Software Compensation Method Research Articles

Field distortion correction in galvanometric scanning system by interpolation with symmetric polynomials

Due to its high precision and flexibility, laser process system is widely used in laser marking, drilling, cutting and projection. Laser scanning machines are usually equipped with high-speed galvanometric scanning systems, which are inevitably accompanied by field distortion. The error compensation method can help improve the marking quality that minimizes inherent and random errors. This paper introduces a facile software compensation method for this purpose. Based on symmetry of field distortion, the length of four characteristic lines is required to determine the polynomial compensation function. The experimental results verified that the technique could effectively reduce the field-distortion errors in the galvanometer laser-machining system, which verifies the feasibility and effectiveness of the compensation method. Within the processing range of the experiment (100 × 100 mm), the average relative position accuracy is 0.00068 (＜1‰). In the light of these results, high-quality laser processing is promising for achieving by the compensation method.

Temperature Compensation Method for Raster Projectors used in 3D Structured Light Scanners.

Raster projectors are commonly used in many various measurement applications where active lighting is required, such as in three-dimensional structured light scanners. The effect of temperature on the raster projector, in some conditions, can lead to significant deterioration of the measurements performed with such a scanner. In this paper, the outcomes of several experiments concerning the effects of temperature on raster projectors are presented. The described research is focused on the thermal deformations of projected images caused by common thermal effects observed in projectors: those caused by the warming-up process and changes in ambient environmental temperature. A software compensation method is also presented. It is suitable for implementation in any existing measurement method that uses raster projectors. The results of performed verification experiments show that the developed compensation method can decrease the thermal drift of the projected images by up to 14 times in the ambient temperature range °C.

Alternative particle compensation techniques for online water quality monitoring using UV–Vis spectrophotometer

Particles in the water can significantly affect UV–Vis absorption measurements. There is a need for the water industry to develop a reliable technique to eliminate particle impact on on-line water quality monitoring using UV–Vis spectroscopy. This study aims to develop and use digital techniques for particle compensation: single wavelength compensation, linear regression compensation and multiplicative scatter correction method for on-line UV–Vis spectrophotometers. Water quality data were collected from three selected water sources in water treatment plants which represent different water qualities in terms of particles and organic matters. UV254 measurements were determined with these three software compensation techniques in comparison with the proprietary instrument built-in compensation algorithm using Bland-Altman analysis. Linear correction methods were found to be able to adjust the three compensation techniques to achieve acceptable compensated UV254 results, particularly for raw waters. UV254 measurements using single wavelength compensation, linear regression compensation and multiplicative scatter correction techniques with the assistant of linear correction methods were confirmed to be comparable to the instrument built-in compensation method. Our results reveal that these particle compensation techniques can make the UV254 technology reliable for online water quality monitoring in water treatment network. This paper demonstrated the advantage of using software compensation method to establish local compensation and calibration models instead of relying on the predetermined global calibrations for online water quality monitoring.

Software compensation for the coupling error of a single-mode fiber coil under time-varying temperature and magnetic field

Previous studies have shown that there exists a large nonreciprocal phase error in the single-mode fiber coil of a depolarized interference fiber optic gyroscope (De-IFOG) under time-varying temperature and magnetic field, which evidently weakens its environmental adaptability. A real-time software compensation method considering the coupling effect of time-varying temperature and magnetic field is first proposed and verified experimentally. After compensation, the error of De-IFOG decreases from 50 deg / h to 6 deg / h when the magnitude of the magnetic field is 10 G and temperature uniformly increases from 10°C to 60°C with time-varying rate of 36 ° C / h. The compensation method is of great significance in De-IFOG engineering applications.

Temperature Compensation Method for Mechanical Base of 3D-Structured Light Scanners.

The effect of temperature on three-dimensional (3D) structured light scanners is a very complex issue that, under some conditions, can lead to significant deterioration of performed measurements. In this paper, we present the results of several studies concerning the effect of temperature on the mechanical base of 3D-structured light scanners. We also propose a software compensation method suitable for implementation in any existing scanner. The most significant advantage of the described method is the fact that it does not require any specialized artifact or any additional equipment, nor access to the thermal chamber. It uses a simulation of mechanical base thermal deformations and a virtual 3D measurement environment that allows for conducting virtual measurements. The results from the verification experiments show that the developed method can extend the range of temperatures in which 3D-structured light scanners can perform valid measurements by more than six-fold.

Research on the temperature characteristic of magnetic sensor in the magnetic drift compensation fiber-optic gyroscope

Software compensation is an effective method for enhancing the magnetic field environment adaptability of light-small fiber-optic gyroscope (FOG). In order to decrease the magnetic drift of FOG, an accurate magnetic sensor is typically required to measure the intensity of magnetic field in this software compensation method. The magnetic sensor generally suffers from the measurement error due to the variety of temperature. In order to compensate the magnetic drift of FOG preferably in full temperature range (−40 °C to +60 °C), the temperature sensitivity of the Hall sensor manufactured by Allegro is studied in this paper. Temperature compensation models of quescent voltage output and magnetic sensitivity are established, and the variation is compensated respectively. The measurement precision of Hall sensor is 0.02 G over the temperature from −40 °C to 60 °C after compensation, which meets the requirement of magnetic drift compensation of FOG in full temperature.

Software compensation method for achieving high stability of Alpao deformable mirrors.

Deformable mirrors (DMs) are used in adaptive optics for correcting optical aberrations: the DM surface can be deformed to compensate for them. Recently we reported the results on investigation of the stability of Alpao DMs, i.e. how accurately a DM surface shape can be maintained over minutes and hours without any optical feed-back. We observed a creep behavior of the DM surface and we presented a proof-of-concept software compensation for it, showing that very high stability is achievable. In this paper we develop a generalized creep compensation method that covers a wide range of DM use-cases and compensates for 90% - 95% of the creep observed. Furthermore, we report an observation of a DM shape dependence on the magnitude of the DM steering commands over the last few minutes. This effect is likely due to the warming up of the structure supporting the DM surface. Similarly as for creep, we have developed a compensation in software which corrects for about 90% of this effect. Both compensation mechanisms are based solely on pre-calibration input and do not receive any optical feedback about the actual DM surface shape. With the application of these two compensation mechanisms, the Alpao DM exhibits excellent stability and is well suited for feed-forward operation, where high reliability of the DM surface is crucial for operation in the absence of an optical feedback.

圆感应同步器系统误差的动态提取与补偿

As the precision of a photo-turntable control system using rotary inductosyn depends on the dynamic angular position measuring precision of a rotary inductosyn, this paper explores the system error of the rotary inductosyn. The error mechanism of rotary inductosyn was analyzed, and the system error of the rotary inductosyn was quantitatively and dynamically measured by using an experimental platform. Finally, the system error model of the rotary inductosyn was put forward based on the data processing and error mechanism, and the output signals from the rotary inductosyn were compensated by the error model. The software compensation method was verified and the experimental results for the rotary inductosyn with 720 poles, 12 bits show that the dynamic angle measurement accuracy is improved from 11.25″ to 1.17″, while the angular velocity estimation accuracy is improved from 0.72(°)/s to 0.09(°)/s. The test results show that the proposed method improves the dynamic measuring accuracy of the rotary inductosyn significantly and satisfies the accuracy demands of photoelectric platform pointing control systems. ©, 2015, Chinese Academy of Sciences. All right reserved.

CPLD-Based Circuit Design of IGBT Dead-Time Compensation

IGBT (insulated-gate bipolar transistors) dead-time compensation circuit has a very important significant for improving the output voltage waveform of the inverter, reducing the harmonic output current. Thus, many compensation strategies are reported in literatures and have been implemented in industrial drives recently. Overall, the method of dead-time compensation can be divided into hardware compensation and software compensation. Hardware compensation method needs additional hardware circuits, which means additional space and cost. Still more, the additional circuit is easy to interfere with others, which can reduce the compensation accuracy. While the software compensation method takes up a lot of memory space and additional input-output ports of processor, which often result to the added operation and heat dissipation of controller. In this paper, CPLD (complex programmable logic device)-based circuit design of dead-time compensation is presented to solve these existed drawbacks. It is verified that not only can the circuit simplify existed inverter dead-time compensation design, but also it has the advantages of small volume, strong anti-interference ability, and high compensation precision. The simulation results validate that this method is feasible and effective.

Application of an Iterative Learning Control Algorithm to Volumetric Error Compensation for CNC Machines

To promote higher-quality machining, this paper presents a software-based method for compensating for volumetric errors. The developed software compensation method modifies CNC part programs by app...

Intelligent Turbine Flowmeter for Viscous Oil Flow Measurement

Turbine flowmeter is significant, but the change of viscosity has a remarkable impact on the accuracy of the turbine flowmeter. Aiming at this problem, the experiment was carried out on the viscosity variable oil flow facility. New software compensation method for viscosity was put forward with the developed intelligent turbine secondary instrument. Firstly the viscosity was compensated, viscosity was regarded as independent variable, average meter factor was regarded as dependent variable, the polynomial was fitted; then the flow rate was compensated, flow rate was regarded as independent variable, the average offset between meter factor got by viscosity compensation and experiment was regarded as dependent variable. The polynomial was fitted, the sum of results of two functions was regarded as the final meter factor. The test demonstrated: with the software compensation the accuracy of intelligent turbine flowmeter changed from 8.0% to better than 2.3%.

Research on Nozzle Array Structure Fluidic Gyroscope Sensitivity-Temperature Compensation

The nozzle array structure fluidic gyroscope sensitivity-temperature compensation was researched. The fluidic gyroscope’s sensitivity temperature characteristic was analyzed in the sensitive element and two sensitivity-temperature compensation methods were compared. Then, the software compensation method was used, which based on the Single chip microcomputer technology and realized sensitivity compensation for the gyroscope output signal. The results show that after the compensation, the gyroscope’s sensitivity-temperature coefficient decreases from 1.8mV/°/s/°C to 0.1mV/°/s/°C and operating temperature range increases from normal temperature to -40°C～+60°C. Therefore, this method provides the effective way for the gyroscope practical research.

Research on Nozzle Array Structure Fluidic Gyroscope Zero Temperature Compensation

The nozzle array structure fluidic gyroscope’s zero temperature compensation was researched. The fluidic gyroscope’s temperature characteristic was analyzed in the sensitive element and two zero temperature compensation methods were compared. Then, the software compensation method was used, which based on the Single chip microcomputer technology and realized temperature compensation for the gyroscope output signal. The results show that after the compensation, the gyroscope’s zero drift decreases from ≤1.3mV/°C to ≤0.1mV/°C and operating temperature range increases from normal temperature to -40°C~+60°C. Therefore, the fluidic gyroscope has the advantage of low zero drift and width operating temperature range after the zero temperature compensation, which provides the convenience for the production and application.

Research on new software compensation method of static and quasi-static errors for precision motion controller

To reduce mechanical vibrations induced by big errors compensation, a new software compensation method based on an improved digital differential analyzer (DDA) interpolator for static and quasi-static errors of machine tools is proposed. Based on principle of traditional DDA interpolator, a DDA interpolator is divided into command generator and command analyzer. There are three types of errors, considering the difference of positions between compensation points and interpolation segments. According to the classification, errors are distributed evenly in data processing and compensated to certain interpolation segments in machining. On-line implementation results show that the proposed approach greatly improves positioning accuracy of computer numerical control (CNC) machine tools.

A Study of High-Precision CNC Lathe Thermal Errors and Compensation

This study is addressed at the thermal deformation errors resulting from temperature rise that contribute to 40%-70% of the precision errors in machining at a turning centre, and proposes an economic, accurate, and quick measurement method. It also investigates the thermal error differentials between static idle turning and in the actual cutting environment. The temperature measurement units are intelligent IC temperature sensors with correction circuits. The AID card extracts and transforms data and saves data in the computer files, and the displacement sensor measures the displacement deviation online during cutting. The temperatures and the deviation of thermal drifts so obtained are used to establish the relationship function using multivariable linear regression and nonlinear exponential regression models, respectively. Finally, this paper compares software compensation methods for the thermal-drift relationship. As proven by experiments, the software compensation method can limit the thermal error of a turning centre to within 5 μm. Moreover, the software compensation for the thermal error relationship using a single variable nonlinear exponent regression model can reduce the error by 40% to 60%.