External Error Research Articles

Robust Attitude Estimation Using Magnetic and Inertial Sensors

Lightweight and low-cost magnetic and inertial sensors are commonly used for attitude estimation in a wide range of applications, from motion tracking to autonomous navigation. However, the inherent and external sensor errors and the accelerations due to the actual motion of the platform highly affect the estimation accuracy. This study proposes a robust attitude estimation algorithm that compensates the sensor errors and the external accelerations at the algorithm level. The attitude estimation filter, which is structured as a Multiplicative Extended Kalman Filter (MEKF), is modified to compensate for both the long-term and short-term measurement uncertainties. Modification is applied mainly by estimating and compensating the bias and external accelerations for long-term uncertainties and tuning the measurement noise covariance matrix for short-term uncertainties. Simulations test the proposed algorithm, and the results are compared with benchmark algorithms.

Another 6 years of radiocarbon secondary-standard AMS with two spectrometers

The Scottish Universities Environmental Research Centre (SUERC) has analysed >100,000 individual graphite preparations with two accelerator mass spectrometers. Analysis quality is maintained by a programme of secondary-standards measurement, and annual assessment of the resulting large dataset can provide insight into subtle effects. The same analyses that are used to derive external errors within individual batches of samples, or to monitor inter-batch variance, are also employed in aggregate to determine overall instrument and process performance. The recent 2021 findings are consistent with prior years’, including the apparent contradiction that secondary standard analysis can be both consistent and slightly discordant between the two instruments. However, individual sample radiocarbon measurement on both machines remains accurate and typically 3 ‰ precise.

Variable admittance time-delay control of an upper limb rehabilitation robot based on human stiffness estimation

This paper proposes a new variable admittance time-delay control strategy based on human stiffness estimation for improving the effectiveness of robot-assisted cooperative rehabilitation training. This control strategy is developed and implemented on a planar upper limb rehabilitation robot. Given the minimum-jerk-based desired trajectories of human hand position, in the developed control strategy, a time-delay approximator is utilized to estimate the external disturbances and modeling errors without exact knowledge of dynamics parameters, a sliding mode admittance controller is applied to obtained objective admittance characteristics, and an iterative optimization algorithm is used to estimate human arm stiffness and adjust human-robot interaction compliance. The closed-loop stability of the proposed control method is demonstrated via Lyapunov function theory. Experimental investigations involving ten subjects are conducted to validate the feasibility of the proposed control scheme. The experimental results show that the interaction compliance during cooperative rehabilitation training can be accurately adjusted based on selected admittance parameters and human arm stiffness, and it contributes to satisfying the specific training requirements of patients with different weakness levels and promoting the effectiveness of the robot-assisted training.

The effects of visual cues in an immersive virtual reality environment on adaptation to internal and external errors

The effects of visual cues in an immersive virtual reality environment on adaptation to internal and external errors

Adaptive Dynamic Surface Control of Strict-Feedback Fractional-Order Nonlinear Systems with Input Quantization and External Disturbances

In this work, an adaptive dynamic surface control law for a type of strict-feedback fractional-order nonlinear system is proposed. The considered system contained input quantization and unknown external disturbances. The virtual control law is presented by utilizing a dynamic surface control approach at each step, where the nonlinear compensating term with the estimation of unknown bounded parameters is introduced to overcome the influence of unknown external disturbances and surface errors. Meanwhile, the adaptive laws of relevant parameters are also designed. In addition, an improved fractional-order nonlinear filter is developed to deal with the explosion of complexity raised by the recursive process. In the last step, an adaptive dynamic surface control law is proposed to ensure the convergence of tracking error, in which the Nussbaum gain function is applied to solve the problem of the unknown control gain generated by input quantization. Then, the fractional Lyapunov stability theory is applied to verify the stability of the proposed control law. Finally, simulation examples are given to illustrate the effectiveness of the proposed control law.

A spatiotemporal registration method between roadside lidar and camera

With the rapid development of intelligent transportation, it is of great significance to improve road traffic safety and traffic efficiency by tracking road users in real time. In this paper, a roadside multi-source data acquisition platform is designed based on two main sensors, lidar and camera, to perform time synchronization between lidar data and camera data. The point cloud data and image data of the same frame are the research objects. Based on Zhang Zhengyou’s calibration method and the plane target model theory, the camera internal parameters and the joint external parameters of the lidar and camera are respectively calibrated to obtain the internal and external parameter matrix. The error is 0.09 pixels, and the external parameter calibration error is 0.22 pixels. The registration test of lidar and camera under different roadside layout conditions is designed to verify the adaptability of the registration method. When the camera is arranged and installed, the distance between the horizontal and vertical directions should not exceed 90 cm.

Integration of ground-based and space-borne radar observations for three-dimensional deformations reconstruction: application to Luanchuan mining area, China

Luanchuan mining area, which is located in Henan Province, China and characterized by undulating topography and large precipitation, is vulnerable to the landslide disasters. The observations from the space-borne radar (ascending and descending TerraSAR-X) images and the ground-based radar (GPRI-II) images are integrated to monitor the surface deformations in Luanchuan mining area. Before the integration of the observations from multi-source SAR images, the coordinate systems of multi-source images are required to be unified by geographical projection. However, the accuracy of the commonly used geographical coding will be degraded by external DEM errors and inaccurate satellite orbit, which makes it difficult to achieve the high-precision registration of space-borne and ground-based radar scenes. Therefore, in this paper the iterative closest point (ICP) method is introduced to register the space-borne and ground-based images, yielding sub-pixel registration accuracy. Reasonable weights are then assigned to multi-source observations through Strain Model and Variance Component Estimation (SM-VCE) method, from which the high-precision three-dimensional deformations can be reconstructed. The results show that the maximum deformation rates in the east-west, north-south and vertical directions of Luanchuan mining area from July 20, 2019, to August 1, 2019, are about 0.2, 0.4 and 0.7 mm/day, respectively. The deformations are mainly on the loose slags in the Luanchuan pit rather than the bedrock, as a result of the accumulation of waste slags. Some suggestions on the installation location of ground-based radar are also provided to better combine the space-borne and ground-based observations.

Clutch Mechanical Leg Neural Network Adaptive Robust Control of Shift Process for Driving Robot With Clutch Transmission Torque Compensation

In order to improve the motion accuracy and robustness of the clutch mechanical leg for driving robot (CMLDR), and to improve the shift performance of the driving robot vehicle (DRV) for the engagement operation of CMLDR, a neural network adaptive robust control method of shift process for CMLDR with clutch transmission torque compensation is proposed. First, the dynamics model of the driving robot is established considering an external interference force and dynamic modeling error of the mechanical leg. Second, the upper clutch controller including a two-parameter shift module, a switch controller, and a finite-time linear quadratic regulator of the clutch transmission torque is designed. Third, the estimator of clutch engagement torque through a Kalman filter in the process of shift is constructed. Then, the neural network adaptive robust (NNAR) controller of the mechanical leg is designed. Finally, the proof of stability analysis for NNAR controller is conducted. Experiment and simulation results show that the designed controller of the mechanical leg has a strong antiinterference ability. And the DRV accurately tracks the target speed after compensating for the transmission torque.

Disturbance observer-based prescribed performance super-twisting sliding mode control for autonomous surface vessels

This paper proposes a disturbance observer-based prescribed performance super-twisting sliding mode control (DOB PPSTSMC) for trajectory tracking of the autonomous surface vessels (ASVs) subject to unknown external disturbances and modeling errors. Both unknown external disturbances and system modeling errors are approximated by the disturbance observer, thus eliminating most of the effect caused by lumped disturbances in the control performance. Based on this, a prescribed performance super-twisting sliding mode controller is explored to further suppress the residual error of disturbance compensation. Prescribed performance constraints are considered in the coming up with the super-twisting sliding mode controller, so that ASVs not only achieve effective tracking of time-varying desired trajectories, but also improve the transient performance of the control system. In addition, the controller is continuous and chatter-free, which has greater practical value. The excellence of the control project design is highlighted through the simulation and comparison results.

THE MEMS-BASED BAROMETRIC ALTIMETER INACCURACY AND DRIFT PHENOMENON

MEMS technology has made sensors for measuring barometric pressure and altitude above sea level very cheap and widely used in many consumer electronic devices. This paper presents a theoretical analysis of the sources and types of errors in the barometric altimeter using the standard atmosphere model (ISA). Methods for correcting principal errors caused by non-standard sea level conditions are described and compared. A method of correcting errors in the case of altimeter horizontal movement to the air column and total pressure measurement was proposed. It was compared with another method known from the literature. In the numerical experiment, data recorded by a bicycle computer equipped with a MEMS-based barometric altimeter was analyzed. As the GPS data of the route covered was also known, it was possible to compare the recorded altimeter data with the heights determined from the digital terrain model (DTM), which in this case were considered accurate. The error of the measured altitude calculated in this way was tried to be divided into the principal error, the external error caused by the sensor movement, and the barometer drift. Hence, a numerical experiment was carried out in which, based on the recorded data, an attempt was made to reconstruct non-standard sea level conditions and the impact of speed on the sensor measurements. Furthermore, a method of solving such a reverse problem was proposed. The results of the presented studies can be used in the design of systems correcting the indications of barometric altimeters. The accuracy of the altitude measurement is especially important for small controlled flying objects (UAH) and when recording the route of vehicles moving on the ground.

Evaluation of the Development Efficiency of China's Regional Low-Carbon Economy Based on Three-Stage DEA Model

With the goal of achieving carbon peak by 2030, it is necessary to objectively and correctly evaluate the development efficiency of low-carbon economy in China's provinces and municipalities. Starting from a review of the existing relevant literature, this paper uses a three-stage DEA Model, incorporating elements of the degree of low-carbon human development into external environmental variables, to conduct an empirical study of the development efficiency of low-carbon economy in 30 provinces and municipalities in China from 2017 to 2019. It is found that environmental factors such as the ratio of tertiary industry to secondary industry output, the intensity of R&D investment, and per capita disposable income had an impact on the evaluation results. After excluding external environmental factors and random errors, the overall low-carbon economic development level has improved, but there is still room for improvement of 29%. In particular, pure technical efficiency is underestimated, while scale efficiency is overestimated. In addition, regional differences are evident, with a pattern of "East China > Central China > Southwest China > North China = South China > Northeast China > Northwest China", which is basically consistent with the three-year average GDP ranking of each region.

The Implementation of the Black Box Method for Testing Smart Hajj Application Ministry of Religion

This research was conducted to assist the Ministry of Religious Affairs in testing the quality and accuracy of the Haji Pintar application. The main purpose of testing is to design tests that systematically uncover types of errors that have not been detected before. The Haji Pintar application will be tested using the Black Box method thoroughly with respect to application functionality, interfaces , data structures or external database access, performance, initiation and termination errors, usage, benefits, and results obtained from the use of the application. In testing the Haji Smart application, there are 5 types of testing from the Black Box method. The value of the overall effectiveness of the Haji Pintar application is 83.75%. With this value, the Haji Pintar application has been running according to the expected functionality but there are still errors in the application that must be updated immediately regarding the cancellation information menu and the payment information menu, which experienced problems when checking the status of the cancellation process that the congregation submitted and checking the congregation portion. Hajj includes the right to pay off or not.

열변형을 고려한 함정 통합마스트 탑재 센서 성능 보정 방안에 관한 연구

In general, conformal type sensor’s alignment error is measured before and after mounting on the integrated mast and used for sensor’s performance compensation. However, in case of integrated mast made of metal, there is a possibility that additional deformation may occur due to external temperature and solar heat, and it could affect detection performance of conformal type radar even a slight deformation. In this paper, the thermal deformation level of the integrated mast considering external environment and detection performance error level of mounted sensor are described. Finally, a performance compensation method of the integrated mast mounted sensor is proposed. The thermal deformation level of the integrated mast is not dramatic considering its size, and detection performance error is calculated under 1%. However, those error should be compensated considering sensor’s detection range. Accordingly, performance compensation methods applicable to the integrated mast mounted sensor were proposed.

High-precision Sr and Nd isotope measurements using a dynamic zoom lens-equipped thermal ionisation mass spectrometer

Techniques for the determination of radiogenic strontium (87Sr/86Sr) and neodymium (143Nd/144Nd) isotope ratios by Thermal Ionisation Mass Spectrometry (TIMS) are presented in this study. We have developed a 5 lines acquisition routine for both elements, taking advantage of the 16 Faraday cups available on the Nu Instruments TIMS in conjunction with an efficient zoom lens system. This allows increased flexibility regarding the number of lines in a multidynamic acquisition routine whilst maintaining optimal peak alignment and peak shape for every measurement line despite the fact that the detectors are not movable. The long-term reproducibility obtained for our Sr (NBS 987) and Nd (Rennes-Ames) standard solutions gives a (87Sr/86Sr)multidyn of 0.7102467 ± 0.0000043 (6.0 ppm, 2 s.d., n = 38) and a (143Nd/144Nd)multidyn of 0.5119537 ± 0.0000022 (4.2 ppm, 2 s.d., n = 31), respectively. We also report (87Sr/86Sr)multidyn and (143Nd/144Nd)multidyn for a set of terrestrial rock standards (including 5 basalts (BCR-2, BHVO-2, BIR-1, Be-N and BR-24), one rhyolite (RGM-1) and one andesite (AGV-2)) with the same, or greater, level of precision as for the pure standards solutions. This level of precision is 2 to 3 times better than the literature data for Sr isotope ratios, and comparable to the latest high precision data reported for Nd isotope ratios. This is the first paper reporting such high precisions for radiogenic Sr and Nd data generated using a TIMS from Nu Instruments. Significant statementHigh precision Sr and Nd isotopic measurements are of key importance in the field of Earth Sciences because they are powerful tools to trace sources of materials and to date them. Here, we report the first high-precision data for 87Sr/86Sr and 143Nd/144Nd (external error of 5–6 ppm for Sr and 4–5 ppm for Nd) measured using a Nu Instruments TIMS. Such precisions will open new opportunities in fields such as geochemistry, geochronology, cosmochemistry, archaeology or forensics.

Forming Quality Research on the Variable-Diameter Section of the Hollow Axle in Three-Roll Skew Rolling.

The hollow axle is the key component of the high-speed train, and the realization of high-quality forming is the key to ensure the safety of train operation. In this paper, the specimen of the variable-diameter section of the hollow axle is taken as the research object, and the generation mechanism of surface spiral mark defects and the formula of spiral mark depth of variable-diameter section in the TRSR (three-roll skew rolling) process with variable roll spacing are explored. The external roundness error and the function C to measure the wall thickness uniformity of the cross-section were taken as the evaluation indexes and the single-factor simulation experiment was established and simulated in the software Simufact.forming16.0 to obtain the influence law of each process parameter on the external roundness error and wall thickness uniformity of the rolled piece. Orthogonal tests were designed and the order and optimal combination of process parameters on the forming quality were obtained by range analysis and ANOVA analysis. The research results provide theoretical guidance for improving the forming quality of the variable-diameter section of the hollow axle in three-roll skew rolling, and promote the transformation of the TRSR process to high performance and accurate forming.

In Situ Calibration of Six-Axis Force–Torque Sensors for Industrial Robots With Tilting Base

The accuracy of the force–torque sensors generally decreases with time under standard operating conditions. Therefore, periodic calibration for force–torque sensors is necessary. Specialized devices or subsidiary sensors are required during the traditional calibration process which bring in external measurement errors. In this article, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> calibration method is proposed to calibrate the force–torque sensor with a single standard mass to generate expected wrenches of the sensor during some arbitrary robot poses. Since the tilt of the mounting base of the robot can affect the direction of the gravity expressed with respect to the sensor frame, we first derive a model to express the relationship between the raw measurements and the expected wrenches under the influence of the tilted base, and then introduce subspaces and take advantage of projection and Rayleigh quotient to obtain the calibration matrix and angles of tilting simultaneously. The proposed algorithm is validated on simulation and the industrial automation (ATI) force–torque sensor. The results show that the proposed method is more cost-effective and reliable than existing technologies.

Hybrid Position Estimation Strategy With a Smooth Transition for IPMSM Sensorless Drives in the Wide Speed Range

In this article, an innovative hybrid position estimation strategy along with the minimum voltage vector injection (MVVI) method and the back electromotive force (back EMF) based method is proposed for interior permanent magnet synchronous motors (IPMSMs) in full-speed regions. At zero- and low-speed, the MVVI method based on rotor saliency is used for position estimation; the inverter voltage error is counteracted in estimating the rotor position, minimizing the inverter nonlinearity effect without introducing external errors. For IPMSMs at the initial state, this article proposes to utilize the high frequency <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current excited by injection voltage itself directly for the polarity detection. The position estimation at low-speed based on the MVVI method has such advantages as no requirement for filters, fast convergence, and reliability of magnetic polarity detection. In addition, a smooth transition blends the MVVI method and the back EMF based method is proposed, and a compensation term based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis feedback current is added on the error of both the reference and feedback speed to reject the load-disturbance within the low speed and transition region. Experimental results show that the proposed hybrid sensorless control strategy exhibits excellent performance in the full speed range for both steady-state and dynamic operations.

명리학의 학문적 정체성 확립에 관한 연구

The Saju Myeongli get more popular in modern times as its culture still gets active. Accordingly, it is important to check out the Classification of Academic Research Fields set by National Research Foundation of Korea as the requirements for establishing the academic identity of Myeongli Science. The Saju Myeongli shall be the process in which the possibility contained in one Saju shall be analyzed to expand that person’s potential in a more positive way instead of the necessity and determinancy. It means that the Saju Myeongli shall play a role of consultant for people by communicating with that person based on the logical and systematic inference. The reason why Myeongli Science has been considered as fake science up to now is more attributable to the field of Myeongli Science not preparing the academic requirements rather than the external error or prejudice. Therefore, though it is late, it is absolutely necessary for the in-depth academic review and criticism for the Myeongli Science itself. Even though, in early 2000s, there were almost no academic and systematic researches on the Myeongli Science itself, the academic papers on Myeongli Science started to be posted on the registered (candidate) academic journals in 2006. The number of academic papers started to rise from 2011 and made the continuous increase from 2016. For the continuous publications of in-depth academic papers and the systematic researches on Saju Myeongli, there need the granting of proper classification code and classification name to the Myeongli Science at the Classification of Academic Research Fields. Considering all kinds of requirements, it is most appropriate for Myeongli Science to be large classified as an ‘interdisciplinary science’ and then is assigned to ‘interdisciplinarity’ rather than oriental philosophy in humanities or consulting psychology in sociology. So, the classification of ‘interdisciplinary science (large classification) - interdisciplinarity (middle classification) - Myeongli Science (small classification)“ is suggested. For the total access to Saju Myeongli, the interdiciplinarit of folk study, religion, psychology, philosophy, astronomy, sociology and history are very important in terms of consilience with related studies.

Simultaneous Calibration Method for Doppler Velocity Log Errors Based on a Genetic Algorithm

Doppler velocity log (DVL) errors affect the accuracy of strapdown inertial-navigation system (SINS)/DVL integrated navigation. Most existing calibration methods do not consider the problem of DVL sampling frequencies that are not fixed, and they cannot cope with large misalignment angles. This study proposes a method to calibrate internal and external DVL errors simultaneously, based on a genetic algorithm. To solve the problem of asynchronous SINS and DVL sampling, a method for unifying the time reference using cubic-spline interpolation is proposed. An error model for the DVL is established; the scale factor and misalignment angles are used as optimization genes for a genetic algorithm. The method can achieve high accuracy without requiring the misalignment angles to be small, significantly reducing the practical difficulty of installation. The results of simulation and shipboard experiments indicate that the calibration accuracy of the proposed algorithm is significantly better than that of the traditional method. For example, when the misalignment angle reaches 15°, the proposed algorithm has only a small error. If the carrier pitch angle changes to 5°, the root-mean-square error is reduced by 31.15% in the x-direction and 69.15% in the z-direction under highly dynamic conditions. The method thus seems likely to be useful in real-world engineering settings.

Research on Multicamera Photography Image Art in BERT Motion Based on Deep Learning Mode.

In order to improve the artistic expression effect of photographic images, this article combines the deep learning model to conduct multicamera photographic image art research in BERT motion. Moreover, this article analyzes the external parameter errors caused in the calibration process and uses the checkerboard in the common field of view to calibrate the spatial coordinates of the corners of the board in multiple camera coordinate systems. In addition, this article aims to match the spatial coordinates of the corresponding points to each other and solve the rotation and translation matrix in the transformation process. Finally, this article uses the LM algorithm to optimize the calibration parameters of the camera and combines the deep learning algorithm to perform image processing. The experimental research results show that the research method of multicamera photography image art in BERT motion based on the deep learning mode proposed in this article can effectively improve the expression effect of image art.