305 research outputs found

    Motion Simulation of a New High Overload Flight Simulator

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    提出一种新型的基于绳牵引并联机器人技术的飞行模拟器,针对其大过载机动特性进行仿真分析。首先根据绳牵引并联机器人理论,设计了9根绳牵引具有6自由度的运动平台;通过建立平台动力学模型,设计了对干扰项进行补偿的前馈PD控制率;其中前馈项主要确保动态过程中绳索处于张紧状态。进一步给出了系统控制稳定性分析;并以大过载机动和单自由度俯仰振荡运动为例进行了数值仿真。分析结果表明,在大过载机动情况,瞬时正加速度超过4 g,平台位置能够迅速衰减并稳定;基于绳拉力前馈,可以避免绳索松弛,能够满足飞行员过载训练;俯仰运动也具有较好的跟踪特性。研究成果可为进一步分析工作空间、动态特性及控制稳定性等奠定基础,为绳牵引并联支撑的飞行模拟器设计提供指导与依据。A new kind of flight simulator based on the cable-driven parallel robot was proposed, and the over-load maneuver properties were emphatically analyzed. According to the fundamental theories of cable-driven parallel robot, the motion platform suspended by nine cables with a six-DOF is designed. The dynamic equations of the platform is established, and a PD control law incorporating feedforward term and disturbance compensation term is given. The stability analysis of control law is also made. Finally, numerical simulations of overload maneuver and pitch oscillation are taken as examples, and results show that the platform can achieve a high overload with more than 4 g, meanwhile the position attenuates and tends to be stable in a short time. The cable tension is also guaran-teed to be positive and secure during the motion process. Moreover, the case of pitch oscillation shows a good track-ing property. Researches studied above could lay on foundation for the workspace analysis, dynamics and control stability, and furthermore, provide guidance and evidence for the practical design of flight simulator.航空科学基金(20141368007); 福建省自然科学基金计划(2016J05134)资

    基于作图法和解析法的铰链四杆机构瞬心线研究

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    针对机械原理中平面铰链四杆机构的瞬心线问题,采用作图法和解析法进行研究,清楚地展示了动瞬心线和定瞬心线的作图过程,并以解析的方式给出了两条瞬心线的轨迹方程,同时还解释了动瞬心线沿定瞬心线做无滑动的滚动,有利于学生加深理解,为瞬心线机构的分析设计提供帮助。In view of the centrode problem of planar hinge four-bar linkage in the course of mechanical principle, method of graphic and analytic is applied to clearly show the drawing process of moving centrode and fixed centrode, as well as the trajectory equation of centrode in an analytic mode.The reason of moving centrode rolling without sliding along the fixed centrode is also explained in order to help student understand the theory, and design the centrode mechanism

    风洞试验绳牵引并联支撑技术研究进展

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    新型飞行器的研制越发强调先进的飞行性能,这对风洞试验模型支撑技术提出了高的要求,为扩展风洞试验的能力,迫切需要研究新型的智能支撑技术。绳牵引并联支撑是基于机器人技术的一种新型机构,具有刚度较大,动态性能良好等优点,为风洞试验提供了一种新的手段。首先,全面论述了绳系支撑在风洞试验中的应用,并给出动态分析;进一步根据绳牵引并联支撑技术的特点,将其分为可实现受迫运动的冗余约束支撑,以及可实现受迫+自由运动的欠约束支撑;其次,重点阐述了冗余约束与欠约束两类支撑系统的若干关键技术问题及其研究进展;最后,指出绳牵引并联支撑技术的发展方向是具有可重构性和智能化。可为绳牵引并联支撑技术在风洞试验中的工程应用提供一定的理论指导与技术支持。国家自然科学基金(11472234,11702232,11072207,50475099);;中央高校基本科研业务费专项资金(20720180071)~

    论专利无效宣告的追溯力——认真对待知识产权的特殊性

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    专利宣告无效后,对已经执行的侵权赔偿金、已经履行的专利许可与转让合同,专利侵权赔偿、许可与转让费作为不当得利予以返还的观点,属于民法具体规则套用性的论证,这种观点完全忽视了知识产权的特殊性。实际上,我国《专利法》第47条对专利无效宣告追溯力的安排因契合知识产权的特殊性而具有合理性与正当性,应该予以坚持。由此推及知识产权的其他特殊制度,应该认真对待知识产权的特殊性,以此为基础进行制度构建与理论思考

    基于RBF神经网络补偿的一种绳牵引并联机器人支撑系统的力/位混合控制

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    为了保证用于风洞试验的绳牵引并联机器人支撑系统(Wire-Driven Parallel Robot Support System WDPRSS)的末端执行精度,设计了一种采用Hamilton-Jacobi Inequality(HJI)定理并基于RBF神经网络补偿的力/位混合控制。通过对WDPRSS的动力学建模分析,选择以位姿作为变量建立WDPRSS的整体动力学方程。将所设计的力/位混合控制代入到整体动力学方程中得误差闭环系统,对闭环系统进行稳定性分析,结果证明WDPRSS是趋于渐进稳定特性的。对八绳牵引的并联机器人支撑系统进行MATLAB/SIMULINK仿真实验,仿真结果表明所设计的力/位混合控制是正确有效的,满足控制精度要求,并将所设计的力/位混合控制与PD控制进行对比分析。最后,通过样机实验验证了所提控制方案的有效性。仿真实验和样机实验为在样机上进行技术实现提供了理论依据和实验基础

    政府审计移送对司法效率的影响

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    党的十八届三中全会以来,我国全面深化司法体制改革,着力推进社会体制改革。基于审计移送制度,本文以2001~2016年我国31个省(自治区、直辖市)的数据为样本,考察了政府审计对司法效率的影响以及司法公正水平对这一过程的调节作用;在此基础上进一步研究了法制环境对政府审计治理效果的影响。研究发现:政府审计移送力度越大,司法机关的司法效率越高,与此同时,司法公正水平对政府审计提高司法效率的效果具有明显的调节作用。研究结果表明,充分发挥审计机关移送线索的作用,需要从审计移送力度入手,加强部门间协作,这为我国审计机关和司法机关的高效协作提供了有益的思路

    风洞试验绳牵引并联支撑系统自适应滑模控制

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    针对绳牵引并联支撑系统在风洞试验中的应用,提出一种自适应滑模控制方法以提高飞行器模型动态试验的运动精度.首先,详细分析了系统不确定因素,并重点考虑了气动力与绳弹性变形的影响,重构了系统动力学方程;基于奇异摄动理论,提出一种复合控制律,其中对慢变状态量采用自适应连续非奇异终端滑模控制,对快变状态量采用微分控制;通过李雅普诺夫函数法对系统的稳定性进行了分析,确定了控制律中微分增益项的影响.最后,以两种典型的动态轨迹为例,考虑气动力建模,对所设计控制律进行多参数仿真分析.结果表明该复合控制律可以减小绳弹性以及气动力等不确定性参数对跟踪误差的影响,提高运动控制精度,因此该控制方法有效可行,可为绳牵引并联支撑的动态试验应用提供理论指导.国家自然科学基金项目(11702232,11472234)中央高校基本科研业务费(20720180071)资助~

    AERODYNAMIC MOMENTS CONTROL OF WING MODEL USING PLASMA JET

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    为考察火花放电等离子体射流控制机翼气动力矩的效果,在NACA0021平直机翼模型上安装火花放电等离子体射流发生器,通过改变射流发生器安装位置、射流角度及加载电参数,研究其控制机翼模型气动力矩的性能及机理。在NACA0021机翼模型近前缘处,布置2个火花放电等离子体射流发生器,采用气动力测量技术,在来流风速为20 m/s时测得,攻角-4°~10°时,滚转力矩系数最大减小了0.0024,攻角为12°~16°时,滚转力矩系数最大增加了0.0021;偏航力矩系数最大减小了0.00097。实验研究结果表明:等离子体射流可改变机翼模型横航向气动力矩,并可通过改变射流角度和加载电压频率调节等离子体射流控制横向气动力矩的效果。To investigate the control effect of Spark Discharge Plasma Jets(SPJs) on the aerodynamic moments of a wing, SPJ generators were used for active flow control experimental study on an NACA0021 straight wing model. The location of SPJ generators along the chord of the airfoil, the jet flow direction relative to the chord, and the driving voltage parameters were changed to research the control effect and mechanism of SPJ generators on the aerodynamic moments of a wing model. The aerodynamic moments were measured with a six-component balance at a wind speed of 20 m/s. Two SPJ generators, arranged near the leading edge, reduced the rolling moment coefficient by a maximum of 0.0024 for angles of attack-4°~10°, but increased the rolling moment coefficient by a maximum of 0.0021 for angles of attack 12°~16°. The yaw moment coefficient was reduced by a maximum of 0.00097. The results show that aerodynamic moments control of wings can be realized using SPJs. The control effect of SPJs on the aerodynamic moments is changeable by adjusting the driving voltage frequency and the jet flow direction relative to the chord.航空科学基金项目(20141368007);; 福建省自然科学基金项目(2010J01014

    风洞试验绳牵引并联支撑系统自适应滑模控制

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    针对绳牵引并联支撑系统在风洞试验中的应用,提出一种自适应滑模控制方法以提高飞行器模型动态试验的运动精度。首先,详细分析了系统不确定因素,并重点考虑了气动力与绳弹性变形的影响,重构了系统动力学方程;基于奇异摄动理论,提出一种复合控制律,其中对慢变状态量采用自适应连续非奇异终端滑模控制,对快变状态量采用微分控制;通过李雅普诺夫函数法对系统的稳定性进行了分析,确定了控制律中微分增益项的影响。最后,以两种典型的动态轨迹为例,考虑气动力建模,对所设计控制律进行多参数仿真分析。结果表明该复合控制律可以减小绳弹性以及气动力等不确定性参数对跟踪误差的影响,提高运动控制精度,因此该控制方法有效可行,可为绳牵引并联支撑的动态试验应用提供理论指导.国家自然科学基金项目(11702232,11472234);;中央高校基本科研业务费(20720180071)资

    Feasibility analysis of WDPR support cone model application in hypersonic wind tunnel

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    绳牵引并联机构(WDPR)能够有效调整飞行器模型的位姿,为扩展风洞试验能力提供了一种新型支撑手段,具有很大的应用潜力。本文将对其在高超声速风洞中; 应用所涉及的稳定性与气动干扰问题进行研究。以10°尖锥标椎模型为例,设计了8绳牵引的并联支撑系统,可以通过调整绳长控制模型的位置和姿态。模拟了气; 动载荷作用下支撑系统的稳定性,优化牵引绳直径。基于构建的三维模型,借助CFD软件进行气动计算,包括马赫数为7.8时,不同迎角下绳牵引并联支撑锥体; 模型的气动力系数,通过与无绳支撑结果以及文献试验数据进行比较,表明在小迎角情况下,绳系支撑引起的气动干扰相对误差较小,但会随迎角的增大而增加。此; 外,分别对弯刀支撑和绳牵引并联支撑进行了模态分析,对比了2种支撑的固有频率。结果显示绳系支撑固有频率较高,系统刚度较大。本文的理论研究成果可为绳; 牵引并联支撑技术在高超声速风洞中的应用提供一定的技术支持。Wire-driven parallel robot (WDPR) provides a new support method for wind; tunnel tests due to its effective simulation of the aircraft model's; pose, and has a great application potential. This paper gives details of; an investigation of stability and aerodynamic interference referring to; the application of WDPR in hypersonic wind tunnel. The parallel support; system with 8 wires was constructed, and the 10° cone model was selected; as the test model whose position and pose can be adjusted through the; wire length. The support system's stability under the action of; aerodynamic force is simulated, and the wire diameter is optimized.; Based on the constructed three-dimensional model, under the condition of; Mach numuber is 7.8, the aerodynamic coefficient of the model suspended; with WDPR at different angles of attack is calculated in CFD. The; comparison of the simulation result with the result of the same model; without wires and the experimental data in reference indicates that, at; small angle of attack, the relative error of the aerodynamic; interference caused by the wires is small, and the interference; increases with the increase of angle of attack. In addition, modal; characteristics of the WDPR and the crescent shape support system are; analyzed and the natural frequencies of the two support systems are; compared. The comparison result shows that the natural frequency and the; stiffness of the WDPR are higher than those of the crescent shape; support system. The academic research work of this paper provides; reference to the application of wire-driven parallel support technology; in hypersonic wind tunnel.国家自然科学基
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