A multifrequency AM-based ultrasonic system for accuracy distance measurement

To promote underwater construction, the tools such as underwater robotic manipulator system, underwater vehicles and so on are necessary. Furthermore, these system need an accurate 3D position parameters. If no position information for automatic control system that system is difficult to be operated. Hence, it is important to take position information. Although 3D position camera can offer 3D position parameters, it has still some deviation. In addition, the manipulator system need accurate distance information for fast and accurate operation. Hence, an accurate distance measurement system is necessary for a remotely teleoperated robotic manipulator system for underwater constructions. This paper focus on the distance measurement study to offer a accurate target distance information. The information can combine with 3D position camera to obtain more accurate 3D position parameters to offer a useful position information for underwater constructions, with a remotely teleoperated robotic manipulator system. In this paper, three distance measurement system, includes commercial ultrasonic distance measurement system, fabricated ultrasonic system and a laser distance measurement system is study. The commercial distance measurement system have a distance measurement system rang 8~35 cm, plusmn0.1 cm. However, a short distance measurement is difficult to be measured with the measurement system. On the other side, the fabricated measurement system can measure a short distance. Information from 0~5 cm, accuracy plusmn0.3 cm. The fabricated distance measurement system fabricated with PZT thin film. In this study, a horn is added to improve the accuracy of distance measurement. In addition, the laser distance measurement system, measurement system is used to measure the distance information also in this study. The combination of these distance measurement system to form a multiple range distance measurement can offer a long measurement range for accurate distance measurement underwater. A detailed experiment is to be studied in the future. Furthermore, the distance measurement system has been offered a distance measurement in a remotely teleoperated robotic manipulator system for underwater constructions

Fiber probe is an important component in optical coherence tomography (OCT) and distance measurement system, its collection efficiency of the light reflected from target surface directly affects the signal-to-noise ratio (SNR) of the system, while the target distance will have direct influence on the collection efficiency. However, there are few researches on specific analysis of the collection efficiency variation of fiber probe when target distance change. In this paper, we proposed the theoretical model of fiber probe, and we deduce the collection efficiency of the light reflected from the target surface which is deviated from the ideal image plane of the fixed-focus fiber probe with Δl in the direction of the optical axis. The theoretical result is testified by ZEMAX simulation, and the difference between the simulation result and the theoretical calculation is 0.0023 when Δl = -5mm. In addition, ZEMAX is utilized to simulate the light collection efficiency when target distance change for reflective target surface. The results of simulation are basically consistent with theoretical calculation. It is concluded that the rate of descent for the collection efficiency is greater when target surface is placed in front of the ideal image plane, and the working range of the fiber probe increases with the increase of ideal image distance. The findings can guide us to make effective use of fiber probe and chose a detector with the right dynamic range to improve distance measurement precision.

Ultrasonic system for accurate distance measurement in the air

In this contribution, a novel opto-acoustic indoor navigation system for linear distance measurement is presented. The novelty consists in the simultaneous use of envelope time-of-flight (ETF) and carrier phase (CPH) measurements. In particular, we establish a two-channel link consisting of an ultrasound and infrared channel, the latter using a carrier frequency equal to the ultrasound frequency. In order to render the system extendible for multiple transmitters and receivers, code-division-multiple-access using Gold codes is employed, as all ultrasound and infrared signals share the same carrier frequency. This is also beneficial for multipath scattering suppression. The time difference between the carrier phase of the received ultrasound and infrared signals offers a high resolution but ambiguous distance signal. On the other hand, correlation of the received signals yields a coarse but unique distance signal. Experimental results show that a measurement resolution in the submillimeter range is feasible.

This paper presents a novel person to camera distance measuring system based on eye-distance. The distance between centers of two eyes is used for measuring the person to camera distance. The variation in eye-distance (in pixels) with the changes in camera to person distance (in inches) is used to formulate the distance measuring system. The system starts with computing the distance between two eyes of a person and then person to camera distance is measured. The proposed distance measurement system is relatively simple and inexpensive to implement as it does not require any other external distance measuring tools. Experimental results show the effectiveness of the system with an average accuracy of 94.11%.

An electroacoustic measurement model of an immersion ultrasonic NDE measurement system is developed which explicitly characterizes all the electrical, electromechanical, and acoustic/elastic components of the measurement process. It is demonstrated that for a typical commercial ultrasonic measurement system all of the components of this model can either be directly modeled or measured experimentally using purely electrical measurements. This complete measurement/modeling capability provides an important new means for understanding and modifying the behavior of complex ultrasonic NDE systems.

This paper presents a multi-resolution masks based pattern matching method for person identification. The system is commenced with the construction of multi-resolution mask cluster pyramid, where the mask size is chosen depending on the distance between two eyes, computed from the detected face. Experimental results show the effectiveness of the system with significantly higher precision, recall rates and matching probability comparing with conventional single resolution mask based person identification systems. This paper also presents a novel person to camera distance measuring system based on eye-distance. The distance between centers of two eyes (interocular distance) is used for measuring the person to camera distance. The variation in eye-distance (in pixels) with the changes in camera to person distance (in inches) is used to formulate the distance measuring system. Experimental results show the effectiveness of the distance measurement system with an average accuracy of 94.11%. Key words: Single resolution mask, multi-resolution masks, person to camera distance, person identification.

An automated AT89C55WD microcontroller based surface roughness and distance measurement system is developed. An IR diode and detector are used for the measurement. In this paper, the experimental arrangement for the measurement of distance and classification of surface roughness is explained. An artificial neural network (ANN), trained with a back propagation algorithm is employed for the data processing to classify the roughness of the surface and for the distance measurement. A three layer ANN is used to learn the type of surface and corresponding output using a back propagation algorithm. After training, the neural network is used to classify the roughness of the surface and to measure distance.

In this paper, a miniaturized D-band frequency-modulated continuous-wave (FMCW) radar sensor with 48-GHz bandwidth (32.8%, 122-170 GHz) and a high measurement rate of > 1 kHz for multi-target vibration measurements is presented. The sensor is based on a SiGe transceiver monolithic microwave integrated circuit manufactured via Infineon's B7HF200 bipolar production technology with an fT of 170 GHz and fmax of 250 GHz. Gilbert cell, push-pull, and varactor-based doubler concepts on manufactured chips are compared, and the most promising signal source is embedded into a transceiver chip, which forms the main component of the presented radar sensor. The maximum output power of the system is ≈ -10 dBm and a phase noise of ≈ -80 dBc/Hz is achieved. Measurements are provided to demonstrate the sensor characteristics and show the promising results of FMCW radar in highest precision distance and multi-target vibration measurement applications. Due to the covered wide bandwidth, a range resolution of 5.88 mm is achieved ( -6-dB width, Tukey window). The sensor's distance measurement repeatability is 290 nm (65 nm with 10 × averaging and 0.5-m target distance), and the distance measurement accuracy is m for a target in 65-cm distance moving 1 cm. Additionally, vibration measurement results and range-Doppler plots for advanced multi-target applications are presented.

Estimation of harvested fruit weight using volume measurements with distance sensors: A case study with olives in a big box

Recently, the distance measurement system that can measure a big object such as a clay model or a die at high speed, in non-contact and with high accuracy is demanded. The distance measurement system which used a laser and triangulation has been used for such distance measurement until now. But it was difficult to reconcile the large distance measurement such as about 100mm and high resolution such as about 10μm because large focal depth is incompatible with a small beam diameter in illumination optics of conventional distance measurement system. So we develop the distance measurement system that used axicon lens for illumination optics to realize large focal depth and small beam diameter. In this paper, it is reported about principle of an axicon lens, experimental result using axicon lens, method of distance calculation and experimental result using this system.

The distances to 1,576 targets between 0.3 and 10.4km from two ships were measured using the reticle scale in 253 binoculars during cetacean surveys in the eastern tropical Pacific Ocean. Distances were measured under a range of conditions representing the environmental variability in three years of field surveys. Alternative formulae for calculating distance from optical devices were applied to the reticle measurements and compared to distances measured by radar. Reticles in 253 binoculars provided unbiased measurements to about a third of the way to the horizon, or from 0-4km for the 10.5m platform heights used for the study. Between 4 and 8km (approximately one-third to two-thirds of the distance to the horizon), distances tended to be slightly underestimated, reaching a maximum bias at the most distant targets of 6% for one ship and 16% for the other. Distances beyond about two-thirds of the way to the horizon were not measurable because the angles were too small. The negative bias in measurements of distances from 4-8km was due to refraction of light and other factors. Refraction had less of an effect than expected for a temperature gradient based on a standard atmosphere, suggesting a mean gradient for the eastern tropical Pacific of –0.02°C m–1 in the first 10m above the sea surface rather than the standard value of –0.0065°C m–1. Correcting the measurements for refraction improved their accuracy, eliminating the bias for one ship and reducing it for the other. Adjusting for refraction should improve measurements of distance using theodolites or photographic/video imaging as well as measurements using binoculars. An additional regression-based correction suggested that the remaining negative bias for one ship was a complex interaction of Beaufort Sea state, swell height and wind speed. Precision of distance measurements decreased multiplicatively with target distance. Including errors due to bias, the multiplicative standard error was 12%, or a 95% confidence interval from 0.8-1.2km for a target at 1km and from 6.5-9.9km for a target at 8km. Compared with other methods of measuring distance to marine mammals at sea, measurements using binocular reticles are more precise than distances estimated by eye, less precise than distances measured with photographic imaging, and useful over a larger range.

A phased array ultrasonic measurement system is a particularly complex collection of electrical, electromechanical, and acoustic/elastic processes because of the number of sending and receiving circuits and transducer elements present. In this chapter, we will use linear system theory concepts of two-port systems and single input–single outputlinear time shift invariant (LTI) systems to describe phased array measurement systems at different levels of detail, following an approach similar to that described in [Schmerr-Song] and (Dang et al. (Res NDE 14:141–176, 2002; Res NDE 14:177–201, 2002) for single element transducer systems. Our goal is to develop a model of a phased array flaw measurement system that can be used to predict quantitatively the signals that are produced in a given experiment in terms of parameters of the measurement system instrumentation and probes and the characteristics of the unknown flaw being examined.

In this paper a new system for distance measurement is proposed. Both optical and acoustical sensors have been adopted. Fuzzy data fusion methodologies, adopted to perform high quality measurements from the multiple sensor estimations, are described. The experimental set-up and the metrological characterization of the measuring system are also reported.

We propose a technique to achieve high-speed and high-precision distance measurement via phase demodulation of broadband optical carrier-based microwave interferometry (OCMI). An in-phase and quadrature (I/Q) processing scheme is designed and incorporated to measure the phase shift induced by target distance. The results could be efficiently derived from a minimum of one pair of detected outputs with immunity to power fluctuations. To extend the non-ambiguous measurement range while maintaining high resolution, a multifrequency-based phase unwrapping procedure is implemented. In the meantime, a driving module is utilized to effectively amplify and stabilize the signal. Experiments were carried out to evaluate the feasibility and performance of the proposed OCMI distance measurement method, which exhibits good accuracy, stability, and reliability. The maximum residual error is found to be 0.084 mm and the relative error is less than 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> . Moreover, the method is capable to perform thousands of measurements within a few seconds, thus the OCMI-based dynamic target tracking has been achieved.