压阻式压力传感器实时自校正方法研究

目前的传感器误差校正方法,由于都是以传感器初始标定数据作为依据,从而随着使用时间的增加,传感器参数发生变化,其校正误差会逐步增大。针对这种情况,研究了用多基准恒流源模拟标准压力自动对传感器进行标定得到实时输出特性曲线,并据此求得测量压力。实验结果表明:该校正方法切实可行,若采用4个基准源校正,可在一定的温度和压力范围内实现0.15%的精度。     

基于Hermite基函数的液位传感器温度补偿方法

针对液位传感器易受温度影响的问题,提出了基于Hermite基函数的液位非线性校正和温度补偿的复合校正方法,该方法使用递推最小二乘法对标定液位进行拟合以获取复合补偿模型的参数,由此根据液位传感器的测量值和环境温度即可高精度计算出实际液位。仿真结果表明,补偿后的最大相对误差不超过1.23×10^-6%,具有良好的非线性校正和温度补偿效果,在液位检测领域具有重要的理论和应用价值。     

一种湿度传感器温度补偿的非线性校正方法

针对湿度传感器易受温度影响的问题,提出了基于Laguerre多项式的湿度非线性校正和温度补偿的复合校正模型,采用递推最小二乘法对标定湿度进行拟合以确定复合补偿模型的参数.该方法根据湿度传感器的测量值和环境温度即可高精度计算出实际湿度.仿真结果表明,补偿后的最大相对误差不超过4.5576e-4％,具有良好的非线性校正和温度补偿效果,在湿度检测领域具有重要的理论和应用价值.     

基于DE-SVM的硅基压阻式压力传感器温度补偿研究

针对硅基压阻式压力传感器易受环境温度影响的特点,提出了一种基于DE-SVM的硅基压阻式压力传感器温度补偿方案。该方案主要由训练数据预处理模块、DE参数寻优模块、SVM训练模块、数据采集模块、测量数据预处理模块及SVM校正等模块组成,以SVM算法的非线性回归功能为核心,通过DE算法优化SVM参数,经训练后得到温度校正模块,模块接收测量数据后输出校正后的压力值。实验表明,对单个传感器压力值使用DE-SVM模型进行校正,最大误差和均方误差分别下降了93.87%和99.89%;在七块硅基压阻式压力传感器构成的多传感器情况下,最大误差和均方误差分别下降了93.17%和99.27%,平均相对误差由14.06%下降至1.20%;最后选取训练数据不包含的温度点使用所建立的模型进行测试,模型仍能够较好地进行温度补偿。     

电梯运行轨迹测试系统标定平台控制算法研究

简述了用于电梯运行轨迹测试的惯性测量系统的特点及其标定平台的重要性,介绍了电梯运行轨迹测试系统标定平台的硬件结构、控制算法以及软件流程;针对标定平台的设计要求以及其系统特性提出了采用最小方差自校正算法的设计思想,用自回归滑动平均数学模型描述系统,运用增广最小二乘法估计系统参数,最小方差自校正控制系统输入,解决了标定平台做正弦运动时的精度问题;实际使用表明运用最小方差自校正控制能使系统各项指标达到设计要求。     

基于Laguerre基函数的液位传感器温度补偿方法

针对环境温度影响液位传感器的检测问题,提出了基于Laguerre基函数的液位非线性校正和温度补偿的复合校正模型,采用递推最小二乘(RLS)法对标定液位进行拟合以确定复合补偿模型的参数.根据液位传感器的测量值和环境温度可高精度计算出实际液位.仿真结果表明:补偿后的最大相对误差不超过(3.4145×10-7)％,具有良好的非线性校正和温度补偿效果,在液位检测领域具有重要的理论和应用价值.     

双摄像机模组的组合式标定和校正方法

提出了双摄像机模组的组合式标定和校正方法,能够将传统的标定和校正2道工序合并为1道工序,不需要借助于外部测量设备,仅利用双摄像机同时对目标模板拍摄的1幅图像,即可实现双摄像机模组的标定和校正。先基于交比不变性计算摄像机的径向畸变系数,将摄像机畸变成像模型转换为线性模型,利用线性模型分别对2个摄像机进行标定;然后计算2个摄像机之间的位姿偏移参数,调节右摄像机位姿,进行双摄像机之间的位姿校正;最后标定2个摄像机之间的位姿参数。实际应用结果表明,所提出的双摄像机模组校正和标定方法,校正和标定精度高,缩短了工艺时间,提高了工艺效率,能够满足双摄像机模组封装生产工艺的要求。     

基于双目视觉动态跟踪的机器人标定

采用双目视觉动态跟踪技术对自主研发的工业机器人进行运动学标定。区别于以往机器人运动学标定中复杂模型计算,在此利用双目视觉动态跟踪系统的静态测量和动态跟踪等优势特性来跟踪测量机器人的连杆参数误差,结合机器人控制系统开放性特点,运用提出的动态标定原理对机器人实施连杆参数测量、辨识、修正及补偿。实验表明,通过参数反馈补偿,自主研发的机器人的定位误差明显降低,且该方法易于实现,为机器人精度研究提供了可靠依据。     

线结构光视觉传感器直接标定方法

分析了传感器测量模型,推导了摄像机畸变模型下的像坐标与像素坐标变换关系,在此基础上,提出了一种基于二元五次多项式拟合的线结构光视觉传感器物像标定模型。在数控平台上,利用锯齿形标定块获取一组标定点,应用最小二乘方法实现参数标定。标定与测量实验表明：本方法实现简单,精度较高,满足测量要求。     

基于线结构光视觉的燃料组件变形测量技术研究

针对快堆燃料组件外形变形参数的测量,设计了基于线结构光的燃料组件变形测量系统,并考虑到辐射对电子元器件和测量精度的影响,进行了测量系统的辐射屏蔽设计。对辐射屏蔽玻璃的折射对测量的影响进行了研究,并在空气中线结构光测量模型的基础上提出一种折射校正的线结构光测量模型。在空气中进行测量系统标定,然后对加玻璃的测量值进行折射校正,通过多组测量实验表明折射校正模型校正误差为±0.05 mm,线结构光燃料组件测量系统的全局参数测量的标准差不大于0.03 mm。组件测量系统能在一定辐照剂量下能实现燃料组件变形参数的高精度测量,对于获取燃料组件物理参数和堆芯设计具有重要的意义。     

备份航姿系统的磁传感器在线校准方法

磁航向角是备份航姿系统的重要输出参数,为提高测量性能,需对磁传感器进行误差标定。对于机载应用的磁传感器,地面标定方法需要耗费大量的时间且操作不便,在地表标定结果的适用性随距离标定的时间和使用空间位置的变化而降低。基于备份航姿系统的实际工作特点,提出一种在备份状态下利用飞机主惯导的姿态角信息对磁传感器误差进行在线校准的方案,设计了误差校准数据存储的数据结构,提出了校准数据对航向空间覆盖的充分性评价策略,最后利用无磁转台模拟环境,验证了某备份航姿系统的磁传感器在线校准方案的可行性和有效性。     

多惯组冗余系统安装误差的空中标定技术

以多组平行安装的捷联惯导构成的冗余系统为研究对象,提出了一种GPS辅助条件下惯导间安装误差的空中标定算法。该算法以其中一套惯导系统为安装基准,与GPS伪距、伪距率信息深组合后的导航结果为真实参考信息,标定前利用飞机机动提高基准惯导的姿态精度,标定开始时刻将基准惯导的导航信息装订给待标定惯导作为导航初值并进行姿态更新,利用待标定惯导的导航误差模型建立卡尔曼滤波器,量测量取为组合姿态与待标定惯导姿态的姿态误差,通过姿态匹配的方式对两套惯组之间安装误差进行标定。仿真结果显示,该方法不需要飞机做精确的角机动,只利用简单的摇翼和盘旋机动就可以对安装误差进行精确标定,且标定精度可达到角秒级水平。     

瞬态表面温度传感器动态建模方法研究

测量瞬态高温时,由于传感器自身的热惯性,测量结果与真实结果之间存在很大的动态误差.动态补偿或动态误差修正对于改善测温系统动态特性,减小动态误差有重要意义,而建立温度传感器动态数学模型则是进行动态补偿或动态误差修正的前提.本文首先设计了瞬态表面温度传感器动态校准系统;然后,利用系统所测得输入输出数据,采用系统辨识方法建立了测温系统的动态数学模型;最后,利用交叉检验法验证该模型的正确性.经检验该方法可以达到理想的辨识效果,从而为系统反滤波动态误差修正奠定了基础.     

激光陀螺捷联惯导系统的误差参数标定方法

为降低激光陀螺捷联惯导系统误差参数标定对高精度转台的要求,在不精确对北和调平的情况下,综合分析北向基准误差、水平基准误差、转台轴正交度误差、角位置误差以及标定时间等诸多因素,考虑对称位置和整周期旋转等编排原则,改进了速率标定方案,标定出陀螺仪的标度因数和安装误差,同时提出了一种十二位置连续转动标定方法,标定出陀螺仪的零偏以及加速度计的误差参数项.实验结果表明,与传统方法相比,标定精度相当,降低了对标定转台的要求,减少了标定时间,有较高的工程应用价值.     

A two-step method for kinematic parameters calibration based on complete pose measurement—Verification on a heavy-duty robot

The poor pose accuracy of industrial robots restricts their further application in aviation manufacturing. Kinematic calibration based on position errors is a traditional method to improve robot accuracy. However, due to the difference between length errors and angle errors in the order of magnitude, it is difficult to accurately calibrate these geometric parameters together. In this paper, a two-step method for robot kinematic parameters calibration and a novel method for position and orientation measurement are proposed and combined to identify these two kinds of errors respectively. The redundant parameter errors that affect the identification are also analyzed and eliminated to further improve the accuracy of this two-step method. Taking the Levenberg-Marquardt algorithm as the underlying algorithm, simulation results indicate that the proposed two-step calibration method has faster iteration speed and higher identification accuracy than the traditional one. On this basis, the calibration and measurement methods proposed in this paper are verified on a heavy-duty robot used for fiber placement. Experimental results show that the mean absolute position error decreases from 0.9906 mm to 0.3703 mm after calibration by the proposed two-step calibration method with redundancy elimination. The absolute position accuracy has increased by 41.81% compared with the traditional method based on position errors only and 14.97% compared with the two-step calibration method without redundancy elimination. At the same time, the orientation errors after calibration are not more than 0.1485°, and the average of absolute errors is 0.0447.     

Uncertainty propagation in multibody human model dynamics

In biomechanics, calibration of body segment inertial parameters (BSIP) is crucial to take into account subject morphological specificities. To avoid strenuous protocols, identification methods based on rigid body dynamics laws have been proposed. Thanks to a motion capture system and force platforms, these methods optimize BSIP by minimizing errors in the equations of motion. These errors can be defined as the dynamic residuals reflecting inaccuracies arising from estimated BSIP, as well as from kinematics and force plate measurements. The current study aims at evaluating the part of uncertainty on the dynamic residuals directly related to kinematics and force plate measurements. To answer this question, we captured the movements of 10 participants performing a standardized motion. We then applied a Monte Carlo-based approach to introduce variations in the kinematics and force plate measurements, and evaluated the reconstructed difference on the dynamic residuals. Results show that, first, the BSIP evaluation using a regression method seemed to be an acceptable estimate for the studied subjects. Second, the part of uncertainty in the dynamic residuals was significantly higher than the dynamic residuals obtained. In conclusion, a subject-specific calibration of the BSIP based on dynamic residuals, for this model and protocol, seems irrelevant and prone to overfitting of BSIP.     

A self-calibration method for error of photoelectric encoder based on gyro in rotational inertial navigation system

As a precision goniometer, photoelectric encoder plays an important role in rotational inertial navigation system (RINS). The encoder is used to measure the rotate angle of rotating mechanism for attitude calculation and feedback of motor control. However, the experiment shows that there are position-related errors in the encoder output, so calibration is necessary in high precision applications. This paper presents a calibration method designed by the characteristics of encoder errors and the structure of a tri-axis RINS. In RINS, the gyro sensitive axis can be coincided with the motor axis by gimbals rotation, and then the gyro and the photoelectric encoder measure the same angle, so the error can be calculated as the difference between the encoder output and the integral of gyro output. The error will be analyzed through Fourier method, then the error will be fitted by least squares method and a harmonic model will be established. The verification experiments demonstrate that the angle measurement error is reduced from ± 40″ to ± 2″, and the attitude output error drops 75″. The calibration method is proved to be experimentally effective.

     

捷联惯导系统加速度计标度因数和安装误差的试验标定

研究了捷联惯导系统惯性测量组合中加速度计标度因数和安装误差的标定问题。对捷联惯性测量组合中3路加速度计建立了输出模型,提出了在三轴转台上采用多位置试验对加速度计标度因数和安装误差进行标定的方法。实验表明,本方法能够有效地标定出惯性测量组合中加速度计的标度因数和安装误差,具有较高的精度,对提高捷联惯导系统的精度有着重要的作用。     

基于模值估计的三轴磁力计标定方法研究

现有的三轴磁力计标定方法大都是对采样数据进行归一化,然后利用样本数据求解参数.为了提高标定算法的通用性和有效性.提出了一种改进的标定方法,首先将磁力计所处位置磁场向量的模作为误差模型参数,然后对其进行估计算法设计,接着提出一种两步标定方法进行参数初值的选取,然后应用Levenberg-Marquardt方法进行磁力计标定算法设计.仿真和实验结果表明,本文所提算法对类似的三轴传感器具有通用性,不依赖于传感器的观测向量,同时能够对所观测向量的模值进行精确的估计,可以标定三轴磁力计的安装误差、静态灵敏度误差和零位误差,标定过程简便,适用性广.     

Calibration of stewart platforms and other parallel manipulators by minimizing inverse kinematic residuals

This paper focuses on the accuracy enhancement of Stewart platforms through kinematic calibration. The calibration problem is formulated in terms of a measurement residual, which is the discrepancy between the measured leg length and the computed leg length. With this formulation, one is able to identify kinematic error parameters of the Stewart platform without the necessity of solving the forward kinematic problem; thus avoiding the numerical problems associated with any forward kinematic solution. By this formulation, a concise differential error model with a well-structured identification Jacobian, which relates the pose measurement residual to the errors in the parameters of the platform, is derived. Experimental studies confirmed the effectiveness of the method. It is also shown in this paper that the proposed approach can be applied to other types of parallel manipulators, assuming that their inverse kinematic solution is simpler than its forward kinematic solution. Because this condition is satisfied by almost all parallel manipulators, the method is very useful for kinematic calibration of such machines. © 1998 John Wiley & Sons, Inc.