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1.
《中国航空学报》2021,34(5):573-584
To ensure tasks can be completed after a free-swinging joint failure occurs, a multi-stage regulation strategy of space manipulators is proposed. Considering all terms of the dynamics equation, an evaluation model of the regulation ability (EMRA) of active joints over the fault joint is established based on the fuzzy entropy. And then a multi-stage regulation strategy based on the EMRA is designed to regulate the fault joint. The strategy divides the regulation process into several stages, and select a certain active joint to regulative the fault joint in every stage. With this multi-stage regulation strategy, the fault joint can be regulated to the desired angle without huge torque on regulative joints. The simulation is carried out with a 7-DOF space manipulator, verifying the correctness and effectiveness of the multi-stage regulation strategy. The strategy has three advantages: Coriolis and centrifugal terms are both considered for the first time in selecting the regulative joint, making the selection result more in line with the actual regulation process; The influence of the model uncertainty is eliminated in establishing the EMRA, making the evaluation of regulative ability more precise; The fault joint is successfully regulated to the desired angle without huge torque on regulative joints. 相似文献
2.
Fault mode probability factor based fault-tolerant control for dissimilar redundant actuation system
This paper presents a Fault Mode Probability Factor (FMPF) based Fault-Tolerant Control (FTC) strategy for multiple faults of Dissimilar Redundant Actuation System (DRAS) composed of Hydraulic Actuator (HA) and Electro-Hydrostatic Actuator (EHA). The long-term service and severe working conditions can result in multiple gradual faults which can ultimately degrade the system performance, resulting in the system model drift into the fault state characterized with parameter uncertainty. The paper proposes to address this problem by using the historical statistics of the multiple gradual faults and the proposed FMPF to amend the system model with parameter uncertainty. To balance the system model precision and computation time, a Moving Window (MW) method is used to determine the applied historical statistics. The FMPF based FTC strategy is developed for the amended system model where the system estimation and Linear Quadratic Regulator (LQR) are updated at the end of system sampling period. The simulations of DRAS system subjected to multiple faults have been performed and the results indicate the effectiveness of the proposed approach. 相似文献
3.
分析了 K8、 JL8机翼接头孔精加加后与检验量规位置协调的条件,介绍了为提高它们之间协调准确度所采取的措施及其效果。 相似文献
4.
L. B. F. M. Waters 《Space Science Reviews》1992,61(1-2):25-43
In this review the IR emission from circumstellar material is discussed, both of ionized gas and dust grains, and the astrophysical information that can be extracted from such observations. Some emphasis is placed on the possibilities of stellar IR astronomy using a large space-borne telescope, especially with respect to the much better spatial and spectral resolution of such a telescope compared to the current generation of ground-based and space IR telescopes. 相似文献
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介绍美国和台湾用对流炉和沸腾床制备多孔高氯酸铵(PAP)及包覆法。同时介绍了用PAP部分取代HTPB体系推进剂中的AP和全部取代双基推进剂中的超细AP的燃烧性能研究。结果表明,用包覆的PAP取代超细AP是提高燃速的较好途径。 相似文献
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液体压力激波加工技术研究 总被引:3,自引:1,他引:3
机械产品的零部件,通常需要通过成形与改性才具有所需形状及实用功能,本文提出了一种新型材料成形与改性加工的方法——液体压力激波加工。采用脉冲超声波聚焦技术,通过压电陶瓷激波发生器在液体介质中产生高能瞬时压力激波,对材料进行冲击,产生变形或表面改性。经过理论研究和试验验证,初步掌握了液体压力激波的产生、激波能量的控制和激波加工的动力学机制。这种加工方法具有能量可控性好、成本低廉和安全高效等优点,非常适合具有复杂结构和型面的中小零件加工,是一种颇具竞争力的先进制造技术手段。 相似文献
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电阻式传感器的核心部件——电阻应变计是目前最常用的应力分析的敏感元件。也常用于测量力、压力、扭矩和加速度等物理量。作者简要回顾了电阻应变计的发展历史,介绍了电阻应变计的结构、分类及现状,展望了电阻式传感器的前景。 相似文献
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