Abstract:In order to achieve the strategic goal of "carbon peak and carbon neutrality", the development of a high proportion of renewable energy will be promoted continuously in our country. Therefore a new power system based on new energy will formed gradually. As a renewable clean source, the development and utilization of wind energy has become an important research direction. Studies have shown that the wind speed in the higher altitude is stronger and the wind direction is more stable. Therefore, breakthroughs in wind power generation can be achieved by capturing highaltitude wind energy. In order to ensure the safe, economical and efficient operation of the highaltitude kite power generation system, the design of its control system has extremely high requirements. This paper starts from the basic principles, development history and application status of several highaltitude wind power technologies. Then, a typical Yo-Yo structure kite is modeled. Based on this model, the principles and characteristics of various nonlinear control technologies are analyzed, and the principle of nonlinear model predictive control and simulation results of trajectory tracking control are described in detail. It summarizes that the key problems of highaltitude wind energy control include that control algorithm calculation is too consuming, the research of control system reliability is lack and the control methods are not intelligent.

Abstract:In this paper, the undetermined tensor method is used to Birkhoffize the Appell equation for a nonholonomic system. The generating functions are obtained according to the construction principle of generating functions, and then a Birkhoff symplectic scheme is given. Finally, a specific example of Appell equation is provided to verify the above theory and simulate this example. The results show that the preserving algorithm is more effective and superior with the evolution of time.

Abstract:There are a large number of high-speed micrometeoroids in space. The collision between micrometeoroids and spacecraft in orbit will lead to orbit deviation, performance degradation, structural damage, or even failure. Due to the instability of the Halo orbit, the effects of micrometeoroid collisions on the dynamic evolution of the Halo orbit around the Sun-Earth L₂ point are studied in this paper. First, an orbital model around the Sun-Earth L₂ is established, and the initial conditions of the Halo orbit are constructed using the differential correction method. Based on the Grün micrometeoroid flux model, the number of collisions between micrometeoroids and spacecraft is calculated. The velocity variation caused by the collision is evaluated. Then, the Runge-Kutta algorithm is used to solve the orbital dynamic equations of the Halo orbit, and the evolution of orbit deviation caused by the collisions is studied. Besides, the state transition matrix method is used to analyze the evolution of the initial state deviation, which is then compared with the numerical integration method. Finally, based on the state transition matrix method, the dynamic responses caused by different magnitudes and directions of the velocity increments are analyzed. It was found that the results obtained by the state transition matrix in a short time are basically consistent with the numerical integration method, while the final deviation can be calculated from the initial deviation with only one matrix multiplication, which is highly efficiency. The results also showed that due to the inherent instability of the Halo orbit, the initial small micrometeoroid collisions would grow rapidly. This may lead to more control fuel consumption and ultimately affect the life of the spacecraft. In addition, the direction of velocity increments caused by micrometeoroid collision has an important effect on the deviation transmission.

Abstract:Dynamics of axially moving laminated composite thinwalled beams is studied in the paper. Based on the variational asymptotic method (VAM) for the composite thin-walled beams, and using the EulerBernoulli beam model and Hamilton's principle, the dynamical equations of the composite thin-walled beam are established. The free vibration of the thinwalled beam is analyzed by the assumed mode method, and the accuracy of the modeling approach is verified by comparison to the other approaches. Then, the transverse vibration equation of the axially moving composite thin-walled beams is derived, which is solved numerically by the fourth-order Runge-Kutta method. Lastly, the effects of various fiber layup techniques and uniform velocities on the tip displacement response are investigated.

Abstract:Taking the central rigid body and flexible beam as examples, the dynamic modeling of the rigid-flexible coupling system lacking a strong component of mass and inertia is studied in this paper. The simulation results show that the established model can explain the cause of the dynamic stiffening phenomenon and calculate the system frequency at different rotating speeds, which can accurately explain the dynamic stiffening phenomenon of the rigid-flexible coupling system. At the same time, considering the translational motion of the central rigid body, the influence of the mass and inertia of the rigid body on the attitude angular vibration frequency of the system after maneuvering is obtained.

Abstract:High-G training for pilots has commonly performed in the centrifuge-based flight simulators. In this paper, algorithms for overload simulation in a threeaxis human centrifuge are developed and validated. To this end, a kinematic model is established for kinematic analysis. A moving average algorithm is employed to smooth the inputs and to alleviate the abrupt changes in pitch and roll angles of the centrifuge. An optimization algorithm for overload simulation is proposed and verified. The algorithm minimizes the error between the simulated and expected overloads to find the optimized kinematic variables of each axis of the centrifuge. Numerical results show that: (1) the moving average algorithm substantially alleviate the abrupt changes in pitch and roll angles of the centrifuge. (2) the proposed optimization algorithm is more accurate compared to traditional algorithms.

Abstract:Axle box bearing is a key rotating component in the bogie of high-speed trains. Under complex wheel/rail excitations, localized defects caused by fatigue, overload, etc. will threaten the operation safety of railway vehicles. In this paper, a coupled dynamic model of axle box bearing-flexible axle box-vehicle system with different bearing localized defects is established using UM/Simulation cosimulation. The vibration responses of axle box with fault on outer raceway, inner raceway and roller under track irregularities and wheel ovalization are studied. In addition, the fault responses from typical points of axle box and rotary arm are compared to select the optimal mounting position of accelerometer on the axle box. The simulated results are helpful to the condition monitoring and fault diagnosis of axle box bearings in industrial applications.

Abstract:Aiming at the steering problem of the multi-articulated virtual rail train, an all-wheel active steering control method is proposed based on the idea that the rear vehicles follow the traveling trajectory of the head one. Firstly, the traveling trajectory of the head vehicle is computed as the target path and stored in the shift register. Secondly, according to the lateral deviation of the rear axle of the vehicle from its target path, the steering angle of the rear wheel of the vehicle is determined based on the PID controller and the Stanley algorithm, and the steering angle of the front wheel of the rear vehicle is further computed using the principle of Ackermann steering geometry. Finally, the co-simulation platform of TruckSim and Matlab/Simulink is established and the simulation analysis is carried out with typical operation conditions. Obtained results show that the control method designed improves the following performance of the trailer module to the tractor module, reduces the articulation forces between the adjacent vehicles, the center-of-mass lateral deflection angle of the vehicle body and the lateral force of the tires, and thus improves the stability of the train during the steering.

Abstract:The braking performance of trains directly affects the safety, stability, and stability of vehicle operation. This article studies the impact of installing a linear track eddy current braking system on the braking dynamics characteristics of high-speed trains with different power distribution methods. Firstly, a train dynamics simulation model was established for two grouping modes, 6M2T and 4M4T, and its effectiveness was verified by comparing it with experimental data on the line. Based on this model, the dynamic characteristics of trains at different speeds under different power distribution forms were studied. The Sperling index, derailment coefficient, wheel load reduction rate, and wheel rail interaction force of the the 1st, 5th, and 8th carriages were studied for the combined braking conditions of coasting, electro-pneumatic braking, and linear track eddy current braking system. The research results showed that the dynamic force distribution method and braking system have a significant impact on the dynamic performance parameters of the vehicle, The key dynamic performance indicators involved all meet the safety limit standards, and the research results provide theoretical reference for installing a linear track eddy current braking system on highspeed trains.

Abstract:As a key actuator in a flight control system, the performance of an electromechanical actuator has a significant impact on the dynamic responses of the system. Based on the structural composition of the directdrive electromechanical actuator, a simulation model is established that considering the control of a permanent magnet synchronous motor and nonlinear factors of a planetary roller screw mechanism. The step responses of the system under the current vector control of “id=0” are studied. The results show that the system based on the threeclosedloop servo control strategy of the PMSM has the good dynamic performance under different position commands with the step signal. With the comparison to the literature, it is shown that the proposed simulation model of the electromechanical actuator under this control strategy is effective.

Abstract:Due to its sensitivity to temperature and the significant influence on vibration isolation performance, it is crucial to investigate the dissipation characteristic and parameter identification of metal rubber vibration isolation structure in thermal environments. In this study, a dual-layer metal rubber vibration isolation structure is designed. The influence of environmental temperature on the dissipation characteristic of the isolation structure is investigated. A nonlinear constitutive model for the dual-layer metal rubber isolation structure is established. At first, a series of dissipation characteristic tests are conducted on the isolation structure at different temperatures. Dissipation characteristic curves of the isolation structure under various operating conditions are obtained. The dissipation coefficient, dissipated energy, and maximum deformation potential energy are calculated. The effects of temperature, amplitude, and frequency on the dissipation characteristic of the dual-layer metal rubber isolation structure are analyzed. Then, the parameters of the isolation structure are identified using nonlinear least squares method. A nonlinear functional constitutive model for the metal rubber isolation structure is established. It can accurately predict the dissipation characteristic curves of the isolation structure under different operating conditions.