Relative Angular Displacement Research Articles

Research on Angular Displacement Detection Technology of Inter-satellite Laser Communication Based on Coherent System

With the rapid development of spatial information networks technologies, inter-satellite laser communication links have played an important role in the satellite Internet. High-precision relative angular displacement detection is the foundation for achieving real-time tracking of laser communication links, and its accuracy directly impacts the tracking performance and communication quality of the laser communication link. Traditional laser communication systems utilize intensity-based position detection methods to calculate angular displacement, requiring setting separate Charge Coupled Device (CCD) or Four-quadrant Detector (QD) as well as independent optical tracking branches. This setup makes it difficult to integrate with high-speed coherent communication systems. Additionally, the method employing intensity detection to determine angular displacement based on spot position has lower accuracy in theory. A angular displacement detection of coherent-based inter-satellite laser communication is proposed in this paper. Firstly, real-time calculation of phase differences at different positions of the beam is achieved through heterodyne coherent array detection and dual high-precision phase-locked loops. Then, a model correlating wave front phase difference with relative angular displacement is established, phase noise during beam transmission and detection processes is analyzed, and algorithm for detecting angular displacement in coherent systems is studied. Finally, a laser communication link is constructed under laboratory condition, and experimental validation work is carried out. When the relative angle deviation is 1°, the phase difference changes by 0.089049795rad, and the angular displacement detection error of . When the relative angle error is , the detection sensitivity is -43.93dBm. The experimental results show that in the coherent system, the relative angular displacement detection with high precision can be realized by using the wavefront phase difference of beam, which can support the laser communication tracking system to achieve higher precision beam tracking.

Influence of the Suspension Model in the Simulation of the Vertical Vibration Behavior of the Railway Vehicle Car Body

The evaluation of the vibration behavior of railway vehicle car bodies based on the results of numerical simulations requires the adoption of an appropriate theoretical model of the suspension which considers the important factors that influence the vibration level of the car body. In this paper, the influence of the secondary suspension model on the vertical vibration behavior of the railway vehicle car body is investigated, based on the results of numerical simulations on the frequency response functions of the acceleration, the power spectral density of the acceleration and the root mean square of the acceleration of the car body. Numerical simulation applications are developed based on a rigid-flexible coupled vehicle model with seven degrees of freedom, corresponding to car body vibration modes: bounce, pitch, and first vertical bending mode, and bogie vibration modes: bounce and pitch. Four different models of secondary suspension are integrated into the vehicle model, namely a reference model and four analysis models. Analysis models include systems through which the pitch vibration of the bogies is transmitted to the car body, influencing its vibration behavior and, respectively, a system that takes the relative angular displacement between the car body and the bogie and a system that models the transmission system of the longitudinal forces between the bogie and the car body are analyzed. The effects of these two systems on the vibration behavior of the railway vehicle car body are analyzed both for each system separately and together. In the conclusions of the paper, the influence of the secondary suspension model on the vibration level at the resonance frequencies of the vertical bending of the car body and the pitch of the bogie is pointed out. It also highlights the important contribution of the transmission system of the longitudinal forces between the bogie and the car body in transmitting pitch vibrations of the bogies to the car body, with effects on the vibration level of the car body at high speeds.

Nonlinear vibration characteristics of rolling bearing considering flexible cage fracture

Rolling bearing is one of the critical parts of the transmission system and has a high demand for operating conditions. Suitable operating conditions can ensure that the rolling bearing has a higher rotation accuracy, which significantly impacts the performance of the transmission system. However, under some unsuitable operating conditions, the rolling bearing in the transmission system is faced with failure and other problems. Cage failure is one of the most common bearing failures. In particular, the cage fracture analysis is the most difficult among rolling bearing failures. In order to research its nonlinear vibration characteristics under cage fracture, a nonlinear model of the rolling bearing (4Nb+4 degrees of freedom) considering cage fracture is established. The contact between bearing rings and the rollers, the circumferential interaction between the flexible cage and the rollers, and the interaction between the rollers under the cage fracture fault are considered. Subsequently, the nonlinear characteristics under cage fracture are analyzed. The nonlinear collision forces of roller and cage under cage fracture and different cage clearances are compared. The results show that the collision force between rollers and the cage is greater when fractured than when the cage is healthy. Under multiple cage fractures (the roller number is odd), more prominent frequency doubling phenomena may occur as the number of fractures increases. More shocks are reflected in the relative angular displacement and waveform. Under multiple cage fractures (the roller number is even), the number and interval of fractures can be determined through the waveform and envelope spectrum. The research in this paper can help the health monitoring and fault diagnosis of bearing cages.

Differential contribution of lateral plantar foot ligaments to lateral column stability – A cadaver based sectioning analysis

Lateral column (LC) instability occurs in adult acquired flatfoot deformity (AAFD). Differential ligament contribution to LC stability is unknown. The primary aim was to quantify this by using cadaver sectioning of lateral plantar ligaments. We also determined the relative contribution of each ligament to dorsal translation of the metatarsal head in the sagittal plane.17 below-knee cadaveric specimens, preserved by vascular embalming method, were dissected to expose plantar fascia, long/short plantar ligaments (L/SPL), calcaneocuboid (CC) capsule and inferior 4th/5th tarsometatarsal (TMT) capsule. Dorsal forces of 0 N, 20 N and 40 N were applied to the plantar 5th metatarsal head after sequential ligament sectioning in different orders. Pins provided linear axes on each bone, allowing relative angular bone displacements to be calculated. Photography and ImageJ processing software were then used for analysis.The LPL (and CC capsule) had the greatest contribution to metatarsal head motion (107 mm) after isolated sectioning. In the absence of other ligaments, sectioning these resulted in significantly increased hindfoot-forefoot angulation (p ≤ 0.0003). Isolated TMT capsule sectioning demonstrated significant angular displacement even when other ligaments remained intact (with intact L/SPL, p = 0.0005). CC joint instability required both LPL and capsular sectioning for significant angulation to occur, whilst TMT joint stability was largely dependent on its capsule.The relative contribution of static restraints to the lateral arch has not yet been quantified. This study provides useful information on relative ligament contribution to both CC and TMT joint stability, which may in turn improve understanding of surgical interventions used to restore arch stability.

Two second order instantaneous invariants of axodes

It is well established that generalized spatial motion of a rigid body can be defined in terms of two axodes; a fixed axode and a moving axode. These axodes are ruled surfaces that uniquely roll and slide upon one another. Presented are two instantaneous invariants that define relative motion between two axodes. These invariants are based on the instantaneous screw axis (ISA) or line-tangency shared by two axodes in mesh. One invariant is the relative angular displacement (rolling) about the ISA and the other invariant is the relative axial displacement (sliding) along the ISA. Both invariants are ratios expressed in terms of the normal curvature and geodesic torsion for any point on the ISA. An induced curvature is introduced to quantify the combined rolling and sliding displacement. Two osculating hyperboloids are established in terms of induced curvature, which when combined, create a skew axis gear pair with uniform motion that matches the instantaneous invariants of the axodes. A skew axis gear set with elliptical motion is presented to demonstrate generalized axodes, instantaneous invariants, induced curvature, and osculating hyperboloids.

Approximate Motion Generation of an Epicyclic Gear Train With Noncircular Gears Based on Optimization–Homotopy Algorithm

Abstract This study aims to make approximate motion generation that has multiple solutions to facilitate the selection of the best mechanism parameters. Therefore, an approximate synthesis method for an epicyclic gear train (EGT) with noncircular gears based on optimization–homotopy algorithm is proposed in this paper. First, the multipose synthesis objective function of a simplified model of EGT (planar RR dyad) is established. The approximate motion generation is transformed into the extremum problem of multivariate function, and a variable is introduced to expand the solution space. A homotopy algorithm is used to solve the gradient equation of the objective function to obtain the finite range solution domain. Second, the feasible solution domain of EGT is obtained by identifying the total rotation of revolute joints of the RR dyad, and a mechanism error evaluation index is established. In accordance with actual constraints, the most suitable solution is selected in the feasible solution domain, and the relative angular displacement relationship of the selected RR dyad is used to determine the transmission ratio and pitch curve of noncircular gears to realize the design of an EGT. Lastly, a design example is provided to illustrate the feasibility of the method.

Bond Graph-Based Approach to Modeling Variable-Speed Gearboxes with Multi-Type Clutches

The modeling and simulation of gearboxes is important for analyzing the dynamic characteristics and designing control strategies of transmission systems. Variable-speed gearboxes include compound planetary gear trains and clutches, which complicates dynamic modeling. Here, a procedural bond graph-based modeling method that considers many uncertainties is proposed. The proposed method yields a constant system–structure model. First, bond graph models of the two most common planetary gears were summarized, and were used as sub-models of a compound planetary gear train. Then, the Karnopp friction sub-model of the friction clutch and a relative angular displacement sub-model of the one-way clutch were constructed. Based on the dynamic coupling between the sub-models, the modeling steps of the gearbox, including the compound planetary gear train friction clutch one-way clutch coupling system, are described in detail. Next, the main sources of uncertainties of gearbox were analyzed and the simulation methods were given. Finally, the novel uncertain bond graph model was used to simulate the double planetary gearbox; the transmission ratio before and after the shift was 2.42 and 1.72, compared with the design values of 2.41 and 1.71, respectively; the deviation is within 5.8%; The average rotating speeds of the output shaft fluctuated by 6 and 2.5% respectively, which was within a reasonable range, so the effectiveness of the method is verified.

Computer diagnostics of clutching mechanical transmission

A new method of computer diagnostics or continuous monitoring of the technical condition of mechanical transmission clutch during the operation of city buses and minibuses based on monitoring the relative angular displacements of the drive and driven transmission shafts by the slipping parameters when transmitting the maximum torque and the leash moment off clutch, as well as on the analysis of the rate of engagement of the clutch when starting the car. Keywords diagnostics, failure, coupling, transmission, route, service frequency, reliability

Gear Rattle during a start-up transient in a driveline equipped with a tuneable torsional Vibration Damper with Magneto-Rheological Elastomers

The paper reports a numerical investigation on the dynamic behaviour of a vehicle driveline, equipped with a Torsional Vibration Damper (TVD) based on Magneto-Rheological Elastomeric (MRE) spring elements, during the start-up transient considering an abrupt manoeuvre of clutch engagement. The TVD device consists of a flywheel and a damper disk, with interposed some elastomeric samples which react for relative angular displacements of the two disks. The dynamical parameters of the TVD can be properly tuned by varying the magnetic field surrounding the MRE springs to mitigate the torsional oscillations of the flywheel, causes of many undesired inconveniences as critical speeds or vibro-acoustic issues. The present study promotes the use of the MRE torsional vibration damper to reduce the annoying vibroacoustic phenomenon of “gear rattle” arising in the unloaded gear pairs of the gear box, during and after the rapid clutch engagement transients in the vehicle start-up phase and is conducted on a simplified automotive driveline equipped with a dry clutch. The possibility of quickly tuning the mechanical properties of the MRE-TVD, makes this device particularly eligible for suppressing the above disturbance, adapting to the various operative conditions of the automotive driveline. Results of the analysis, by the help of a Gear Rattle Index (GRI), demonstrate the effectiveness of the proposed device in reducing the vibroacoustic phenomenon during the transient phases of the vehicle start-up, until the vehicles speed conditions are reached.

Metamaterial design strategy for mechanical energy absorption under general loading

This article proposes a design strategy for two-dimensional, multi-stable cellular materials which leverages local rotational degrees of freedom in support of mechanical energy absorption under general loading. The approach aligns the rotation centers of two layers of identical patterning but opposite chirality such that the relative angular displacement accompanying any in-plane deformation facilitates local snap-through events which contribute to the global mechanical energy absorption performance. The rotation symmetry of the underlying (quasi-)crystalline layers governs the directionality of the energy absorption capacity. Moreover, cellular materials emerging from the proposed strategy possess an absorption capability for all loading modes — tension, compression, and shear. Simulations reveal the energy absorption capacity and the directionality thereof for several cellular bi-layers as well as the impact of key tuning parameters. The cellular materials constructed following the proposed design strategy fill the need for omni-directional, multi-modal energy absorption in a low-density, tunable, and re-usable platform.

Design of clamping-pot-type planetary gear train transplanting mechanism for rice wide–narrow-row planting

To design a clamping-pot-type wide–narrow-row pot seedling transplanting (WPST) mechanism with desired spatial beak-shaped trajectory and working posture, a new design method of planetary gear train transplanting mechanism (PGTM) with non-circular gears based on several key spatial poses (position and posture) was proposed. The PGTM was simplified to a spatial open-loop chain with two-revolute (2R) joints. The geometric constraint equations containing only the structural parameters of the chain were then established on the basis of the three key spatial poses, and the homotopy algorithm was used to obtain all the required parameters of the mechanism. In accordance with the parameters obtained, the relative angular displacement relation between the planet carrier and the transplanting arm was optimized, the trajectory of the mechanism was replayed, and the total transmission ratio was determined. The degree of freedom of the spatial 2R mechanism was reduced by attaching to the unequal gear pair, and the transmission ratio was distributed in accordance with the gear type to realize the design of a non-circular gear pitch curve. Lastly, a clamping-pot-type PGTM for rice WPST driven by the combination of planar non-circular and non-conical gears was designed, and virtual simulation and prototype test were conducted. Results showed that the simulation and prototype test trajectories were consistent with the desired trajectory. Under the operating speeds of 50 r/min and 90 r/min, the success rates of seedling picking were 95.32% and 90.15%, respectively, which verified the feasibility of the theoretical method. This method could provide a reference for the design of a spatial PGTM with nonuniform transmission. Keywords: rice pot seedling, wide–narrow-row transplanting, spatial trajectory, planetary gear train, non-circular gear DOI: 10.25165/j.ijabe.20211402.5975 Citation: Wang L, Sun L, Huang H M, Yu Y X, Yu G H. Design of clamping-pot-type planetary gear train transplanting mechanism for rice wide–narrow-row planting. Int J Agric & Biol Eng, 2021; 14(2): 62–71.

Biomechanical Comparison of Fibertape Device Repair Techniques of Ligamentous Lisfranc Injury in a Cadaveric Model.

Lisfranc ligamentous injuries are complex, and their treatment, along with the preferred method of fixation, is controversial. Implementing a flexible synthetic augmentation device (fibertape) has been described as an alternative to traditional screw fixation. This biomechanical study evaluated two fibertape devices with interference screw fixation: InternalBrace, and InternalBrace with supplementary intercuneiform stabilization. The diastasis and relative angular displacement between bones were measured at three midfoot joints in the Lisfranc articulation. Measurements were obtained for the pre-injured, injured, and post-fixation stages under static loading. Specimens then underwent stepwise increases in cyclic loading performed at 1 Hz and 100 cycles, at 100 N ground reaction force intervals from 500 to 1200 N to simulate postoperative loading, and then up to 1800 N to simulate high loads. Failure of fixation was defined as diastasis greater than 2 millimeters at the second-metatarsal - medial-cuneiform joint. InternalBrace specimens demonstrated failures in 3 of 9 (33%) specimens at cyclic loads of 1000 N. Conversely, InternalBrace with Supplementary Limb specimens had 1 failure at 1200 N. The difference in diastasis at the second metatarsal-medial cuneiform joint was statistically significant between the two groups at higher loads of 1600N (p=0.019) and 1800N (p=0.029). The use of InternalBrace for ligamentous Lisfranc injuries appears to provide a biomechanically viable alternative for withstanding early postoperative protected weight bearing. Furthermore, the use of a supplementary limb in addition to the InternalBrace fibertape fixation method appears to enhance its biomechanical efficacy.

A simple, clinically applicable motor learning protocol to increase push-off during gait: A proof-of-concept.

ObjectiveTask-specific training is often used in functional rehabilitation for its potential to improve performance at locomotor tasks in neurological populations. As push-off impairment are often seen with these patients, this functional approach shows potential to retrain gait overground to normalize the gait pattern and retrain the ability to improve gait speed. The main objective of this project was to validate, in healthy participants, a simple, low-cost push-off retraining protocol based on task-specific training that could be implemented during overground walking in the clinic.Methods30 healthy participants walked in an 80-meter long corridor before, during, and after the application of an elastic resistance to the right ankle. Elastic tubing attached to the front of a modified ankle-foot orthosis delivered the resistance during push-off. Relative ankle joint angular displacements were recorded bilaterally and continuously during each walking condition.ResultsOn the resisted side, participants presented aftereffects (increased peak plantarflexion angle from 13.4±4.2° to 20.0±6.4°, p<0.0001 and increased peak plantarflexion angular velocity from 145.8±22.7°/s to 174.4±37.4°/s, p<0.0001). On the non-resisted side, aftereffects were much smaller than on the resisted side suggesting that the motor learning process was mainly specific to the trained leg.ConclusionThis study shows the feasibility of modifying push-off kinematics using an elastic resistance applied at the ankle while walking overground. This approach represents an interesting venue for future gait rehabilitation.

Vibration based gear fault detection

Any transmission system is having gear is of important requirement. Early fault detection is a primary necessity. For this purpose a nonlinear mathematical model has been considered of gear contact .The entire system is represented by discretized ordinary differential equation taking backlash error and transmission error into consideration. The overall contact modeling is done in MATLAB simulink. A linear vibration analysis of normal gear and faulty gear is done using ANSYS Software. Two different types of conditions were considered, one with perfect condition and other with small crack. So for the gear contact analysis a nonlinear mathematical model has been considered. It is found that whenever b < δ, the frequency component is becoming strong with increasing in ω but becomes constant when δ < b, i.e. a very low relative angular displacement with high backlash. The ANSYS results concluded that fault detected near the mode shape frequency. And with comparative harmonic analysis it is being observed that the faulty gear has more fluctuating frequency response than the healthy one.

Biomechanical Comparison of FiberTape Device Repair Techniques of Ligamentous Lisfranc Injury in Cadaveric Model

Category:Trauma; Basic Sciences/Biologics; Midfoot/Forefoot; SportsIntroduction/Purpose:Lisfranc ligamentous injuries are complex. Controversy exists regarding their treatment and preferred method of fixation. Fixation methods employing a FiberTape device and interference screw fixation have been described as an alternative to traditional screw fixation. The purpose of this biomechanical study was to evaluate two methods of fixation utilizing interference screw fixation with FiberTape augmentation in a cadaveric model.Methods:9 paired cadaveric feet (mid tibia/fibula) were separated into two groups based on fixation method: FiberTape alone and FiberTape with supplementary limb into the middle cuneiform via anchor. At three joints of the midfoot (second metatarsal - medial cuneiform, intermediate cuneiform - medial cuneiform, second metatarsal - intermediate cuneiform), the diastasis and relative angular displacement between bones in the coronal plane were measured for static and cyclic loading. Measurements were obtained for the native (pre-injured), injured, and post-fixation in static loading. Fixed specimens then underwent stepwise increases in cyclic loading performed at 1 Hz and 100 cycles, at 100 N intervals from 500 to 1800 N ground reaction force. The Achilles tendon was also loaded to simulate postoperative weightbearing. Failure of fixation was defined as diastasis at the second metatarsal - medial cuneiform joint greater than 2 millimeters.Results:FiberTape specimens demonstrated diastasis failures of 3 of 9 (33%) specimens at cyclic loads of 1000 N. Conversely, FiberTape with supplementary limb specimens all survived past this loading magnitude, with 1 failing at supraphysiologic loads (>1200 N). The difference in diastasis at the second metatarsal-medial cuneiform joint was statistically significant between the two groups at forces of 1600N (p = 0.019) and 1800N (p = 0.029). There were no significant differences between the other joint diastases and relative angular displacements.Conclusion:The use of FiberTape for fixation of ligamentous Lisfranc injuries appears to provide a biomechanically viable alternative for withstanding early post-operative protected weightbearing. Furthermore, the use of a supplementary limb in addition to the FiberTape fixation method appears to enhance its biomechanical efficacy under cyclic loading especially at higher loads.

Investigation of the Torque Transmission Characteristics in Dual-Flux-Modulated Magnetic Gear

Due to the field-modulation effect, the coaxial magnetic gear (CMG) can achieve a low-speed high-torque transmission. To further improve the torque capability, a dual-flux-modulated CMG (DFM-CMG) derived from conventional CMGs is presented. The DFM-CMG has two rotors, two modulators, and three air gaps. The operation principle and torque transmission are revealed. The air-gap magnetic fields are modulated by the two modulators. The output torque of DFM-CMG can be adjusted by the relative angular displacement between the two modulators. The optimal shift angle of the inner modulator is 0. The DFM-CMG is a combination of CMGs I and II. The CMG I component makes a major contribution to the output capability. The measured pull-out torque of the DFM-CMG prototype is 6.08 $\text{N}\cdot \text{m}$ . It shows a 28.3% growth over CMG I.

Interpersonal problems of cocaine dependent adults differ from those of a normative sample

Our research examined patterns of interpersonal problems in patients with a primary diagnosis of cocaine dependence (CD), comparing them with those in a normative sample. We hypothesized that the patterns of individuals with CD would reveal constellations of interpersonal problems distinct from those of the sample, not only at baseline, but also at termination of treatment. Analysis was conducted on 402 CD patients from the training and the main trial phases of the National Institute on Drug Abuse Collaborative Cocaine Treatment Study. Responses to the Inventory for Interpersonal Problems were analyzed—from baseline, from month one, and at treatment termination—according to the Interpersonal Circumplex Model and were compared to the normative sample. The CD sample was described using four distinct subtypes, named according to their relative angular displacement at baseline and highest two subscale means: Cold and Socially Avoidant, Vindictive and Domineering, Overly Nurturant and Intrusive, Nonassertive and Exploitable. Each subtype remained distinct across treatment and consistently reported different types of interpersonal difficulties than the normative population at termination, consistent with the interpersonal pathoplasticity model. In all subtypes, overall interpersonal distress decreased over the course of treatment, to the extent that by treatment termination they were no more or less distressed than the normative sample. These findings have important clinical implications. The interpersonal challenges of patients struggling with addiction to cocaine warrant clinical attention, beyond mediating levels of distress.

Control of self-excited vibrations in face milling with two-rim mill

The paper provides an overview of self-excited vibration damping methods for face milling. The main source to maintain and develop self-excited vibrations is the mechanism of their regeneration. To suppress it, two methods are currently actively used: tools with variable tooth pitch and cutting speed modulation. A combination of these methods was used to develop a vibration-resistant face mill with two-rims provided with alternating teeth and connected with adjustable stiffness by spring. The spring also allows a variable pitch of adjacent teeth to be adjusted. During cutter operation, the elastic connection of the rims creates difference in the cutting speed of adjacent teeth, which suppresses regeneration of self-excited vibrations and decreases their amplitude. The self-excited vibration damping efficiency of the proposed mill was determined by comparing its operation with that of a conventional mill in the same conditions of roughing a steel workpiece. The dynamics of the milling machine technological system during operation of both tools was studied using a simulation method. It was found that the conventional mill cannot be used under cutting conditions accepted in the study because of increased vibrations of the technological system elements. On the contrary, a two-rim mill provides almost quiescent processing conditions at appropriate values of the elastic connection stiffness of rims and their relative angular displacement. The settings of the two-rim mill were determined with respect to a moving rim and a spindle with another rim as a dual-mass system with two degrees of freedom.

Correction: Liu, C., et al. A Novel System for Correction of Relative Angular Displacement between Airborne Platform and UAV in Target Localization. Sensors 2017, 17, 510.

The authors wish to make the following correction to this paper [...].

Novel approach for planetary gear train dimensional synthesis through kinematic mapping

The synthesis of a kinematic trajectory traversed by an output link (planet gear) and posture of a planetary gear train with noncircular gears can be divided into two phases: dimensional synthesis of the open-chain 2R mechanism (planetary carrier) and optimization of the transmission ratio of noncircular gear pairs. According to kinematic mapping theory, more than one closed coupler trajectory can be obtained by five preset poses. Simultaneous consideration of the trajectory shape, posture, and gear ratio is difficult during planetary gear train synthesis. This work therefore proposes a new method for the synthesis of planetary gear train in which different path segments in different trajectories are selected and a group of same-type 2R mechanisms is employed to pass through them in order to rebuild a new, closed trajectory. Subsequently, the transmission ratio of noncircular gear pairs can be determined using the relative angular displacement of the 2R mechanism. To improve the roundness of the pitch curves of noncircular gears, two optimization steps are implemented using a genetic algorithm without alternating the data points of the requisite open trajectories. For example, a mechanism for rice pot seedling transplanting is obtained by using the method.