High-precision Angle Measurement Research Articles

High-Precision Angle Measurement for Position Control in Industrial Drives Systems with Shaft Resolver

Resolver is a shaft angle sensor, which is mechanically connected to the motor shaft and operates according to the induction principle. A high frequency sinusoidal signal is applied to its input and produces two signals in the form of sine and cosine at its output. The output signals include the angle information of the motor shaft. Using these signals, the shaft angle of the motor is determined. In the study, a sinusoidal signal at the 5 kHz frequency was applied to an input resolver as the conventional method. After, the fact that applied to two PWM signals which has a duty ratio d=0.5 at 20 kHz and 100 kHz frequency is proposed as different from the conventional method. These PWM signals are the input signals of the resolver. Thus, complex equipment will not be needed to produce the high frequency sinusoidal signal. With only a simple amplifier circuit, a high frequency input signal will be produced. More sensitive angle information will be obtained with high frequency stimulation. A simulation study of conventional and proposed methods has been performed in MATLAB/Simscape environment. As a result of the simulation study, the information on the motor angle obtained from both methods was compared by using figures and details. By increasing the applied PWM signal from 20 kHz to 100 kHz, measurement errors related to shaft angle change were minimized and more precise position information was obtained.

Ground-based simulation of laser link acquisition for inter-satellite laser interferometry

Laser link acquisition and pointing technique is one of the essential techniques for the inter-satellite laser interferometry for space-based gravitational waves detection and next-generation Earth gravity measurement missions. The first step of building up inter-satellite laser link is using an acquisition camera to capture the inter-satellite laser beam signals within a pre-scanning uncertain cone. Subsequently, high-precision angle measurement technology, namely differential wavefront sensing, is used to achieve a high pointing precision required. Due to the distance constraint of a ground-based simulation experiment, it is difficult to verify directly the feasibility of an inter-satellite laser link acquisition and pointing control scheme. By means of controlling the optical properties of the received laser beam, the long-distance beam propagation is simulated with two optical benches of an inter-satellite interferometer, and the process of a laser link acquisition experiment has been demonstrated. The experimental results show that the inter-satellite laser beams could establish the dual-way locking successfully. The fluctuation of the laser beam pointing direction (in-loop) can be suppressed to about 5 µrad in atmospheric environment. The results verify the feasibility of the laser link acquisition scheme. The experimental setup can be extended to conduct experiments with various parameters, providing technical support for further testing of the inter-satellite laser link acquisition and pointing control methods.

High precision vertical angle measurement system for calibration of various angle sensors and instruments

A versatile measurement system was developed for efficient calibration of vertical angle sensors or instruments. The vertical angle measurement system (VAMS) comprises a precision rotation stage, a controller, and additional components for fixing an angle sensor or detecting angular deviation. It can generate single-axis rotation within ±120° range with a resolution of 0.01″. To detect angular deviation in angle instrument calibration, a special miniature autocollimator was developed using a diffractive optical element, providing high-precision angle measurement even with the short focal length of its lens. The performance of the VAMS was evaluated by comparing face angles of two optical polygons, measured by the VAMS and other reference systems. As typical exemplary calibrations, an electronic level and vertical angle readouts of a total station were calibrated with expanded uncertainty (k = 2) of 0.19″ and 0.51″, respectively.

A Review: High-Precision Angle Measurement Technologies.

Angle measurement is an essential component of precision measurement and serves as a crucial prerequisite for high-end manufacturing. It guides the implementation of precision manufacturing and assembly. The current angle measurement methods mainly focus on multiple axes, high precision, and large measurement ranges. This article introduces the technology of angle measurement from the perspectives of single-axis and multi-axis measurement schemes. Firstly, the single-axis measurement scheme is primarily achieved through optical methods, such as encoder discs that measure energy changes and interferometric phase changes, as well as mechanical, electromagnetic, and inertial angle measurement methods, among which interferometric methods offer the highest accuracy, with high cost, and encoder discs provide the largest measurement range with an ordinary price. Secondly, in the multi-axis measurement scheme, autocollimation instruments, including plane mirrors, gratings, and self-designed targets, are the main options. Although grating encoders can achieve three degrees of freedom in angle measurement with an ordinary price, they are limited in terms of measurement range and sensitivity compared to self-designed targets. Lastly, artificial intelligence assistance precision measurement is increasingly being embraced due to significant advancements in computer performance, making it more convenient to identify the relationship between measured values and detection values. In conclusion, angle measurement plays a crucial role in precision manufacturing, and the evolving and improving technologies provide the manufacturing industry with greater choices. The purpose of this review is to help readers quickly find more suitable technical solutions according to current application requirements, such as single/multiple axes, accuracy level, measuring range, budget, etc.

High-precision angle measurement based on two-dimensional hybrid position encoding

High-precision angle measurement based on two-dimensional hybrid position encoding

Design of high precision angle measuring instrument based on Kalman filter

Angle parameters are common parameters in production and life. The main process is converting the inclination signal into other signals for measurement. In order to overcome the problems of low-cost, long-term, and high-precision angle detection that traditional angle measurement systems cannot solve, a high-precision, low-cost, and small-size angle measurement system is designed. The high-precision angle sensor signal used in this paper is based on MEMS angle sensor. The angle sensor has the characteristics of extremely low temperature dependence, low noise and high resolution. In terms of hardware, various methods are used on the circuit board to eliminate noise during signal transmission. These methods are used to improve the accuracy of the angle measurement system. The Kalman filter algorithm is used to filter out noise to reduce the influence of noise on high-precision angle signals in terms of software. Experiments on the system show that the accuracy of the angle measurement system reaches 0.0014°, which achieve the goal of system design, can solve the problem of long-term, high-precision angle measurement, and completes the system design.

UAV low-altitude obstacle detection based on the fusion of LiDAR and camera

In this paper, aiming at the flying scene of the small unmanned aerial vehicle (UAV) in the low-altitude suburban environment, we choose the sensor configuration scheme of LiDAR and visible light camera, and design the static and dynamic obstacle detection algorithms based on sensor fusion. For static obstacles such as power lines and buildings in the low-altitude environment, the way that image-assisted verification of point clouds is used to fuse the contour information of the images and the depth information of the point clouds to obtain the location and size of static obstacles. For unknown dynamic obstacles such as rotary-wing UAVs, the IMM-UKF algorithm is designed to fuse the distance measurement information of point clouds and the high precision angle measurement information of image to achieve accurate estimation of the location and velocity of the dynamic obstacles. We build an experimental platform to verify the effectiveness of the obstacle detection algorithm in actual scenes and evaluate the relevant performance indexes.

Phased array radar system design based on single-send and multiple-receive for LSS-UAV target

In order to improve the precision of radar target positioning, the phased array frequency modulated continuous wave (FMCW) radar system based on single-send and multiple-receive is proposed for low altitude, slow speed, small Unmanned Aerial Vehicle (LSS-UAV) target. The much lower-cost passive electronically scanned array (PESA) radar technology has been employed for the azimuth electronically scanning. In addition, wide beam scanning beam of elevation direction is used to further expand the range of space coverage. Phase-comparison method is adopted to high-precision angle measurement of elevation direction in interferometer angle measurement system with dual distributed receivers. As a result, the novel radar system possesses the abilities of Doppler velocity measurement and linear FMCW distance measurement, as well as the high precision angle measurement at the same time. It can provide long distance, wide range, all-weather/time detection accurate target location information for optical system and electronic interception system to detect LSS-UAV targets for some more cost-sensitive applications in the homeland security market.

Research on High Precision Angle Measurement and Compensation Technology Based on Circular Grating

In this paper, the angle measurement method of high-precision circular grating is studied. The principle analysis of circular grating angle measurement, the principle analysis of multi reading head, and the design of rotary servo control system are carried out. After analyzing the error model of circular grating angle measurement, the research based on harmonic compensation model is carried out respectively. Aiming at the problem of zero crossing oscillation of compensation algorithm, the piecewise compensation strategy is designed, which fully demonstrates the application value of circular grating angle measurement method in high-precision angle measurement system.

Measurement of the apex angle of a small prism by an oblique-incidence mode-locked femtosecond laser autocollimator

A major modification has been made to the conventional mode-locked femtosecond laser autocollimator so that the apex angle of a small prism, which is a transparent object difficult to be measured by the conventional optical methods, can be measured. In the oblique-incidence optical setup, a collimated mode-locked femtosecond laser is at first made incident to a target prism, and the laser beam reflected from the prism surface is then projected onto a reflective-type grating for angle measurement based on the principle of the femtosecond laser autocollimator. With the robust signal processing technique in the femtosecond laser autocollimator where the spectrum of the first-order diffracted beams emanated from the grating is captured by the fiber detector, high-precision angle measurement can be realized even on a surface having a small area for measurement and/or on a surface having low reflectivity. An oblique-incidence femtosecond laser autocollimator with a fiber-based femtosecond laser source is developed, and its basic characteristics are then evaluated in experiments. An experimental setup composed of the oblique-incidence femtosecond laser autocollimator and a high-precision rotary table is also constructed for prism angle measurement. To avoid the influence of the internally reflected beam in a prism, a method employing the characteristic of Brewster's angle is newly proposed, and its feasibility is verified through experiments. The uncertainty analysis on the measurement of the prism apex angle by the oblique-incidence mode-locked femtosecond laser is also carried out based on GUM.

Test Technology in General Assembly of Large Satellites

The special test technology of the assembly, integration and test (AIT) of large satellites was studied, which accurately determine the leakage, alignment and mass property of large satellites, and ensure the reliable operation of large satellites in orbit. The local and total leakage testing technique was developed which based on quadrupole mass spectrometer and helium mass spectrometer. To meet large satellite quality and high precision, the satellite mass property testing equipment of large load bearing based on three coordinate conversion machine has been set up. A laser tracker uniting theodolite measure system with high positional precision and high angle measurement accuracy has been developed. Several large satellites have been tested in the process of AIT with these testing equipment. The quality of the large satellite has been effectively guaranteed.

Note: Comparison experimental results of the laser heterodyne interferometer for angle measurement based on the Faraday effect.

A laser heterodyne interferometer for angle measurement based on the Faraday effect is proposed. A novel optical configuration, designed by using the orthogonal return method for a linearly polarized beam based on the Faraday effect, guarantees that the measurement beam can return effectively even though an angular reflector has a large lateral displacement movement. The optical configuration and measurement principle are presented in detail. Two verification experiments were performed; the experimental results show that the proposed interferometer can achieve a large lateral displacement tolerance of 7.4 mm and also can realize high precision angle measurement with a large measurement range.

The Design and Implementation of a Low Cost and High Precision Angle Measuring Device

Based on SCA830 accelerometer designed a low cost high precision Angle measurement device. The device adopts the real-time mean shift filtering algorithms to reduce the interference of the external environment and noise, uses piecewise linearization method for Angle sensor calibration. The experimental results show that the designed angle detection device precision can reach 0.02 °, the system is stability, digital signal transmission is complete, and it can collect real-time carrier tilt Angle.

Automatic Calibration System for Precision Angle Measurement Devices

A proposed optomechatronic module is intended for the automatic and efficient calibration procedure of compact autocollimators utilized for high precision angle measurement. Conventional autocollimators have the disadvantages, e.g. the large volume and high cost, hence novel compact autocollimators have been developed in the past decade. To satisfy the practical applications, the measuring performance of a compact autocollimator must be determined and it has become important to offer a proper and efficient calibration module for the compact autocollimator.

Analytical Overview of Works on High Precision Angle Measurement Instruments

Considering lack of systemic analysis in the field of high precision angle measurement instruments, an analytical overview of modern angle measurement instruments is performed in this article.

反射式光电编码器

A reflective photoelectric encoder was developed.The grating self-imaging principle was introduced,the production process of a high-density reference grating was improved and a 32768line grating and a highly integrated optical reading head were prepared.Then,the high-precision reflective optical encoder was completed.By using multi reference points,the encoder could confirm the absolute position easyly and quickly,and its standard zero point was determined by the most initialize rotate angle of 5.625°.The angle measuring accuracy of the encoder was measured by a self collimating light tube and a 23surface prism.The measuring results indicate that the Mean Square Root Error for single reading head is 1.11″and that for double reading head is 0.75″.The gap between reflection grating and reading head is about 2.0mm,which is ten times larger than that of tradition type encoders.The results demonstrate that the high-precision reflective optical encoder developed has simple structures and its reading head shows high quality photoelectric signals.It can provide a solution scheme for high precision angle measurement.

A novel instrument for high precision angle measurement of optical axes

A novel instrument for high precision angle measurement of optical axes is presented, which can be used to accurately measure the angles of optical axes of photoelectric payloads. The deviation compensation technology of angle measurement and the extraction technology of the optical axis are also developed. The experiment results demonstrate that the measurement accuracy of the novel instrument can reach as high as 35″. Moreover, the novel instrument needs only one electronic theodolite and has large angle measurement range. Therefore, it is convenient to use it in angle measurement of optical axes.

2次元長さと角度の高精度測定技術とトレーサビリティーの研究

2次元長さと角度の高精度測定技術とトレーサビリティーの研究