Digital Optoelectrical Pulse Method for Vernier-Type Rotary Encoders

Bahn, Wook; Nam, Junghyun; Lee, Sanghoon; Cho, Dong‐il Dan

doi:10.1109/tim.2015.2502878

Cited by 16 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Essentially, Vernier encoders exploit the nonius-Vernier scale, the same utilized in calibers, in order to increase significantly the resolution of the measurement while providing absolute angle information. Some adaptations of such an encoder design have already been inspected in a number of works (see [18]- [20]), are the subject of some patents (see [21], [22]), and are available as commercial products (see [23]).…”

Section: Introductionmentioning

confidence: 99%

“…Decoding the angle from Vernier encoders is computationally more expensive compared to the incremental and Graycode solutions, and requires at least three sensors or three tracks. Specifically, the fundamental design described in [18] and [21] is characterized by three tracks. The first one provides a signal with n = 1024 cycles per revolution and the second one gives a signal with n − 1 cycles per revolution: their difference is a signal that encodes the angular position as a linear function of an index i ∈ [0, n[.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Dalboni

Soldati

2023

IEEE Trans. Instrum. Meas.

View full text Add to dashboard Cite

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 Vernier method are analyzed. One, already discussed in the literature, displays the Vernier scale across the whole circumference (full-Vernier), the other shows half Vernier traces over the entire perimeter (half-Vernier), which is an original feature. Both 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 MCUs. The Vernier encoders are also compared with state-of-the-art absolute and relative solutions, i.e. incremental, binary and Graycode encoders. Experimental tests are carried out to assess the accuracy of the proposed sensors. The investigation shows that (i) 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; (ii) the half-Vernier produces a trusty measurement of the absolute angle and velocity and (iii) can give a reliable position result with less than 30°shaft turn, but (iv) it can suffer from marginal performance degradation at low velocities in conjunction with high accelerations. Compared to 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.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Dalboni

Soldati

2023

IEEE Trans. Instrum. Meas.

View full text Add to dashboard Cite

show abstract

“…It is very challenging to achieve both high-accuracy and long-range displacement measurements [5,6]. Among the various kinds of displacement sensors [7][8][9][10][11], laser interferometers, grating rulers, and capacitive grating sensors are the most commonly used types of transducers for displacement measurement, with comparable accuracy over a relatively long range [12][13][14][15][16][17][18]. Laser interferometers have a range of dozens of centimeters, or even several meters, with an accuracy of greater than ±0.1 ppm [13,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Error Analysis and Modeling for an Absolute Capacitive Displacement Measuring System with High Accuracy and Long Range

Zhang

Zheng

2019

Sensors

View full text Add to dashboard Cite

We proposed a novel kind of absolute capacitive grating displacement measuring system with both high accuracy and long range in a previous article. The measuring system includes both a MOVER and a STATOR, the contact surfaces of which are coated by a thin layer of dielectric film with a low friction coefficient and high hardness. The measuring system works in contact mode to minimize the gap changes. This paper presents a theoretical analysis of the influence of some factors, including fabrication errors, installation errors, and environment disturbance, on measurement signals. The measuring signal model was modified according to the analysis. The signal processing methods were investigated to improve the signal sensitivity and signal-to-noise ratio (SNR). The displacement calculation model shows that the design of orthogonal signals can solve the dead-zone problem. Absolute displacement was obtained by a simple method using two coarse signals and highly accurate displacement was further obtained while using two fine signals with the help of absolute information. According to the displacement calculation model and error analysis, the error in fine calculation functions mainly determines the model’s accuracy and is locally affected by coarse calculation functions. It was also determined that amplitude differences, non-orthogonality, and signal offsets are not related to the accuracy of the displacement calculation model. The experiments were carried out to confirm the abovementioned theoretical analysis. The experimental results show that the displacement resolution and error in the displacement calculation model reach ±4.8 nm and ±34 nm, respectively, in the displacement range of 5 mm. The experiments and the theoretical analyses both indicate that our proposed measuring system has great potential for achieving an accuracy of tens of nanometers and a range of hundreds of millimeters.

show abstract

“…Absolute position displacement measurement sensors play an irreplaceable role in the field of high-precision measurements and as a component in the closed loop feedback control of computer numerical control (CNC) machine tool systems. The rapid development of high-precision positioning technology in CNC machine tool systems has generated an increasing demand for robust absolute displacement measurement sensors with high positioning accuracy and excellent repetitive positioning precision in harsh environments, such as under the conditions of electromagnetic interference, mechanical vibration, extreme temperature variation, and dust contamination [1][2][3][4][5][6][7]. Meanwhile, many types of absolute grating displacement measurement sensors with high precision and high resolution have been developed, including capacitive grating sensors [1,2], magnetic grating sensors [8], and optical grating sensors [9].…”

Section: Introductionmentioning

confidence: 99%

A High Precision Capacitive Linear Displacement Sensor with Time-Grating that Provides Absolute Positioning Capability Based on a Vernier-Type Structure

et al. 2018

View full text Add to dashboard Cite

Nanometer-scale measurement devices with high accuracy and absolute long-range positioning capability are increasingly demanded in the field of computer numerical control machining. To meet this demand, the present report proposes a capacitive absolute linear displacement sensor with time-grating that employs a vernier-type structure based on a previously proposed single-row capacitive sensing structure. The novel proposed vernier-type absolute time-grating (VATG) sensor employs two capacitor rows, each with an equivalent measurement range. The first capacitor row is designed with n periods to realize fine measurement, while the second capacitor row is designed with n − 1 periods, and the phase difference between the second row and the first row is employed to obtain absolute positioning information. A prototype VATG sensor with a total measurement range of 600 mm and n = 150 is fabricated using printed circuit board manufacturing technology, and its measurement performance is evaluated experimentally. Harmonic analysis demonstrates that the measurement error mainly consists of first-harmonic error, which is mostly caused by signal crosstalk. Accordingly, an optimized prototype VATG sensor is fabricated by adding a shielding layer between the two capacitor rows and designing a differential induction structure. Experimental results demonstrate that the measurement error of the optimized prototype sensor is ±1.25 μm over the full 600 mm range and ±0.25 μm over a single 4 mm period.

show abstract

Digital Optoelectrical Pulse Method for Vernier-Type Rotary Encoders

Cited by 16 publications

References 10 publications

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Error Analysis and Modeling for an Absolute Capacitive Displacement Measuring System with High Accuracy and Long Range

A High Precision Capacitive Linear Displacement Sensor with Time-Grating that Provides Absolute Positioning Capability Based on a Vernier-Type Structure

Contact Info

Product

Resources

About