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21.
Kun Yan Mou Chen Bin Jiang Qingxian Wu 《International Journal of Adaptive Control and Signal Processing》2019,33(4):684-711
This paper proposes a robust active fault‐tolerant control (AFTC) approach for medium‐scale unmanned autonomous helicopter (UAH) with rotor flapping dynamics in the presence of unknown external disturbances and actuator faults. The robust items are adopted to improve the disturbance rejection capability of the UAH system. The adaptive fault observers are developed to estimate the fault parameters and the fault detection (FD) algorithms are presented to detect the actuator faults in different loops. In order to obtain satisfactory trajectory tracking performance, a backstepping‐based robust AFTC scheme is designed for the simplified 6‐degree‐of‐freedom (DOF) UAH nonlinear dynamics model and the global stability of the closed‐loop system is proved by using the Lyapunov method. Several groups of numerical simulation results are carried out to verify the effectiveness of the developed method. 相似文献
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结合高耸落地反应器构架的特点,以具体工程为依托,对构架风荷载计算、梁柱选型及斜撑布置、框架柱地脚螺栓计算及基础计算进行了综述,为高耸落地反应器构架设计提供了指导。 相似文献
24.
Daniele Martella Sara Nocentini Dmitry Nuzhdin Camilla Parmeggiani Diederik S. Wiersma 《Advanced materials (Deerfield Beach, Fla.)》2017,29(42)
Grabbing and holding objects at the microscale is a complex function, even for microscopic living animals. Inspired by the hominid‐type hand, a microscopic equivalent able to catch microelements is engineered. This microhand is light sensitive and can be either remotely controlled by optical illumination or can act autonomously and grab small particles on the basis of their optical properties. Since the energy is delivered optically, without the need for wires or batteries, the artificial hand can be shrunk down to the micrometer scale. Soft material is used, in particular, a custom‐made liquid‐crystal network that is patterned by a photolithographic technique. The elastic reshaping properties of this material allow finger movement, using environmental light as the only energy source. The hand can be either controlled externally (via the light field), or else the conditions in which it autonomously grabs a particle in its vicinity can be created. This microrobot has the unique feature that it can distinguish between particles of different colors and gray levels. The realization of this autonomous hand constitutes a crucial element in the development of microscopic creatures that can perform tasks without human intervention and self‐organized automation at the micrometer scale. 相似文献
25.
Adaptive trajectory generation based on real-time estimated parameters for impaired aircraft landing
《International journal of systems science》2012,43(15):2733-2751
ABSTRACTThis paper is motivated by a need to address the challenge of securing a safe landing after suffering from inflight impairment. In this paper, a new adaptive generalised model predictive static programming (G-MPSP) is developed to generate a safe emergency landing trajectory for impaired aircraft. Utilising the computationally efficient G-MPSP framework, the proposed algorithm enables adaptation of model parameters based on the prediction errors to ensure reasonable guidance performance. Based on the estimated parameters, a feasible landing trajectory is then generated by the flexible finite-horizon G-MPSP with input constraints. The integrated approach features explicit closed-form solutions for both parameter estimation and trajectory generation. Its effectiveness is demonstrated by simulations in the presence of parameter uncertainties and noises and by comparison studies with the non-adaptive G-MPSP. 相似文献
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采用了在冲床上两工位无搭边冷冲孔—落料+挤压的复合工艺塑性成形高颈铝法兰管的先进工艺。与传统冷挤压工艺相比省工省料,生产效率高,制件质量好。该工艺在冲挤之前先对条料进行固溶处理,冲挤之后再进行时效处理,从而达到了挤压力量小,制件精度好,外形和性能俱佳的效果。 相似文献
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An autonomous entry guidance law is developed based on 3-D analytical glide formulas, where the downrange formula is used to plan the longitudinal reference profile in order to meet the downrange and final energy requirements, and the crossrange formula is used to regulate the bank reversals in order to eliminate the crossrange error. As the analytical glide formulas ignore the effects of the Earth׳s rotation, a series of strategies is proposed for compensating these effects, which provides the guidance with the capability of steering the hypersonic glide vehicle with high Lift to Drag ratio (L/D) to any place of the world accurately. The compensation strategies can be summarized into two parts: (1) the reference profiles are properly adjusted by roughly evaluating the effects of the Earth׳s rotation on the aerodynamic profiles over the whole flight, which can compensate most of the effects; (2) the current effects are accurately evaluated and then the guidance commands are slightly modulated for compensating the remaining effects. Due to careful design, the strategies will not result in drastic changes in the Angle of Attack (AOA) and can keep the bank angle almost constant during most of flight. 相似文献
28.
This paper considers the pursuing or target tracking problem where an autonomous robotic vehicle is required to move towards a maneuvering target using range‐only measurements. We propose a switched logic‐based control strategy to solve the pursuing problem that can be described as comprising a continuous cycle of two distinct phases: (1) the determination of the bearing, and (2) the steering control of the vehicle to follow the direction computed in the previous step while the range is decreasing. We provide guaranteed conditions under which the switched closed‐loop system achieves convergence of the relative distance error to a small neighborhood around zero. Simulation results are presented and discussed.Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
29.
介绍了一种自动寻迹智能车的设计,研究了采用光电传感器作为路径采集模块实现自动寻迹的软硬件设计方法。系统采用Freesca le16位单片机MC9S12X S128为核心控制器,利用11个光电传感器构成的光电传感器阵列采集路面信息,单片机获得传感器采集的路面信息和车速信息,经过分析后控制智能车的舵机转向,同时对直流电机进行调速,从而实现智能车沿给定的黑线快速平稳地行驶。 相似文献
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