Transverse Angular Velocity Research Articles

Establishment and Analysis of Four-degree-freedom Dynamic Model Considering Lateral Tilt

In order to reduce the rate of traffic accidents under extreme working conditions and to achieve stability control of the vehicle system under these conditions, a theoretical model of vehicle dynamics with four degrees of freedom was derived with full consideration of lateral, transverse, lateral and longitudinal motions, and a joint simulation was carried out on MATLAB/CarSim software with steering wheel angular step input. The difference between the lateral velocity output of the model built in this paper and the output of the CarSim model is 0.005m/s at most, and the difference between the transverse swing angular velocity output and the output of the CarSim model is no more than 0.2deg/s; the difference between the lateral tilt angle output and the output of the CarSim model is no more than 0.5deg. In summary, the output of the model built in this paper matches well with the output of the CarSim model, that is to say In other words, the dynamics model developed in this paper can better reflect the vehicle driving characteristics under the vehicle angular step conditions.

Coordinated Optimal Control of AFS and DYC for Four-Wheel Independent Drive Electric Vehicles Based on MAS Model.

The problem that it is difficult to balance vehicle stability and economy at the same time under the starting steering condition of a four-wheel independent drive electric vehicle (4WIDEV) is addressed. In this paper, we propose a coordinated optimal control method of AFS and DYC for a four-wheel independent drive electric vehicle based on the MAS model. Firstly, the angular velocity of the transverse pendulum at the center of mass and the lateral deflection angle of the center of mass are decoupled by vector transformation, and the two-degree-of-freedom eight-input model of the vehicle is transformed into four two-degree-of-freedom two-input models, and the reduced-dimensional system is regarded as four agents. Based on the hardware connection structure and communication topology of the four-wheel independent drive electric vehicle, the reduced-dimensional model of 4WIDEV AFS and DYC coordinated optimal control is established based on graph theory. Secondly, the deviation of the vehicle transverse swing angular velocity and mass lateral deflection angle from their ideal values is oriented by combining sliding mode variable structure control (SMC) with distributed model predictive control (DMPC). A discrete dynamic sliding mode surface function is proposed for the ith agent to improve the robustness of the system in response to parameter variations and disturbances. Considering the stability and economy of the ith agent, an active front wheel steering and drive torque optimization control method based on SMC and DMPC is proposed for engineering applications. Finally, a hardware-in-the-loop (HIL) test bench is built for experimental verification, and the results show that the steering angle is in the range of 0-5°, and the proposed method effectively weighs the system dynamic performance, computational efficiency, and the economy of the whole vehicle. Compared with the conventional centralized control method, the torque-solving speed is improved by 32.33 times, and the electrical consumption of the wheel motor is reduced by 16.6%.

Swing Steadiness Regulation of Electric Vehicles with Improved Neural Network PID Algorithm

With the intensification of global environmental pollution and the energy crisis, the new energy EV industry is developing rapidly, and FWID-EV is a popular direction for future vehicle development. For the sake of improving the swing regulate steadiness and safety of EV, the study uses a particle swarm algorithm to optimize and improve the BP neural network PID, and designs an EV steering regulator to regulate the transverse swing torque and slip rate of EV to improve the safety and steadiness of EV steering. The research results display that the maximum value of the transverse swing angular velocity of the regulation algorithm is 0.156 rad/s, that the car slip rate is controlled within 0.046, and the steadiness is high, and that the maximum values of the car torque under the double shift line and snake conditions are 100 N-m and 179.4 N-m, respectively, which can effectively avoid the danger caused by steering. This demonstrates that the improved neural network PID regulator can effectively distribute the steering torque of the EV and improve the steering steadiness and safety of the EV while maintaining the driving dynamics. The use of the improved neural network PID algorithm to achieve the steering steadiness regulation of EV is of great significance to improve the safety of new energy EV, and helps to promote the widespread use of new energy EV.

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.

Research on Trajectory Tracking of Sliding Mode Control Based on Adaptive Preview Time

The preview model is one of the common methods used in trajectory tracking. The traditional fixed preview time is not adaptable to most speeds and road conditions, which not only reduces the tracking accuracy but also reduces the vehicle stability. Therefore, a controller can be designed to determine the adaptive preview time based on an optimization function of the lateral deviation, the road boundary, and the road boundary of the whole vehicle motion response characteristics. Traditional optimal preview control theory predicts the next state of the vehicle by the assumption of constant transverse pendulum angular velocity. In this paper, an expectation-based approach is used to find the ideal steering wheel turning angle based on the adaptive preview time, and a single-point preview model is established. Based on the two-degree-of-freedom dynamics model, a sliding mode controller is designed for control, and the low-pass filters are designed to suppress jitter in the sliding mode controller. Simulation results with different preview times, different speeds and different road adhesion coefficients prove that the controller has a good control effect and has good effectiveness and adaptability to speed and adhesion coefficient.

Nonlinear vibration analysis of axially moving string

In this paper, the nonlinear transverse vibration arising from axially moving string is investigated analytically. Translating string eigenfunctions are employed to reduce a partial-differential equation to a set of second degree of freedom nonlinear systems. The multi-step differential transform method (MsDTM) is proposed in order to find accurate solutions of time-varying length of an axially moving string. To illustrate the applicability and accuracy of MsDTM, the axial motion model is treated with two different sets of parameters. The relationship between transverse displacement, angular velocity and time is obtained and discussed. The effect of the string’s speed, damping and tension on the transverse displacement of the string are also taken into consideration.

A method of improving the anti-rudder beating of Si micromechanical gyro driven by rotating carrier

The Si micromechanical gyro driven by rotating carrier is a new kind of MEMS gyro. Since it has no a driving structure itself, it differs from the conventional Coriolis vibratory gyro. The gyro is installed on a rotating aircraft and utilizes the spinning of the carrier as a driving. Its sensing output is a amplitude-modulated signal. The amplitude is proportional to the transverse input angular velocity of the carrier, while frequency tunes the spin frequency of the carrier automatically. So the gyro is used for the damping of the single-channel control system of the rotating carrier. The control system uses a pair of the rudder surfaces to control the flight attitude of the carrier. The polar changing of the rudder surfaces will conduct a beating to the body of the carrier. In application, we found that the rudder beating distorts the gyro output signal. Thus the gyro will not work properly and even cause the channel jam of the control system. Aiming at the problem, in this paper we firstly introduce the structural principle and working mechanism of the gyro, and obtain its angular vibrating equation and the solution of the equation by using Euler dynamics equation of the rigid rotating around a fixed point. Then, we analyzed interference of the rudder beating on the gyro output signal in details. The analyses have indicated that the first harmonic of the rudder beating bring the interfering moment since the force arm between the rudder beating and the sensing axis of the gyro exists. Moreover, we tested the resonant frequency of the gyro. The tested result has shown that the second harmonic of the rudder beating is close to the resonant frequency. The situation will cause the resonance of the gyro. In order to improving the ability of anti-rudder beating of the gyro, we putted forward the installed method of 90 ° to eliminate the interfering force arm of the first harmonic. In addition, based on the model of the elastic torsion beams, we increased the thickness of the beams and enlarged the resonant frequency to avoid the resonance of the gyro. Finally, we carried out the experimental validation. The experimental results have demonstrated that the method can effectively suppress the influence of rudder beating on the output signal of the Si micromechanical gyro.

A resolving method of transverse input angular velocity based on Si micromechanical gyro driven by rotating carrier

A single-channel control system is a common control method for a rotating aircraft. In order to improve the flying dynamic quality of the aircraft, the control system adds a damping loop, of which a gyro is one of the key components. The gyro is used to sense the attitude motion of the rotating carrier, and feeds back the transverse input angular velocity of the rotating carrier to the control end of the system to adjust the damping of the aircraft. In this paper, a solving method of the transverse input angular velocity has been proposed based on a new type of Si micromechanical gyro. Firstly, we introduce the structure and working mechanism of the Si micromechanical gyro driven by a rotating carrier in detail. Utilizing Euler’s dynamics equation, the motion equation of the gyro and its solution were obtained. Next, the output voltage signal of the gyro was attained by a sensing circuit. Then, we analyzed the signal in detail. The analyses have shown that the gyro output signal is an amplitude-modulated (AM) signal. Its envelope is proportional to the transverse input angular velocity of the rotating carrier, and the carrier frequency can automatically tune the spin frequency of the rotating carrier. Finally, an algorithm was proposed by using Hilbert transform for solving the transverse input angular velocity of the rotating carrier. The algorithm was validated through different experiments under three working conditions. The theoretical analyses and experimental results have demonstrated that the method can effectively realize the solving of the transverse input angular velocity of the gyro.

Stability analysis in state space for non-driven MEMS gyro

The non-driven MEMS gyro is a new kind of micromechanical vibratory gyro, which has no a driving structure itself. The gyro is installed on a rotating aircraft and utilizes the spinning of the carrier to obtain an angular momentum. When the carrier produces a transverse rotation, a periodic Coriolis force acts on the sensitive mass of the MEMS gyro to sense the transverse input angular velocity of the rotating carrier. In applications, we found that the MEMS gyro is subjected to a high shock when the carrier begins to launch. If the sensitive mass cannot return to balance, the gyro will not work properly. So the stability of the gyro is the key issue on whether it can properly work. In this paper, we have analyzed the stability of the MEMS gyro in details by using Lyapunov stability principle for the first time. Firstly, based on the designed structural principle of the MEMS gyro, by using Euler dynamic equation of a rigid body rotating around a fixed point, we have described the angular vibration of the sensitive mass of the gyro and obtained its motion equation. The motion is the second order system. Then, we have chosen an appropriate state vector and established a state space model in state space for describing the motion of the sensitive mass. In order to research the stability of the designed MEMS gyro by using Lyapunov stability principle, a Lyapunov function needs to be found. Therefore, we have built a quadratic function and proved that its Lyapunov matrix equation has a solution. The matrix solution is symmetric and positive definite. Thus, the found quadratic function is a Lyapunov function. According to Lyapunov stability principle, the designed MEMS gyro is asymptotically stable. Next, utilizing numerical calculation, we have done the simulation of the unit-impulse response. The response curve has shown that the system of the designed MEMS gyro can come back to the balance after 160 ms. Finally, for further verification, the MEMS gyro is fixed on the shock table to test. The shock wave is a half-sine with the strength of 60 g and the impulse width of 80 ms. The tested result has demonstrated that the output signal of the designed MEMS gyro can again come back to zero state position after 150 ms under shock disturbance.

Can the use of proprioceptive knee braces have implications in the management of osteoarthritic knees: An exploratory study.

Use of proprioceptive knee braces to control symptomology by altering neuromuscular control mechanisms has been shown in patellofemoral pain. Although their potential in patients with knee osteoarthritis is vast, little research has examined their efficacy. This study examines the effect of a proprioceptive knee brace on lower limb kinematics and kinetics in healthy participants and in participants with OA. Thirteen healthy participants were asked to perform a 10-cm step-down task with and without a proprioceptive brace. Data were collected using a 10-camera Qualisys system. Individuals with osteoarthritis completed the Knee injury and Osteoarthritis Outcome Score before and after 4 weeks of intervention. During step-down reductions in knee maximum internal rotation, transverse range of movement, transverse plane angular velocity and maximum internal rotation angular velocity was seen. Ankle plantar flexion and inversion angular velocity decreased while inversion and maximum supination angular velocity increased. Improvements in Knee injury and Osteoarthritis Outcome Score were noted across all parameters with brace use. Positive changes in kinematic variables in multiple planes can be achieved with proprioceptive bracing alongside improved patient outcome. These changes occur at the knee but analysis of other weight bearing joints should not be overlooked in future studies. This study supports the concept of neuromuscular reinforcement and re-education through proprioceptive bracing and its application in the management in knee osteoarthritis. Proprioception can alter symptoms and biomechanics embraced and adjacent lower limb joints. The results of this study highlights the potential uses of non-mechanical bracing in the treatment of osteoarthritis and other potential to bridge the osteoarthritis treatment gap. Furthermore, large-scale research is needed to match disease subset to brace type.

Prospects of using a permanent magnetic end effector to despin and detumble an uncooperative target

Space debris, such as defunct satellites and upper stages of rockets, becomes an uncooperative target after losing its attitude control and communication ability. In addition, tumbling motion can occur due to environmental perturbations and residual angular momentum prior to the object’s end-of-mission. To minimize the collision risk during docking and capturing of the tumbling target, a non-contact method based on the eddy current effect is put forward to transmit the control torque to the tumbling target. The main idea is to induce a controllable torque on the conducting surface of the tumbling target using a rotational magnetic field generated by a Halbach rotor. The radial and axial Halbach rotors are used to damp the spinning and nutation motions of the target, respectively. The normal and tangential force are evaluated concerning the relative pose between the chaser and the target. A simplified dynamic model of the nutation damping and despinning processes is developed and the influences of the asymmetrical principal moments of inertia and transverse angular velocity are discussed. The numerical simulation results show that the designed Halbach rotor stabilized the target attitude within an acceptable time. The electromagnetic nutation damping and despinning method provides new solutions for the development of on-orbit capture technology.

Impact analysis of convected motion on the carrier frequency of a carrier-driven gyroscope signal

A carrier-driven gyroscope, which is a new type of MEMS angular velocity gyroscope, is driven by carrier spin in its operation when transverse angular velocity is inputted (i.e., yaw or pitch in the direction of the vertical spin axis). The sensitive element of the gyroscope (i.e., silicon plate) will then generate the Coriolis effect and output a voltage signal. The carrier frequency in the gyroscope output signal is not completely identical to the spin frequency of the rotating carrier. The uncertainty of the motion trail synthesized by the carrier yaw or pitch will exert different levels of influence on the carrier frequency of the gyroscope output signal. Analyzing the influence of this convected motion on the output signal of the gyroscope installed on a spinning carrier can determine the accuracy of a carrier-driven gyroscope in solving carrier attitude information through experimental and numerical simulations of multiple scenarios of convected motion. The different levels of influence exerted by the carrier frequency of the carrier-driven gyroscope are obtained after the analysis. Experimental results and numerical analysis indicate that the carrier frequency of the carrier-driven gyroscope is the carrier spin frequency, which is obtained through the superposition of the convected motion frequency caused by the transverse angular velocity.

Kinematics of the Handball Power Serve

Handball is a court sport practiced by recreational and competitive athletes to develop speed, agility, power, muscular endurance, ambidexterity, and similar skills and components of fitness. Handball is a paragon of the principle of generality/cross transfer; it develops skills and fitness which directly transfer to many team, individual sports and physical activities. The elemental nature of handball (no external implements) emphasizes the importance of biomechanics; only the kinetic chain influences and contributes to interactions with the ball. Despite the elemental, minimalistic mechanics of handball, research regarding biomechanics of performance is scarce. PURPOSE: To determine transverse plane angular velocity of hip and shoulder rotation and resultant linear velocity of the ball associated with the power serve. METHODS: Eighteen handball players competing at the B-class level or above (4 professional, 2 qualifiers, 4 open, 5 A and 3 B) provided informed consent and were videotaped in the transverse and sagittal plane while performing 10 power serves. Vicon Motus 9.2 software was used to quantify peak hip (HAV) and shoulder (SAV) angular velocity in the transverse plane, and peak resultant linear velocity of the ball (RVB). RESULTS: HAV ranged from 3.2 to 12.3 rad[BULLET OPERATOR]s-1 in individual players; grand mean = 8.13 rad[BULLET OPERATOR]s-1. SAV ranged from 10.5 to 18.4 rad[BULLET OPERATOR]s-1 in individual players; grand mean = 13.98 rad[BULLET OPERATOR]s-1. RVB ranged from 25.5 to 36.7 m[BULLET OPERATOR]s-1 in individual players; grand mean = 29.4 m[BULLET OPERATOR]s-1. To evaluate sequentially accumulated angular velocity within the kinetic chain, the proportion of serves in which HAV preceded SAV were tallied, and ranged from 30% to 100%; grand mean = 72.2 %. SAV was more strongly related to peak ball velocity (r=.205; p<0.05) than was HAV (r=.139; p>0.05). Players in higher competitive divisions exhibited faster ball velocity and angular kinematics, and more effective timing within the kinetic chain. CONCLUSIONS: Angular kinematics, linear ball velocity and kinetic chain sequence and timing of the handball serve were comparable to those reported for throwing sports. The experience, practice and playing time necessary to achieve higher competitive status in handball were related to faster angular kinematics and linear ball velocity, and more effective timing within the kinetic chain.

English

This paper evaluates the impact that helical motion of fluid products of combustion within the combustion chamber of a rocket can have on the attitude dynamics of rocket systems. By developing the study presented by Sookgaew (2004), we determined the configuration of the Coriolis moment components, which catch the impact of the combustion product's whirling motion, for the radial and centripetal propellant burn pattern specific to S-5M and S-5K solid rocket motors. We continue the investigation of the effects of internal whirling motion of fluid products of combustion on the attitude behavior of variable mass systems of the rocket type by examining the spin motion and transverse attitude motion of such systems. The results obtained show that internal fluid whirling motion can cause appreciable deviations in spin rate predictions, and also affects the frequencies of the transverse angular velocity components.

Measurement of phase difference for micromachined gyros driven by rotating aircraft.

This paper presents an approach for realizing a phase difference measurement of a new gyro. A silicon micromachined gyro was mounted on rotating aircraft for aircraft attitude control. Aircraft spin drives the silicon pendulum of a gyro rotating at a high speed so that it can sense the transverse angular velocity of the rotating aircraft based on the gyroscopic precession principle when the aircraft has transverse rotation. In applications of the rotating aircraft single channel control system, such as damping in the attitude stabilization loop, the gyro signal must be kept in sync with the control signal. Therefore, the phase difference between both signals needs to be measured accurately. Considering that phase difference is mainly produced by both the micromachined part and the signal conditioning circuit, a mathematical model has been established and analyzed to determine the gyro's phase frequency characteristics. On the basis of theoretical analysis, a dynamic simulation has been done for a case where the spin frequency is 15 Hz. Experimental results with the proposed measurement method applied to a silicon micromachined gyro driven by a rotating aircraft demonstrate that it is effective in practical applications. Measured curve and numerical analysis of phase frequency characteristic are in accordance, and the error between measurement and simulation is only 5.3%.

Generalized extended Navier-Stokes theory: Correlations in molecular fluids with intrinsic angular momentum

The extended Navier-Stokes theory accounts for the coupling between the translational and rotational molecular degrees of freedom. In this paper, we generalize this theory to non-zero frequencies and wavevectors, which enables a new study of spatio-temporal correlation phenomena present in molecular fluids. To discuss these phenomena in detail, molecular dynamics simulations of molecular chlorine are performed for three different state points. In general, the theory captures the behavior for small wavevector and frequencies as expected. For example, in the hydrodynamic regime and for molecular fluids with small moment of inertia like chlorine, the theory predicts that the longitudinal and transverse intrinsic angular velocity correlation functions are almost identical, which is also seen in the molecular dynamics simulations. However, the theory fails at large wavevector and frequencies. To account for the correlations at these scales, we derive a phenomenological expression for the frequency dependent rotational viscosity and wavevector and frequency dependent longitudinal spin viscosity. From this we observe a significant coupling enhancement between the molecular angular velocity and translational velocity for large frequencies in the gas phase; this is not observed for the supercritical fluid and liquid state points.

Two-Impulse Reorientation of Spinning Axisymmetric Body: Single Axis Thrust

It is well known that a sequence of two impulses can be used to redirect the spin axis of an axisymmetric rigid body. The first impulse initiates the coning motion by imparting an initial transverse component of angular velocity. The second impulse brings the coning motion to a halt by completely canceling the transverse angular velocity. When the torque can be given along only one axis in the transverse plane then a two-impulse maneuver can be designed with a coast time before the initiation of the maneuver. The coast time is required to align the torque axis in a specific direction. Further, by appropriately choosing the time of the second impulse, a solution is found when the impulse is restricted to only one direction along a single axis.

Attitude Dynamics of a Torque-Free Variable Mass Cylindrical Body

This paper investigates the attitude behavior of a variable mass system of the rocket type in free flight. The initial shape of the system is taken to be that of a right circular cylinder, and continuous and substantial mass loss is permitted from one of the ends of the cylinder. The model used allows internal fluid flow within the system, and permits mass center shift as well as variations in system inertia. The focus is on the qualitative and quantitative characteristics of the system’s rotational motion as propellant is depleted. Results obtained indicate that mass loss has, in general, minimal effect on spin rate. The magnitude of the transverse angular velocity will generally decrease with time as a result of mass loss. However, it is possible for the transverse angular velocity magnitude to grow exponentially with time for certain system geometries and fuel depletion patterns. The analyses presented capture a great deal more of the vital characteristic of the attitude motion of the system than previous work in this area.

Stability of elliptical cylinders in two-dimensional channel flow.

The flow around rigid cylinders of elliptical cross section placed transverse to Poiseuille flow between parallel plates was simulated to investigate issues related to the tumbling of red blood cells and other particles of moderate aspect ratio in the similar flow in a Field Flow Fractionation (FFF) channel. The torque and transverse force on the cylinder were calculated with the cylinder freely translating, but prevented from rotating, in the flow. The aspect ratios (long axis to short axis) of the elliptical cylinders were 2, 3, 4, and 5. The cylinder was placed transversely at locations of y0/H = 0.1, 0.2, 0.3, and 0.4, where y0 is the distance from the bottom of the channel and H is the height of the channel, and the orientation of the cylinder was varied from 0 to 10 deg with respect to the axis of the channel for a channel Reynolds number of 20. The results showed that equilibrium orientations (indicated by a zero net torque on the cylinder) were possible for high-aspect-ratio cylinders at transverse locations y0/H < 0.2. Otherwise, the net torque on the cylinder was positive, indicating that the cylinder would rotate. For cylinders with a stable orientation, however, a transverse lift forced existed up to about y0/H = 0.25. Thus, a cylinder of neutral or low buoyancy might be lifted with a stable orientation from an initial position near the wall until it reached y0/H < 0.2, whereupon it would begin to tumble or oscillate. The dependence of lift and torque on cylinder orientation suggested that neutral or low-buoyancy cylinders may oscillate in both transverse location and angular velocity. Cylinders more dense than the carrier fluid could be in equilibrium both in terms of orientation and transverse location if their sedimentation force matched their lift force for a location y0/H < 0.2.

Dynamics of Axisymmetric Rockets in Free Flight

The attitude behavior of an axisymmetric, solid-propellant rocket in a torque-free environment is examined. The focus is on assessing the impact of substantial mass variation on the behavior of such systems. The main finding is that both the spin rate and the transverse angular velocity can differ substantially from those that would be observed if mass variation were neglected. The deviation is exacerbated by the presence of large amounts of propellant (variable mass) in the system. The attitude motion of such systems is also greatly influenced by the shape of the propellant grain.