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为解决双绳驱动空中机械臂协同搬运时的接触控制问题,提出了一种基于非奇异快速终端滑模的阻抗控制策略。首先,考虑绳驱动机制的柔性效应,建立计及关节柔性的双机协同系统动力学模型,并推导出任务空间内的阻抗方程。然后,设计协同阻抗控制策略,借助非奇异快速终端滑模面来加快系统状态量的收敛速度,利用幂次函数削弱输出力矩抖振效应。同时,在Lyapunov框架下分析了所设计控制器的稳定性。最后,通过控制器性能比较仿真和协同搬运仿真对所提控制策略的有效性进行了验证。结果表明,所提控制器响应速度快、控制精度高及稳定性好,能够有效抑制系统抖振。 相似文献
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现代的战场环境复杂多变,机载雷达除了需要具备较高的目标分辨力来完成目标探测任务外,还应具备大时间带宽积、低截获因子、低功率谱幅度、不均匀频谱及最大不确定性等良好的射频隐身性能。为了设计性能良好的射频隐身波形,本文以脉间脉内双重频率编码(interpulse Costas and intrapulse Costas,Costas-Costas)信号的时频特征为基础,在保持子脉冲间频率捷变的同时,在子脉冲内采用Costas频率编码和非线性调频相结合的复合调频方式,得到脉间频率编码脉内复合调频(interpulse Costas frequency coded and intrapulse Costas and NLFM composite frequency modulation,Costas-CN)雷达信号。与单一调制信号、脉间频率编码脉内非线性调频(interpulse Costas frequency coded and intrapulse nonlinear frequency modulation,Costas-NLFM)信号和Costas-Costas信号相比,该信号极大地增... 相似文献
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乡村振兴示范镇建设是实施乡村振兴战略的平台之一,产业发展为乡村振兴提供了重要支撑,促进了镇域经济的高质量发展。本文以彬州市北极镇为研究对象,采用实地调研、问卷调查等方法,对北极镇产业现状进行分析,总结了北极镇现状问题及发展优势,从全产业统筹、塑造品牌优势和建设人才队伍3个方面提出了一系列针对性的策略。在探索农业产业类乡村振兴示范镇发展新路径的同时,延伸至整个乡村发展范畴,推动乡村产业发展,助力乡村全面振兴。 相似文献
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Hong LI 《等离子体科学和技术》2018,20(12):125504
Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters (HETs). In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency. 相似文献
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面对新技术在制鞋业各环节中的创新应用和具有数控技术为特征的自动化鞋机设备则呈现高增长销售态势。在传统鞋机与自动化鞋机,平淡与激增的销售差异状况背后,专家认为,9011年中国鞋机市场酝酿着巨大的市场需求机遇,但产业产销失衡,升级乏力,鞋机企业要苦练内功,升级转型,才能使企业走上可持续发展之路。 相似文献
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日前,记者从国家科学技术部最近公示的2013年度国家重点新产品计划项目获悉,广东大族粤铭激光科技股份有限公司(股票代码:002008)“激光智能LCD修补机”项目被列入国家重点新产品。 相似文献
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