Error modeling and analysis of inclinometer based on digital accelerometer

Measuring accuracy of inclinometer based on accelerometer is mainly influenced by the adopted accelerometer sensor.To improve the measuring accuracy of the inclinometer,the structure of the measuring system is given and measuring principle is analyzed,and the error model is established in this paper.Furthermore,the model is verified by simulation and experiment,which not only gives the smallest errors of the measured pitch and roll,but also lays foundation for sensor selection,error analysis and error compensation.The results show that the error model is of practical value.

Multi-type sensor placement and response reconstruction for building structures: Experimental investigations

Estimation of lateral displacement and acceleration responses is essential to assess safety and serviceability of high-rise buildings under dynamic loadings including earthquake excitations. However, the measurement information from the limited number of sensors installed in a building structure is often insufficient for the complete structural performance assessment. An integrated multi-type sensor placement and response reconstruction method has thus been proposed by the authors to tackle this problem. To validate the feasibility and effectiveness of the proposed method, an experimental investigation using a cantilever beam with multi-type sensors is performed and reported in this paper. The experimental setup is first introduced. The finite element modelling and model updating of the cantilever beam are then performed. The optimal sensor placement for the best response reconstruction is determined by the proposed method based on the updated FE model of the beam. After the sensors are installed on the physical cantilever beam, a number of experiments are carried out. The responses at key locations are reconstructed and compared with the measured ones. The reconstructed responses achieve a good match with the measured ones, manifesting the feasibility and effectiveness of the proposed method. Besides, the proposed method is also examined for the cases of different excitations and unknown excitation, and the results prove the proposed method to be robust and effective. The superiority of the optimized sensor placement scheme is finally demonstrated through comparison with two other different sensor placement schemes： the accelerometer-only scheme and non-optimal sensor placement scheme. The proposed method can be applied to high-rise buildings for seismic performance assessment.

The Error Compensation of Inclinometer Based on Polynomial Fitting

In order to reduce the influence of nonlinear characteristic and temperature on the measuring accuracy of inclinometer, the application of polynomial fitting principle to compensate the measuring error of inclinometer is studied. According to the analysis of the experimental data of inclinometer, a polynomial model of the nonlinear error and the measured value is constructed, and then the relation between the coefficient of the polynomial model and the temperature is obtained by fitting, and finally the function of the measurement error of inclinometer on the measured inclination and temperature is obtained. The results show that this method is feasible and effective, which can not only reduce the influence of temperature, but also correct its nonlinear error.

运用人体运动能耗监测仪ActiGraph GT3X测定不同BMI分类中习惯久坐的成年人群站立、平躺和坐立的时间指标（英文）

背景:超重和肥胖已成为世界上很多地区严重的公共健康问题。研究表明,在日常生活中做一些小的改变,诸如中断久坐(站立一会),可能有助于缓解久坐带来的健康风险。本研究旨在用人体运动能耗监测仪Acti Graph GT3X检测有久坐习惯的成年人(根据BMI分为相同的体重状况)用于站立(用计数阈值测定)、平躺和坐立(用倾角仪功能测定)的时间。方法:受试者包括22名有久坐习惯的成年人(14名男性,8名女性);平均年龄26.5±4.1岁。所有受试者均完成国际体力活动问卷(IPAQ)的自我报告,以此测定受试之前7天坐立的时间。每天坐立7 h及以上者被选取为受试者,用Acti Graph GT3X的测斜仪功能确定不同姿势。受试者须连续7天(每天24 h)携带加速器。按照BMI将受试者分类:18.5-25 kg/m2为正常,25-30 kg/m2为超重,大于30 kg/m2则为肥胖。结果:正常组(n=10)和超重组(n=6)站立的时间(在对MVPA和磨损时间进行调整后)分别为6.7 h和7.3 h,显著多于肥胖组(n=6,5.5 h);坐立时间(分别为7.1 h和6.9 h)显著少于肥胖组(8.0 h,p<0.001)。正常组和超重组站立及坐立时间均无显著差异(p=0.051,p=0.67)。3组的平躺时间也无显著差异(p=0.55)。结论:本研究描述了有久坐习惯的体重正常、超重、肥胖成年人的站立、坐立以及平躺姿势的分配情况。研究结果为通过增加站立时间防止肥胖的策略提供了新的证据。

Counting Steps in Research: A Comparison of Accelerometry and Pedometry

The objective of this study was to assess the validity of the step count functions in Actical accelerometers and activPAL inclinometers, compared with pedome-ter-derived step count data. Firstly, directly observed step counts over 3 treadmill speeds were compared with steps collected from 3 pedometers, accelerometers, and inclinometers in 10 adults. Secondly, step count data were derived from 22 participants who wore a pedome-ter, accelerometer, and inclinometer over 48 hours. Agreement between measurement tools was determined. All monitors appropriately measured steps in the labo-ratory conditions. In free living conditions, the mean percentage differences with pedometer-determined step counts were -7.3% and 7.0% for the Actical and ac-tivPAL monitors, respectively. With the exception of slow walking for the Actical units (ICC < 0.001), acceptable reliability was found within units for all treadmill speeds, and across units during the free living condition. The 95% prediction interval ranges were wide, ranging from -68.8% to 54.2% for the Acticals, and from -39.1% to 53.2% for the activPALs. Step counts gathered from Actical and activPAL units should not be used interchangeably with pedometer-derived step count data.

Quaternion Realization of Mobile Weapon Aiming Stabilization

Quaternion realization of aiming stabilization of the mobile weapon is considered.Gyro compassing combined with an inclinometer is used for the measurement of the initial chassis orientation in respect of the geographical north and the horizontal plane.The same 3D gyroscope is used for the measurement of the subsequent incremental change of the chassis orientation.The goal of the proposed stabilization is to maintain the aiming geo coordinates generated by the fire control system while moving in an uneven terrain.

Transportation infrastructure settlement and heave distress:challenges and solutions

Transportation agencies spend millions of dollars annually to repair civil transportation infrastructure including pavements,earth structures and approach slabs distressed by soft compressible soils and expansive soils.Several research studies performed at the University of Texas at Arlington(UTA) focused on stabilizing these problematic soils so that they will provide better and more stable support to the transportation infrastructure.This paper focuses on a summary of two major distresses and mechanisms,and remedial measures for addressing these distress problems.A combined lime-cement stabilization method is fully evaluated in providing better support of pavement infrastructure,and these results are described here.Another major transportation infrastructure problem involving bridge approach slabs requires different treatment methods,and these results are briefly described.As a part of the recently completed research study assessments,both shallow and deep soil treatment methods for stabilizing soils are fully evaluated for their effectiveness in arresting the distress posed to the pavements and bridge approach slabs.These results along with a few future research needs are presented in this paper.