共查询到20条相似文献,搜索用时 15 毫秒
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为了研究产品装调过程中,套孔法和CCD成像法得到的激光发散角偏差较大原因,采用ZEMAX仿真进行了理论分析,并结合相关试验进行了验证。结果表明,在CCD白光观瞄系统中利用CCD成像法测量激光光斑大小时,由于白光与激光间存在光程差,计算激光发散角时,需要消除光程差导致的图像误差的影响。激光光斑大小与距离符合双曲线规律变化。近场条件下不成线性关系,CCD成像法测量得到的激光光斑图像偏大,计算得到的激光发散角远大于套孔法的测量值;远场条件下近似成线性关系,套孔法及CCD成像法测算得到的激光发散角数值基本一致。该研究可以根据产品的设计参量,消除光程差对激光激光束散角的影响,提高测量精度。 相似文献
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Willemsen A.T.M. Frigo C. Boom H.B.K. 《IEEE transactions on bio-medical engineering》1991,38(12):1186-1193
Closed-loop control techniques for the restoration of locomotion of paraplegic subjects are expected to improve the quality of functional neuromuscular stimulation (FNS). We investigated the use of accelerometers for the assessment of feedback parameters. Previously, the possibility of angle assessment of the lower extremities using accelerometers, but without integration, was demonstrated. The current paper evaluates and assesses this method by an error and sensitivity analysis using healthy subject data. Of three potential error sources, the reference system, the accelerometers, and the model assumptions, the last was found to be the most important. Model calculations based on data obtained by the Elite video motion analysis system showed the rigid-body assumption error to be dominant for high frequencies (greater than 10 Hz), with vibrations in the order of 1 mm resulting in errors of one radial or more. For low frequencies (less than 5 Hz), the imperfect fixation of the accelerometers combined with a nonhinge type knee joint gave an error contribution of +/- 0.03 rad. The walking pattern was assumed to be two-dimensional which was shown to result in an error of +/- 0.04 rad. Accelerations due to rotations of the segments could be neglected. The total error computed for low frequencies (+/- 0.07 rad) was comparable to the experimental difference between the current and the reference system. 相似文献
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Performance analysis of optimised CMOS comparator 总被引:2,自引:0,他引:2
A high-speed low-power latched CMOS comparator circuit is presented. Demonstrated is a circuit optimisation technique to obtain minimum offset error at 500 MHz sampling speed. Also, a mathematical model representing the noise in the device is developed. After optimisation, the comparator achieved 10-bit resolution on a 1 V differential input at 500 MHz speed and had a noise figure of 4.747 dB at this frequency. 相似文献
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A large-scale spatial angle measurement method is proposed based on inertial reference. Common measurement reference is established in inertial space, and the spatial vector coordinates of each measured axis in inertial space are measured by using autocollimation tracking and inertial measurement technology. According to the spatial coordinates of each test vector axis, the measurement of large-scale spatial angle is easily realized. The pointing error of tracking device based on the two mirrors in the measurement system is studied, and the influence of different installation errors to the pointing error is analyzed. This research can lay a foundation for error allocation, calibration and compensation for the measurement system. 相似文献
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角度测量广泛应用于工业生产和国防军事领域,介绍了大间距空间角测量技术研究进展并对典型测量设备进行了分析。提出了一种基于机器视觉的动态角测量方法,利用高精度两轴伺服系统识别跟踪远处场景中的十字分划靶标,利用图像处理算法实时计算跟踪偏移量并传递给两轴伺服系统进行高低、方位角度修正。通过构建被测对象、合作目标和角度测量传感器三者之间的角度坐标系传递模型,实现了武器系统调炮精度检测。另外也可用于光电桅杆偏移量及火炮身管晃动量检测,具有精度高、成本低等特点,适合于外场条件下大间距空间角测量。 相似文献
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在拦截超低空目标时,海面多路径效应会严重影响被动制导型舰空导弹的测角精度。首先阐述海面多路径效应产生机理,然后结合旋转式相位干涉仪的测角原理,通过建立海面多路径镜面反射几何模型,给出了双天线直达信号和镜面反射信号表达式。在此基础上,选取典型超低空弹道,根据仿真结果代入多路径计算模型,分析超低空弹道多路径效应对测角精度的影响。仿真结果表明,海面多路径效应对被动微波体制导引头测角影响显著,为下一步研究抑制多路径影响措施提供了重要参考。 相似文献
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The design and implementation of a simple load angle measurement instrument built around a Z80 microprocessor is described. The task of the microprocessor is to measure the load angle of a synchronous generator which is equal to the phase angle between the internal excitation voltage and the generator output. The load angle is displayed on an on line screen. It is also converted to an analogue value and recorded by an online plotter for transient analysis a feature that makes such an instrument suitable for either digital or analogue controllers. The tests carried out showed that the instrument has a very fast response. It is accurate, reliable and inexpensive. The resolution in the load angle measurements can be increased by a simple procedure.<> 相似文献
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A key element in the mechanisation of fault-tolerant system or error-detection system is a logic device call a `comparator?.The device detects computer failures by data comparison. The letter describes a `self-testing comparator?. We show that, in the circuit, described, only the output wire must be considered hard core. All the gates and connections of this circuit are tested during the working phases. 相似文献
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《Electronics letters》1969,5(18):428-429
A new method of measuring transient load angle of a synchronous machine system is described which self-compensates for the variation of base frequency of the system. The measurement system was designed for use with an ultraviolet recorder. 相似文献
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A modified method of fibre end-cleave angle measurement is described and compared with alternative techniques. The device has no precision parts and has a resolution of better than 0.25 degrees of end angle. 相似文献