共查询到20条相似文献,搜索用时 11 毫秒
1.
《European Journal of Mechanics - A/Solids》2006,25(5):854-866
This paper considers the problem of optimal controlling a spacecraft programmed motion without its angular velocity measurements. An optimal control law that stabilizes this programmed motion and minimizes the cost that transfers the spacecraft from arbitrary initial state to the programmed state is obtained as a function of the kinematics attitude parameters and their estimates as well as the angle of programmed rotation. The stabilizing properties of the proposed controllers are proved using Liapunov techniques. Numerical simulation study is presented. 相似文献
2.
D. I. Bugrov A. V. Lebedev V. A. Chertopolokhov 《Moscow University Mechanics Bulletin》2014,69(1):25-27
The problem of finding the angular rotation velocity of a body using the orientation matrix whose elements are determined by a tracking system is considered. Two methods of solving this problem are compared. One of them is based on the representation of the function in the form of a partial sum of the Fourier series and the second one is based on using the Savitzky-Golay filter. 相似文献
3.
Farah Bouakrif 《Meccanica》2017,52(4-5):861-875
This paper deals with trajectory tracking control for rigid robot manipulators with model uncertainty and subject to external disturbances. The approach suggested herein does not require velocity measurement, because these robots are not equipped by tachometers for velocity measurement. For this purpose, two observers are proposed. The first is a velocity observer to estimate the missing velocity, and the second one is a disturbance observer to estimate the disturbance. Thereafter, these observers are integrated with the controller. Furthermore, semi-global asymptotic stability conditions of the composite controller consisting of a nonlinear controller, the velocity observer and the disturbance observer are established, and an estimate region of attraction is also given. This proof is based on Lyapunov theory. Finally, simulation results on two-links manipulator are provided to illustrate the effectiveness of the velocity observer based control using disturbance estimation (namely VOBCDE), when the Coulomb and viscous friction is considered as an external disturbance. 相似文献
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In this paper, an adaptive fuzzy sliding mode control (AFSMC) for Micro-Electro-Mechanical Systems (MEMS) triaxial gyroscope is proposed. First, a novel adaptive identification approach with sliding mode controller which can identify angular velocity and other system parameters is developed. And in order to reduce the chattering, an AFSMC is designed to approximate the upper bound of the uncertainties and external disturbances. Based on Lyapunov methods, these adaptive laws can guarantee that the system is asymptotically stable. Numerical simulations are investigated to verify the effectiveness of the proposed AFSMC scheme. 相似文献
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Nonlinear Dynamics - In this paper, the problem of distributed finite time six-degree-of-freedom (6-DOF) synchronization control for spacecraft formation flying (SFF) with the external disturbances... 相似文献
6.
Trajectory tracking control for tractor-trailer vehicles: a coordinated control approach 总被引:1,自引:0,他引:1
Nonlinear Dynamics - This article presents a coordinated control approach for a tractor-trailer vehicle such that a satisfactory trajectory tracking performance can be achieved, simultaneously... 相似文献
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This paper describes a new stochastic control methodology for nonlinear affine systems subject to bounded parametric and functional
uncertainties. The primary objective of this method is to control the statistical nature of the state of a nonlinear system
to designed (attainable) statistical properties (e.g., moments). This methodology involves a constrained optimization problem
for obtaining the undetermined control parameters, where the norm of the error between the desired and actual stationary moments
of state responses is minimized subject to constraints on moments corresponding to a stationary distribution. To overcome
the difficulties in solving the associated Fokker–Planck equation, generally experienced in nonlinear stochastic control and
filtering problems, an approximation using the direct quadrature method of moments is proposed. In this approach, the state
probability density function is expressed in terms of a finite collection of Dirac delta functions, and the partial differential
equation can be converted to a set of ordinary differential equations. In addition to the above mentioned advantages, the
state process can be non-Gaussian. The effectiveness of the method is demonstrated in an example including robustness with
respect to predefined uncertainties and able to achieve specified stationary moments of the state probability density function. 相似文献
8.
Laminar-to-turbulent flow transition in microchannels can be useful to enhance mixing and heat transfer in microsystems. Typically, the small characteristic dimensions of these devices hinder in attaining higher Reynolds numbers to limit the total pressure drop. This is true especially in the presence of a liquid as a working medium. On the contrary, due to lower density, Reynolds number larger than 2000 can be easily reached for gas microflows with an acceptable pressure drop. Since microchannels are used as elementary building blocks of micro heat exchangers and micro heat-sinks, it is essential to predict under which conditions, the laminar-to-turbulent flow transition inside such geometries can be expected. In this paper, experimental validation of a two equations transitional turbulence model, capable of predicting the laminar-to-turbulent flow transition for internal flows as proposed by Abraham etal. (2008), is presented for the first time for microchannels. This is done by employing microchannels in which Nitrogen gas is used as a working fluid. Two different cross-sections namely circular and rectangular are utilized for numerical and experimental investigations. The inlet mass flow rate of the gas is varied to cover all the flow regimes from laminar to fully turbulent flow. Pressure loss experiments are performed for both cross-sectional geometries and friction factor results from experiments and numerical simulations are compared. From the analysis of the friction factor as a function of the Reynolds number, the critical value of the Reynolds number linked to the laminar-to-turbulent transition has been determined. The experimental and numerical critical Reynolds number for all the tested microchannels showed a maximum deviation of less than 12%. These results demonstrate that the transitional turbulence model proposed by Abraham etal. (2008) for internal flows can be extended to microchannels and proficiently employed for the design of micro heat exchangers in presence of gas flows. 相似文献
9.
Yuan Dossmann Alexandre Paci Francis Auclair Jochem W. Floor 《Experiments in fluids》2011,51(4):1013-1028
We present experimental results of internal wave generation by the oscillation of a two-dimensional topography in a linearly
stratified fluid. Simultaneous synthetic schlieren and particle image velocimetry high-resolution measurements are made in
a series of experiments with different forcing frequencies, all other parameters being kept constant. This setup allows us
to obtain the potential and kinetic components of the mechanical energy transported by the internal wave beam for different
relative values of the maximum topographic slope to the slope of internal wave phase lines, in a quasi-linear regime. Measurements
are carefully validated and a combined wavelet and principal component analysis are carried out to extract the most energetic
physical processes associated with the internal waves. The duration of the transient regime is evaluated in order to consider
only results during the steady regime. We discuss the evolution of the radiated mechanical energy with respect to the forcing
frequency, and we show that it reaches a maximum in the near-critical regime, in good agreement with recent numerical and
theoretical works. New insights are provided about the role played by the relative values of the maximum topographic slope
and the internal wave beam slope in the efficiency of energy transfers from barotropic tide to radiated internal waves. This
study is a step toward a better quantification of the energy transported away by internal waves and available for mixing the
ocean. 相似文献
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Based on single-lane traffic model, a two-lane traffic model is presented considering the velocity difference control signal. The stability condition of the model is obtained by the control theory. The delayed feedback control signal is added to the two-lane model, and the corresponding stability condition is derived again. The numerical simulations show that as the stability conditions are satisfied, the small disturbance will not amplify with and without control signal. In the meantime, the stability is strengthened as the control signal is considered. So the control signal would suppress the traffic disturbance successfully. 相似文献
12.
给出了计算粉尘层流火焰速度的直接方法,此法简便易行,在粉尘浓度较低时,计算精度较高。实验结果表明:粉尘浓度对火焰传播速度和燃烧速度有很大的影响,粉尘浓度过大时,粒子运动轨迹就难观测,用直接法计算层流火焰速度的误差增大;管径大小也对燃烧速度有很大影响;小管径中的所得值比大管径中的所得值约低8%。 相似文献
13.
In this paper, a mathematical model is first established for an electromagnetic actuated polymer composite-based MEMS hard-magnetic micromirror. The model consists of the analyses of the mechanical parts for torsional scanner, the electro-coils parts and the magnetic actuator parts of the hard-magnetic films. To illustrate the effectiveness of such a model, the static and dynamic performance is further analyzed using both finite element method and it is experimentally validated. The experimental results show that our models are valid. Finally, considering the high performance requirements of optical switching applications proportional-integral-derivative (PID) controller with incomplete differentials and the integral sliding mode surface with PID form controller which is based on the established mathematical model is designed to improve its transient response. And the experimental results of set-point regulation have demonstrated that the 95% setting time is shortened from 45 to 10 ms while improving the overshoot. 相似文献
14.
Nonlinear Dynamics - This research proposes an adaptive terminal sliding mode control strategy dedicated to motion tracking control of an electrostatic-actuated nanopositioning system. The... 相似文献
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无陀螺捷联惯导系统(GFSINS)是用加速度计的合理空间组合解算出载体的角速度。载体角速度的解算精度是GFSINS的技术关键。在分析GFSINS九加速度计配置方案的基础上,提出一种新的角速度融合算法,消除该方案解算过程中开方计算及符号判断带来的误差。该算法还明显抵消了加速度计输出中包含的常值零点偏移误差和温度漂移误差等,具有实时性好、计算量小、通用性强的优点。仿真计算表明该算法可行,并能在一定程度上提高系统解算精度。 相似文献
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This paper presents a robust nonlinear control strategy to deal with the trajectory tracking control problem for a laboratory helicopter. The helicopter model is considered as a nominal one with uncertainties such as unmodeled nonlinear dynamics, parametric uncertainties, and external disturbances. The proposed control approach incorporates the feedback linearization technique (FLT) and the signal compensation technique. The FLT is first applied to achieve the linearization of the nominal nonlinear model for reducing the conservation of the robust compensator design. A nominal controller based on the linear quadratic regulation method is designed for the linearized nominal system, whereas a robust compensator is introduced to restrain the influences of the uncertainties. It is shown that the trajectory tracking errors of the closed-loop system are ultimately bounded, and the boundaries can be specified by choosing the controller parameters. Simulation and experimental results on the lab helicopter verify the effectiveness of the proposed method. 相似文献
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The observation motivating this contribution was a perceived lack of expeditious deformable terrain models that can match in mobility analysis studies the level of fidelity delivered by today’s vehicle models. Typically, the deformable terrain-tire interaction has been modeled using Finite Element Method (FEM), which continues to require prohibitively long analysis times owing to the complexity of soil behavior. Recent attempts to model deformable terrain have resorted to the use of the Discrete Element Method (DEM) to capture the soil’s complex interaction with a wheeled vehicle. We assess herein a DEM approach that employs a complementarity condition to enforce non-penetration between colliding rigid bodies that make up the deformable terrain. To this end, we consider three standard terramechanics experiments: direct shear, pressure-sinkage, and single-wheel tests. We report on the validation of the complementarity form of contact dynamics with friction, assess the potential of the DEM-based exploration of fundamental phenomena in terramechanics, and identify numerical solution challenges associated with solving large-scale, quadratic optimization problems with conic constraints. 相似文献