• International Journal of Control, Automation, and Systems
• /
• 제2권4호
• /
• pp.536-541
• /
• 2004

It is important to estimate and calibrate sensor errors in maintaining the performance level of SDINS. In this study, an estimation technique of fixed sensor errors for SDINS calibration is discussed. First, the fixed errors of gyros and accelerometers, excluding gyro biases are estimated by the navigation information of SDINS in multi-position. The SDINS with RLG includes flexure errors. In this study, the gyros flexures are out of consideration, but the proposed procedure selects certain positions and rotations in order to minimize the influence of flexures. Secondly, the influences of random walks, flexures and orientation errors are verified via numerical simulations. Thirdly, applying the previous estimated errors to SDINS, the estimation of gyro biases is conducted via the additional control signals of close-loop self-alignment. Lastly, the experiments illustrate that the extracted calibration parameters are available for the improvement of SDINS.

• 한국산업융합학회 논문집
• /
• 제24권6_2호
• /
• pp.947-952
• /
• 2021

In this paper, the simplified kinematic error model for Delta parallel robot is presented, which can enable the analytical forward kinematics essentially for kinematic calibration calculations instead of the numerical one. The simplified kinematic error model is proposed and the forward kinematics including the error parameters is analytically derived. The kinematic calibration algorithm of the Delta parallel robot with 90 degree arrangement using laser tracker and the experiment result are presented.

• Geomechanics and Engineering
• /
• 제16권5호
• /
• pp.471-482
• /
• 2018

A flat-jointed bonded-particle model (BPM) has been proved to be an effective tool for simulating mechanical behaviours of intact rocks. However, the tedious and time-consuming calibration procedure imposes restrictions on its widespread application. In this study, a systematic approach is proposed for simplifying the calibration procedure. The initial relationships between the microscopic, constitutive parameters and macro-mechanical rock properties are firstly determined through dimensionless analysis. Then, sensitivity analyses and regression analyses are conducted to quantify the relationships, using results from numerical simulations. Finally, four examples are used to demonstrate the effectiveness and robustness of the proposed systematic approach for the calibration procedure of BPMs.

• ETRI Journal
• /
• 제44권5호
• /
• pp.816-825
• /
• 2022

Nondestructive testing, which can monitor a product's interior without disassembly, is becoming increasingly essential for industrial inspection. Computed laminography (CL) is widely used in this application, as it can reconstruct a product, such as a printed circuit board, into a three-dimensional (3D) high-magnification image using X-rays. However, such high-magnification scanning environments can be affected by minute vibrations of the CL device, which can generate motion artifacts in the 3D reconstructed image. Since such vibrations are irregular, geometric corrections must be performed at every scan. In this paper, we propose a geometry calibration method that can correct the geometric information of CL scans based on the image without using geometry calibration phantoms. The proposed method compares the projection and digitally reconstructed radiography images to measure the geometric error. To validate the proposed method, we used both numerical phantom images at various magnifications and images obtained from real industrial CL equipment. The experiment results confirmed that sharpness and contrast-to-noise ratio (CNR) were improved.

• 제어로봇시스템학회논문지
• /
• 제17권12호
• /
• pp.1256-1265
• /
• 2011

Automated parking assist systems are being commercialized and rapidly spread in the market. In order to improve odometry accuracy, we proposed a practical odometry calibration scheme of Car-Like Mobile Robot (CLMR). However, there were some open problems in our prior work. For example, it was not clear whether the kinematic parameters always converged or not using the proposed calibration scheme. In addition, test driving had to be carried out "twice" without detailed explanation. This research aims to provide answers for the addressed questions though the convergence property analysis of the calibration scheme. In this paper, we evaluate on the effect of the kinematic parameter error on the odometry error at the final pose by numerical computation. The evaluation will show that the wheel diameter and tread of the CLMR can be calibrated by iterative test drives. In addition, the region of convergence in the parametric space will be discussed. Presented experimental results clearly showed that the proposed calibration scheme would be useful in practical applications.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
• /
• pp.381-388
• /
• 2001

Behavior characteristics of coil shaped elastoplastic dampers, a sort of hysteretic damper, are studied on through experiments and numerical analyses. The coil shaped elastoplastic damper shows bilinear force-deformation relationship, and no stress concentration is occurred in the device. Numerical model, which is constructed through calibration with experimental results, shows good agreement with experiment, The coil shaped elastoplastic damper has lower yielding strength and stiffness under transversal loading compared to axial leading. Additional studies are required on behavior characteristics according to configuration variation of coil shaped elastoplastic dampers.

• Journal of the Optical Society of Korea
• /
• 제19권4호
• /
• pp.397-402
• /
• 2015

In this paper, we propose a method used to measure the polarization state of a field with multiple polarization singularities (PSs), such as an array of PSs and PSs in vector speckle. A checkerboard is used to construct characteristic points, which makes it possible to calibrate the mismatches between pictures obtained during the rotation of a quarter-wave plate and a polarizer. Using this method a field with an array of PSs is measured. The experimental result is compared with the numerical simulation. We also carry out some data analysis. The comparison and analysis emphasize the necessity and feasibility of this method to measure the PSs.

• Structural Engineering and Mechanics
• /
• 제60권5호
• /
• pp.749-760
• /
• 2016

The objective of the study is to investigate the effects of model calibration on seismic behaviour of a historical mosque which is one of the most significant Ottomon structures. Seismic analyses of calibrated and noncalibrated numeric models were carried out by using acceleration records of Kocaeli earthquake in 1999. In numerical analysis, existing crack zones on real structure was investigated in detail. As a result of analyses, maximum stresses and displacements of calibrated and noncalibrated numerical models were compared each other. Consequently, seismic behaviour and damage state of historical masonry Hafsa Sultan mosque was determined as more realistic in the event of a severe earthquake.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1615-1620
• /
• 2003

Kinematic calibration is a process whereby the actual values of geometric parameters are estimated so as to minimize the error in absolute positioning. Measuring all components of Cartesian posture, particularly the orientation, can be difficult. With partial pose measurements, all parameters may not be identifiable. This paper proposes a new device that can identify all kinematic parameters with partial pose measurements. Study is performed for a six degree-of-freedom fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector's motion to five degree-of-freedom and can measure position of the end-effector and one of its rotations. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise. Intrinsic inaccuracies of the device can significantly deteriorate the calibration results. A measurement procedure is proposed and formulations of cost functions are discussed to prevent propagation of the inaccuracies to the calibration results.

• Journal of Astronomy and Space Sciences
• /
• 제19권4호
• /
• pp.293-304
• /
• 2002

본 논문에서는 2002년 하반기에 발사 예정인 과학로켓 3호에 탑재되어 있는 자력계의 비행모델(flight model) 제작 모델의 디지털 회로 설계와 부품선정 및 Fluxgate 자력계 AIM(Attitude Information Magnetometer)과 지구 자기장 섭동 측정용 Search-Coil 자력계 SIM(Scientific Investigation Magnetometer)의 검교정시험 수행 결과에 대해 기술하였다. 초기 설계된 자력계 디지털 회로는 자료의 샘플링 속도가 낮고, 잡음이 많이 발생되어 이를 향상시켰으며, 자료의 신뢰성을 확보하기 위해 부품 재선정 및 회로를 다시 설계하였다. 재구성이후 자력계의 디지털 검교정시험을 실시하였고, 그 결과, 최초 아날로그 검교정시험때 설정한 AIM 센서의 InT의 분해능보다 실제 측정된 분해능 값이 떨어졌음을 확인할 수 있었다. 이를 보정하기 위해 수치계산법을 이용하여 보정치와 오차값을 계산하였으며, 이 보정치들을 과학로켓 3호 발사 이후 얻어지는 자력계 자료에 적용할 예정이다.