Error Compensation Method Research Articles

A New Self-Calibration and Compensation Method for Installation Errors of Uniaxial Rotation Module Inertial Navigation System.

Calibration and compensation techniques are essential to improve the accuracy of the strap-down inertial navigation system. Especially for the new uniaxial rotation module inertial navigation system (URMINS), replacing faulty uniaxial rotation modules introduces installation errors between modules and reduces navigation accuracy. Therefore, it is necessary to calibrate these systems effectively and compensate for the installation error between modules. This paper proposes a new self-calibration and compensation method for installation errors without additional information and equipment. Using the attitude, velocity, and position differences between the two sets of navigation information output from URMINS as measurements, a Kalman filter is constructed and the installation error is estimated. After URMINS is compensated for the installation error, the average of the demodulated redundant information is taken to calculate the carrier’s navigation information. The simulation results show that the proposed method can effectively assess the installation error between modules with an estimation accuracy better than 5”. Experimental results for static navigation show that the accuracy of heading angle and positioning can be improved by 73.12% and 81.19% after the URMINS has compensated for the estimated installation errors. Simulation and experimental results further validate the effectiveness of the proposed self-calibration and compensation method.

An Enhanced Positional Error Compensation Method for Rock Drilling Robots Based on LightGBM and RBFN.

Rock drilling robots are able to greatly reduce labor intensity and improve efficiency and quality in tunnel construction. However, due to the characteristics of the heavy load, large span, and multi-joints of the robot manipulator, the errors are diverse and non-linear, which pose challenges to the intelligent and high-precision control of the robot manipulator. In order to enhance the control accuracy, a hybrid positional error compensation method based on Radial Basis Function Network (RBFN) and Light Gradient Boosting Decision Tree (LightGBM) is proposed for the rock drilling robot. Firstly, the kinematics model of the robotic manipulator is established by applying MDH. Then a parallel difference algorithm is designed to modify the kinematics parameters to compensate for the geometric error. Afterward, non-geometric errors are analyzed and compensated by applying RBFN and lightGBM including features and kinematics model. Finally, the experiments of the error compensation by combing combining the geometric and non-geometric errors verify the performance of the proposed method.

A finite difference method on irregular grids with local second order ghost point extension for solving Maxwell's equations around curved PEC objects

A new finite difference method on locally perturbed rectangular grids has been developed for solving electromagnetic waves around curved perfect electric conductors (PEC). This method incorporates the back and forth error compensation and correction method (BFECC) and level set method to achieve convenience and higher order of accuracy around complicated PEC boundaries. A PDE-based local second order ghost cell extension technique is developed based on the level set framework and then BFECC is applied to further improve the accuracy while increasing the CFL number. Numerical experiments are conducted to validate the properties of the method.

Influence of guide rail error on machining accuracy and compensation method

This paper introduces the guide rail error and analyses the influence of the guide rail error on the machine tool. Several common measuring and error compensation methods are introduced. To reduce the error of machine tool guide, researchers need to have a full understanding of it, and then take appropriate measures to reduce this error, so as to achieve the purpose of improving the machining accuracy. In this paper, through theoretical analysis, the variation trend of guide rail contour error is obtained, which is verified by laser interferometer, and the appropriate position is selected for error compensation. After the test verification, the test proves that the compensation method can effectively compensate the model rail error.

Nonlinear Error Compensation Method for 3D Sensing System Based on Grating Image Projection

Correcting the sensing error caused by the gamma nonlinear response of the three-dimensional (3D) sensing system (SS) is a key factor in improving the accuracy of sensing. To deal with the nonlinear error of the SS, we propose a sub-area Hilbert transform (SA-HT) method. First, we employ Hilbert transform (HT) on the grating image captured by the camera sensor. Then the coefficient of the nonlinear error model can be fitted in the reference area. Second, the phase disturbance (PD) area is detected. We calculate the phase maps in spatial domain and in HT domain. Then the PD area can be detected according to the absolute phase difference in the two domains. Finally, the Newton iteration method is adopted to obtain the truth-phase in the PD area. In addition, the phase values in spatial domain and in HT domain are averaged outside of the PD area. The results of experiments show that the proposed method can avoid the influence of non-smooth reflectively (NSR) when performing nonlinear error compensation on 3D sensing.

A positioning error compensation method for multiple degrees of freedom robot arm based on the measured and target position error

A novel positioning error compensation method (PECM) based on the measured and target position error for multiple degrees of freedom (DOF) robot arm control is proposed, which is used to improve positioning accuracy of multiple-DOF robot arm end-effector in accurate positioning applications such as in the medical and mechanical fields. Based on the idea of PID to increase adaptiveness and robustness of the method, a positioning compensation model between the measured and target position error tracked by an optical tracking system and compensated joint angle is derived with inverse kinematic model. Based on error analysis of the compensation model regarding geometry errors, the proportional joint angle compensated coefficient deduced from Jaccobian matrix of the error is proposed and identified with position error data. Calibration experiments for position conversion matrix and positioning accuracy verification experiments are conducted consisting of an optical tracking system and a robot arm. The results of positioning accuracy verification experiments show that the average resultant positioning error in three directions reduces from 1.89 mm (before compensation, model based on Denavit-Hartenberg (DH)), 0.39 mm (model based on modified Denavit-Hartenberg (MDH) with Levenberg-Marquardt (LM)) to 0.34 mm (decreasing 82%, 15%), which demonstrates the efficiency and robustness of the method.

High-resolution integral imaging display with precise light control unit and error compensation

3D resolution is an important display performance of integral imaging system. In this paper, an integral imaging system with improved resolution was proposed by using precise light control and error compensation. In the proposed system, a precise light control unit was used instead of the conventional diffused backlight unit, so as to reduce the voxel size. Additionally, an error compensation method was proposed to avoid the mismatch between the pitches of the lens array and the elemental image array, so as to eliminate the crosstalk of reconstructed 3D images. In the optical experiment, a prototype was developed using the proposed structure and error compensation method. It reconstructed vivid 3D images with higher resolution and less crosstalk compared to the conventional system.

A spatial grid point compensation method for a one-translational two-rotational power head

Positioning accuracy is an important index used to indicate the accuracy of the moving parts in a machine tool under the control of CNC system. In order to improve positioning accuracy, error compensation is needed. Existing error compensation methods include model compensation and non-model compensation. However, due to the simplification of the error mapping model, some error parameters cannot be mapped to the model, so only part of the error parameters can be modified, and the compensation result is not ideal. In the present work, based on the thinking method of finite element, a non-model compensation method is used to compensate for the geometric error of a one-translational two-rotational (1T2R) power head (which is independently developed by Tianjin University). First, the pose error prediction model will be established, and the error of any point in the workspace can be predicted. The input correction method is then proposed to compensate for the pose error. Finally, both the proposed error prediction model and error compensation method are verified by simulation and experiment, and the results show that the proposed method can reduce the error of this 1T2R power head.

Online Compensation of Phase Delay Error Based on P-F Characteristic for MEMS Vibratory Gyroscopes.

In this paper, an online compensation method of phase delay error based on a Phase-Frequency (P-F) characteristic has been proposed for MEMS Coriolis Vibratory Gyroscopes (CVGs). At first, the influences of phase delay were investigated in the drive and sense mode. The frequency response was acquired in the digital control system by collecting the demodulation value of drive displacement, which verified the existence and influence of the phase delay. In addition, based on the P-F characteristic, that is, when the phase shift of the nonresonant drive force through the resonator is almost 0° or 180°, the phase delay of the gyroscope is measured online by injecting a nonresonant reference signal into the drive-mode dynamics. After that, the phase delay is self-corrected by adjusting the demodulation phase angle without affecting the normal operation of the gyroscopes. The approach was validated with an MEMS dual-mass vibratory gyroscope under double-loop force-to-rebalance (in-phase FTR and quadrature FTR) closed-loop detection mode and implemented with FPGA. The measurement results showed that this scheme can detect and compensate phase delay to effectively eliminate the effect of the quadrature error. This technique reduces the zero rate output (ZRO) from −0.71°/s to −0.21°/s and bias stability (BS) from 23.30°/h to 4.49°/h, respectively. The temperature sensitivity of bias output from −20 °C to 40 °C has reached 0.003 °/s/°C.

LASSO based compensation method for geometric errors of large coordinate measuring machine

The quasi-rigid body model is the relationship model between the volume error and the geometric error of the CMM under the consideration of simple deformation. The quasi-rigid body model reflects the comprehensive influence of all geometric errors and ensures the calibration accuracy of geometric errors. However, the geometric error solution based on the quasi-rigid body model has the problem of multicollinearity. To solve this problem, in this study, the geometric errors of CMM are compensated using laser tracing multistation measurement technology and the LASSO (Least absolute shrinkage and selection operator, LASSO) algorithm. First, a laser tracing multi-station measurement model is established, and then the coordinates of the laser tracer station are obtained by solving the redundant equations provided by the laser tracer multi-station measurement system using the L-M (Levenberg Marquardt) algorithm. The global positioning system localization principle combined with the L-M algorithm is used to determine the actual position of the CMM measurement point. Then, the volume error is determined by calculating the difference between the actual position of the measurement point and the planned position. A mathematical model of the volumetric and geometric errors is obtained from the CMM quasi-rigid body model, and the LASSO algorithm is used to solve the model to obtain the 17 geometric errors of the CMM. Using the relationship between the volume error and the uniaxial geometric error, the 4 rotational errors are solved of εz (x), εx- (z), εv (z), εz (z). To verify the measurement accuracy of the compensated CMM, the compensation effect is verified by using the XL80 interferometer with the measuring block. The experimental results indicate that when error compensation is performed, the measurement accuracy of the CMM is improved by >50% compared to the initial state, and no mechanical processing is involved.

Error research of attitude measurements on low-cost UAV-borne missile

The framed gyroscope can significantly reduce the cost of missile. However, the gyroscope error problem restricts the acquisition probability and guidance precision of air-to-ground missile. A gyroscope error compensation method based on Taylor series formula is proposed in this paper. Gyro output error sources are analysed in detail, and the gyro output error model of unmanned aerial vehicle load space missile is established, and the mathematical relationship between missile attitude angle and the gyroscope output is deduced. Through the gyroscope on three-axis turntable hardware-in-the-loop simulation test, the correctness and effectiveness of the gyro error model established is verified. The test results show that the proposed error compensation method can control yaw attitude angle error and oblique attitude angle error of UAV-borne missile within 1° respectively in 20 s, and easy to project implementation.

Current Measurement Offset Error Compensation in Vector-Controlled SPMSM Drive Systems

Current measurement offset errors occur in current sensors and related circuits, because of various factors, such as thermal drift, aging, and nonlinearity. The current offset error results in undesired torque ripples, which deteriorate the speed and torque control performances of vector-controlled drive systems. This study proposes an online current measurement offset error compensator for vector-controlled surface permanent magnet synchronous motor (SPMSM) drive systems. The proposed compensator requires only phase current sensors and no additional hardware. This method is applicable for all systems using two and three phase current sensors. The current offset error is estimated using the motor parameters, stator current, and command voltage in the stationary reference frame. This scheme can continuously adjust the current offset during motor operation. In addition, this study analyzes the effect of parameter errors and confirms that the proposed method is robust to variations in the machine parameters. Simulation and experimental results are provided to verify the performance of the proposed current measurement offset error compensation method.

Review of Ultrasonic Ranging Methods and Their Current Challenges.

Ultrasonic ranging has been widely used in automobiles, unmanned aerial vehicles (UAVs), robots and other fields. With the appearance of micromachined ultrasonic transducers (MUTs), the application of ultrasonic ranging technology presents a more extensive trend. This review focuses on ultrasonic ranging technology and its development history and future trend. Going through the state-of-the-art ultrasonic ranging methods, this paper covers the principles of each method, the signal processing methodologies, the overall system performance as well as key ultrasonic transducer parameters. Moreover, the error sources and compensation methods of ultrasonic ranging systems are discussed. This review aims to give an overview of the ultrasonic ranging technology including its current development and challenges.

FEM simulation based adaptive sensors array error compensation method for impact monitoring on stiffened composite structures

To eliminate the sensor array based impact localization bias on stiffened composite structures, a finite element method (FEM) simulation based adaptive sensors array errors compensation method for impact monitoring is introduced. Firstly, detailed analysis and comparison discussion about Lamb wave propagation errors between the simple and stiffened plate are provided using FEM simulation, and the gain-phase errors obtained are structured as a array error matrix. Secondly, array error matrix is substituted into the steering vector of standard two-dimensional Multiple Signal Classification (2D-MUSIC) algorithm to compensate the stiffener effect. And then initial estimates of impact could be estimated by the compensated 2D-MUSIC algorithm. Finally substituting these initial estimates, the cost function is minimized by adaptive iterative to calculate the reasonable location of the impact source. The experiments on a carbon fiber composite stiffened plate demonstrate the validity and effectiveness of the proposed method.

A method to improve position accuracy for the dual-drive feed machines by state-dependent friction compensation

Due to high stiffness and quick response, dual-drive feed machines (DDFMs) are widely used in many precision CNC machines. The tracking errors of the two feed drives directly determine the machines’ accuracy. The performance of the position accuracy can be easily affected by the difference in the friction dynamic characteristics of the two axes. This paper proposes the state-dependent friction compensation (SFC) as an improved DDFMs error compensation method that can achieve better accuracy under unequal friction on the two feed drives. It is theoretically analyzed the influence of friction on the transmission stiffness of DDFMs. Moreover, the effects of time-varying factors (feed rates and mechanical structures) on the friction of dual axes are discussed. The innovation of the paper is that the SFC can adaptively take into account the influence of the variable dual-drive structure and feed rate on DDFMs’ position accuracy, and the compensation method combined with cross-coupled strategy is suitable for general dual-drive structure. Simulation and experiment results show that the proposed method can effectively improve the synchronization accuracy and tracking accuracy in a variety of feed operations (different feed rates, starting, and reversing).

A method for temperature error compensation in fiber-optic gyroscope based on machine learning

This work presents a machine-learning based method for temperature error compensation of fiber optic gyroscope (FOG). Alternative to existing methods for constructing samples by single data point, a novel method of constructing samples by sequence is proposed, which fully considers the hysteresis and delay of temperature error. Moreover, temperature experiments with three distinct temperature trends, i.e., heating, holding and cooling, are conducted. Following the construction of training and test sets, the relevant training and test processes are completed using SVR algorithm. According to the degree of approximation in predicted value relative to the real value and the degree of improvement in gyro stability, the effects of various sample construction methods on the corresponding error compensation are analyzed. Considering the root mean square error (RMSE), mean absolute value error (MAE) and improvement-factor of FOG zero-bias stability as measurement indicators, this work proposes to construct samples by sequence with temperature trend feature-extraction, which effectively improves the overall accuracy of gyroscope. Allan variance is also utilized to verify the effectiveness of our proposed method. Lastly, this study also provides a theoretical guidance and reference for temperature error compensation in other types of sensors.

A High-Precision Motion Errors Compensation Method Based on Sub-Image Reconstruction for HRWS SAR Imaging

High-resolution wide-swath (HRWS) synthetic aperture radar (SAR) plays an important role in remote sensing observation. However, the motion errors caused by the carrier platform’s instability severely degrade the performance of the HRWS SAR imaging. Conventional motion errors compensation methods have two drawbacks, i.e., (1) ignoring the spatial variation of the phase errors of pixels along the range direction of the scene, which leads to lower compensation accuracy, and (2) performing compensation after echo reconstruction, which fails to consider the difference in motion errors between channels, resulting in poor imaging performance in the azimuth direction. In this paper, to overcome these two drawbacks, a high-precision motion errors compensation method based on sub-image reconstruction (SI-MEC) for high-precision HRWS SAR imaging is proposed. The proposed method consists of three steps. Firstly, the motion errors of the platform are estimated by maximizing the intensity of strong points in multiple regions. Secondly, combined with the multichannel geometry, the equivalent phase centers (EPCs) used for sub-images imaging are corrected and the sub-images imaging is performed before reconstruction. Thirdly, the reconstruction is performed by using the sub-images. The proposed method has two advantages, i.e., (1) compensating for the spatially varying phase errors in the range direction, by correcting EPCs, to improve the imaging quality, and (2) compensating for the motion errors of each channel in sub-image imaging before reconstruction, to enhance the imaging quality in the azimuth direction. Moreover, the experimental results are provided to demonstrate that the proposed method outperforms PGA and BP-FMSA.

Research on geometric error modeling and compensation method of CNC precision cylindrical grinding machine based on differential motion theory and Jacobian matrix

Research on geometric error modeling and compensation method of CNC precision cylindrical grinding machine based on differential motion theory and Jacobian matrix

Analysis of fiber optic gyroscope dynamic error based on CEEMDAN

The fiber optic gyroscope (FOG) is an angular rate sensor based on Sagnac effect. It has been widely used in aviation, unmanned, robot, and other fields due to its benefits of all solid state, high precision, and low cost. However, the photoelectric devices inside the FOG will produce a non-negligible error in the dynamic environment, resulting in zero bias drift and increased noise. Currently, research on the dynamic error of FOG focuses primarily on linear vibration, assuming that no input angular rate exists at this moment. However, the dynamic errors caused by angular vibration are more complicated in the practical application environment. The output of FOG includes both effective angular information and dynamic error at this moment, which means that the dynamic error should be removed while the effective angular information must be retained. In this paper, we focus on the effect of angular vibration on FOG, and propose a dynamic error compensation method of FOG based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) that properly separates the effective signal and dynamic error. We also consider the amplitude frequency characteristics of FOG under dynamic conditions and utilize the FOG bandwidth test experiment to verify the effectiveness of our method. The experimental results show that the compensated signal can correctly calculate the bandwidth of FOG. It indicates that our method can effectively compensate the dynamic error in angular vibration environment while improving the performance of FOG in dynamic environment.

Effectiveness of the heartbeat interval error and compensation method on heart rate variability analysis.

The purpose of this study is to evaluate the effectiveness of heartbeat error and compensation methods on heart rate variability (HRV) with mobile and wearable sensor devices. The HRV analysis extracts multiple indices related to the heart and autonomic nervous system from beat‐to‐beat intervals. These HRV analysis indices are affected by the heartbeat interval mismatch, which is caused by sampling error from measurement hardware and inherent errors from the state of human body. Although the sampling rate reduction is a common method to reduce power consumption on wearable devices, it degrades the accuracy of the heartbeat interval. Furthermore, wearable devices often use photoplethysmography (PPG) instead of electrocardiogram (ECG) to measure heart rate. However, there are inherent errors between PPG and ECG, because the PPG is affected by blood pressure fluctuations, vascular stiffness, and body movements. This paper evaluates the impact of these errors on HRV analysis using dataset including both ECG and PPG from 28 subjects. The evaluation results showed that the error compensation method improved the accuracy of HRV analysis in time domain, frequency domain and non‐linear analysis. Furthermore, the error compensation by the algorithm was found to be effective for both PPG and ECG.