双目立体视觉在模型姿态监测中的应用研究

风洞试验模型姿态的实时、精确非接触测量对于提高风洞试验的精度和可信度有重要意义。但实现却十分困难．尤其是模型姿态侧滑角的实时精确测量。提出采用双目立体视觉实时、精确测量模型姿态，简要说明了硬件组成和基本原理，深入探讨了技术要点和主要算法。最后给出了测量结论。     

某高超声速风洞模型底压精确测量方法改进研究与试验验证

针对某高超声速风洞模型底压量值低精确测量难度大、底压传感器容易过温超载等问题,在某高超声速风洞中建立了一套可精确测量风洞模型底压的专用装置。该装置采用了小量程绝压式薄膜电容规作为主要的测量元件,并有针对性的设计了传感器过压保护气路、水冷隔热结构和测控程序。该装置布置于该风洞试验段内模型支撑机构上,可大幅缩短测压气路,减少转接环节。该装置在马赫数5～9试验条件下开展了HB-2标模试验验证,试验结果表明：该模型底压精确测量装置达到了设计要求,集成度高,故障率低,系统稳压时间显著缩短,可快速响应模型底部压力变化情况,可适应高马赫数试验条件下模型底压测量要求,系统测量精度优于0.5%,能大幅度提高了高超声速风洞模型底压测量的精准度。     

基于双目立体视觉的风洞模型姿态测量研究

风洞试验中,模型姿态是实验数据修正的重要环节,测量的准确与否对实验结果有着重要影响.从风洞试验实际出发,提出一种基于双目立体视觉的风洞模型姿态测量技术,并介绍了该技术在风洞中的应用.试验表明文中使用的方法与美国兰利研究中心31-inch Mach 10风洞中使用的视觉姿态测量系统精度相当,具有广泛的使用前景.     

手持式天线姿态检测仪表在通信网络优化的实现和应用

在移动通信系统中,天线的位置和姿态直接影响覆盖区域、网络质量和用户感知.本文提出一种基于智能磁方位传感器实现天线姿态的自动采集系统,并创新性的设计成手持式仪表,使该系统同时具备精确测量与便携灵活的特点,实现了天线姿态信息从人工机械测量向自动精确测量的飞跃.     

基于CPLD的三轴转台姿态信号测量板卡的设计

飞行控制系统半物理仿真中三轴转台姿态信号精确测量是实现闭环飞行控制仿真可靠、稳定运行的关键;文章介绍了一种基于CPLD的三轴转台姿态信号测量板卡,采用原理图和VHDL硬件描述语言完成了CPLD内部逻辑电路的设计;板卡上一片CPLD芯片完成了三轴转台姿态信号的实时测量与数据处理,C8051F005单片机实现与上位机的数据通信和指令的接收;测量数据和上位机指令均采用Modbus协议在RS485总线上传输;在半物理仿真中的实测结果表明:姿态角测量误差小于3″,使用CPLD降低了成本,提高了数据处理速度和计算精度,数据传输稳定。     

基于四元数与卡尔曼滤波的四旋翼飞行器姿态估计

设计了一款基于嵌入式处理器STM32的四旋翼飞行器,利用低成本传感器测量加速度和机体的角速率,提出一种结合算法,从而实现飞行器姿态的精确测量。采用四元数法描述飞行器的姿态,在测量过程中结合互补滤波算法进行测量数据的矫正;同时针对出现的随机噪声干扰,采用卡尔曼滤波算法,实现姿态的准确测量,最终在实际的飞行器平台上得到了验证。     

多气参测量的压力型基准大气数据系统研制

针对某飞行器嵌入式大气数据传感(FADS)系统的飞行试验校准问题,研制了一套压力型姿态角测量的多气参基准大气数据系统。设计了可实现高线性度、解耦的压力型姿态角测量空速管,并配套研制了大气数据计算机。解决了有限空间内多气路之间密封、同时精确取气和压力测量、飞行器机体干扰下的风洞试验标定、多参数拟合修正的气参解算等难题,获得了机体干扰下的空速管测量修正解算公式,实现了基准气参的高精度测量。在完成基准空速管的风洞试验标定和联调试验后,实现了对全系统正常工况下的飞行参数测量精度及系统稳定性考核,最终成功应用于飞行试验中。     

基于可穿戴式惯性测量单元的行人室内定位技术

通过将惯性测量单元系在脚背上,实时测量出人体在行走时的加速度和角速度信息;通过阈值判断和零速校正模型完成对行人步长、步频和方向的解算,绘制出行人的运动轨迹;在搭建的可穿戴式惯性测量单元轨迹监测实验平台中进行模型验证,并将解算绘制出的行人轨迹实验结果与行走时测量的轨迹进行比对。实验结果表明:该方法的准确率均达到在98%以上,实现了对行人在室内环境下的便携式、可穿戴式实时精确测量。     

磁罗盘误差分析与校准

根据磁罗盘的工作原理,在详细分析了磁干扰和仪表误差等影响磁罗盘精度各因素的基础上,首先建立了一个用矩阵方程描述的磁罗盘方位指向输出的精确测量模型;接着证明了目前广泛使用的几种罗盘指向解算模型仅是上述精确测量模型在不同特定条件下的简化或泛化;随后基于不同姿态下的椭圆拟合算法对上述精确测量模型各个参数进行辨识,提出了全面校准磁罗盘方位指向的方法和步骤;最后用实例检验并比较了采用椭圆拟合模型和精确测量模型对罗盘方位解算的效果,验证了该精确测量模型的广泛适用性。     

基于加速度计和磁强计的随钻姿态测量观测模型

水平定向钻进中钻具姿态的实时测量是实现导向的关键因素。推导了钻具姿态角的测量方法,给出了姿态转换矩阵的解算公式。针对姿态测量的非线性问题和已有算法的不足,建立了姿态测量系统的线性观测方程,该观测方程利用加速度计和磁强计分别测得的地球重力场分量和地磁场分量来构造新的观测向量,并以姿态四元数的误差向量作为观测模型的输入。给出了线性观测模型的求解方法,最小二乘递推法。仿真结果表明:该算法收敛速度快,能够得到钻具准确的姿态信息,即使起始姿态的估计值与真实值之间的偏差很大,该算法仍能很好地收敛到真实值。     

The reliability of the Extra Load Index as a measure of relative load carriage economy

Abstract

The aim of this study was to measure the reliability of the extra load index (ELI) as a method for assessing relative load carriage economy. Seventeen volunteers (12 males, 5 females) performed walking trials at 3 km·h^?1, 6 km·h^?1 and a self-selected speed. Trial conditions were repeated 7 days later to assess test–retest reliability. Trials involved four 4-minute periods of walking, each separated by 5 min of rest. The initial stage was performed unloaded followed in a randomised order by a second unloaded period and walking with backpacks of 7 and 20 kg. Results show ELI values did not differ significantly between trials for any of the speeds (p = 0.46) with either of the additional loads (p = 0.297). The systematic bias, limits of agreement and coefficients of variation were small in all trial conditions. We conclude the ELI appears to be a reliable measure of relative load carriage economy.

Practitioner Summary: This paper demonstrates that the ELI is a reliable measure of load carriage economy at a range of walking speeds with both a light and heavy load. The ELI, therefore, represents a useful tool for comparing the relative economy associated with different load carriage systems.     

Design of carriage with two-layer coils for hard disk drive actuator

We proposed a carriage called a two-layer coil carriage that attenuates an out-of-plane mode. The coil of the proposed carriage is divided into two parts that are stacked on one another. The ratio of the current for the two coils can be changed by optimizing the coil coefficients. We have clarified the mechanism of excitation of the out-of-plane mode. We constructed the two-layer coil carriage, and measured the frequency response from the voice coil motor current of the two coils to head displacement. The effectiveness of the proposed carriage in reducing excitation of the coil torsion mode was demonstrated through simulation and experiment.     

汽车空调压缩机的能耗测量系统的研究

车用空调是以耗用发动机的动力为代价来完成调节车厢内空气环境的,其中用于制冷系统的压缩机是车用空调主要的能耗部分.因此,通过开发可用于实际车辆行驶状态下测量车用空调压缩机驱动扭矩的扭矩计,将其用于车用空调压缩机在车辆行驶中的能耗测量;将其用于FTP75模式下的车辆行驶状态的压缩机能耗的测量,并分析测量结果.有助于车用空调压缩机动力特性的研究及分析器影响因素,优化空调控制策略.     

Effect of load carriage on spinal compression

Backpack is commonly carried either posteriorly or anteriorly. Although load carriage has been shown to have significant effects on postural alignment and spinal muscle activity, its effect on spinal loading was not studied. The objective of this study is to investigate the effect of different load carriage methods on spinal loading over time via the measurement of spinal compression. Eight male adults participated in this study. They were asked to carry a load equivalent to 15% of their body weight either anteriorly or posteriorly for 20 min followed by 10 min of unloading. Their statures were measured before load carriage and every 2 min after carrying the load. The sequence of loading conditions was randomized and the participants took a 20-min rest with Fowler’s posture for spinal length recovery prior to each testing condition. The amount of spinal compression was found to be associated with carrying duration. Spinal compression during anterior carriage was larger than that of posterior carriage. There was a mild recovery of spinal compression after the removal of the carried load for both the anterior and posterior carriage conditions.

Relevance to industry

Short-term putting a backpack anteriorly might be useful for temporarily relieving postural changes induced by posterior carriage. However, prolonged anterior carriage is not recommended. The effects of load carriage on spinal compression should be considered in the design of a load carriage system with load partially or completely positioned in the front     

Low back pain: Some real answers

The aim of this study was to simultaneously assess the changes in physiology, and kinematic and spatiotemporal features of gait, during prolonged load carriage in individuals without load carriage experience. Eleven males, representative of new military recruits, walked for 120 min at 5.5 km h^? 1, 0% grade, on a motorised treadmill while carrying a 22 kg load. The load ( ≤ 30% body mass) was distributed over a weighted vest, combat webbing and replica model firearm, to reflect a patrol order load. Oxygen consumption and heart rate increased throughout the trial; however, apart from a minor increase in step length, there were no changes in the kinematic or spatiotemporal parameters, despite an increase in perceived exertion and discomfort. These data suggest that individuals with no experience in load carriage are able to maintain normal gait during 2 h of fixed speed walking, while carrying a patrol order load ≤ 30% body mass.     

步行机能量效率问题的计算机辅助研究

本文首先根据移动耗能率的定义,推导了两种不同模型腿足机构的步行机移动耗能率计算公式.再用计算机模拟计算得到了不同参数下的移动耗能率曲线.最后得到的主要结论是:(1)对相对坐标系型腿足机构来说,哺乳动物型姿态比昆虫型姿态在能效特性上优越.(2)对机体坐标系型腿足机构来说,在相对步距为0.1到0.6m 的范围内昆虫型姿态优越;而在相对步距为0.7到1.0m 的范围内哺乳动物型姿态优越.     

Changes in spinal curvature and proprioception of schoolboys carrying different weights of backpack

Despite evidence linking backpack carriage and back pain, previous studies to examine the effects of backpack carriage have focused on changes in physical performance rather than the direct effects on the spine itself. Spinal curvature and proprioception (in terms of spinal repositioning consistency) of 15 schoolboys during normal upright stance without a backpack and while carrying a specially adapted backpack loaded at 10, 15 and 20% of their bodyweight were measured and compared using repeated measures ANOVA. A significant flattening of the lumbar lordosis and the upper thoracic kyphosis was found with increasing backpack load, as well as a significant decrease in the thoraco-lumbar and lumbar repositioning consistencies. Carriage of a loaded backpack causes immediate changes in spinal curvature and appears to have a direct effect on the repositioning consistency. Further investigation of the changes in spinal curvature and repositioning consistency over time with prolonged backpack carriage is warranted. Daily carriage of a school backpack on the musculoskeletal health of children and adolescents has become an area of concern due to the association between backpack carriage and back pain. Data regarding the direct effect of backpack carriage on the spine in children are limited.     

Optimization using simulation and response surface methodology with an application on subway train scheduling

This paper presents a technique based on discrete‐event simulation and response surface methodology to model and then optimize the schedule of subway train travels. The aim of this study is to find appropriate headways—time intervals between the travels of two consecutive trains—at different hours in order to optimize average passenger travel time and rate of carriage fullness. For physical reasons and the observance of safety standards, an increase in the train speed in order to decrease average passenger travel time may not exceed some specified limits. One of the ways to decrease this average is to appropriately adjust headways of trains in the schedule. For this purpose, a metamodel of multinomial type is fitted to the data obtained from simulation tests to describe the relation between input variables (headways) and output variables (average passenger travel time in system and carriage fullness rate), and then optimal combinations of input variables are obtained using a weighed metric method and sequential quadratic programming.     

Changes in spinal curvature and proprioception of schoolboys carrying different weights of backpack

Despite evidence linking backpack carriage and back pain, previous studies to examine the effects of backpack carriage have focused on changes in physical performance rather than the direct effects on the spine itself. Spinal curvature and proprioception (in terms of spinal repositioning consistency) of 15 schoolboys during normal upright stance without a backpack and while carrying a specially adapted backpack loaded at 10, 15 and 20% of their bodyweight were measured and compared using repeated measures ANOVA. A significant flattening of the lumbar lordosis and the upper thoracic kyphosis was found with increasing backpack load, as well as a significant decrease in the thoraco-lumbar and lumbar repositioning consistencies. Carriage of a loaded backpack causes immediate changes in spinal curvature and appears to have a direct effect on the repositioning consistency. Further investigation of the changes in spinal curvature and repositioning consistency over time with prolonged backpack carriage is warranted. Daily carriage of a school backpack on the musculoskeletal health of children and adolescents has become an area of concern due to the association between backpack carriage and back pain. Data regarding the direct effect of backpack carriage on the spine in children are limited.     

Short-term effects of backpack load placement on spine deformation and repositioning error in schoolchildren

Backpack weight of 10–15% has been recommended as an acceptable limit for schoolchildren. However, there is still no clear guideline regarding where the backpack centre of gravity (CG) should be positioned. The changes of spinal curvature and repositioning error when carrying a backpack loaded at 15% of body weight at different CG locations (anterior or posterior at T7, T12 or L3) in schoolchildren were analysed. Both spinal curvature and repositioning error were found to be affected by backpack anterior–posterior position and CG level. A relatively smaller change was observed during anterior carriage with the least change when the backpack CG was positioned at T12. The results also suggested that alternative carriage by changing the backpack position occasionally between anterior and posterior positions might help to relieve the effects of backpack on spine. However, future study is recommended to further substantiate the beneficial effects of alternative carriage on children.

Statement of Relevance: Anteriorly carried backpack with centre of gravity positioned at T12 was shown to induce relatively less effect on spinal deformation and repositioning error in schoolchildren. Changing backpack carriage position occasionally may help to relieve its effects on spinal deformation. The findings are important for ergonomic schoolbag design and determining a proper load carriage method.