Measurement Subsystem Research Articles

Discriminators for Instantaneous Frequency Measurement Subsystem Based on Open-Loop Resonators

The authors have studied a new way to design an instantaneous frequency measurement subsystem (IFMS). The method is based on bandstop filters. The device uses rectangular open-loop resonators instead of delay lines. The resonance frequency is adjusted by a resonator perimeter that must be approximately a half-wavelength long, and also by coupling distance between the resonators and the main transmission line. Simulated and experimental results are presented for a 5-bit IFMS.

Single-mass 6-DOF isotropic accelerometer with segmented PSD sensors

This paper outlines the novel design of a single-mass six-degrees-of-freedom (6-DOF) accelerometer, distinguished by a high level of isotropy. The six spatial coordinates (three linear and three angular) of the movements of its proof mass and their derivatives are obtained from simple measurement of the linear displacements of specially chosen points in the proof mass. Calculation of the accelerometer's six acceleration components is then possible according to a specially developed mathematical algorithm. Exceptional isotropy of sensitivity is ensured by the symmetrical structure of the device's three subsystems (inertial, suspension, and measurement). The accelerometer's structural symmetry is imparted by the proof mass’ cubic shape and 24 elastic supports (springs with damping inserts) that are mounted along the x-, y-, and z-axes in threes at the cube's vertices. The measurement subsystem consists of six differential optical displacement sensors, symmetrically located facing the centers of the cube faces, and a light source mounted at the center of the cube. Each optical sensor is based on three-component position-sensitive detectors of the segmented type. Working prototypes of the isotropic 6-DOF accelerometer have been manufactured, adjusted, and tested.

A system for rapid design and manufacturing of custom-tailored shoes

Rapid design and production techniques are indispensable for the custom-made production systems. For manufacturing custom-made shoes, the shoelast should be designed rapidly from the individual foot model. In this paper, we develop an integrated system for rapid design and manufacturing of custom-tailored shoes. The foot shape measurement sub-system allows scanning a standard shoelast and an individual foot and then extracts the three-dimensional crosssectional data of the shoelast and the human foot shape from the captured image data. The shoelast design sub-system uses the scanned data to design new customized shoelast curves or surfaces with the heeling and mixing algorithms built in this system. The pattern design subsystem provides a method, which transforms a shoe-upper surface designed by a stylist into a flat-pattern that can be manufactured. We also export the surface model to an NC machine to manufacture the physical shoelast model.

植物における生体電位波形群の音表現

A sound expression methodology for AC components of bioelectric potential and a conversion system in real-time manner has been proposed in order to express spatial and temporal diversity in the potential changes on the leaf surface.The system consists of measurement subsystem of bioelectric potential including disk electrodes and amplifiers of thirty two channels, a computer of thirty two bits CPU, digital sound sources based on MIDI standard, thirty two speakers and a modem. In the system, three techniques for bioelectric data conversion have been essentially employed, namely, Pitch Modulation (P.M.) for converting the potential change to frequency of audible sound, Amplitude Modulation (A.M.) for the intensity to sound amplitude, and Threshold Triggering (T.T.) for triggering one-shot sound in excess of threshold level.Throughout an evaluation study of the system, the combination of P.M. and A.M. has made the adaptation to various wave forms in the bioelectric potential changes possible and its effective performance has been confirmed by the simultaneous processing of bioelectric wave forms from different leaves.

Space-qualified superconductive digital instantaneous frequency-measurement subsystem

We have constructed a five-bit high temperature superconductive digital instantaneous frequency measurement (DIFM) subsystem capable of determining the frequency of unknown signals over a 500-MHz bandwidth, centered on 4 GHz, with a resolution of 17.8 MHz. The system consists of three parts: a limiting amplifier and filter, a comparator and data processing unit operating at room temperature, and a cryogenic subsystem containing five discriminator modules based on superconductive delay lines, GaAs mixers and power dividers. With a single-tone CW input between -40 dBm and +10 dBm, the frequency quantization boundaries of the subsystem are, on average, 3.1 MHz from their design values. This system was built for the High-Temperature Superconductor Space Experiment, Phase II (HTSSE II). It has passed all required qualification tests for vibration, shock and thermal cycling. The system is currently scheduled for satellite launch in fall 1996. Compared to a conventional system, the superconductive version of the DIFM is considerably smaller and provides enhanced resolution. In addition, the technology employed can be readily extended to a system with additional bits and wider instantaneous bandwidth. The system built demonstrates the potential for system-level applications of high-temperature superconductive electronics in instrumentation, communications, radar, and electronic warfare.

On the optimality of open-loop LQG measurement scheduling

Revisits the problem of optimally controlling a linear-quadratic-Gaussian (LQG) plant and its measurement subsystem. The standard treatment of this problem uses dynamic programming to establish that LQG regulation and open-loop measurement scheduling are optimal. Here it is shown that these results can be obtained more directly using a straightforward conditioning argument that highlights the dependence of the results on the data independence, for open-loop schedules, of the LQG cost.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optimal sensor selection strategy for discrete-time state estimators

A novel sensor selection strategy is introduced, which can be implemented on-line in time-varying discrete-time system. We consider a case in which several measurement subsystem are available, each of which may be used to drive a state estimation algorithm. However, due to practical implementation constraints (such as the ability of the on-board computer to process the acquired data), only one of these subsystems can actually by utilized at a measurement update. An algorithm is needed, by which the optimal measurement subsystem to be used is selected at each sensor selection epoch. The approach described is based on using the square root V-Lambda information filter as the underlying state estimation algorithm. This algorithm continuously provides its user with the spectral factors of the estimation error covariance matrix, which are used in this work as the basis for an on-line decision procedure by which the optimal measurement strategy is derived. At each sensor selection epoch, a measurement subsystem is selected, which contributes the largest amount of information along the principal state space direction associated with the largest current estimation error. A numerical example is presented, which demonstrates the performance of the new algorithm. The state estimation problem is solved for a third-order time-varying system equipped with three measurement subsystem, only one of which can be used at a measurement update. It is shown that the optimal measurement strategy algorithm enhances the estimator by substantially reducing the maximal estimation error.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Superconductive digital instantaneous frequency measurement subsystem

A 5-b high-temperature-superconductive digital instantaneous frequency-measurement (DIFM) subsystem has been constructed for the determination of the frequency of unknown signals over a 500-MHz bandwidth, centered on 4 GHz, with a resolution of +or-7.8 MHz. The subsystem contains a cryogenic section with five discriminator modules using superconductive delay lines, GaAs mixers, and power dividers. The subsystem also has a room-temperature GaAs limiting amplifier and a silicon postprocessor. With a single-tone CW (continuous-wave) input between -40 dBm and +10 dBm, the frequency quantization boundaries of the subsystem are, on average, 3.1 MHz from their design values. >

New multiple specimen potentiostatic system: Part 2: Practical examples of use in flowing sea water

AbstractA new potentiostatic system has been designed which is capable of controlling and monitoring a large number of specimen electrodes at many different set potentials, all within a single test tank or process stream, for long periods of time. Block diagrams of the potentiostatic control system are provided, together with details of the current measurement subsystem and power supply. In order to assess the performance of this system, cathodic Tafel plots were obtained with the new system by holding copper wire specimens in flowing sea water at eight different cathodic potentials for up to 8 days. The results were in surprisingly good agreement with Tafel plots obtained using conventional potentiodynamic techniques with copper wires that had been freely corroding for the same length of time. Anodic polarisation plots obtained with the new system for copper wire in flowing sea water showed a minimum in the current density at −125 m J(Ag/AgCl) that was indicative of the development of a protective film. ...

Design and Test of the ROSAT – AMCS

Abstract This paper gives a short outline of the German X-ray observation satellite ROSAT. The mission profile and the design of the attitude measurement and control subsystem are briefly described. The testing philosophy is explained with respect to closed loop software tests, static tests and dynamic tests. The main difficulties arising during testing period are summarized and the experience made is explained in some detail. For selected typical operational manoeuvres the results obtained by dynamic bench testing are presented and shortly described.

Sample Averaging and Rectify, Integrate, and Dump for Synchronous Demodulation Measurement of Mean Radiation

A subsystem which implements two approaches for the synchronous demodulation and measurement of the mean intensity of chopped solar radiation has been designed and built as part of a microprocessor-controlled data acquisition system for the Laser Heterodyne Spectrometer (LHS) instrument built at NASA Langley Research Center, Hampton VA. One approach is based on a commonly used analog technique consisting of full-wave rectification followed by a fixed-interval integrate and dump. The alternate approach consists of a simple amplifier/filter whose output is synchronously sampled, digitized, and averaged. The two approaches are presented and the noise performance compared analytically and empirically. Pertinent issues of performance and implementation are discussed. The complete measurement subsystem is described briefly.

3次元動態計測システムとその応用

A measurement system for the three-dimensional position using "SELSPOT" is shown, which has many advantages over the methods with photographs, movies, or other devices, with respect to its on-line measurement, easy operation, fast sampling, fast data processing, and high accuracy. This is important in view of the application that the display of the analyzed data is required soon after the measurement, such as the experiment of sports physiology and rehabilitation. The system is constructed with a measurement subsystem and an analyzing subsystem. The measurement subsystem is constructed with the dual two-dimensional measurement device which is named "SELSPOT", a communication and timing controller, microcomputer for the filing of the data, and external memory devices. The analyzing subsystem is constructed with the random scan type graphic display with the light pen and ten-keyboard for the interactive analysis, the line printer for the numerical data, and the x-y plotter for the hard copy of the screen. This paper proposes a precise method with which the three-dimensional position is calculated from the dual two-dimensional data. This method defines it as the generalized inverse of the characteristic equation on the camera and the detective device, or the middle point of the segment which determines the minimum length of the two principle rays. By the analysis of the detective device and the lens system, the three factors of the following measurement errors and the methods of their compensation is considered: the non-linearity of the position sensitive detector with the distance between the camera and the LED, the interference of the lightning in the experiment room, and the distortion of the lens. On the other hand, this paper also proposes a new method for camera setting which causes the least error in the calculated data. In the results, the worst accuracy is ±0.4% with error compensation, and ±2.0% without the compensation, respectively. In addition, as the software of the analyzing subsystem realizes the interactive processing and the sufficient function, the period for the display and analysis of the three-dimensional movement is shortened.

Optimal adaptive control of linear systems with unknown measurement subsystems

For the quadratic cost, adaptive stochastic control problem with linear plant and measurement models excited by white Gaussian noise, and with unknown time invariant model parameters in the measurement subsystem, the optimal stochastic control is obtained. It is shown that separation between estimation and control holds in this case. The controller is shown to be linear and deterministic, while the estimator is shown to consist of a bank of known nonlinear functions of model conditional, causal, mean-square state-vector estimates. The estimator can again be partitioned into a bank of linear, model conditional, optimal, nonadaptive estimates, one for each admissible value of unknown parameter vector θ, and a nonlinear bank of a posteriori model probabilities which incorporate the adaptive nature of the optimal adaptive control. The results are presented both for continuous-time and discrete-time systems. A special case of the above problem is also discussed. It is the case of joint detection and control.

NBS Mobile Acoustical Laboratory

In response to the need for research and study of the acoustical problems of urban environments, a mobile laboratory was designed to provide field measurement instrumental capabilities of the quality usually associated only with fixed acoustical laboratories. The facility provides for the field study of the actual acoustical performance of sound-isolating partitions and floor-ceiling assemblies, structureborne sound transmission generated by impacts, vibrating plumbing and electromechanical equipment as installed, and for acquisition of data toward determining relationships between field and laboratory measurement results. Most measurements are conducted from the mobile unit with only loudspeakers and microphones located remotely from the laboratory. For high-rise buildings and situations where lengthy cables are involved, a measurement subsystem is removed and transported readily to the site. Data may be reduced and analyzed at the field site or stored for later reduction and analysis. Some considerations and decisions involved in the preparation of specifications are discussed.

観測システムの最適化と観測情報の価値

観測システムの最適化と観測情報の価値

Optimal control of measurement subsystems

This paper considers an important class of problems known as measurement adaptive problems, in which control is available over not only the plant (i.e., the state equation contains a control variable) but also the measurement subsystem (i.e., the measurement equation contains a control variable). In the general situation the problem is shown to be a generalization of the combined optimization problem. In the special situation of linear systems, quadratic cost, and Gaussian random processes, it is shown that the optimization of plant control can be carried out independently of the measurement control optimization and, furthermore, that optimization of the measurement control can be done a priori. Two examples illustrating this latter situation are presented.

Improvements in surveyor's tripods: Patent granted to W.J. Young, Philadelphia, July 13th, 1858

This article reports a novel precise guiding method for visual guiding theodolite measurement in volume space. The vision guiding automatic theodolite measurement system consists of initial guiding and precise guiding, the latter of which directly determines the final measuring accuracy and measuring efficiency. We put forward a precise guiding method based on the camera optical axis. After being calibrated, the double-theodolite measuring subsystem and vision guiding subsystem are triggered by theoretical model data. Then by using the digital image processing technology, we can obtain the relation between the feature center in the camera view and the image center (the camera optical axis). With this relation and the multiresolution visual imaging and tracking technology, the vision measurement subsystem can be guided to target the feature center precisely. According to the calibration relation, we can obtain the angular deflection of double theodolites and make the double theodolites to intersect at the target point precisely. The method improves the automatic measurement efficiency at no cost of measurement accuracy.