A Flexible Calibration Method of Laser Light-Sectioning System for Online 3D Measurement

A flexible calibration method based on a front-coated flat mirror is proposed for a laser light-sectioning three-dimensional(3D)measurement system. Since the calibration target and its mirror image are spatially separated and can be recorded in an image by a camera,the proposed method requires only a single composite image that contains a non-planar checkerboard pattern,a laser strip projected on the target and their mirror images to complete the calibration of the camera and the laser plane in one step. Levenberg-Marquardt(LM)algorithm is used to optimize the system parameters,and the measurement accuracy and speed are improved to enable online 3D inspection. Static and dynamic online 3D measurements are carried out on a cup and a triple stepped shaft,respectively,to validate the proposed method. The shaft has two steps with the depth of(0.5±0.01)mm and(2±0.01)mm to be measured online when the shaft is rotated and translated at the same time. The measurement results can be output at a frequency of 7 to 11 readings per second with standard deviations of 0.040 mm and 0.051 mm. The experimental results verify the effectiveness and flexibility of the proposed method.

Online asymmetry estimation for whole angle mode coriolis vibratory gyroscopes by high frequency injection

The whole angle mode gyroscope(WAMG)is considered to be the next generation architecture,but it is suffered from the asymmetry errors to conduct real products.This paper proposes a novel high frequency injection based approach for the error parameters online identification for the WAMG.The significance is that it can separate physical and error fingerprints to enable online calibration.The nonlinear WAMG dynamics are discretized to meet the requirement of numerical precision and computation efficiency.The optimized estimation methods are then constructed and compared to track asymmetry error parameters continuously.In the validation part,its results firstly prove that the proposed scheme can accurately identify constant asymmetry parameters with an overall tracking error of less than 1 ppm and the extreme numerical convergence can reach 10^(-12)ppm.Under the dynamic asymmetry variation condition,the root mean square errors(RMSE)indicate that the tracking accuracy can reach the level of10^(-3),which shows the robustness of the proposed scheme.In summary,the proposed method can effectively estimate the WAMG asymmetry errors online with satisfied performance and practical values.

Hierarchical Bayesian Calibration and On-line Updating Method for Influence Coefficient of Automatic Dynamic Balancing Machine

Measurement error of unbalance＇s vibration response plays a crucial role in calibration and on-line updating of influence coefficient（IC）. Focusing on the two problems that the moment estimator of data used in calibration process cannot fulfill the accuracy requirement under small sample and the disturbance of measurement error cannot be effectively suppressed in updating process, an IC calibration and on-line updating method based on hierarchical Bayesian method for automatic dynamic balancing machine was proposed. During calibration process, for the repeatedly-measured data obtained from experiments with different trial weights, according to the fact that measurement error of each sensor had the same statistical characteristics, the joint posterior distribution model for the true values of the vibration response under all trial weights and measurement error was established. During the updating process, information obtained from calibration was regarded as prior information, which was utilized to update the posterior distribution of IC combined with the real-time reference information to implement online updating. Moreover, Gibbs sampling method of Markov Chain Monte Carlo（MCMC） was adopted to obtain the maximum posterior estimation of parameters to be estimated. On the independent developed dynamic balancing testbed, prediction was carried out for multiple groups of data through the proposed method and the traditional method respectively, the result indicated that estimator of influence coefficient obtained through the proposed method had higher accuracy; the proposed updating method more effectively guaranteed the measurement accuracy during the whole producing process, and meantime more reasonably compromised between the sensitivity of IC change and suppression of randomness of vibration response.

Calibration of Discrete Element Heat Transfer Parameters by Central Composite Design

The efficiency and precision of parameter calibration in discrete element method （DEM） are not satisfactory, and parameter calibration for granular heat transfer is rarely involved. Accordingly, parameter calibration for granular heat transfer with the DEM is studied. The heat transfer in granular assemblies is simulated with DEM, and the effective thermal conductivity （ETC） of these granular assemblies is measured with the transient method in simulations. The measurement testbed is designed to test the ETC of the granular assemblies under normal pressure and a vacuum based on the steady method. Central composite design （CCD） is used to simulate the impact of the DEM parameters on the ETC of granular assemblies, and the heat transfer parameters are calibrated and compared with experimental data. The results show that, within the scope of the considered parameters, the ETC of the granular assemblies increases with an increasing particle thermal conductivity and decreases with an increasing particle shear modulus and particle diameter. The particle thermal conductivity has the greatest impact on the ETC of granular assemblies followed by the particle shear modulus and then the particle diameter. The calibration results show good agreement with the experimental results. The error is less than 4%, which is within a reasonable range for the scope of the CCD parameters. The proposed research provides high efficiency and high accuracy parameter calibration for granular heat transfer in DEM.

A calibration and compensation method for an industrial robot with high accuracy harmonic reducers

Industrial serial robots need high stiffness to keep absolute pose accuracy and meet the requirements in practical applications. However, the weak stiffness feature of robot joints and the payloads affected on robot end-effector, which will also increase the pose error of robot. Especially, the existing calibration methods often consider under no-payload condition without discussing the payload state. In this paper, we report a new industrial serial robot composed by a new harmonic reducer: Model-Y, based on high accuracy and high stiffness, and a kinematic parameter calibration algorithm which is based on a harmonic reducer forcedeformation model. To decrease the accuracy effects of payload, an iterative calibration method for kinematic parameters with payload situation was proposed. Simulation and experiments are conducted to verify the effectiveness of the proposed calibration method using the self-developed industrial serial robot. The results show a remarkably improved accuracy in absolute position and orientation with the robot's payload range. The position mean error has 70% decreased to 0.1 mm and the orientation mean error diminished to less than 0.01° after calibration with compensation. Additionally, online linear and circular tests are carried out to evaluate the position error of the robot during large-scale spatial and low-speed continuous movement. The accuracy is consistent with the previous calibration results, indicating the effectiveness and advantages of the proposed strategy in this article.

Development of a Calibration and Monitoring System for GD-1 High Pressure Common Rail Diesel Engine

Based on CAN calibration protocol, a new calibration and monitoring system was developed for the GD-1 high pressure common rail diesel engine. CAN driver block, monitoring program and calibration program for this system were designed respectively. The inquiry mode was used in the monitoring program and the interrupt mode was used in calibration program. The calibration program was designed in structural programming model. This system provides a reliable, accurate and quick CAN bus between ECU and PC, with baud rate up to 500Kbit/s. The implementation of the compatible and universal CAN calibration protocol makes it easy to displace the system and its function modules. It also provides friendly, compatible and flexible calibration interface, and the functions of online calibration and real-time monitoring. This system was successfully used in a GD-1 high pressure common rail diesel engine and the engine performance and exhaust emissions were significantly improved.

Lidar-Visual-Inertial Odometry with Online Extrinsic Calibration

To achieve precise localization,autonomous vehicles usually rely on a multi-sensor perception system surrounding the mobile platform.Calibration is a time-consuming process,and mechanical distortion will cause extrinsic calibration errors.Therefore,we propose a lidar-visual-inertial odometry,which is combined with an adapted sliding window mechanism and allows for online nonlinear optimization and extrinsic calibration.In the adapted sliding window mechanism,spatial-temporal alignment is performed to manage measurements arriving at different frequencies.In nonlinear optimization with online calibration,visual features,cloud features,and inertial measurement unit(IMU)measurements are used to estimate the ego-motion and perform extrinsic calibration.Extensive experiments were carried out on both public datasets and real-world scenarios.Results indicate that the proposed system outperforms state-of-the-art open-source methods when facing challenging sensor-degenerating conditions.

基于光栅尺测量的明渠流量计校准装置及其在线校准方法研究

明渠流量计是监测水流量的一种计量器具,广泛应用于各行各业。因其不便拆卸、堰槽设计不规范、校准方法缺失等原因,使得明渠流量计在线溯源成为业内亟需解决的难题。该文开发出一款基于光栅尺测量的明渠流量计校准装置,并应用该装置研究出模拟液位法的明渠流量计在线校准方法。该方法克服了标准液位计法及流速面积法等现有溯源方法存在的不足,具有操作简便、测量准确、模拟水位可调、过程智能化等特点,为明渠流量计在线溯源提供技术支撑。

一种基于标准样品浓度稀释的在线氚监测仪校准装置

为解决在线氚监测仪的现场校准问题,开展了在线氚监测仪现场校准方法研究,主要包括现场校准装置的机械构造、工作原理、校准装置量值的确定,以及需要开展的校准项目。利用该现场校准装置和氚活度浓度标准装置,对同一台在线氚监测仪进行了校准比较,结果表明两者的校准因子分别为1.07和1.05,相对偏差约为2%,该现场校准装置具备量值传递的能力,可满足现场校准要求。此外,该校准装置具有便携性、可操作性和可拆分的特点,可保证现场校准不受场所作业空间的限制,适合在现场进行校准实验,可解决国内在线氚监测仪设备无法溯源的问题。

光学陀螺旋转调制惯导系统及关键技术发展

面向长航时、高精度的自主导航技术需求,系统梳理光学陀螺旋转调制惯导系统的发展历程及关键技术现状具有重要的现实意义。首先,基于惯导系统误差特性,阐述了旋转调制技术的基本原理。其次,系统回顾和梳理欧美等西方国家旋转惯导系统发展历程,分析了系统发展演变后的技术逻辑,总结了我国旋转惯导系统的研制现状。最后,立足于提高系统自主导航精度,从旋转策略优化、误差标校、初始对准3个方面分析了旋转惯导系统需解决的关键技术及研究现状。在总结光学陀螺旋转调制惯导系统及关键技术发展基础上,针对后续旋转惯导系统研究提出了几点思考,为高精度自主导航技术研究提供参考。

微小气体流量在线校准装置的研制

该文研制了一种微小气体流量在线校准装置,可用于工业生产、医疗卫生、环境监测等领域中不便于拆卸的微小气体流量被测仪器的在线校准。详细介绍了微小气体流量在线校准装置的原理、装置的构成、控制系统的设计及校准操作流程,最后通过性能测试验证了校准装置的准确度和可靠性,最后探讨了该装置的应用前景。

复杂曲面机器人磨抛技术研究现状与趋势展望综述

在航空、能源、交通、军工等国家战略领域中,针对复杂曲面零件的自动化、高质量和高效率磨抛需求,对近年来国内外工业机器人磨抛加工关键技术及集成系统的研究和应用进展进行了综述。首先,从复杂曲面机器人磨抛机理及工艺优化、磨抛运动轨迹规划、磨削力控制等方面总结了复杂曲面机器人磨抛技术的研究成果;然后,介绍了国内外机器人磨抛集成系统应用现状;最后,分析了复杂曲面机器人磨抛技术的主要问题以及发展趋势,为该技术的发展提供了重要的指导和方向。研究结果表明:当前该技术存在的主要问题包括磨抛机理不够清晰,数学模型不够准确,复杂曲面机器人磨抛轨迹规划效率不高,磨抛力的控制仍不够精准等;另外,磨抛工艺参数优化、机器人力位混合控制、机器人高精度标定与误差补偿、基于数字孪生的机器人磨抛在线监控、机器人磨抛细分应用场景等方面的研究和实践将极大地推动机器人磨抛技术的发展和应用。

pH和电导率的在线校准仪

设计了一款应用于电厂水汽系统电导率及pH表检测仪表校准的pH和电导率的在线校准仪。本校准仪采用了计算型pH的检测方法,通过测量电导率间接测量pH值,可避免低电导率水pH测量干扰因素的影响。采用交流电阻箱,用数字电位器的方式实现交流电阻。通过自行设计数字的交流电阻箱模拟水中的电导率,用来对仪表进行校验。在线校准仪采用电脑端LabVIEW软件作为上位机控制软件,单片机为核心的嵌入式系统,可以实现采集、检测、二次表校准、数据处理和数据存储等功能控制。

电磁流量计在线校准方法的探讨

电磁流量计具有操作简单、精度高、适应性强、不影响被测流体的流态分布等优点,广泛应用于供水、化工、制药、水处理、环保、食品饮料等领域。对于不方便拆卸或者由于连续生产的要求无法拆卸的情况下,对电磁流量计进行在线校准不失为一种可行的方法,满足其溯源的要求。介绍了2种电磁流量计在线校准的方法,结果表明这2种方法对于在线校准电磁流量计均是可行的。在测量环境理想的条件下首选标准表法,在测量条件不理想的条件下,电参数法可定性评价电磁流量计的计量性能。

基于改进LSTM网络的无人机MEMS-IMU零偏在线标定方法

针对在卫星信号拒止、视觉系统退化场景中无人机MEMS-IMU零偏无法准确估计并补偿导致导航误差迅速发散的问题,提出一种基于改进长短时记忆(LSTM)网络的零偏在线标定方法。首先,为解决MEMS-IMU零偏数据非线性强、传统循环时间网络训练效果差的问题,设计序列到序列的LSTM神经网络结构,引入教师强迫机制,提高了网络特征学习能力。然后,在导航过程中使用训练后的网络对MEMS-IMU零偏在线标定,补偿后的IMU量测与视觉信息联合优化,保证了导航定位精度。实验结果表明,在纯惯性导航实验中,所提方法的绝对位置误差比传统LSTM方法减小了6.5%;在EUROC数据集下进行的视觉惯性组合导航实验中,所提方法的平均绝对位置误差比传统LSTM方法减小了15%。

基于IMU在线校准的SLAM精度提升方法研究

基于多传感器融合的SLAM算法是当前移动机器人实现精准定位和导航的关键技术之一,在分析了惯性测量单元(IMU)的系统误差会对SLAM算法的建图和导航精度影响较大,并且IMU的系统误差会随工作时间发生变化的问题后,提出了一种易于实现的IMU在线标定方法。该标定方法首先建立了IMU中加速度计和陀螺仪的误差模型。其次通过二维云台实现IMU的姿态调整。然后通过读取加速度传感器的静态数值实现加速度计的误差参数辨识。最后以标定后的加速度计输出数据和陀螺仪计算的旋转矩阵,实现陀螺仪的误差参数辨识。为验证以上标定算法的效果,文中基于标定前后的IMU分别进行SLAM建图实验,实验结果表明,基于标定后IMU的建图精度更好。

CD-CAT中基于SCAD惩罚和EM视角的在线标定方法开发——G-DINA模型

G-DINA(the generalizeddeterministic input,noisy and gate)模型限制条件少,应用范围广,满足大量心理与教育评估测验数据的要求。研究提出一种适用于G-DINA等模型的同时标定新题Q矩阵与项目参数的认知诊断计算机化自适应测验(CD-CAT)在线标定新方法SCADOCM,以期促进CD-CAT在实践中的推广与应用。本研究分别基于模拟题库以及真实题库进行研究,结果表明:相比传统的SIE方法,SCADOCM在各实验条件下均具有较为理想的标定精度与标定效率,应用前景较好;SIE方法不适用于饱和的G-DINA等模型,其各实验条件下的Q矩阵标定精度均较低。

基于激光传感器的机械加工工件尺寸偏差在线检测方法

伴随着现代机械加工行业的飞速发展,其对工件尺寸精度要求逐渐提升。但是,现阶段对于机械加工过程中工件的尺寸精度还存在一定不足,而对于工件尺寸偏差检测的方法,也常常受到图像噪声、算法缺陷的影响,导致工件尺寸偏差检测准确性的降低。故提出基于激光传感器的机械加工工件尺寸偏差在线检测方法研究。选取与配置激光传感器,以此为基础,获取机械加工工件尺寸测量激光数据,利用限幅滤波法去除工件尺寸测量激光数据中的噪声数据,计算机械加工工件的测量尺寸(长、宽与高),加载工件期望尺寸数据,衡量两者之间的差值,以此为依据判定机械加工工件尺寸是否存在偏差,实现工件尺寸偏差的在线检测。实验数据显示:提出方法应用后获得的机械加工工件尺寸(长、宽与高)偏差检测结果与实际偏差相同,最大误差不超过0.5 mm,可分辨的最小偏差为0.2 mm,充分证实了提出方法的有效性。

基于旋转弹体的非理想阵列测向技术研究

[目的]针对旋转弹测向系统在飞行过程中由强杂波环境带来的误差干扰进行研究,提出一种实时校正的波达方向(DOA)估计算法。[方法]该算法利用阵列旋转角度这一先验条件,基于最大似然(ML)准则,实现对共形阵列误差和信号空域-极化域参数的联合估计。[结果]仿真实验表明,该算法对存在方位依赖的幅相不一致性误差的阵列系统,可以实现在线的误差和信号参数联合估计,且该算法的估计性能均与阵列平台旋转次数和信噪比(SNR)相关,当旋转次数达到24以上时,在低信噪比为10 dB情况下空域参数估计误差在1°以下。[结论]所提算法采用分维交替处理的思路来解决多参数估计问题,在保证参数收敛的同时大幅降低了运算的复杂度。

基于多传感器融合的无人舰载机舰面定位研究

无人舰载机在航母舰面的自主定位是实现自主转运、提高驶入/驶出效率的重要前提.其中,如何依靠机载传感设备实现GPS拒止环境下的舰载机自主舰面定位是亟待解决的关键技术.为此,提出了一种基于视觉和激光雷达融合的无人舰载机舰面自主定位算法.该算法通过结合手眼标定和互信息标定方法进行多传感器在线标定,使无人舰载机在面对风浪及航母运行等情况下机身摇晃导致传感器外参标定结果变化后仍能保持稳定运行;引入因子图用于无人舰载机的多传感器位姿联合优化并基于自主转运过程中的运动模型建立了简单高效的传感器失效标准,从而有效地融合了激光雷达和视觉定位结果,使该算法在单个传感器失效的情况下依然可以进行精确的自主定位;最后建立了基于多传感器的舰载机舰面仿真系统对本文算法进行验证,实验结果表明,本文算法在单个传感器失效的情况下定位误差仍维持在0.2m以内,满足实际应用要求.