Estimates of the average angular velocity of the precession of Lagrange's top

Mechanical model of nucleoside and its equilibrium equations are set up, and the mechanical properties on the equilibrium position are analyzed. In the case constraint force and electrostatic attraction between cylinder OH and elastic rod are balanced, the analytic expression of nutation angle of the section and its conditions of existence are given. It is show that the cylinder OH can maintain equilibrium at any range of the precession angle. In the other case when unbanced, there is phenomenon of separation of elastic rod from cylinder OH in the spiral wound 2 circles, and numerical solution of the precession angle at separation points are calculated. Analysis of equilibrium of cylinder H1 illustrates that the generatrix of cylinder H1 and OH are not parallel, and the angle between them is obtained

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An Underwater Vector Propulsion Device Based on the RS+2PRS Parallel Mechanism and Its Attitude Control Algorithm

Applied Sciences ◽

10.3390/app9235210 ◽

2019 ◽

Vol 9 (23) ◽

pp. 5210 ◽

Cited By ~ 1

Author(s):

Wang ◽

Guo ◽

Zhong

Keyword(s):

Attitude Control ◽

Parallel Mechanism ◽

Control Algorithm ◽

Simulation Analysis ◽

Autonomous Underwater Vehicles ◽

Propulsion System ◽

Precession Angle ◽

Nutation Angle ◽

Prismatic Joints ◽

Spherical Parallel Mechanism

In order to overcome the disadvantages of some existing autonomous underwater vehicles (AUVs), such as actuator extraposition and degree-of-freedom (DOF) redundancy, a 2-DOF vector propeller propulsion system with built-in actuator based on the deficient DOF parallel mechanism is proposed. The RS+2PRS (Revolute-Spherical+ Prismatic-Revolute-Spherical) parallel mechanism is used as the main structure, and the driving parts are placed in the interior of the AUV cabin, which is beneficial to the sealing and protection of the propulsion system. In addition, the motion parameters decoupling shows that the two independent parameters are the precession angle and the nutation angle of the propeller installation platform. Therefore, the attitude control algorithm uses two prismatic joints as driving units to establish the nonlinear mapping model with the two Euler attitude angles. In the end, the simulation analysis and the real device are used to verify the feasibility of the attitude control algorithm and the in situ adjustment function of the propeller, which lays the theoretical foundation for engineering applications in the future.

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THE INFLUENCE OF TEMPERATURE ON THE DRIFT OF GYROSCOPE

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-1995-0019 ◽

1995 ◽

Vol 19 (4) ◽

pp. 363-382

Author(s):

Zheng-Ming Ge ◽

Ming-Yen Liu ◽

Sann-Chie Lee

Keyword(s):

Multiple Scales ◽

Nonlinear Differential Equations ◽

Equations Of Motion ◽

Center Of Mass ◽

Approximate Model ◽

Analytical Approximation ◽

Precession Angle ◽

Model Study ◽

Nutation Angle ◽

Influence Of Temperature On

The dynamics, especially the drift, of a gyroscope with slowly varying axisymmetrical mass distribution are studied. By the data of temperature field of the inner gimbal, the changes of the position of center of mass and moments of inertia of the inner gimbal of gyro with time are obtained through the finite element method and approximate model study. The drift of a gyroscope can be analytically investigated according to the variation of the nutation angle and the precession angle. Since the temperature varies with time, the equations of motion are nonautonomous nonlinear differential equations. The analytical approximation is obtained by multiple scales method. The nutation angle and the precession angle in some given time intervals are calculated and are compared with the numerical results, obtained by using the MATLAB software package, with satisfactory consistency.

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Zonal and tesseral harmonic perturbations of an artificial satellite

Symposium - International Astronomical Union ◽

10.1017/s0074180900105625 ◽

1966 ◽

Vol 25 ◽

pp. 323-325 ◽

Cited By ~ 1

Author(s):

B. Garfinkel

Keyword(s):

Angular Velocity ◽

Spherical Harmonics ◽

Artificial Satellite ◽

Compact Form ◽

Earth’S Rotation ◽

Earth's Rotation ◽

Secular Variations ◽

Tesseral Harmonics

The paper extends the known solution of the Main Problem to include the effects of the higher spherical harmonics of the geopotential. The von Zeipel method is used to calculate the secular variations of orderJmand the long-periodic variations of ordersJm/J2andnJm,λ/ω. HereJmandJm,λare the coefficients of the zonal and the tesseral harmonics respectively, withJm,0=Jm, andωis the angular velocity of the Earth's rotation. With the aid of the theory of spherical harmonics the results are expressed in a most compact form.

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The Analysis of Proprioception Alteration during First Five Months after Anterior Cruciate Ligament Reconstruction

Baltic Journal of Sport and Health Sciences ◽

10.33607/bjshs.v1i84.293 ◽

2018 ◽

Vol 1 (84) ◽

Author(s):

Vilma Jurevičienė ◽

Albertas Skurvydas ◽

Juozas Belickas ◽

Giedra Bušmanienė ◽

Dovilė Kielė ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Angular Velocity ◽

Knee Joint ◽

Cruciate Ligament ◽

Position Sense ◽

Joint Position Sense ◽

Joint Position ◽

Starting Position ◽

Angular Velocities ◽

Anterior Cruciate

Research background and hypothesis. Proprioception is important in the prevention of injuries as reduced proprioception is one of the factors contributing to injury in the knee joint, particularly the ACL. Therefore, proprioception appears not only important for the prevention of ACL injuries, but also for regaining full function after ACL reconstruction.Research aim. The aim of this study was to understand how proprioception is recovered four and five months after anterior cruciate ligament (ACL) reconstruction.Research methods. The study included 15 male subjects (age – 33.7 ± 2.49 years) who had undergone unilateral ACL reconstruction with a semitendinosus/gracilis (STG) graft in Kaunas Clinical Hospital. For proprioceptive assessment, joint position sense (JPS) was measured on both legs using an isokinetic dynamometer (Biodex), at knee flexion of 60° and 70°, and at different knee angular velocities of 2°/s and 10°/s. The patients were assessed preoperatively and after 4 and 5 months, postoperatively.Research results. Our study has shown that the JPS’s (joint position sense) error scores to a controlled active movement is significantly higher in injured ACL-deficient knee than in the contralateral knee (normal knee) before surgery and after four and five months of rehabilitation. After 4 and 5 months of rehabilitation we found significantly lower values in injured knees compared to the preoperative data. Our study has shown that in injured knee active angle reproduction errors after 4 and 5 months of rehabilitation were higher compared with the ones of the uninjured knee. Proprioceptive ability on the both legs was independent of all differences angles for target and starting position for movement. The knee joint position sense on both legs depends upon the rate of two different angular velocities and the mean active angle reproduction errors at the test of angular velocity slow speed was the highest compared with the fast angular velocity. Discussion and conclusions. In conclusion, our study shows that there was improvement in mean JPS 4 and 5 months after ACL reconstruction, but it did not return to normal indices.Keywords: knee joint, joint position sense, angular velocity, starting position for movement.

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Effect of Inner and Outer Wheels Driving Force Control on Small Electric Vehicle

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.4.2020.02.0622 ◽

2020 ◽

Vol 17 (4) ◽

pp. 8246-8254

Author(s):

K. Shibazaki ◽

H. Nozaki

Keyword(s):

Control System ◽

Angular Velocity ◽

Electric Vehicle ◽

Force Constant ◽

Force Control ◽

Driving Force ◽

Vehicle Control ◽

Steering Angle ◽

Force Control System ◽

The Difference

In this study, in order to improve steering stability during turning, we devised an inner and outer wheel driving force control system that is based on the steering angle and steering angular velocity, and verified its effectiveness via running tests. In the driving force control system based on steering angle, the inner wheel driving force is weakened in proportion to the steering angle during a turn, and the difference in driving force is applied to the inner and outer wheels by strengthening the outer wheel driving force. In the driving force control (based on steering angular velocity), the value obtained by multiplying the driving force constant and the steering angular velocity, that differentiates the driver steering input during turning output as the driving force of the inner and outer wheels. By controlling the driving force of the inner and outer wheels, it reduces the maximum steering angle by 40 deg and it became possible to improve the cornering marginal performance and improve the steering stability at the J-turn. In the pylon slalom it reduces the maximum steering angle by 45 deg and it became possible to improve the responsiveness of the vehicle. Control by steering angle is effective during steady turning, while control by steering angular velocity is effective during sharp turning. The inner and outer wheel driving force control are expected to further improve steering stability.

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