end-effector were decreasing by 0.1033 mm and 0.0730 mm on the X and Y axes, respectively. 相似文献
16.
为解决目前高速机构存在的高速与高精度之间的矛盾,研究了高速并联测量机的柔性问题。应用弹性梁运动学理论和Galerkin模态截断法推导了一维弹性梁运动学变形位移模型;以欧拉-贝努利梁为假设,应用Hamilton原理建立了考虑中线变形的柔性结构耦合动力学模型。最后,基于中线耦合动力学模型,测试了不同速度下弹性振动产生的误差,提出了通过调节黏滞摩擦系数来降低振动耦合误差,进而提高测量精度的方法。基于仿真实验验证了提出方法的有效性和可行性。结果表明:在忽略结构误差前提下,角速度为300rad/s时产生的横向一阶振动耦合误差最大值为28.6μm;合理调整黏滞摩擦在0.4~0.5时,振动耦合误差降低至15μm以内,相比调整前误差降低了13.6μm。提出的方法为进一步解决高速与高精度之间的矛盾和研究高阶弹性振动与精度的耦合机理提供了理论基础。 相似文献
17.
This paper proposes a backstepping control system that uses a tracking error constraint and recurrent fuzzy neural networks (RFNNs) to achieve a prescribed tracking performance for a strict-feedback nonlinear dynamic system. A new constraint variable was defined to generate the virtual control that forces the tracking error to fall within prescribed boundaries. An adaptive RFNN was also used to obtain the required improvement on the approximation performances in order to avoid calculating the explosive number of terms generated by the recursive steps of traditional backstepping control. The boundedness and convergence of the closed-loop system was confirmed based on the Lyapunov stability theory. The prescribed performance of the proposed control scheme was validated by using it to control the prescribed error of a nonlinear system and a robot manipulator. 相似文献
18.
This paper presents an uncertainty analysis of a Positional Error Calibrator based on a laser interferometer system. This laser calibration system is capable of evaluating the positioning accuracy of a numerically controlled axis of machine tools and coordinate measuring machines (CMM) under dynamic conditions. In order to assess the measurement uncertainty of this calibrator, an analysis of the uncertainty components that make up the uncertainty budget of this calibrator has been carried out. These uncertainty components can be classified into three categories as follows: (1) uncertainties intrinsic to the laser system; (2) uncertainties due to environmental effects; (3) measuring uncertainties due to the installation. The procedure for evaluating the uncertainty of this calibrator follows GUM (“Guide to the Expression of Uncertainty in Measurement”). This uncertainty analysis was carried out when this calibrator was used to assess the positional errors of the “X” axis of a moving bridge type CMM. 相似文献
19.
V. P. Korol’kov S. A. Konchenko 《Optoelectronics, Instrumentation and Data Processing》2012,48(2):211-217
A method for measuring the groove depth of calibration gratings is proposed which is based on measuring the spectral dependence of the the zero-order reflection diffraction efficiency. The errors of the method are determined by three main factors: the shift of the maxima of the spectrum due to the wall slope of the grating grooves, the error in setting the wavelength of the spectrophotometer, and the divergence of the light beam in the setup. It is shown theoretically that the measurement error is in the range of 0.25–1%, depending on the fabrication technology of the grating and measuring equipment. The method was tested experimentally using commercial calibration gratings. The range of applicability of the method is discussed in terms of the geometrical parameters of the microstructure of reflection gratings and the characteristics of the spectrophotometer used. 相似文献