Distance measurement technology development at remotely teleoperated robotic manipulator system for underwater constructions

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%.

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.

Low-power, low-cost accurate ranging methods implemented using narrow-band wireless (NBW) devices provide key enablement for a diverse set of applications in the vastly growing Internet of Things (IoT) and smart access control market segments. Applications of wireless ranging and localization include home and automotive access systems, indoor ranging, asset tracking, proximity sensing, distance estimation, gaming, security perimeter enforcement, and relay attack prevention to name a few. Unlike wide-band systems, NBW systems consume much lower power for each transmission and reception making them suitable for battery powered applications and possess wireless range that is an order of magnitude higher than wideband systems, allowing them to meet the requirements for several line-of-sight (LOS) and non-line-of-sight (NLOS) application conditions. An accurate multi-carrier phase-based distance measurement technique using Bluetooth-LE is described in this paper. The paper describes a practical implementation and describes some of the signal processing techniques and challenges that extend beyond existing standardized wireless protocols.

Ultrasonic system for accurate distance measurement in the air

This paper presents a high accuracy air-coupled reflective ultrasonic rangefinder based on piezoelectric micromachined ultrasonic transducers (pMUTs) using multi-frequency continuous waves (MFCWs). Two pieces of 5 times 5 AlN pMUTs arrays at the resonant frequency of 492 kHz are employed to transmit and receive ultrasonic signals, respectively. The MFCW method, where the distance information is calculated from the phase difference, can cancel out the random noise in numerous repeating periods. Therefore, high-accuracy range measurement is achieved. The 3σ accuracy of the short distance measurement (<; 100 mm) is 0.0711 mm with 0.096 mm/° first-order resolution and 1.934 μm/° second-order resolution. For long distance measurement (100-300 mm), the 3σ accuracy is 1.8208 mm with 0.481 mm/° first-order resolution and 1.954 μm/° second-order resolution. The MFCW-based rangefinder using pMUTs is a good candidate for short distance measurement with high accuracy. [2018-0267].

Pulsar timing arrays (PTAs) are anticipated to detect continuous gravitational waves (GWs) from individual supermassive black hole binaries (SMBHBs) in the near future. To identify the host galaxy of a GW source, PTAs require significantly improved angular resolution beyond the typical range of 100–1000 square degrees achieved by recent continuous GW searches. In this study, we investigate how precise pulsar distance measurements can enhance the localization of a single GW source. Accurate distance information, comparable to or better than the GW wavelength (typically 1 pc) can refine GW source localization. In the near future, with the advent of Square Kilometre Array (SKA), such high-precision distance measurements will be feasible for a few nearby pulsars. We focus on the relatively nearby pulsars J0437-4715 (156 pc) and J 0030 + 0451 (331 pc), incorporating their actual distance uncertainties based on current very long baseline interferometry measurements and the anticipated precision of the SKA-era. By simulating 87 pulsars with the GW signal and Gaussian white noise in the timing residuals, we assess the impact of the pulsar distance information on GW source localization. Our results show that without precise distance information, localization remains insufficient to identify host galaxies under 10 ns noise. However, incorporating SKA-era distance precision for nearby pulsars J0437-4715 and J 0030 + 0451 can reduce localization uncertainties to the required level of 10 − 3 deg 2 under 10 ns noise. Localization accuracy strongly depends on the geometric configuration of pulsars with well-measured distances and improves notably near and between such pulsars. The improvement of the localization will greatly aid in identifying the host galaxy of a GW source and constructing an SMBHB catalog. It will further enable follow-up electromagnetic observations to investigate the SMBHB in greater detail.

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.

With the growing application of autonomous underwater vehicles (AUV) and underwater construction, i.e. robotic manipulator and maintenance systems, there is an increasing demand on precise underwater distance sensors. In this paper we present a low-cost, short-range and contactless sensor which uses electromagnetical (EM) waves for measuring distances underwater. The measurement system is based on interferometric radar applying a six-port interferometer and using EM waves at a frequency of 2.4 GHz. Measurement series in fresh water have been carried out showing an precision of below 100µm up to a distance of 35mm with only 8dBm of transmit power. Due to the high measurement rate the system can also be employed for vibration analysis. Additionally, by connecting a commercial 2.4 GHz data transceiver, it is imaginable for the system to be simultaneously used for high data rate communication between, e.g. AUV and unmanned underwater platforms (UUP).

Application of neural networks for extraction of distance and reflectance in pulsed laser radar

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.

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.

With conventional time-of-flight sonar ranging systems, it is difficult to obtain a high ranging accuracy due to the finite bandwidth of the transducer used and the serious acoustic attenuation in the air for the high acoustic frequencies. In this paper a multifrequency amplitude modulation (AM)-based sonar system is exploited to obtain information about the high-resolution distance measurement for robotic ranging applications. The target distance is obtained by measuring the linear phase shift of the reflected acoustic waves with respect to the reference signal. In order to analyze the ranging error two theoretical formulations are presented for characterization of the noisy phase measurement. The error effects on the phase measurement of the distorted input waveform due to the acoustic cross coupling are detailed, leading to the development of a multitransmitter sensing configuration. Since multifrequency is used, the nature of the target surface may bring about a certain ranging ambiguity to the system. The error effect of the rough surface is also analyzed at the end of the paper. >

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.

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.