Changes In Angular Velocity Research Articles

DEVELOPMENT OF A HIGH-PERFORMANCE HOLDING MACHINE WITH COMPLEX SPATIAL MOVEMENT OF TWO WORKING CAPACITIES

A new design of the galvanizing machine is proposed, which is equipped with two working tanks that perform complex spatial movement. The structure and principle of operation of the developed design of the machine are accurately described. The developed design of the machine with two capacities that perform complex spatial movement allows to increase considerably productivity of processing of details due to the fact that there is a possibility to carry out two different thawing technological operations on one machine or to process two parties of different details at the same time. The design of the machine, during operation, allows to involve in working process, both both working capacities, and one. Equipping the machine with a special drive design with four Hook hinges allows to reproduce the required law of change of angular velocity on each driving shaft of the machine, the implementation of which will create conditions that will ensure the same intensity of the working array between opposite ends of the tank in opposite directions. process, as well as uniform dynamic loading of all moving parts. Analytical studies were performed, within which some geometrical parameters of the machine design were determined, in particular, the value of the angle α between the axes of the shafts of each Hook hinge was established, which will ensure the implementation of the required angular velocity law on the machine drive shaft. The relationship between the extreme values of the law of change of the angular velocity of the driving shafts of the machine and the magnitude of the angles in each Hook hinge is established. The obtained results of analytical research can be used in the relevant design offices of machine-building enterprises at the stage of designing galvanizing equipment with complex spatial movement of working tanks.

Sharp turns and gyrotaxis modulate surface accumulation of microorganisms

The accumulation of swimming microorganisms at surfaces is an essential feature of various physical, chemical, and biological processes in confined spaces. To date, this accumulation is mainly assumed to depend on the change of swimming speed and angular velocity caused by cell-wall contact and hydrodynamic interaction. Here, we measured the swimming trajectories of Heterosigma akashiwo (a biflagellate marine alga) near vertical and horizontal rigid boundaries. We observed that the probability of sharp turns is greatly increased near a vertical wall, resulting in significant changes in the distributions of average swimming speed, angular velocity, and rotational diffusivity near the wall (a quantity that has not previously been investigated) as functions of both distance from the wall and swimming orientation. These cannot be satisfactorily explained by standard hydrodynamic models. Detailed examination of an individual cell trajectory shows that wall contact by the leading flagellum triggers complex changes in the behavior of both flagella that cannot be incorporated in a mechanistic model. Our individual-based model for predicting cell concentration using the measured distributions of swimming speed, angular velocity, and rotational diffusivity agrees well with the experiment. The experiments and model are repeated for a cell suspension in a vertical plane, bounded above by a horizontal wall. The cell accumulation beneath the wall, expected from gyrotaxis, is considerably amplified by cell-wall interaction. These findings may shed light on the prediction and control of cell distribution mediated by gyrotaxis and cell-wall contact.

Fullerene Movement in a Carbon Nanocontainer

The character of C60 fullerene motion inside a cylindrical carbon nanocontainer with flat graphene covers has been studied. A new trajectory approach to describe the three-dimensional motion of fullerene is presented, based on the use of motion equations for its center of mass in the field of van der Waals forces, as well as the rotational motion equations written in the absolute basis. A high-precision computational technology for implementing this approach is described. Calculations have shown the components of the C60 angular velocity change stepwise. This character of the change in rotation is determined by the impacts of the fullerene on the wall of the container. As a result of these impacts, the energy of rotation changes abruptly.

Enhanced DWA algorithm for local path planning of mobile robot

PurposeThe purpose of this study is to solve the problems of poor stability and high energy consumption of the dynamic window algorithm (DWA) for the mobile robots, a novel enhanced dynamic window algorithm is proposed in this paper.Design/methodology/approachThe novel algorithm takes the distance function as the weight of the target-oriented coefficient, and a new evaluation function is presented to optimize the azimuth angle.FindingsThe jitter of the mobile robot caused by the drastic change of angular velocity is reduced when the robot is closer to the target point. The simulation results show that the proposed algorithm effectively optimizes the stability of the mobile robot during operation with lower angular velocity dispersion and less energy consumption, but with a slightly higher running time than DWA.Originality/valueA novel enhanced dynamic window algorithm is proposed and verified. According to the experimental result, the proposed algorithm can reduce the energy consumption of the robot and improves the efficiency of the robot.

Real-Time Detection of Lower Limb Training Stability Function Based on Smart Wearable Sensors

The research of smart wearable sensors in limb training has great application significance. In the face of real-time detection requirements, this paper proposes a hardware solution for the stability function of lower limb training based on the theory of intelligent wearable sensors. For the specific implementation circuit of the device, considering the reliability of the system, the system implements antijamming design for the hardware circuit from three aspects: adding decoupling capacitors, optimizing layout and wiring, and rationally grounding the hardware circuit, and performs moving average filtering on the collected sensor data to remove noise, which solves the problem of sensor data precision issues. During the simulation process, by analyzing the changes of acceleration, angular velocity, and attitude angle under different lower limb training activities and different wearing positions, the characteristics of stability combined acceleration, combined angular velocity, and attitude angle were constructed, and the stability mean, variance, and attitude angle were extracted. The experimental results show that the extracted 57 feature dimensions are first reduced to 21 dimensions by the principal component analysis algorithm, and then, the optimal feature subset is selected by the encapsulation method, and the dimension is reduced to 9. The proposed multifeature fusion algorithm has higher accuracy, and the maximum has increased by 6.5%, effectively improving the accuracy of the lower limb training stability function detection algorithm.

Defining movement strategies in soccer instep kicking using the relationship between pelvis and kick leg rotations

ABSTRACT Growing evidence suggests skilled ball kickers use distinct pelvis and kick leg strategies to achieve successful performance. However, since the interaction between different strategies remains unexplored, the aims of this study were to a) examine relationships between pelvis and kick leg rotations in male players performing soccer instep kicks and b) classify different ‘types’ of kickers based on the observed movement strategies. Twenty semi-professional players performed kicks for maximal speed and accuracy, and kick leg and pelvis kinematics were analysed using 3D motion capture (1000 Hz). A strong relationship was found between change in pelvis transverse angular velocity and thigh-knee angular velocity ratio upon ball contact (r = 0.76, p < 0.001), and participants were categorised by their location on kick leg (thigh-knee) and pelvis (maintainer-reverser) continuums. Knowledge of a player’s preferred strategy can inform departure from ‘one size fits all’ technical and conditioning training practices towards more individualised approaches. For example, pelvis maintainer-thigh dominant kickers might benefit from focus towards the concentric capabilities of the hip flexors, whereas reverser-knee dominant kickers might benefit from developing the ability to decelerate the pelvis and thigh to induce motion-dependent angular acceleration of the lower leg towards the ball.

A Comparison of Inertial Measurement Unit and Motion Capture Measurements of Tibiofemoral Kinematics during Simulated Pivot Landings.

Injuries are often associated with rapid body segment movements. We compared Certus motion capture and APDM inertial measurement unit (IMU) measurements of tibiofemoral angle and angular velocity changes during simulated pivot landings (i.e., ~70 ms peak) of nine cadaver knees dissected free of skin, subcutaneous fat, and muscle. Data from a total of 852 trials were compared using the Bland–Altman limits of agreement (LoAs): the Certus system was considered the gold standard measure for the angle change measurements, whereas the IMU was considered the gold standard for angular velocity changes. The results show that, although the mean peak IMU knee joint angle changes were slightly underestimated (2.1° for flexion, 0.2° for internal rotation, and 3.0° for valgus), the LoAs were large, ranging from 35.9% to 49.8%. In the case of the angular velocity changes, Certus had acceptable accuracy in the sagittal plane, with LoAs of ±54.9°/s and ±32.5°/s for the tibia and femur. For these rapid motions, we conclude that, even in the absence of soft tissues, the IMUs could not reliably measure these peak 3D knee angle changes; Certus measurements of peak tibiofemoral angular velocity changes depended on both the magnitude of the velocity and the plane of measurement.

ОЦЕНКА ПАРАМЕТРОВ КЛОТОИДНОЙ ТРАЕКТОРИИ ВХОДА В ПОВОРОТ КОЛЕСНОЙ МАШИНЫ

A theoretical assessment of the influence of the translational speed of a wheeled vehicle and the angular rotation speed of its steered wheels on the main characteristics of the clotoid curve is carried out. The calculations were carried out with the following initial parameters characterizing the structural and geometric features of the wheeled vehicle: the longitudinal base of the machine is 2.6 m; the distance between the axes of the front axle pins is 1.8 m; the maximum angle of rotation of the driven wheels is 33 °30'. The speed of the translational movement of the machine and the angular rotation speed of the controlled wheels was varied. The results of the evaluation are as follows. With a constant angular rotation speed of the front wheels of 0.195 s-1 and with a change in the speed of translational motion in the range from 0.57 m/s to 1.78 m / s, the maximum abscissa of the clotoid curve increased from 0.113 m to 1.074 m – almost tenfold, and the maximum ordinate from 1.703 m to 5.141 m - approximately three times. At a constant translational speed of 1.41 m/s and with a change in angular velocity in the range from 0.0974 s-1 to 0.292 s-1, which corresponds to the time interval of turning the wheels at a maximum angle from 2 s to 6 s, it was obtained: the maximum abscissa decreases with an increase in angular velocity from 2.585 m to 0.305 m - by 8.5 times, and the maximum ordinate - from 7,689 m to 2.79 m - 2.8 times. The calculation established that the minimum radius of curvature of the trajectory at the end of the section of the entrance to the turn is equal to 5,061 m, which corresponds, as it should be, to the value of the minimum theoretical radius given in the technical characteristics of some wheeled vehicles with the accepted initial parameters.

A numerical model of dust particle impacts during a cometary encounter with application to ESA’s Comet Interceptor mission

The attitude perturbations caused by large dust particle impacts on a three-axis stabilized spacecraft during a high velocity encounter with a comet are studied. Specifically, a numerical model is used to make order of magnitude estimations in relation to the European Space Agency’s Comet Interceptor mission and help constrain requirements for guidance, navigation and control (GNC). Our model is able to reproduce the measurements acquired by the spin-stabilized Giotto spacecraft during its encounter with comet 1P/Halley in 1986. For realistic scenarios the total change in angular velocity that needs to be corrected can reach 1–10 °/s. At closest approach the median shift of the target object on the Comet Camera (CoCa) detector is typically larger then 10 pixels for the modelled scenarios. Our model shows that the encounter velocity, the spacecraft radius and the attitude control rate are the most critical factors. For the free parameters scaling laws are derived.

Is Skull-Vibration-Induced Nystagmus Modified with Aging?

Background: Despite clinical practice utilizing the Dumas test (SVINT), some questions remain unanswered, including the age-related changes in frequency (FN) and slow-phase angular velocity (SPAV). This study aims to retrospectively evaluate their variations in subjects affected by unilateral peripheral vestibular loss (UPVL). Methods: We evaluated the selected samples based on the results of the SVINT, the results of the vestibular-evoked potentials (C-VEMP and O-VEMP), and the results of the head impulse test (HIT) and we compared the results against the age of the patients. We calculated the timing between the onset of UPVL and clinical evaluation in days. The presence or absence of VEMP indicated the UPVL severity. UPVL and BPPV patients with spontaneous or pseudo-spontaneous nystagmus were compared. Results: Statistical analysis showed changes in the FN and SPAV depending on age and the side of the application of the stimulus. We also observed that, in the UPVL, the severity of the disease modifies the SPAV, but not the frequency. Conclusions: The SVINT is a simple, reliable, and straightforward test that, if evaluated instrumentally, can show significant differences with aging. Further studies need to be performed to refine the clinical significance of the test and clarify its physiological background.

Quantification of Head Acceleration Events in Rugby League: An Instrumented Mouthguard and Video Analysis Pilot Study.

Instrumented mouthguards (iMG) were used to collect head acceleration events (HAE) in men’s professional rugby league matches. Peak linear acceleration (PLA), peak angular acceleration (PAA) and peak change in angular velocity (ΔPAV) were collected using custom-fit iMG set with a 5 g single iMG-axis recording threshold. iMG were fitted to ten male Super League players for thirty-one player matches. Video analysis was conducted on HAE to identify the contact event; impacted player; tackle stage and head loading type. A total of 1622 video-verified HAE were recorded. Approximately three-quarters of HAE (75.7%) occurred below 10 g. Most (98.2%) HAE occurred during tackles (59.3% to tackler; 40.7% to ball carrier) and the initial collision stage of the tackle (43.9%). The initial collision stage resulted in significantly greater PAA and ΔPAV than secondary contact and play the ball tackle stages (p < 0.001). Indirect HAE accounted for 29.8% of HAE and resulted in significantly greater ΔPAV (p < 0.001) than direct HAE, but significantly lower PLA (p < 0.001). Almost all HAE were sustained in the tackle, with the majority occurring during the initial collision stage, making it an area of focus for the development of player protection strategies for both ball carriers and tacklers. League-wide and community-level implementation of iMG could enable a greater understanding of head acceleration exposure between playing positions, cohorts, and levels of play.

Sloshing of Fluid Between Rotating Inner Vertical Shaft and Stationary Outer Casing

Abstract Unsteady behaviors of free surface around a rotating vertical shaft in cylindrical stationary casing were investigated. Experiments were carried out with various rotating frequency of the shaft at two initial water levels. An axi-symmetrical free surface oscillation took place when the rotational speed of the shaft became larger than a certain value. The frequency of the free surface oscillation decreased as the rotating frequency increased. A theoretical model was developed, and the mechanisms of the free surface oscillation were clarified. The oscillation was found to be a sloshing mode excited by the change of fluid angular velocity, caused by the change of wetted areas on the inner rotating shaft and outer stationary casing, associated with the change in free surface height.

An Inexpensive Apparatus to Study Conservation of Angular Momentum in the Introductory Laboratory

While the three laws of conservation of energy, momentum, and angular momentum are all mentioned in introductory textbooks, there are few experiments through which students can investigate the conservation of angular momentum. Most experiments consist of collisions between rotating disks, in which one disk is dropped on another, or in which the rotational inertia of a single object is changed and the resulting change in angular velocity measured. This paper presents a method for studying collisions that centers on the conservation of angular momentum, and of rotational energy.

Linear and non-linear transformation of coordinates and angular velocity and intensity change of basic vectors of tangent space of a position vector of a material system kinetic point

Linear and non-linear transformation of coordinates and angular velocity and intensity change of basic vectors of tangent space of a position vector of a material system kinetic point

Self-Consistent Adiabatic Inspiral and Transition Motion.

The transition motion of a point particle around the last stable orbit of Kerr is described at leading order in the transition-timescale expansion. Taking systematically into account all self-force effects, we prove that the transition motion is still described by the Painlevé transcendent equation of the first kind. Using an asymptotically matched expansions scheme, we consistently match the quasicircular adiabatic inspiral with the transition motion. The matching requires us to take into account the secular change of angular velocity due to radiation reaction during the adiabatic inspiral, which consistently leads to a leading-order radial self-force in the slow timescale expansion.

Influence of Test Conditions on Sliding Wear Performance of High Velocity Air Fuel-Sprayed WC-CoCr Coatings.

Sliding wear performance of thermal spray WC-based coatings has been widely studied. However, there is no systematic investigation on the influence of test conditions on wear behaviour of these coatings. In order to have a good understanding of the effect of test parameters on sliding wear test performance of HVAF-sprayed WC–CoCr coatings, ball-on-disc tests were conducted under varying test conditions, including different angular velocities, loads and sliding distances. Under normal load of 20 N and sliding distance of 5 km (used as ‘reference’ conditions), it was shown that, despite changes in angular velocity (from 1333 rpm up to 2400 rpm), specific wear rate values experienced no major variation. No major change was observed in specific wear rate values even upon increasing the load from 20 N to 40 N and sliding distance from 5 km to 10 km, and no significant change was noted in the prevailing wear mechanism, either. Results suggest that no dramatic changes in applicable wear regime occur over the window of test parameters investigated. Consequently, the findings of this study inspire confidence in utilizing test conditions within the above range to rank different WC-based coatings.

Dynamic modeling and characteristics analysis of cylindrical roller bearing with the surface texture on raceways

The vibration responses of cylindrical roller bearings can be affected by the surface texture on raceways, which includes surface waviness and roughness. Thus, it is very important to develop a dynamic model which can describe the surface texture comprehensively and simulate vibration responses of bearings accurately at high rotating speed. In this paper, a complex dynamic model of cylindrical roller bearings with consideration of surface texture is developed. The developed model is verified by simulations and experiments about the relationship between wave numbers and vibration responses. Based on the developed model, several dynamic characteristics of roller bearings are discussed: a) the influence of radial clearance and rotation speed on the stability of cage; b) the contact between a roller and raceways; c) the variation of rotation angular speed of roller. Results show that with the radial clearance increase, the stability of cage rise first and decrease. The cage stability is also affected by the rotation speed of inner raceway. The constitution of contact force between a roller and raceway are different between loaded zone and unloaded zone. Changes of angular rotation velocity of roller also have some regulations.

Lower Limb Model Based Inertial Indoor Pedestrian Navigation System for Walking and Running

Foot-mounted inertial navigation systems are suitable in GNSS denied environment for special tasks such as fire rescue, soldier, etc. These tasks are often accompanied by vigorous movements such as running and jumping, which is a challenge for the Zero Velocity Update (ZUPT) based inertial navigation system. As the speed increases, the inertial sensor drift increases, while the zero-velocity interval shortens, making the gait detection more difficult and resulting in a limited error correction. And as the motion intensifies, the stability of the system decreases. A multi-node inertial pedestrian navigation system based on the lower limb model constraint is proposed in this paper. Our first contribution in this paper is studying a simplified adaptive zero-bias estimation algorithm. The changes in velocity and angular velocity between two steps are used to estimate and compensate for the drift of accelerometers and gyroscopes. Our second contribution is proposing a novel gait segmentation method by lower limb motion statistics feature. A hybrid detection model of dual IMU is conducted to improve the accuracy of gait recognition. After that, the maximum distance inequality constraint is studied to correct the position error when the still phase is not available in vigorous movement. The final contribution is studying the chi-square fault detection method to improve the stability of KF. Multiple experiments prove that the proposed multi-node inertial pedestrian navigation system is effective in dealing with various challenging in walking, running, and hybrid motion pedestrian inertial navigation problems which could achieve less than 0.3% average distance error.

VSG-Based Parameter Adaptive Control Strategy

As a large number of converters composed of power electronic devices are connected to the grid, power system has gradually decreased stability. How to increase dynamic response of the converter has become one of the research hotspots. Virtual synchronous generator technology (VSG) can endow the converter with moment of inertia and damping characteristics, thereby enhancing dynamic response, but the traditional VSG technology cannot achieve the optimal control effect. To solve this problem, an adaptive control strategy is proposed, which takes logical combination of system angular velocity and frequency change as the real-time change condition, with exponential function as the change expression. Finally, this paper uses MATLAB / Simulink to compare the method in this paper with several existing typical control strategies.

On-line measurement method of transmission backlash based on angular velocity and double-end angular position information

Backlash is the inherent characteristic of gear transmission system. It is an important mean to measure and compensate backlash to improve transmission performance. When the driving gear reverses, due to the existence of backlash, the driven gear will still keep its original steering due to inertial motion until the driven gear collision with the driving gear. In this paper, based on the analysis of the tooth gap of the driving gear and the driven gear, an on-line measurement method of the meshing tooth gap combining the angular velocity of the load end with the information of the Angle position of the two axes of the master-slave gear is presented. This method uses the gyroscope at the load end (driven wheel) to monitor the sudden change of angular velocity at the moment of gear reverse impact and re contact, and the signal is used as the judgment basis for the reverse contact moment of the driving gear and driven gear. Then, the angular position data of driving gear and driven gear are fused at the time of reverse rotation and contact impact, and the backlash of the gear is calculated online. Finally, setting up an experimental platform for measuring backlash, and the proposed method is verified. The experimental results show that the proposed method can achieve accurate backlash measurement.