Axial Motion Research Articles

Improved Spatiotemporal Resolution in Echocardiography Using Mixed Geometry Imaging Sequences.

Cardiac ultrasound seeks to image the most dynamic environment in the body-the moving heart. Many modern ultrasound imaging techniques address the tradeoff between spatial and temporal resolution using either narrow focused beams or with broad beam, synthetic aperture (SA) sequences that have been shown to suffer from motion artifacts. Retrospective encoding for conventional ultrasound sequences (REFoCUS) unifies the processing of these various geometric sequences, but the motion sensitivity of this approach has yet to be investigated. We hypothesize that a "mixed sequence" enabled by the REFoCUS method incorporating several beam geometries may better resolve cardiac motion over a wide field of view (FOV) and at a high frame rate. First, the motion sensitivity of REFoCUS was evaluated in simulation for several focused and broad transmit profiles. Focused transmissions resolve both lateral and axial motion much more effectively than broad transmissions, with performance similar to conventional beamforming techniques. Second, a mixed sequence was designed that insonifies the full field-of-view with plane wave (PW) transmissions and key moving targets with focused transmissions. This mixed sequence was tested in simulation and in vivo and was used to image the heart as well as the liver, a low-motion control. By combining a sparse PW sequence ( n=60 ) with a small group of targeted focused transmissions ( n = 10), the anterior mitral valve leaflet (AML) at its peak observed velocity was better resolved. We believe that mixed sequences have strong potential to resolve cardiac motion at clinically relevant frame rates.

Structural Design and Dynamic Characteristic Analysis of Short-column Micro Piezoelectric Power Actuator

Background:: With the rapid development of science and technology, industrial products continue to develop towards the direction of lightweight and miniaturization, and the demand for power sources to drive micromachinery is increasing, so the patents related to microactuators are also increasingly valued. The microactuator based on a piezoelectric drive converts the deformation energy of the piezoelectric body into the kinetic energy of the transmission mechanism to drive the output shaft rotation. The stator and the rotor of the existing actuator are the surface contact with a certain preload force. After working for a long time, the contact surface will be lost due to friction, which will reduce the response speed and rotation accuracy and even cause the rotor to slip, affecting the actuator operating life. Objective:: In order to solve the above technical problems, the author innovates the driving mode between stator and rotor and proposes a novel short-column micro piezoelectric actuator based on multi-tooth alternating meshing transmission. Methods:: Firstly, the structure and operating principle of short-column micro piezoelectric power actuator, which can realize linear motion into rotary motion, and has three main advantages: compactness in size, multi-tooth meshing drive and large driving torque, are proposed and elucidated. Secondly, the structure size of each component of the actuator is determined to complete the 3D structure design. Thirdly, the modal analysis and the harmonic response analysis of the actuator are studied. The frequency range of the sawtooth wave voltage excitation signal applied to the actuator is determined. Finally, the prototype is made, and the performance test is carried out. Results:: In this paper, a micro piezoelectric power actuator different from the existing patent is proposed, which is assembled by a drive module, a transmission module, an elastic element, an output shaft, a base module and a shell. The results show that when the excitation frequency applied by the actuator is 157Hz, the amplitude of the tooth column along the axis of the actuator is 3.071mm, the axial amplitude of the output shaft is zero, and there is no axial motion. At this time, the displacement of the tooth column is the largest, and the driving performance is the best. From the experimental results, it can be seen that the prototype appears to have intermittent rotation under this frequency excitation. Conclusion:: The proposed micro piezoelectric power actuator adopts multi-tooth alternating meshing between the stator and the rotor to transfer power, which changes the transmission mode relying on friction in the existing technology, reduces the friction loss, avoids rotor slip, and improves the response speed, rotation accuracy and operating life of the actuator. The research work in this paper provides a new idea and a new method for the research and design of micromechanical power sources.

Effect of Distal Tibiofibular Destabilization and Syndesmosis Compression on the Flexibility Kinematics of the Ankle Bones: An In Vitro Human Cadaveric Model.

Overcompression of the distal tibiofibular syndesmosis during open reduction and internal fixation of ankle fracture may affect multidirectional flexibility of the ankle bones. Ten cadaveric lower limbs (78.3±13.0 years, 4 female, 6 male) underwent biomechanical testing in sagittal, coronal, and axial rotation with degrees of motion quantified. The intact force (100%) was the force needed to compress the syndesmosis just beyond the intact position, and overcompression was defined as 150% of the intact force. After intact testing, the anterior inferior tibiofibular ligament (AITFL), interosseus membrane (IOM), and posterior inferior tibiofibular ligament (PITFL) were sectioned and testing was repeated. The IOM and AITFL were reconstructed in sequence and tested at 100% and 150% compression. Overcompression of the syndesmosis did not significantly reduce ROM of the ankle bones for any loading modality (P > .05). IOM+AITFL reconstruction restored distal tibiofibular axial rotation to the intact condition. Axial rotation motion was significantly lower with AITFL fixation compared with IOM fixation alone (P < .05). The proximal tibiofibular syndesmosis demonstrated significantly higher motion in axial rotation with all distal reconstruction conditions. As assessed by direct visualization, overcompression of the distal tibiofibular syndesmosis did not reduce ROM of the ankle bones. Distal tibiofibular axial rotation was significantly lower with IOM+AITFL fixation compared with IOM augmentation alone. Distal tibiofibular axial rotation did not differ significantly from the intact condition after combined IOM+AITFL fixation. Dynamic fixation of the distal tibiofibular syndesmosis resulted in increased axial rotation at the proximal tibiofibular syndesmosis. These biomechanical data suggest that inadvertent overcompression of the distal tibiofibular syndesmosis when fixing ankle fractures does not restrict subsequent ankle bone ROM. The AITFL is an important stabilizer of the distal tibiofibular syndesmosis in external rotation. controlled laboratory study.

凸轮原理启发的经济林树干自动环剥装置的设计与实验研究

In order to solve the problem of complicated processes, low efficiency and high cost of economic tree trunks girdling, inspired by cam mechanism this study developed a new type of automatic half-ring girdling device, which can automatically complete a series of operations, including the tree trunk profile scanning, girdling trajectory calculating and automatic bark cutting. A pair of laser rangefinders and guide screws were symmetrically arranged on a half-ring rotating rail, which could rotate around the tree trunk, and two chainsaws assembled above the guide screws were controlled to move radially. The laptop was used as upper computer, and a 4-axis motion control card was used as the lower computer, which constituted the control system of precise movement. The programs of the tree trunk profile scanning, the xylem profile curve fitting and the chainsaw centre trajectory calculation were designed in LabVIEW. The scanning tests and girdling experiments were carried out on the different sections of the tree trunks in the laboratory. The feasibility of the automatic girdling device for economic tree trunks was verified with one complete and automatic girdling operation finished by this device, which took 150 seconds, and the error range of automatic girdling was within ±2mm. This device improves the automation degree of girdling operation and provides a support for the development of economic forestry.

Актуализация методики учета аэродинамического воздействия от поездов на высокоскоростных железнодорожных магистралях

In the calculation of structures located near railway tracks (noise protection screens along the tracks, overpasses over high-speed railway lines (HSM) of deck elements with downhill driving, etc.), the aerodynamic effects of high-speed trains shall be considered. Objective: study of the aerodynamic impact of a moving high-speed train on structures and structures, Located in the immediate vicinity of the highspeed railway line with subsequent adjustment of the current regulatory framework for the design of TSM infrastructure facilities. Methods: mathematical modeling in a specialized software complex of computational hydrogas dynamics with experimental verification of the developed calculation models and subsequent analysis and generalization of the obtained results. Results: distribution patterns and aerodynamic intensities from a moving high-speed train for the two most characteristic design cases: impact on a vertical surface parallel to the track axis and on a horizontal surface, located above the axis of train movement. For the calculation cases under consideration, the intensity of the impact was related to parameters such as the distance to the structure from the path axis (for the vertical surface) and the height above the rail head (for the horizontal surface). Practical importance: the need Development of proposals for adjustment and addition of the current regulatory framework for the design of structures and structures included in the infrastructure of high-speed railway lines.

Effect of slug characteristics on the nonlinear dynamic response of a long flexible fluid-conveying cylinder

Hydrocarbon flows in a marine riser may appear in multiple phases with varying flow patterns, among which, slug flows are known to exhibit complex flow characteristics due to fluctuations in multiphase mass, velocities, and pressure changes. Bulk of the literature concerning internal single and two-phase flow induced vibrations have largely focused on the use of a linearized tension beam model. In this study, the fluid-structure interaction phenomena of a submerged long flexible cylinder conveying two-phase slug flows is investigated taking into account the geometric and hydrodynamic nonlinearities. A semi-empirical theoretical model which consists of nonlinear structural equations of coupled out-of-plane, in-plane and axial structural motions is presented for the analysis and prediction of two-phase slug flow induced vibrations (SIV). The model includes equations involving centrifugal and Coriolis forces to capture mass variations in the slug flow regime. A numerical space-time finite difference approach combined with a frequency domain analysis is used for analyzing the highly nonlinear three-dimensional responses. The model assumes constant geometric properties across the span of the cylinder and utilizes an idealized slug unit concept, wherein slug properties are considered to be fully developed and undisturbed by pipe oscillations. Model validations are performed through comparisons with published experimental internal flow-induced vibration results. Parametric study captures the effects of several key slug characteristics on the vibration responses of a fluid-conveying cylinder. The results demonstrate amplitude-modulation response, mean displacements, three-dimensional cylinder displacements due to geometric nonlinear couplings and the influence of internal flow velocities. Higher dominant modes and oscillation frequencies were observed when the cylinder experiences large amplitude motions at specific slug formations. A new dimensionless parameter is introduced to predict scenarios of high amplitude oscillations for long flexible cylinders carrying two-phase slug flows.

A novel camera calibration method based on known rotations and translations

It is often difficult to align the camera optical center with the rotation center of the motion mechanism during active vision calibration, and this dis-alignment could lead to inaccuracy of the constraint equations and calibration results. To circumvent such issues, this paper proposes a novel method for active vision camera calibration and facilitates its real-world implementation. In this method, the rotational motion axis is assumed not necessarily to pass through the camera’s optical center, and the constraint equations are established by correlating image matched points before and after camera motions. The displacements caused by rotation are incorporated into the constraint equations to improve the accuracy of calibration. Numerical simulation and experiments are conducted. The feasibility of this proposed method is justified by using both synthetic and experimental data, and the results show that this method could estimate camera intrinsic parameters with high accuracy. Furthermore, it is found that small rotation angles can better the calibration accuracy even under the influence of external noises. This study suggests that this novel method has great potential for visual and image applications.

The Difference in the Assessment of Knee Extension/Flexion Angles during Gait between Two Calibration Methods for Wearable Goniometer Sensors.

Frontal and axial knee motion can affect the accuracy of the knee extension/flexion motion measurement using a wearable goniometer. The purpose of this study was to test the hypothesis that calibrating the goniometer on an individual's body would reduce errors in knee flexion angle during gait, compared to bench calibration. Ten young adults (23.2 ± 1.3 years) were enrolled. Knee flexion angles during gait were simultaneously assessed using a wearable goniometer sensor and an optical three-dimensional motion analysis system, and the absolute error (AE) between the two methods was calculated. The mean AE across a gait cycle was 2.4° (0.5°) for the on-body calibration, and the AE was acceptable (<5°) throughout a gait cycle (range: 1.5-3.8°). The mean AE for the on-bench calibration was 4.9° (3.4°) (range: 1.9-13.6°). Statistical parametric mapping (SPM) analysis revealed that the AE of the on-body calibration was significantly smaller than that of the on-bench calibration during 67-82% of the gait cycle. The results indicated that the on-body calibration of a goniometer sensor had acceptable and better validity compared to the on-bench calibration, especially for the swing phase of gait.

Parameter influence analysis of stochastic resonance and stochastic P-bifurcation for the shape-memory alloy laminate

This paper investigates the transverse vibration of an axially moving shape-memory alloy (SMA) fiber hybrid laminations under the combined action of transverse harmonic excitation and stochastic disturbance. Considering the shape memory alloy (SMA) fiber volume fraction random field, the kinetic energy and strain potential energy of SMA laminates are solved, and the axial motion equation of SMA laminates is derived according to Hamilton principle, a non-dimensional differential equation of the transverse vibration of the axially moving SMA laminated plates is obtained by adopting the Galerkin integral method. Considering the volume-fraction stochastic field, the stochastic natural vibration of a SMA laminate is analyzed. Considering the stochastic resonance of the SMA laminate under the action of Gaussian white noise and harmonic excitation, the effects of geometric parameters, physical parameters of materials, and temperature on the stochastic resonance behavior of the SMA laminate is analyzed. Finally, the effect of the stochastic P-bifurcation phenomenon of the parameters on the steady-state response of the SMA laminate is analyzed.

Design optimization of bellow joints used in liquid propellant rocket engines

Abstract Bellow joints are frequently used in hydraulic lines, constructions, and various areas such as nuclear stations to absorb the energy caused by flow and external forces, provide flexibility to the lines, and prevent damages such as cracking and deterioration in the flow lines. There exist various types of bellow joints (e.g., axial type, gimbal type, and hinge type) that allow axial, lateral, and angular movements. Bellow joints that assist thrust vector control in liquid propellant rocket engines prevent the hydraulic lines from being damaged during the orientation movements of the missile. While providing this flexibility to the lines in rocket engines, they create additional force against the linear actuators that move the liquid motor nozzle. This additional force causes the need for larger actuators, resulting in more weight and volume. In this study, design optimization of the bellow joint used in liquid propellant rocket engines is conducted to minimize the force transferred to the actuators by minimizing the bending moment developed in the bellow joint. It is found that the bending moment developed in the bellow joint could be reduced by a significant rate of 75 % without compromising the structural integrity of the bellow joint.

Transient lubrication analysis of journal-thrust coupled bearing considering time-varying loads and thermal-pressure coupled effect

The journal-thrust coupled bearing (abbreviated as JTC bearing) works at the end of the crankshaft in diesel engine, with the function of carrying radial load and prevent axial movement of the crankshaft. The journal part and the thrust part of this special bearing both form the oil film lubrication when subjected to the time-varying loads in axial and radial directions during the working condition. In this work, the JTC bearing in marine diesel engines was analyzed using a transient thermal elastohydrodynamic (TEHD) lubrication model. The thermal and pressure (thermal-pressure) coupled effects were taken into consideration based on the flow, pressure, and thermal continuity conditions between the journal and thrust parts. Moreover, the transient time-varying load was considered in the lubrication analysis to explore the coupled effect under the actual operating conditions. A test rig was built to validate the established transient TEHD lubrication model for the JTC bearing. The thermal-pressure coupled effect between the journal and thrust parts was found to significantly affect the transient lubrication behaviors of the JTC bearing, which cannot be ignored. Also, different boundary conditions were investigated for the influence of the coupled effect on transient lubrication characteristics, including axial clearances, radial clearances, waveforms of radial load, incline angles and inlet oil temperatures. This work could theoretically support the lubrication design of the JTC bearings used in the diesel engine crankshafts.

In Vivo Intelligent Fluorescence Endo-Microscopy by Varifocal Meta-Device and Deep Learning.

Endo-microscopy is crucial for real-time 3D visualization of internal tissues and subcellular structures. Conventional methods rely on axial movement of optical components for precise focus adjustment, limiting miniaturization and complicating procedures. Meta-device, composed of artificial nanostructures, is an emerging optical flat device that can freely manipulate the phase and amplitude of light. Here, an intelligent fluorescence endo-microscope is developed based on varifocal meta-lens and deep learning (DL). The breakthrough enables in vivo 3D imaging of mouse brains, where varifocal meta-lens focal length adjusts through relative rotation angle. The system offers key advantages such as invariant magnification, a large field-of-view, and optical sectioning at a maximum focal length tuning range of ≈2mm with 3µm lateral resolution. Using a DL network, image acquisition time and system complexity are significantly reduced, and in vivo high-resolution brain images of detailed vessels and surrounding perivascular space are clearly observed within 0.1 s (≈50 times faster). The approach will benefit various surgical procedures, such as gastrointestinal biopsies, neural imaging, brain surgery, etc.

Turbulent mixed convection in a horizontal cylindrical cavity with the off-lattice Boltzmann method

Large-eddy simulations (LES) of turbulent mixed convection in a horizontal concentric cylindrical cavity when cylinders are subjected to rotations are investigated in the present study. A characteristic-based finite-difference off-lattice Boltzmann method solver is employed to investigate whether rotation enhances heat transfer in a horizontal concentric cylindrical cavity configuration where buoyancy acts perpendicular to the cylinder axis. The study focuses on assessing heat transfer characteristics for different rotation intensities in both counter-rotating-cylinders (CRC) and outer-rotating-cylinder (ORC) configurations. The LES simulations are performed for Rayleigh number, Ra=106, and Reynolds numbers, Re=0,500,1000, and 5000 for air (Pr=0.71), employing a classical Smagorinsky sub-grid-scale (SGS) model. The numerical solver is verified using two benchmark problems, namely (i) Buoyancy-driven flow in a differentially heated air-filled cubic enclosure and (ii) turbulent Taylor-Couette flow. The CRC and ORC configurations are chosen for the three-dimensional simulations in this study, prompted by the notable improvement in heat transfer observed in their respective two-dimensional simulations. A thorough comparison between two- and three-dimensional mixed convection results reveals substantial influence from secondary flow in the axial direction. While three-dimensional CRC simulations exhibit a modest increase in heat transfer at Re=500, the ORC configuration experiences a decrease in heat transfer rate as the Reynolds number increases, contrasting with two-dimensional simulation trends. The CRC configuration enhances the axial motion of the flow with Reynolds number, and its magnitude is larger than that of the ORC configuration and natural convection. A significant difference between two-dimensional and three-dimensional mixed convection simulation results is observed because of considerable secondary flow. Furthermore, the flow and thermal characteristics of turbulent mixed convection are investigated using streamlines, isotherms, Q-criterion, Nusselt number variation along the cylinders, anisotropy analysis, turbulent kinetic energy (TKE), dissipation, contours of radial and axial components of velocity.

Stability and nonlinear vibrations of an inclined axially moving beam considering self-weight

The transmission device of the astronautic exploration vehicle can be regarded as an inclined beam experiencing axial motion under varying gravitational acceleration and tilt angle. Understanding the instability and vibration characteristics of this structure with axial movement is crucial for the dynamic design of the astronautic exploration vehicle. This paper discusses the stability and non-linear vibration nature of a self-weight inclined beam. The governing equations of the system are established and discretized using the hypothesized mode method and the extended Hamilton principle. The stability of the inclined beam is explored through an analysis of its natural frequency. The amplitude-frequency responses of the first four generalized coordinates of the inclined beam are analyzed by the Matcont toolkit. The influence of the axial velocity, the value of external excitation, the gravitational acceleration, and the tilt angle on the nonlinear vibration characteristics of the beam are discussed. Through the numerical discussion in this paper, a diverse range of nonlinear dynamic phenomena are observed and valuable insights for the stability design of the transmission device are provided.

Human estimates of descending objects' motion are more accurate than those of ascending objects regardless of gravity information.

Humans can accurately estimate and track object motion, even if it accelerates. Research shows that humans exhibit superior estimation and tracking performance for descending (falling) than ascending (rising) objects. Previous studies presented ascending and descending targets along the gravitational and body axes in an upright posture. Thus, it is unclear whether humans rely on congruent information between the direction of the target motion and gravity or the direction of the target motion and longitudinal body axes. Two experiments were conducted to explore these possibilities. In Experiment 1, participants estimated the arrival time at a goal for both upward and downward motion of targets along the longitudinal body axis in the upright (both axes of target motion and gravity congruent) and supine (both axes incongruent) postures. In Experiment 2, smooth pursuit eye movements were assessed while tracking both targets in the same postures. Arrival time estimation and smooth pursuit eye movement performance were consistently more accurate for downward target motion than for upward motion, irrespective of posture. These findings suggest that the visual experience of seeing an object moving along an observer's leg side in everyday life may influence the ability to accurately estimate and track the descending object's motion.

AMPK-mediated autophagy pathway activation promotes ΔFosB degradation to improve levodopa-induced dyskinesia

BackgroundParkinson's disease patients on chronic levodopa often suffer from motor complications, which tend to reduce their quality of life. Levodopa-induced dyskinesia (LID) is one of the most prevalent motor complications, often characterized by abnormal involuntary movements, and the pathogenesis of LID is still unclear but recent studies have suggested the involvement of autophagy. MethodsThe onset of LID was mimicked by chronic levodopa treatment in a unilateral 6-hydroxydopamine (6-OHDA) -lesion rat model. Overexpression of ΔFosB in HEK293 cells to mimic the state of ΔFosB accumulation. The modulation of the AMP-activated protein kinase (AMPK)-mediated autophagy pathway using by metformin, AICAR (an AMPK activator), Compound C (an AMPK inhibitor) and chloroquine (an autophagy pathway inhibitor). The severity of LID was assessed by axial, limb, and orofacial (ALO) abnormal involuntary movements (AIMs) score and in vivo electrophysiology. The activity of AMPK pathway as well as autophagy markers and FosB-ΔFosB levels were detected by western blotting. RT-qPCR was performed to detect the transcription level of FosB-ΔFosB. The mechanism of autophagy dysfunction was further explored by immunofluorescence and transmission electron microscopy. ResultsIn vivo experiments demonstrated that chronic levodopa treatment reduced AMPK phosphorylation, impaired autophagosome-lysosomal fusion and caused FosB-ΔFosB accumulation in the striatum of PD rats. Long-term metformin intervention improved ALO AIMs scores as well as reduced the mean power of high gamma (hγ) oscillations and the proportion of striatal projection neurons unstable in response to dopamine for LID rats. Moreover, the intervention of metformin promoted AMPK phosphorylation, ameliorated the impairment of autophagosome-lysosomal fusion, thus, promoting FosB-ΔFosB degradation to attenuate its accumulation in the striatum of LID rats. However, the aforementioned roles of metformin were reversed by Compound C and chloroquine. The results of in vitro studies demonstrated the ability of metformin and AICAR to attenuate ΔFosB levels by promoting its degradation, while Compound C and chloroquine could block this effect. ConclusionsIn conclusion, our results suggest that long-term metformin treatment could promote ΔFosB degradation and thus attenuate the development of LID through activating the AMPK-mediated autophagy pathway. Overall, our results support the AMPK-mediated autophagy pathway as a novel therapeutic target for LID and also indicate that metformin is a promising therapeutic candidate for LID.

Finite element analysis of different pedicle screw internal fixations for first lumbar vertebral fracture in different sports conditions.

Lumbar fractures are the most common spinal injuries, and surgery is required for severe fracture. This study aimed to investigate the variations in motion and stress in varying states of activity after minimally invasive and traditional open pedicle screw placement for L1 vertebral fracture stabilization. We studied a male volunteer (26 years old) with no history of chronic back pain or lumbar spine trauma. We used the finite element method for this investigation. Using finite element software, we created a three-dimensional model of L1 vertebral compression fracture. We also constructed models for four percutaneous pedicle screws spanning the fractured vertebra and four screws traversing the damaged vertebra with transverse fixation. In all three-dimensional movement directions, the open pedicle fixation system experienced maximum stress higher than its percutaneous counterpart. With axial spinal rotation, von Mises stress on the traditional open pedicle screw was considerably lower than that with percutaneous pedicle fixation, but peak stress was elevated at the transverse connection. Traditional open pedicle fixation displayed less maximum displacement than percutaneous pedicle internal fixation. During axial spinal movements, high peak stress is observed at the transverse connection. Patients should avoid excessive axial rotation of the spine during recovery.

Prevertebral Anchored Kevlar Band to Recover Intact Spine Movement Ranges in Lumbar Disc Arthroplasty

Anterior longitudinal ligament and annulus fibrosus removal in total disc replacement induces excessive spinal mobility with zygapophyseal joint overload and osteoarthritic changes causing chronic back pain. To control disc arthroplasty-induced hypermobility with a Kevlar® band. A 3 × 3 cm Kevlar® band implanted in twelve human lumbar cadaveric spines substituted the anterior longitudinal ligament and annulus in disc arthroplasty. Biomechanical studies compared the intact spine, after discectomy, post-disc arthroplasty, and with the Kevlar® band inserted. The Kevlar® band recovered the extension and axial rotation movement ranges without regaining the intact status. Improvement was moderate in lateral bending. The Instantaneous Axis of Rotation improved the discectomy and total disc prosthesis conditions without recovering the initial state. The disc above the operated one also showed increased mobility, particularly in extension and axial rotation, improved by Kevlar® band insertion without recovering the intact spine values. The Kevlar® band improves excess mobility ranges induced by anterior longitudinal ligament and anterior annulus removal in disc arthroplasty in the operated and supra-adjacent discs without recovering the baseline status.

Research on Precise Tracking Control of Gear-Shifting Actuator for Non-Synchronizer Automatic Mechanical Transmission Based on Sleeve Trajectory Planning

The Non-Synchronizer Automated Mechanical Transmission (NSAMT) demonstrates a straightforward structure and cost-effectiveness; however, the primary obstacle to its widespread application lies in NSAMT shift control. The implementation of active angle alignment effectively addresses the issue of shifting quality, but achieving active angle alignment necessitates precise tracking of the planned shifting curve by the gear-shifting actuator. To tackle the control problem of accurate tracking for NSAMT shift actuators, this paper initially analyzes the structure and shift characteristics of the NSAMT. Based on this analysis, a physical model is established using Amesim, incorporating a drive motor, two-gear NSAMT, shift actuator, sleeve, and DC motor model. An extended state observer (ESO) is designed to mitigate unknown interference within the system. Furthermore, an active angle alignment control algorithm based on “zero speed difference” and “zero angle difference” for double target tracking is constructed while planning the axial motion trajectory of the sleeve. The Backstepping algorithm is employed to successfully track and regulate this planned trajectory. Finally, through Hardware-in-the-Loop testing, we validate our proposed control strategy, which demonstrates consistent results with simulation outcomes, thereby affirming its effectiveness.

Investigation of the Possibility of Using Turn-by-Turn Measurements to Detect Perturbations in the Magnetic Structure of Accelerators

The PCA correction method consists of a global analysis of turn-by-turn data obtained from beam position monitors (BPMs). One of its main advantages is speed of operation and the ability to detect pulsating power supplies. Along with this, a wide range of applications characterizes the PCA method: determination of perturbations of the accelerator magnetic structure, calculation of transport matrix elements and optical functions, and determination of the magnitude of the transverse coupling. A software prototype implementing the proposed correction method was written and tested on the electron-positron collider VEPP-4M for experimental validation. In the experiments, perturbations were introduced one by one into individual elements of the skew-quadrupole and quadrupole corrections. In one case, the excitation of betatron oscillations was carried out by the kick of the inflector. In another case, the oscillations were excited by resonant swing with a depolariser. It was found that, despite the simplicity of practical implementation, the examined method has some nuances that make it difficult to obtain and identify correct results. Nevertheless, it was possible to identify the introduced perturbations of quadrupole and skew-quadrupole corrections. Moreover, it was possible to detect a magnet with low-frequency pulsations by characteristic changes in the estimated invariants. In addition, the possibility of determining the integral coupling parameters in experiments on the observation of resonantly excited eigen modes having the shape of ellipses in the plane transverse to the beam motion axis is considered.