Vernier Method Research Articles

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Driving synchronous machines requires early and accurate knowledge of the absolute position of the rotor; current solutions based on resolvers, sin–cos, or absolute encoders are complex, bulky, and costly. Hence, in this work two variants of absolute rotary encoder based on the Vernier method are analyzed. One, already discussed in the literature, displays the Vernier scale across the whole circumference (full-Vernier), and the other shows half Vernier traces over the entire perimeter (half-Vernier), which is an original feature. Both the implementations are characterized by only two tracks and as many sensors: the proposed conditioning algorithms provide the absolute angular position as a function of the time delays between the wave edges generated by the two traces, thus being of easy implementation on low-cost microcontroller units (MCUs). The Vernier encoders are also compared with the state-of-the-art absolute and relative solutions, i.e., incremental, binary, and Gray-code encoders. Experimental tests are carried out to assess the accuracy of the proposed sensors. The investigation shows that: 1) the full-Vernier cannot provide, in practice, a reliable estimate of the direction of rotation and of the actual angular sector without resorting to a third sensor; 2) the half-Vernier produces a trusty measurement of the absolute angle and velocity; and 3) can give a reliable position result with less than 30° shaft turn, but it can suffer from marginal performance degradation at low velocities in conjunction with high accelerations. Compared with the Gray encoder, the half-Vernier provides a simpler and more compact hardware for a given resolution, similar to that of an incremental encoder, at the expense of a small accuracy reduction at low speed.

Vernier time-to-digital converter with ring oscillators for in-pixel time-of-arrival and time-over-threshold measurement in 28 nm CMOS

The paper describes a design of a prototype chip in 28 nm CMOS technology, consisting of 8 × 4 pixels with 50 μm pitch, dedicated for the precise measurement of Time-of-Arrival (ToA) and Time-over-Threshold (ToT) with a resolution within the picosecond range. To address this requirement, in-pixel Vernier time-to-digital converter (TDC) has been implemented, which utilizes two ring oscillators per pixel. Overall chip architecture is introduced as well as pixel architecture and selected simulation results. The pixel consists of a recording channel and TDC part. The recording channel is composed of an inverter-based front-end amplifier with Zimmerman feedback, a discriminator, a calibration block and a threshold setting block. TDC part includes two ring oscillators together with their calibration blocks and additional logic with counters/shift registers that allow for precise ToA measurement (using Vernier method) as well as ToT measurement (using one of the oscillators). Alternatively, single photon counting (SPC) mode can be used. Frequency of oscillators is set in three steps. First, two global 8-bit digital-to-analog converters (DACs) are used for initial setting of all ring oscillators. Then, per-oscillator capacitance bank and 6-bit DAC are used for fine setting. Simulation results of core blocks suggest that the ToA resolution on the order of tens of picoseconds may be achieved. The chips are already fabricated and are currently being prepared for measurements.

Application of the Vernier method with the phase shift time of flight technique for optical metrology

The phase shift (PS) continuous wave time of flight (PS CW TOF) method is an optical measuring technique that can be used to obtain high accuracy absolute and relative distance measurements. Optical systems based on this method can be applied as a simple and low-cost metrology solution for application in an industrial and scientific context.A PS CW TOF range finder determines a source-target distance by comparing the phase difference of a continuously modulated signal in its source and when it is detected. Due to the cyclical properties of the phase angle, the position information is contained within an ambiguity interval. There are several established techniques that can be used to remove the ambiguity in this method, they usually rely in increasing the unambiguous range, using auxiliary measuring techniques or multiple modulation frequencies.In this work, we present a Vernier approach applied to the dual-frequency PS CW TOF method to remove the ambiguity in a phase measurement. We validate the proposed methodology by constructing an experimental setup based on heterodyne down conversion to perform distance measurements in a [0, 5] m range. This technique allowed reaching an expanded uncertainty in the distance measurement of ≈ 530 μm with k = 2 with a modulation frequency of 1.825 GHz.

Vernier: Accurate and Fast Acoustic Motion Tracking Using Mobile Devices

Acoustic motion tracking has been viewed as a promising user interaction technique in many scenarios such as Virtual Reality (VR), Smart Appliance, video gaming, etc. Existing acoustic motion tracking approaches, however, suffer from long window of accumulated signal and time-consuming signal processing. They are inherently difficult to achieve both high accuracy and low delay. In this paper, we present Vernier, an efficient and accurate acoustic tracking method based on commodity mobile devices. We design a new approach to efficiently and accurately derive phase change and thus moving distance. Vernier significantly reduces the tracking delay/overhead by removing the complicated frequency analysis and long window of signal accumulation, while keeping a high tracking accuracy. We implement Vernier on Android, and evaluate its performance with COTS mobile devices including Samsung Galaxy S7 and Sony L50t. Experimental results show that Vernier outperforms previous approaches with a tracking error less than 4 mm. The tracking speed achieves 3× improvement to the previous phase based approaches and 10× to Doppler Effect based approaches. Vernier is also validated in applications like controlling and drawing, and we believe it is generally applicable in many real applications.

Method and Device Based on Multiscan for Measuring the Geometric Parameters of Objects

The article deals with the issues of improving the accuracy of measurements of the geometric parameters of objects by optoelectronic systems, based on a television multiscan. A mathematical model of a multiscan with scanistor activation is developed, expressions for its integral output current and video signal are obtained, and the mechanism of their formation is investigated. An expression for the video signal is obtained that reflects the dual nature of the discrete–continuous multiscan structure: the video signal can have a discrete (pulse) or analog (continuous) form, depending on the step voltage between the photodiode cells of the multiscan. A Vernier discrete–analog method for measuring the parameters of the light zone on a multiscan is proposed, in which in order to increase the accuracy of the measurements, the location of the video pulse is determined relative to the neighboring reference pulses of a rigid geometric raster due to the slope of the discrete structure of the multiscan. It is established that the Vernier method enables one to make precision measurements of the coordinates, dimensions, and movements of the light zones by an overlay on a video raster of reference pulses from cells—a uniform sequence of Vernier pulses with a recurrence interval, followed by determining the number of the Vernier pulse that coincides with the raster pulse. An optoelectronic device based on a discrete–continuous multiscan, implemented on the basis of the proposed Vernier method of measuring the coordinates of the light zones, which has a high sensitivity to movement, is characteristic of continuous structures, and has increased stability and linearity of the coordinate characteristics typical for discrete structures, is developed.

Application of the Vernier method for absolute distance metrology with CW TOF phase shift technique

A phase shift time of flight technique determines a position by comparing the phase angle of a continuously modulated signal in the source and its reflection on a target. However, due to its cyclical properties, the position information is contained within an ambiguity interval. For an absolute measurement, this interval is repeated N times plus a residual part given by the phase shift. In this work we propose an application of the Vernier method to determine N and a setup for mid-range applications (10-20) m with a 3 GHz amplitude modulated source to allow accuracies ≤ 100 μm.

Experience in Designing Multi-Channel Time-To-Digital Converter

Objectives: The article presents the results of the development of multi-channel timeslot measurement system for laser radar for space application. Methods: FPGA Spartan-6 system (Xilinx, USA) was used for the development of our system. Vernier method was applied for timeslot measurement that enabled to obtain high accuracy of the results without using high-frequency signals. Findings: The result of our work was the development of time-to-digital converters (TDC) with extremely low sensitivity to temperature changes. At the same time our TDC was a complete digital device and had lower sensitivity to electromagnetic interference and noise in the supply chain. The results of this development could be interesting to a wide range of specialists focusing on the development of digital systems for both ground and space application. Improvements: A 64-channel TDC has been developed. Due to the self-measurement of characteristics in real time the developed TDC does not require additional correction and adjustment before use. Keywords: Programmable Logic Device (PLD), Time-to-Digital Converters (TDC)

Digital Optoelectrical Pulse Method for Vernier-Type Rotary Encoders

This paper proposes the digital optoelectrical pulse (DOP) method for vernier-type rotary encoders in high-resolution applications. A 25-b encoder using the DOP method is demonstrated. In rotary encoders, the low-bit data of an angle measurement are easily generated using a periodic signal. The high-bit data of an absolute angle measurement can be obtained using various methods such as binary code, gray code, pseudorandom code, $M$ code, or the vernier method. The vernier method has a significant advantage over the above methods for small-sized rotary encoders because it requires fewer grating tracks than do other methods. The vernier method uses grating tracks to generate periodic signals rather than digitally coded signals. In the vernier method, periodic signals with slightly different frequencies are used. The high-bit data of an absolute angle measurement can be obtained using the difference of two periodic signals. Complete absolute angle data are obtained by concatenating the high-bit data and the low-bit data. However, the high-bit data and the low-bit data are, in general, not synchronized. As a result, significant intermediate-bit errors occur at the concatenation point. The DOP method is developed in this paper to mitigate these intermediate-bit error problems. A system on a chip (SoC) that uses the proposed method is designed and fabricated using a 0.18- $\mu \text{m}$ CMOS image sensor process. A 25-b absolute encoder is constructed using an SoC that provides absolute angle data without intermediate-bit errors.

НОНИУСНЫЙ ФАЗОМЕТР

Shows the development phase meter multiplying the time interval by vernier method. The functional diagram of the phase meter. This Arrington relevant for industrial and laboratory conditions. The objective of the pilot study is the analysis of the phase meter with digital vernier multiplying the duration of the time interval

Фазометра с умножением временного интервала по нониусному методу

Фазометра с умножением временного интервала по нониусному методу

Comparison of three quick methods to estimate crab size in the land crabs <i>Cardisoma guanhumi</i> Latreille, 1825 and <i>Ucides cordatus</i> (Crustacea: Brachyura: Gecarcinidae and Ucididae)

<span>Para la estimación de la estructura de tamaños en cangrejos terrestres comerciales y la obtención de información relevante para su manejo, es necesario utilizar métodos rápidos, confiables y no destructivos. Cardisoma guanhumi y Ucides cordatus son dos cangrejos terrestres que son explotados comercialmente en el Caribe y en Brasil. El propósito de este trabajo es suministrar métodos indirectos para la estimación del tamaño del caparazón de los cangrejos y por consiguiente, de la estructura de tallas. Los muestreos se llevaron a cabo en Carenero <em>(C. guanhumi</em>) y en Cumaná (<em>U. cordatus</em>) (Venezuela). Se utilizaron tres métodos para estimar el diámetro de sus madrigueras: Vernier, compás y fotografía. Estos se correlacionaron con el tamaño real del cangrejo. Se aplicó el análisis de regresión Ordinary Least Squares Model II y la capacidad de predicción se probó utilizando el modelo II Mayor Axis para las regresiones. <em>Cardisoma guanhumi</em> mostró una fuerte dispersión de sus datos en los métodos de Vernier y fotografía. Menos dispersión se obtuvo con el método del compás y fue el más preciso (r2= 0.61). Para <em>U. cordatus</em> las medidas con Vernier fueron la más adecuadas (r2= 0.71). Sin embargo los tres métodos fueron confiables. Los diferentes métodos mostraron ventajas y desventajas y dependerá del que aplique los métodos, decidir cuál será el más adecuado para sus propósitos</span>

Controlled growth of DNA structures from repeating units using the vernier mechanism.

In this report, we demonstrate the assembly of length-programmed DNA nanostructures using a single 16 base sequence and its complement as building blocks. To achieve this, we applied the Vernier mechanism to DNA assembly, which uses a mismatch in length between two monomers to dictate the final length of the product. Specifically, this approach relies on the interaction of two DNA strands containing a different number (n, m) of complementary binding sites: these two strands will keep binding to each other until they come into register, thus generating a larger assembly whose length (n × m) is encoded by the number of binding sites in each strand. While the Vernier mechanism has been applied to other areas of supramolecular chemistry, here we present an application of its principles to DNA nanostructures. Using a single 16 base repeat and its complement, and varying the number of repeats on a given DNA strand, we show the consistent construction of duplexes up to 228 base pairs (bp) in length. Employing specific annealing protocols, strand capping, and intercalator chaperones allows us to further grow the duplex to 392 base pairs. We demonstrate that the Vernier method is not only strand-efficient, but also produces a cleaner, higher-yielding product than conventional designs.

A Nanosecond Vernier Time Analyzer

The instrument is the result of the development work started three years ago when we introduced the Vernier method (1), (2), (3), (4), but since then other instruments, based on the Vernier technique, have been developed (5), (6) and used (7). The block scheme of the instrument is shown in Fig. 1.

Review of methods for time interval measurements with picosecond resolution

This paper is a review of methods and techniques used for precise measurement of time intervals (TIs) or precise conversion of TIs to digital data. The following methods are described: the counter method and averaging, time stretching, time-to-amplitude conversion followed by analogue-to-digital conversion, the Vernier method, conversion utilizing tapped delay lines, and interpolation methods. Special attention has been paid to converters utilizing integrated delay lines for digital conversion of TIs, including designs with phase-locked loop and delay-locked loop circuits. This review is illustrated by design examples and contains a comprehensive list of references.

Characterization of field stitching in electron-beam lithography using moiré metrology

We describe a method for characterizing field stitching in e-beam lithography systems. The method, which is based upon the moiré principle, enables one to measure interfield stitching errors to the nanometer level using only a conventional optical microscope. The technique is more sensitive than the commonly used vernier method, and it does not require the use of a coordinate-measuring tool. Our experiments show that this technique can determine the interfield stitching to within 2 nm.

Objektive Noniussehschärfenprüfung bei Erwachsenen, Kindern und Kleinkindern - Möglichkeiten und Grenzen einer neuen Methode

Recently, a method of objective Vernier acuity testing using a modified Catford drum was presented. A tight correlation between the objective Vernier acuity and the Snellen acuity was reported (Hopkisson et al. 1991). In 41 cooperative patients with strabismic amblyopia and 20 normal subjects were compared the subjective Landolt acuity with the objective Vernier acuity and the individual interocular differences of the objective Vernier acuity. The Vernier method was then tested in 44 healthy 6- to 36-months-old infants. In 39 of the amblyopic and 15 of the normal subjects we compared the Landolt acuity with the grating acuity as measured with the Teller-acuity-card-test, and the interocular differences of the grating acuity. The Vernier target was a black line with an offset of one fifth of its thickness. In a distance of 1 m the offset appeared under visual angles of 15.9' to 0.3' corresponding to acuities of 0.06 to 3.2. The line was moving back and forth in its longitudinal direction. The objective Vernier acuity was defined by the smallest offset causing pursuit eye movements. Strabismic amblyopia was detected by the Vernier method with a sensitivity of 54%. In infants, however, the sensitivity would be less than 30%. In both eyes only 45% of the infants could be tested at all. The sensitivity of the Teller-acuity-card-test was 28%. Many cases of strabismic amblyopia will escape detection by the described method of Vernier acuity testing.

An afterimage vernier method for assessing the precision of eye movement monitors: Results for the scleral coil technique

A method is described to assess the precision of eye movement monitors by comparing the difference in two sequentially measured eye positions with the relative positions of afterimages that were induced at the same moments. A 0.1ȁ0.3 min of arc sensitivity could be reached, using a vernier method. The precision of the scleral coil technique was 1 min of arc.

Vernier fringe-counting device for laser wavelength measurements

A vernier fringe-counting circuit designed for use with a Kowalski-type wavemeter is described. Wavelength measurements made with this device have a high reproducibility of 5×10−9 (or 1/50 of a fringe) and measured accuracy of 4×10−9. The results of accuracy tests are presented along with systematic errors incurred when the wavelengths of two He–Ne lasers (632.9 nm) are compared by the vernier method.

An analysis of ultraviolet magneto-optical spectra

An analysis of recently observed magneto-optical spectra is presented. A vernier method is described in which, by considering the full profile and including both the contribution due to birefringence and that due to dichroism, an enhanced accuracy can be achieved in the determination of relative oscillator strengths as compared with that achievable in methods based on Faraday rotation alone.

Vernier method of measuring time intervals

Vernier method of measuring time intervals