Calculation Of Angle Research Articles

Intelligent Tracking Technology of Light Source Based on Feedforward Inverse Compensation Control

In the construction of a photovoltaic power station, the effect of ray tracing directly affects the efficiency of power generation. In order to effectively control the tracking photovoltaic bracket and present the actual situation of the tracking bracket truly, intuitively and conveniently, a roamable photovoltaic tracking bracket control system is designed in this study. The system provides assistant decision-making for operators, and can remotely control the tracking support in real-time. It can also work independently according to the set parameters to realize the functions of the sun position calculation, tracking angle calculation, and tracking command output, and can communicate with the monitoring terminal. During the experimental test, the computer resource occupation is low, the operation is stable and reliable, and the monitoring terminal can run with a relatively smooth frame number. According to the system architecture mentioned in this paper, the verification platform is built, and the effectiveness of the photovoltaic tracking bracket control system is confirmed. The control system of the photovoltaic tracking bracket designed in this paper can effectively solve the problem of solar tracking accuracy of the photovoltaic power station, and play an important role in improving the power generation efficiency of the photovoltaic power station. At the same time, it can provide a reference for the same industry in light source tracking technology.

Neutrino Directionality According to Spatial Resolution of Liquid Scintillation Detector and Angle Calculation Method

Neutrino Directionality According to Spatial Resolution of Liquid Scintillation Detector and Angle Calculation Method

Research on the Springback Behavior of 316LN Stainless Steel in Micro-Scale Bending Processes

Hydrogen fuel cells have been used worldwide due to their high energy density and zero emissions. The metallic bipolar plate is the crucial component and has a significant effect on a cell’s efficiency. However, the springback behavior of the metallic bipolar plate will greatly influence its forming accuracy in the micro-scale sheet metal forming process. Therefore, accurate calculation of the springback angle of the micro-scale metallic bipolar plate is urgent but difficult given the state of existing elastoplastic theory. In this paper, a constitutive model that simultaneously considers grain size effect and strain gradient is proposed to analyze micro-scale bending behavior and calculate springback angles. The specialized micro-scale four-point bending tool was designed to better calculate the springback angle and simplify the calculation step. A pure micro-bending experiment on a 316LN stainless steel sheet with a thickness of 0.1 mm was conducted to verify the constitutive model’s accuracy.

Digitalization and Quantitative Flow Visualization of Surrounding Flow over a Specially-Shaped Column-Frame by Luminescent Mini-Tufts Method

The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, mean field mini-tufts calculation, inclination angle calculation, oscillation area calculation, etc. The model is subjected to a newly proposed digitalization method and realized by in-house code. The time mean angle’s changing mode, along the mini-tuft, are analyzed, which shows that the mini-tuft follows the inflow well. The transient oscillation of mini-tufts is observed as well, which shows that on the middle part of the irregularity cylinder, the flow oscillates more intensively.

관성센서 및 로드셀 인솔 결합형 보행측정 시스템 개발: 예비 연구

In this study, an insole-type ground reaction force (GRF) measurement system using a load cell was manufactured and configured as a system that can measure joint angle and GRF, when walking in conjunction with a commercialized inertial sensor. The data acquisition device was used to acquire synchronized data, between the inertial measurement unit (IMU) sensor and the load cell insole. A three-dimensional motion analysis system comprising six infrared cameras and two ground reaction forces, was used to check the accuracy of the gait measurement system, comprising an inertial sensor and a load cell insole. The motion and force data were acquired while performing five times six-meter walking test by five young adult male subjects (Age: 26.0±1.8, Height: 171.4±6.8 cm, Weight: 62.2±10.8 kg). It was measured and as a result of comparing the calculated sagittal joint angle with the vertical GRF, the sagittal lower extremity joint angle correlation coefficient (Pearson’s r) was 0.40 to 0.94, and the vertical GRF to be 0.98 to 0.99. It is necessary to upgrade the joint angle calculation algorithm through future research. Additionally, the possibility of clinical application for actual stroke patients will be reviewed.

Intra-subject stability of different expressions of spatial QRS-T angle and their relationship to heart rate.

Three-dimensional angle between the QRS complex and T wave vectors is a known powerful cardiovascular risk predictor. Nevertheless, several physiological properties of the angle are unknown or poorly understood. These include, among others, intra-subject profiles and stability of the angle relationship to heart rate, characteristics of angle/heart-rate hysteresis, and the changes of these characteristics with different modes of QRS-T angle calculation. These characteristics were investigated in long-term 12-lead Holter recordings of 523 healthy volunteers (259 females). Three different algorithmic methods for the angle computation were based on maximal vector magnitude of QRS and T wave loops, areas under the QRS complex and T wave curvatures in orthogonal leads, and weighted integration of all QRS and T wave vectors moving around the respective 3-dimensional loops. These methods were applied to orthogonal leads derived either by a uniform conversion matrix or by singular value decomposition (SVD) of the original 12-lead ECG, giving 6 possible ways of expressing the angle. Heart rate hysteresis was assessed using the exponential decay models. All these methods were used to measure the angle in 659,313 representative waveforms of individual 10-s ECG samples and in 7,350,733 individual beats contained in the same 10-s samples. With all measurement methods, the measured angles fitted second-degree polynomial regressions to the underlying heart rate. Independent of the measurement method, the angles were found significantly narrower in females (p < 0.00001) with the differences to males between 10o and 20o, suggesting that in future risk-assessment studies, different angle dichotomies are needed for both sexes. The integrative method combined with SVD leads showed the highest intra-subject reproducibility (p < 0.00001). No reproducible delay between heart rate changes and QRS-T angle changes was found. This was interpreted as a suggestion that the measurement of QRS-T angle might offer direct assessment of cardiac autonomic responsiveness at the ventricular level.

Numerical Computation-Based Position Estimation for QR Code Object Marker: Mathematical Model and Simulation

Providing position and orientation estimations from a two-dimensional (2D) image is challenging, as such images lack depth information between the target and the automation system. This paper proposes a numerical-based monocular positioning method to determine the position and orientation of a single quick response (QR) code object marker. The three-dimensional (3D) positional information can be extracted from the underdetermined system using the QR code’s four vertices as positioning points. This method uses the fundamental principles of the pinhole imaging theory and similar triangular rules to correspond the QR code’s corner points in a 3D environment to the 2D image. The numerical-based model developed with suitable guessing parameters and correct updating rules successfully determines the QR code marker’s position. At the same time, an inversed rotation matrix determines the QR code marker’s orientation. Then, the MATLAB platform simulates the proposed positioning model to identify the maximum rotation angles detectable at various locations using a single QR code image with the known QR code’s size and the camera’s focal length. The simulation results show that the proposed numerical model can measure the position and orientation of the tilted QR code marker within 30 iterations with great accuracy. Additionally, it can achieve no more than a two-degree angle calculation error and less than a five millimeter distance difference. Overall, more than 77.28% of the coordinate plane simulated shows a converged result. The simulation results are verified using the input value, and the method is also capable of experimental verification using a monocular camera system and QR code as the landmark.

A novel method to predict and prevent commutation failures in LCC-HVDC systems

Commutation failures are the main drawbacks of the line-commutated converter-based high-voltage direct-current transmission systems. In this paper, the influences of the fault occurring moment on the commutation process are investigated quantitatively to predict and prevent commutation failures effectively. Then, the critical fault voltage and extinction angle calculation methods are presented based on the voltage–time area theory. The concept of the commutation failure domain and the security domain is determined to estimate the probability of commutation failures. Furthermore, the direct current and RMS voltage calculation methods under asymmetrical faults are presented. Based on them, we eventually propose a novel commutation failure prediction and prevention strategy. Compared with conventional methods, the proposed strategy takes account of the probabilistic characteristic of commutation failures. Moreover, the direct current is predicted rather than real-time measured, and the RMS voltage under asymmetrical faults can be calculated instantaneously. Therefore, the proposed strategy can obtain a rapid response and a stronger commutation failure immunity. The accuracy of the method proposed in this paper is validated by EMT results with PSCAD/EMTDC and the experimental results with RTDS.

Artificial intelligence in orthopaedic and trauma surgery imaging

Artificial intelligence (AI) is playing an increasing role in radiological imaging in orthopaedics and trauma surgery. The algorithms available to date are predominantly used in the detection of (occult) fractures and in length and angle measurements in conventional X‑ray images. However, current AI solutions also enable the analysis and pattern recognition of CT datasets, e.g. in the detection of rib or vertebral body fractures. Aspecial application is EOS™ (ATEC Spine Group, Paris, France), which enables a3‑D simulation of the axial skeleton and semi-automatic length and angle calculations based on adigital 2‑D X‑ray image. In this paper, the current spectrum of AI applications for orthopaedics and trauma surgery is presented and discussed.

Experimental study of wetting effect of surfactant based on dynamic wetting process and impedance response of coal.

Surfactant can improve the wettability of water to coal, which is beneficial to reduce the production of coal dust in coal seam water injection. Through the measurement and calculation of contact angle and its decay rate, the wettability differences of SDS (C12H25OSO3Na), AES (C14H29O5NaS), OP-10 (C18H30O10), and JFC (RO(CH2CH2O)nH) to anthracite were compared. In addition, the wetting modification effect and infiltration rate of anthracite by water, AES, and OP-10 were studied by infrared spectroscopy and complex impedance monitoring of coal pillar immersion process. The results show that when the concentration of surfactant is 0.1%, the contact angle decay time of OP-10 is very short, and the contact angle decay rate is as high as 19°/s. The decay rate can more obviously reflect the wettability difference of surfactants. And the wetting modification effect of OP-10 on anthracite is stronger than that of AES, and the peaks of oxygen-containing functional groups such as carboxyl and hydroxyl groups are stronger. Furthermore, the capillary force between OP-10 and anthracite is much larger than that of water, which shows the characteristics of fast water absorption and wide distribution in the infiltration experiment of columnar coal. The results of complex impedance measurement indicate that the impedance decay rate of coal is well correlated with capillary rise factor FC, contact angle decay rate, and contact angle. It is hoped that the research results can provide help for coal seam water injection and dust prevention.

The calculation and research of spatial angle of double deflection inclined hole parts based on the CNC milling

In this paper, the projection method, the stereographic method and the spherical map method are used to calculate the spatial angle of the parts with the oblique hole in the numerical control machining center. At the same time, the calculation principle and method of the spatial double deflection angle hole system in the numerical control machining center are studied.The projection method is used to analyze the spatial angle relation of Φ10 holes in milling. V spherical method and H spherical method are used to calculate the positioning angle and the orientation angle. The spatial angle of a valve body part in milling Φ12 space inclined hole is calculated by using the stereographic method, and the positioning angle and the orientation angle are calculated by using the V spherical graph method and the H spherical graph method.The calculation results show that the spatial angles obtained by the above methods are the same, which verifies the correctness and the feasibility of the calculation method.

Anti-Sway Control on a Harbor Crane System Using a Command Smoothing Iterative Method

The requests for relatively large-sized mobile harbor cranes are increasing. Typically, harbor cranes are self-traveling but do not require any additional civil works to improve the bearing strength of foundation soil. This work describes a novel method able to reduce the sway of a suspended load during the slewing motion of a Harbor Crane. The proposed method is based on an iterative calculation of the sway angle, and the corresponding applied velocity profiles as input to the crane motors. The 'command smoothing' method is used to reduce the sway: additional damping is introduced into the system to control the sway. The multiple-input and multiple-output (MIMO) mechanical system is modeled by a set of non-linear differential equations in which the mathematical model is divided into two subsystems: the first for actuated outputs and the second for underactuated outputs. After defining the stability of the proposed solution and the kinematics of the hydraulic actuators on the boom, a detailed mathematical model is developed, taking into account the non-linear components of the forces, such as centrifugal and Coriolis forces, on the system. Simulation results show that the proposed anti-sway method can dampen the suspended load's oscillations during the harbor crane's slewing movement.

Automatic Extraction of Muscle Parameters with Attention UNet in Ultrasonography.

Automatically delineating the deep and superficial aponeurosis of the skeletal muscles from ultrasound images is important in many aspects of the clinical routine. In particular, finding muscle parameters, such as thickness, fascicle length or pennation angle, is a time-consuming clinical task requiring both human labour and specialised knowledge. In this study, a multi-step solution for automating these tasks is presented. A process to effortlessly extract the aponeurosis for automatically measuring the muscle thickness has been introduced as a first step. This process consists mainly of three parts. In the first part, the Attention UNet has been incorporated to automatically delineate the boundaries of the studied muscles. Afterwards, a specialised post-processing algorithm was utilised to improve (and correct) the segmentation results. Lastly, the calculation of the muscle thickness was performed. The proposed method has achieved similar to a human-level performance. In particular, the overall discrepancy between the automatic and the manual muscle thickness measurements was equal to 0.4 mm, a significant result that demonstrates the feasibility of automating this task. In the second step of the proposed methodology, the fascicle’s length and pennation angle are extracted through an unsupervised pipeline. Initially, filtering is applied to the ultrasound images to further distinguish the tissues from the other muscle structures. Later, the well-known K-Means algorithm is used to isolate them successfully. As the last step, the dominant angle of the segmented muscle tissues is reported and compared with manual measurements. The proposed pipeline is showing very promising results in the evaluated dataset. Specifically, in the calculation of the pennation angle, the overall discrepancy between the automatic and the manual measurements was less than 2.22° (degrees), once more comparable with the human-level performance. Finally, regarding the fascicle length measurements, the results were divided based on the muscle properties. In the muscles where a large portion (or all) of the fascicles are located between the upper and lower aponeuroses, the proposed pipeline exhibits superb performance; otherwise, overall accuracy deteriorates due to errors caused by the trigonometric approximations needed for the length calculation.

Measurements of roll, steering, and the far-field wake in track cycling

A series of measurements taken with two instrumented track bicycles in a velodrome are presented. The bicycle wheel speed, cadence, roll angle, steering angle, power, and airspeed are recorded. The experimentally-measured values are compared to existing theoretical models of roll and steering angles. The accuracy of the roll angle calculations is dependent on the fidelity of the modelled cyclist path and decreases for higher riding speeds. Experimental measurements of the steering angle show a reasonable agreement to theoretical calculations, albeit with reduced steering angles on the bends at higher speeds. There is also seen an increasing steering angle oscillation within each pedal cycle with increasing bicycle velocity which may influence a cyclist’s rolling resistance and the aerodynamic flow around the bicycle’s front end. Observations are made of changes in the flow field ahead of the bicycle due to the presence of other riders on the track, showing an effective tailwind of up to 0.7 m/s. The measured power shows a decrease at the bend entry due to the changing roll angle. Data presented in this paper provides new insights and can help to provide a validation of values used in existing track cycling analytic models.

Poster 173: Using Dynamic Digital Radiography to Measure Variation in Scapulohumeral Rhythm of Pathologic Shoulders

Objectives:Patients with various shoulder pathologies suffer from diminished range of motion and scapulohumeral rhythm (SHR), defined as the ratio of the respective contributions of glenohumeral and scapulothoracic motion to arm elevation. While previously challenging to measure SHR in a clinical setting, a novel technique known as Dynamic Digital Radiography (DDR) provides a safe and cost-effective method to directly evaluate aberrancies in motion. The purpose of this study was to measure the SHR of pathologic shoulders using Dynamic Digital Radiography (DDR).Methods:Shoulders were prospectively analyzed using DDR via obtaining a series of pulsed radiographs at up to 15 Hz of the joint in motion. Scapulothoracic motion and glenohumeral motion were quantified based on DDR images (figure 1). Measurements were taken in humeral abduction at 0-30°, 30-60°, 60-90°, and full abduction using the Grashey view. SHR at different points was calculated by dividing humeral arc of motion by scapular arc of motion in each of the aforementioned ranges. ANOVA testing was conducted to analyze differences among treatment groups and post-hoc Tukey testing was utilized to identify the specific groups between which differences occurred. Pairwise t-testing was performed to isolate differences between preop and postop radiographs. An alpha of 0.05 was set for determining significance for all outcome measures.Results:121 shoulders were analyzed, including 40 controls, 13 small rotator cuff tears (SRT), 29 massive rotator cuff tears (MRCT), 16 adhesive capsulitis, and 23 glenohumeral osteoarthritis (table 1). The final angle calculations are displayed in Table 2. SHR for full arc of abduction differed significantly in patients with massive rotator cuff tear (1.91 ± 0.51), adhesive capsulitis (1.55 ± 0.13), and glenohumeral osteoarthritis (2.31 ± 1.03) compared to controls (3.39 ± 0.62). No statistically significant difference was found in overall SHR between small rotator cuff tear (3.04 ± 1.62) and controls (3.39 ± 0.62). When analyzed across 30-degree intervals of humeral abduction, there was a statistically significant lower SHR found at 0-30°, 30-60° and 60-90° of humeral abduction in MRCT, adhesive capsulitis and glenohumeral osteoarthritis patients compared to controls. No significant difference was found in the SHR of patients with SRCT compared to controls across all 30-degree intervals of humeral abduction. SHR changes across these intervals of humeral abduction are plotted in figure 2. Control patients had average overall humeral abduction range of motion of 103.40 ± 31.97° which was significantly larger compared to all included shoulder pathologies (MRCT: 75.75 ± 22.61, SRCT: 80.93 ± 20.71, adhesive capsulitis: 64.49 ± 27.02, osteoarthritis: 71.05 ± 34.88). During humeral abduction, control patients had average overall scapular range of motion of 32.57 ± 13.60 which was significantly smaller compared patients with a MRCT (45.57 ± 10.41) and adhesive capsulitis (64.49 ± 27.02). No statistically significant difference was found when comparing scapular range of motion during humeral abduction in patients with small rotator cuff tears (29.71 ± 12.91) and glenohumeral osteoarthritis (34.77 ± 17.52) compared to normal controls.Conclusions:DDR is sensitive enough to detect a lower SHR in massive rotator cuff tears, adhesive capsulitis, and glenohumeral osteoarthritis compared to normal shoulders. While SHR varies throughout the arc of motion, it remained drastically different these 3 pathologies compared to controls. Moreover, when isolating for humeral and scapular motion on DDR, all 4 pathologic shoulder conditions had decreased humeral abduction compared to normal controls. Patients with adhesive capsulitis and massive rotator cuff tear also had an increased reliance on scapular contribution to overall humeral elevation. Ultimately, further study and validation of this dynamic assessment of SHR has the potential to augment the diagnostic algorithm for various shoulder pathologies.Figure 1.Reference lines used for calculation of the humeral and seapular abduction ares. Measurements were taken in reference to a vertical line. Calculations were made in the neutral position, at initiation of abduction, 30℃, 60℃, 90℃ and full abduction.Table 1.Patient DemographicsTable 2.Relative contributions by glenohumeral (GH) and scapulothoracie (ST) joint girdle motion in pathologic shoulder compared to normal control Figure 2.SHR was calculated for each patient at 0-30, 30-60, and 60-90 degrees and plotted

Poster 153: Dynamic Radiographic Evaluation of Scapulohumeral Rhythm in Patients with Massive vs Small Rotator Cuff Tears

Objectives:The management of rotator cuff tears varies based on patient age, function, tear size, and chronicity. Treatment of massive tears results in less favorable or predictable outcome, presenting a challenge in determining the optimal intervention. Classification of a tear as “massive” is often based on MRI and confirmed intraoperatively. However, the use of a functional measure of shoulder motion, such as the scapulohumeral rhythm (SHR), offers an alternate, clinically relevant method to help guide diagnosis and surgical management. Defined as the ratio of glenohumeral (GH) to scapulothoracic (ST) motion, SHR is known to be altered in patients with rotator cuff tears. While previously challenging to measure SHR in a clinical setting, a novel technique known as Dynamic Digital Radiography (DDR) provides a safe and cost-effective method to directly compare changes in motion between patients with rotator cuff tears and correlate these changes to tear severity. The purpose of this study was to evaluate patients with massive and small rotator cuff tears using DDR, assessing for differences in SHR and range of motion between the two groups.Methods:Shoulders were prospectively analyzed using DDR via obtaining a series of pulsed radiographs at up to 15 Hz of the joint in motion. Scapulothoracic motion and glenohumeral motion were quantified based on the DDR images (figure 1). Measurements were taken in humeral abduction at 0-30°, 30-60°, 60-90°, and full abduction using the Grashey view. SHR at different points was calculated by dividing the humeral arc of motion by the scapular arc of motion in each of those motion ranges. Pairwise t-tests were performed on the obtained data to compare differences between groups at an α level of 0.05.Results:42 patients with a primary diagnosis of rotator cuff tear matched for age and BMI were analyzed (table 1). Based on clinical presentation and MRI, 29 patients were classified as massive rotator cuff tear (MRCT) and 13 patients were classified as small rotator cuff tear (SRCT). The final angle calculations are displayed in table 2. SRCT patients had a significantly higher average overall SHR of 3.04 ± 1.16 compared to the MRCT SHR of 1.91 ± 0.51 (p=0.003). When analyzed across 30-degree intervals of humeral abduction, MRCT patients had a significantly lower SHR compared to SRCT patients at 30-60° (1.83 ± 0.97 vs 3.39 ± 1.62, p=0.005). MRCT also had a lower SHR between 0-30° (2.63 ± 2.08 vs 4.74 ± 3.83, p=0.08) and 60-90° (2.13± 0.80 vs 2.91 ± 1.41 , p=0.13) of humeral abduction compared to SRCT patients, but these differences were not statistically significant. SHR changes across these intervals of humeral abduction are plotted in figure 2. Scapular range of motion during humeral abduction was lower in SRCT compared to MRCT (29.71 ± 12.91 vs 41.57 ± 10.41, p=0.08). No statistically significant difference was found in humeral range of motion between MRCT (76.02 ± 22.66) and SRCT (80.93 ± 20.71).Conclusions:A dynamic measurement of motion demonstrates that scapulohumeral rhythm is significantly different between patients with small vs. massive rotator cuff tears. Based on DDR analysis, patients had a marked difference in the initiation of motion and through the first 60 degrees of humeral abduction, resulting in a nearly 2x lower SHR in MRCT compared to SRCT. Moreover, evaluation of glenohumeral and scapulothoracic motion during humeral abduction demonstrated that patients with larger tears had an increased reliance on scapular contributions to overall humeral elevation. Dynamic measurement of SHR represents a novel method for evaluating rotator cuff tears, with marked differences noted in the earlier phases of shoulder motion. Further study and validation of the dynamic assessment of SHR has the potential to augment the diagnostic algorithm for rotator cuff tears, and ultimately inform prognostic and functional expectations for both the patient and the physician.Table 1.Patient DemographicsTable 2.Relative contributions by glenohumeral (GH) and scapulotlioracic (ST) joint to shoulder girdle motionFigure 1.Reference lines used for calculation of the humeral and scapular abduction arcs. Measurements were taken in reference to a vertical line. Calculations were made in the neutral position, at initiation of abduction, 30°, 60°, 90° and full abduction.Figure 2.SHR measured at 30-degree intervals of humeral abduction. The * Indicates a statistically significant difference at α = 0.05 in SHR measured between massive rotator cuff tear and small rotator cuff tear patients. P-values from left to right are 0.08 (0-30 °), 0.005 (30-60 °), 0.13 (60-90 °), and 0.003 (total)

DESIGN AND CONTROL OF A MOBILE STEWARD PLATFORM WITH FOUR INDEPENDENT WHEELS

For today’s automated vehicles and robots’ technologies in driving dynamics, the elasticity in movements has a critical role. These movements can be simulated by using some platforms which are staying on balance. It is possible to perform a few linear and angular movements according to the platform model. The purpose of this study is to provide an independent drive and keep the carrier shaft on balance while the vehicle is on the move. The steering system on the vehicle has been specialized and a balancing platform on the vehicle has been achieved to keep the balance. The vehicle in this study has four wheels and they; all have been independently designed and controlled for the requested rotation. Ackermann Steering Geometry has been used for calculations of wheel angles. In this study, the Stewart platform which has a 3x3 connection model and parallel structure has been designed. It is possible to make different linear and angular moves with this model of the platform. The steering system and platform designs have been mounted as one unit of the structure by assembling. The system can be operated manually and automatically. A mobile application has been also developed to monitor the status of the system. After all, using MATLAB simulation, its made phase space limit control of the orientations of the platform's center point relative to the x, y, and z axes has been studied.

Real-time measurement of dynamic micro-displacement and direction using light's orbital angular momentum

In this Letter, we propose an orbital angular momentum (OAM) sensor to simultaneously measure the dynamic micro-displacement and the direction of a moving object in real time. The micro-displacement of the moving object can be detected by the calculation of the petals' rotation angle caused by the coaxial interference between the measured OAM beam and its reference OAM beam, and the direction (forward or backward) of the moving object can be achieved by the clockwise or anticlockwise of the petals' rotation. We also develop an algorithm to monitor the petals' rotation angle and the rotation direction. The experimental results demonstrate that the proposed sensor can achieve high precision (±16.5995 nm) and a longer measuring range (0–1100 cm). Additionally, the OAM sensor is sensitive to the topological charge in the OAM mode, the initial distance, and the velocity of the moving object. The sensor can perform the non-contact measurement, so it will be a promising method in micro-vibration sensing, surface unevenness sensing, and microbial movement sensing.

Identification of Euler angles of permanent magnet spherical motor rotor based on Hall sensors array

Rotor position detection is an indispensable link in the closed-loop control system of permanent magnet spherical motors. This paper proposes a method to determine the position of the rotor by calculating the Euler angles using the Hall sensors array. The accuracy of Euler angle calculation is related to the installation position and quantity of the sensors. This article uses a spherical quadrilateral triangle model to determine the location of the Hall sensors. According to the different rotation axis around which the rotor rotates, the projection planes are calculated respectively. The output result of the Hall sensor array is converted into an encoded signal. The rotor magnetic pole coordinates are calculated according to the encoded signal. The coordinates are projected onto the corresponding projection plane, and the angle of rotation of the rotor is calculated. When the angles obtained at multiple consecutive sampling moments are the same, the angle corresponding to the intermediate moment is used as a sign quantity, and the angle corresponding to each sampling time is calculated according to the sign quantity. Finally, in order to verify the correctness of the method proposed in this paper, the experiments are carried out to verify the different motion postures of the spherical motor, and the experimental results verify the feasibility of the proposed method for calculating Euler angles of the permanent magnet spherical motor.

Spatial Grid-Based Position Calculation Method for Satellite-Ground Communication Links

With the rapid development of global satellite constellation clusters and the popularity of ground-based intelligent terminals, the interconnection between large-scale low Earth orbit satellites and ground base stations has become more frequent. The calculation of satellite position requires a large number of floating point square calculations and coordinate system conversions, with high computational complexity and long computation time. Based on the grid encoding method of GeoSOT, we propose a GeoSOT-based grid calculation for a satellite-ground position (GCSGP) model. We use binary bit operations instead of complex topological operations and floating point calculations, and use grid distance calculations instead of existing angle calculations. Thus, the relative positions of satellites to the ground can be quickly calculated and thus connected to more suitable satellites quickly. The results of the grid calculation were verified by simulation experiments. The calculation speed was improved by about 82% compared with the traditional method. The test accuracy error of the 10-level grid at a terminal 45° inclination was less than 1% at all heights, and the maximum error of the 10-level grid within a 10–45° inclination was 7.2% at 10,000 km altitude, which provides theoretical support for the subsequent grid space calculation.