基于温度补偿倾角传感器的双轴稳定平台设计

针对高精度舰载光瞄设备隔离扰动及高稳定跟踪精度视轴的要求,研究一种基于反方向运动抵消舰艇摇摆运动的双轴机械稳定平台。采用MEMS传感器实现倾角测量,采用直流电机实现平台稳定。通过实验方法,测出MEMS传感器的温度特性,再采用分段线性插值补偿模式,在-40^+100℃范围内提高传感器的精度。采用无超调控制技术实现直流电机快速响应和平稳运动。利用改变电枢电压的方法,可以实现对电机堵转转矩的控制,从而实现带负载的角度位置控制。实验结果表明,双轴稳定平台的最大角加速度为57°/s^2,稳定平台指向复示精度达到0.1°。     

基于预估测量值的EKF在手臂测姿中的应用

针对载体线性加速度以及周围局部磁干扰对姿态测量精度的影响,基于已有的惯性测量单元,设计了一个基于四元数的实时估计手臂姿态的扩展卡尔曼滤波器(EKF)。提出利用四元数引入加速计和磁强计的预估测量值构造自适应测量噪声协方差阵的方法,结合QUEST算法,来判定姿态角解算对陀螺仪、加速计和磁强计输出信息的依赖程度,以此来提高测量精度。文末通过实验仿真对该方法进行了验证,并对实验结果和电磁跟踪系统采集到的数据进行了比较,结果表明,本文提出的方法能显著提高手臂姿态测量精度,可有效满足应用要求。     

惯性测量组合的优化设计与误差补偿算法研究

设计了九加速度计惯性测量组合用于测量飞行体的姿态和位置。通过理论分析和计算机仿真,结果显示由9个加速度计的输出可解算出载体运动角速度和线加速度,但由于加速度计的测量误差引起的角速度的解算误差会随飞行时间的增长而累积,采用误差补偿算法可有效地减小误差。另对加速度计位置误差进行了理论分析和仿真,结果表明,由加速度计组合的惯性测量方案对加速度计位置误差非常敏感。     

基于补偿卡尔曼滤波的姿态估计算法实现

九轴的姿态测量单元包括加速度计、磁力计和陀螺仪,它采用微机电加工工艺,价格低廉但精度较差.为了获得更好的滤波稳定性和估计精度,基于补偿卡尔曼滤波原理,讨论了姿态估计算法的实现.具体过程如下:基于补偿卡尔曼滤波原理,讨论九轴测量信息的融合方法;利用加速度计和磁力计估算姿态初始值;使用手动转台实现静态标定,纠正零偏;使用高精度陀螺仪STIM210实现动态标定,设置滤波系数.结果表明,估计算法具有良好性能.     

The eye-complaint questionnaire in a visual display unit work environment: Internal consistency and test–retest reliability

The internal consistency and test–retest reliability of a 10-item eye-complaint questionnaire (ECQ) were examined within a sample of office workers. Repeated within-subjects measures were performed within a single day and over intervals of 1 and 7 d. Questionnaires were completed by 96 workers (70% female, mean age 36.4 years) who perform more than 4 h of visual display unit work each day. The internal consistency of the ECQ was high (α = 0.801). Although test–retest reliability was low within a single day (morning and afternoon) (intra-class correlation coefficient (ICC) = 0.68, 95% CI 0.38, 0.82), it was good between two morning measurements over a 1-d interval (ICC = 0.91 95% CI 0.87, 0.94) and between morning measurements with a 7-d interval (ICC = 0.87, 95% CI 0.81, 0.92). The ICC between afternoon measurements over a 1-week interval was moderate (ICC = 0.78, 95% CI 0.66, 0.85). This questionnaire is a reliable and consistent instrument for easily assessing eye complaints in office work. The timing of the measurements must be kept in consideration since measurements are confounded by exposures over the day.     

基于Kalman滤波算法的姿态传感器信号融合技术研究

针对应用三轴陀螺仪和三轴加速度传感器的四旋翼飞行器姿态角测量问题,提出了基于Kalman滤波算法的姿态传感器信号融合方法。该方法将陀螺仪输出的角速度误差作为时变误差处理,认为陀螺仪输出的角速度误差与其所测角速度及上一时刻的角速度输出误差相关,并据此建立陀螺仪测量线性方程,在此基础上,应用Kalman滤波算法,以加速度计输出的姿态角对陀螺仪测量的姿态角进行修正,从而达到姿态角准确测量的目的。实验结果表明：应用Kalman滤波算法对加速度传感器和陀螺仪信号融合后可有效消除姿态角测量累积误差并显著改善姿态角测量的动态特性。     

Cumulative postural exposure measured by a novel device: a preliminary study

The aim of the present study was to examine the within-day reliability of the Spineangel? postural monitoring device and to measure cumulative lumbo-pelvic posture exposure of health care workers. Twenty-one workers from an aged-care residential home wore the Spineangel, attached to the belt or waistband of their normal work apparel, during a period of the work shift. To assess the within-day reliability of measurements, 11 workers performed two sets of three lumbo-pelvic forward flexion, sustaining them for five 5 s each, at the beginning and at the end of the work shift. Different thresholds for cumulative postural exposure were measured. The reliability was found to be excellent (ICC = 0.81). On average, a threshold of 30° of lumbo-pelvic forward flexion was exceeded 1069 times/h (SD 2157.1); at 45°, 121 times/h (SD 223.8); and at 60°, 8 times/h (SD 21.8). The use of Spineangel is thus likely to be a useful device for monitoring work posture. STATEMENT OF RELEVANCE: The Spineangel? is capable of providing reliable postural measurements in the workplace. Different cumulative postural exposure thresholds were established considering three domains of cumulative exposure: magnitude (range of motion), frequency and duration. The implementation of such domains for cumulative exposure allowed us to explore interesting forms of monitoring posture exposure.     

Validity and reliability of the Spineangel® lumbo-pelvic postural monitor

Objective: to determine the reliability and the concurrent validity of the Spineangel^® lumbo-pelvic postural monitoring device. Methods: the dynamic lumbo-pelvic posture of 25 participants was simultaneously monitored by the Spineangel^® and Fastrak^TM devices. Participants performed six different functional tasks in random order. Within-task, within-session and between-day intraclass correlation coefficients (ICC(3,1), ICC(3,5), ICC(2,5), respectively) reliability were calculated for Spineangel^® measurements. Concurrent validity of the Spineangel^® was assessed by means of a Bland and Altman plot and by means of Pearson's correlation coefficient and paired t-test. Results: within-task, within-session and between-day ICC for the Spineangel^® were found to be excellent (>0.93). The Spineangel^® and Fastrak^TM pelvic measurements were found to have a good correlation (R = 0.77). Conclusion: the Spineangel^® is a reliable and valid device for monitoring general lumbo-pelvic movements when clipped on the belt or waistband of workers' clothing during various occupational activities.

Practitioner summary: The Spineangel^® can be used for assessing lumbo-pelvic posture during work or daily-life activities. This device was found to provide reliable and valid measurements for lumbo-pelvic movements. Further research is required to determine whether the use of this device is clinically relevant for patients presenting with low back pain.     

基于新型光栅传感器的微位移测量

实验将新型光栅传感器应用于微位移测量之中。通过比较线(角)位移与莫尔条纹移动个数之间的关系,实验发现,在微位移测量中光栅传感器具有极好的线性度(R2≥0.999)和精确度(误差≤2.0%)。实验验证了光栅传感器在微位移测量中可行性和可靠性。     

电磁振动台角运动分量测量方法

电磁振动台一般产生垂直于其台面的线运动,同时在其主运动分量也会耦合有其他方向的线运动或角运动分量,它们一般比较小.当采用电磁振动台进行陀螺线振动试验时,振动台产生的陀螺敏感轴方向角运动分量会使陀螺产生输出,因而需要对其进行测量.提出了振动台线振动耦合的角运动分量的一种测量方法,从理论上分析了该方法的可行性,并对测量不确定度进行了分析.采用激光干涉仪进行测量的结果表明所提出的方法是有效的.     

一种面向机动的低成本姿态测量系统

载体作机动运动时,基于加速度计和磁传感器的姿态测量系统易受载体运动加速度的影响而导致测量精度降低.通过将GPS加速度引入重力观测方程,有效补偿了载体运动加速度造成的姿态测量误差.利用基于重力场和地磁场矢量观测的迭代最小二乘姿态确定算法得到修正罗德里格姿态参数.姿态信息通过互补滤波器与陀螺仪测量值融合以提高动态响应.实验结果表明,该低成本姿态测量系统可明显提高机动环境下的姿态测量精度,姿态角测量误差小于3°.     

Modeling errors for dimensional inspection using active vision

In active vision inspection, errors in dimensional measurements are often due to displacement of the sensor and image digitization effects. Using a model of error in linear measurements based on a normally distributed sensor displacement, uniform image digitization and geometric approximation, the accuracy of measurements from a particular sensor setting can be assessed. In comparison with experimental measurements, this error model demonstrates a high predictive ability. Related experiments demonstrate a procedure for assessing the accuracy of sensor settings providing insight into what sensor settings lead to lower measurement variances and thus higher measurement reliability.     

基于陀螺仪的炮塔角速度测量装置的设计

针对国内炮控系统性能参数测试中对角速度测量的成本较高、操作复杂、时间较长等问题,设计了一种基于MEMS陀螺仪的炮塔角速度高精度测量装置,通过中值滤波、均值滤波以及加权平均融合的方法,抑制了测量噪声等因素对炮塔角速度值的影响.通过在转台和坦克上对该装置进行标定和测试,分析了滤波和融合前后的实验结果,其对炮塔角速度的测量精度可达0.02°/s.该装置操作简单、灵敏度高、成本较低、实用性强,能有效地提高测试精度,节省了人力物力,缩短了测量时间,满足实际应用的需求,具有很高的实用价值.     

微加速度计在冲击环境下的可靠性研究

微加速度计用于测量载体的加速度,并提供相关的速度和位移信息.微加速度计可以和微型陀螺仪组合构成微型惯性测量单元.但是微加速度计还没有完全实现市场化,微加速度计的可靠性问题已经成为制约其广泛应用的关键因素.微加速度计在加工、封装、运输和实际使用中都可能受到冲击的作用.主要研究压阻式微加速度计在冲击环境下的可靠性问题.通过简化加速度计的结构,得出了悬臂梁上的应力分布.设计了微加速度计在冲击环境下的可靠性试验,分析了加速度计在冲击环境下的主要失效模式及失效机理.得出了压阻式加速度计在冲击环境下的主要失效模式是键合引线的脱落和悬臂梁的断裂.     

Sensor data fusion for body state estimation in a hexapod robot with dynamical gaits

We report on a hybrid 12-dimensional full body state estimator for a hexapod robot executing a jogging gait in steady state on level terrain with regularly alternating ground contact and aerial phases of motion. We use a repeating sequence of continuous time dynamical models that are switched in and out of an extended Kalman filter to fuse measurements from a novel leg pose sensor and inertial sensors. Our inertial measurement unit supplements the traditionally paired three-axis rate gyro and three-axis accelerometer with a set of three additional three-axis accelerometer suites, thereby providing additional angular acceleration measurement, avoiding the need for localization of the accelerometer at the center of mass on the robot's body, and simplifying installation and calibration. We implement this estimation procedure offline, using data extracted from numerous repeated runs of the hexapod robot RHex (bearing the appropriate sensor suite) and evaluate its performance with reference to a visual ground-truth measurement system, comparing as well the relative performance of different fusion approaches implemented via different model sequences.     

Estimating the angular velocity of a rigid body moving in the plane from tangential and centripetal acceleration measurements

Two methods are available for the estimation of the angular velocity of a rigid body from point-acceleration measurements: (i) the time-integration of the angular acceleration and (ii) the square-rooting of the centripetal acceleration. The inaccuracy of the first method is due mainly to the accumulation of the error on the angular acceleration throughout the time-integration process, which does not prevent that it be used successfully in crash tests with dummies, since these experiments never last more than one second. On the other hand, the error resulting from the second method is stable through time, but becomes inaccurate whenever the rigid body angular velocity approaches zero, which occurs in many applications. In order to take advantage of the complementarity of these two methods, a fusion of their estimates is proposed. To this end, the accelerometer measurements are modeled as exact signals contaminated with bias errors and Gaussian white noise. The relations between the variables at stake are written in the form of a nonlinear state-space system in which the angular velocity and the angular acceleration are state variables. Consequently, a minimum-variance-error estimate of the state vector is obtained by means of extended Kalman filtering. The performance of the proposed estimation method is assessed by means of simulation. Apparently, the resulting estimation method is more robust than the existing accelerometer-only methods and competitive with gyroscope measurements. Moreover, it allows the identification and the compensation of any bias error in the accelerometer measurements, which is a significant advantage over gyroscopes.     

智能双轴倾斜传感器的研究

简要介绍了国内外倾斜传感器的发展情况及其测试原理 ,并提出了一种新型的双轴倾斜传感器的设计方案 ,利用压阻式加速度传感器感受重力加速度在传感器三自由度上的大小 ,从而测量物体的倾斜角大小。推导了该传感器的计算公式 ,并详细地介绍了该传感器的系统硬件组成及软件补偿方法     

Verification of the indoor GPS system, by comparison with calibrated coordinates and by angular reference

This paper details work carried out to verify the dimensional measurement performance of the Indoor GPS (iGPS) system; a network of Rotary-Laser Automatic Theodolites (R-LATs). Initially tests were carried out to determine the angular uncertainties on an individual R-LAT transmitter-receiver pair. A method is presented of determining the uncertainty of dimensional measurement for a three dimensional coordinate measurement machine. An experimental procedure was developed to compare three dimensional coordinate measurements with calibrated reference points. The reference standard used to calibrate these reference points was a fringe counting interferometer with the multilateration technique employed to establish three dimensional coordinates. This is an extension of the established technique of comparing measured lengths with calibrated lengths. The method was found to be practical and able to establish that the expanded uncertainty of the basic iGPS system was approximately 1?mm at a 95% confidence level. Further tests carried out on a highly optimized version of the iGPS system have shown that the coordinate uncertainty can be reduced to 0.25?mm at a 95% confidence level.     

Indoor Positioning System Using Axis Alignment and Complementary IMUs for Robot Localization

An indoor positioning method for robots is presented to improve the precision of displacement measurement using only low-cost inertial measurement units(IMUs).Firstly,a high-fidelity displacement estimation for linear motion is proposed.A new robot motion model is designed as well as an axis alignment that only uses a single axis of the accelerometer.The integral error of velocity is eliminated by a new subsection calculation method.Two complementary IMUs are combined by assigning them different weights to obtain high accuracy displacement results.Secondly,an orientation estimation based on a fusion filter for the steering motion is proposed.Experiments show that the proposed method significantly improves the accuracy of linear motion measurement and is effective for the indoor positioning of a robot.     

基于融合模型的高精度倾角测量系统设计

针对现有倾角测量在宽范围内误差大的问题,提出了一种基于融合模型的高精度倾角测量系统设计方案,首先通过测量误差机理分析建立双MEMS加速度计的融合模型,再拟定标定方案确定模型相关参数,最后对硬、软件进行设计,可实现0~360°内角度的高精度测量。经高精度转台对比实验验证,该设计系统具有功耗低、宽测量范围内精度高等优点,能够实现在宽范围（0~360°）的高精度测量,且测量精度达到±0.05°。