基于FPGA的高性能关节伺服系统控制器实现

提出了一种基于NIOS Ⅱ软核处理器的全数字化的关节伺服系统控制器的设计方案.该方案不仅实现了电机的矢量控制算法、M/T测速算法以及SPWM算法,而且还实现了关节空间的轨迹规划、位置控制和力矩控制.同时在所设计的关节控制器FPGA内部嵌入了CAN控制器软核,实现了与主控计算机的CAN总线接口和关节控制器参数的在线调整.关节内部电流环控制采样频率为20 kHz,而位置环、力矩环的控制采样频率低于1 kHz.实验结果表明:关节系统的定位精度优于0.01°,由6个完全相同的关节构成的空间机械臂(臂长1.8 m),末端定位精度为±2.7 mm,完全满足空间机械臂系统的要求.     

一种神经网络复合型机械臂智能控制策略的研究

本文探讨了一种基于遗传算法和双映射神经网络复合型的机械臂智能运动控制器,实现了机械臂的轨迹跟踪控制。计算机仿真表明该控制器具有较高的控制精度和响应速度,可以满足机械臂工作要求。     

工业机械臂末端执行器自动化装配技术研究

工业机械臂的末端执行器在面临实际的装配任时总是出现低、柔顺性低等问题。此次研究创建了一种机械臂UR5的柔顺装配控制方法，结合欧拉拉格朗日法和齐次变换矩阵分析动力学模型和动力学模型，分析关节干扰力矩和外力两者的关系，依据改进的内环阻抗控制器和滑膜控制器设计滑膜阻抗控制器。UR5机械臂外力碰撞仿真实验结果显示，2,3,4关节的角加速度最大值分别为4.2rad/s*s, 3rad/s*s,-7.8rad/s*s。而1,5,6关节角加速度均为±0.1rad/s*s。     

传递对准MRP-CDKF算法

基于主、子惯导系统传递对准受控角运动和修正Rodrigues参数(MRP)的三参数描述姿态运动最小实现特点,建立了主、子惯导系统传递对准MRP非线性误差模型.根据四元数加权均值计算方法以及MRP与四元数关系,实现MRP的间接加权均值计算;根据MRP乘法定义实现MRP预测误差方差矩阵求解,进而建立修正Rodrigues参数-中心差分卡尔曼滤波(MRP-CDKF)算法.利用该算法对MRP非线性传递对准误差模型进行研究,结果表明:该算法的姿态失准角估计误差都能在10s之内收敛到0′附近;考虑杆臂向量与不考虑杆臂向量时的系统速度误差在±0.1m/s内.     

基于扩张状态观测器的机械臂分散自适应模糊控制

针对机械臂控制中各子系统间交联项难于处理的问题,提出了一种基于扩张状态观测器(extended state observer,ESO)和模糊策略的分散控制方法.将机械臂系统考虑为各关节交联子系统的集合,采用扩张状态观测器去实时估计机械臂各关节间的状态、耦合交联项及非线性项,利用模糊系统去逼近机械臂动力学模型中的建模不确定项,从而设计分散自适应模糊控制器以实现机械臂的轨迹跟踪控制,给出了控制器中参数的自适应更新律,并对该控制器进行了Lya-punov稳定性分析.最后将该方法应用于一个4自由度机械臂的轨迹跟踪控制中,仿真结果表明了该方法对处理耦合交联项及在各关节轨迹跟踪控制中的有效性.     

无末端力传感器的可重构机械臂分散力控制

针对存在关节摩擦和外扰的可重构机械臂系统在受限空间内的力控制问题,提出一种无需使用力传感器即可同时控制受限空间内机械臂力和位置的分散阻抗内环/力外环控制方案.采用模糊系统逼近机械臂系统中的不确定项及子系统间的耦合关联项,通过基于模糊预测的力外环控制器为内环的阻抗控制器提供参考轨迹,并利用模糊系统逼近实际的接触力.该方案为没有力传感器情况下的可重构机械臂的力控制提供了一种可能的解决方案,且模糊预测调节参考轨迹的阻抗内环控制使机械臂具有一定的柔顺性,能较好地实现机械臂由自由空间向受限空间的过渡.通过对2自由度平面机械臂和3自由度机械臂的仿真验证了该方法的有效性.     

漂浮基空间机械臂姿态与末端爪手协调运动的模糊变结构滑模控制

讨论了载体姿态受控、位置不受控制情况下,漂浮基空间机械臂载体姿态与末端爪手协调运动的控制问题.结合系统动量守恒关系,分析、建立了空间机械臂系统运动的Jacob i关系及完全能控形式的系统动力学方程.在此基础上,应用变结构滑模控制理论设计了空间机械臂载体姿态与末端爪手惯性空间轨迹协调运动的变结构滑模控制方案;为了克服上述变结构滑模控制器抖振的缺点,附加设计了一个模糊控制器,以根据系统的控制输出来动态调节变结构滑模控制器等速趋近率的系数,从而达到既保证系统具有快速响应又能消除原有控制器具有抖振缺点的目的.系统数值仿真运算,证明了上述控制方案的有效性.     

六自由度机械臂运动轨迹自动生成方法仿真与实现

运用运动捕捉系统,结合机器人运动学方法,提出一种六自由度机械臂运动轨迹自动生成方法.首先,在运动捕捉系统下得到人手臂末端的Marker标记点的位姿信息;然后,通过数据处理得到标记点的位姿矩阵,并将其作为机械臂末端执行器的位姿矩阵,进而通过数据流通道将该数据传入机器人运动学仿真系统,在仿真系统中运用代数解法求机器人运动学逆解,并进行运动学仿真.最后,将逆解求得的6个关节角度传入机械臂本体,实现机械臂末端执行器按照运动捕捉系统下手臂末端标记点的运动轨迹而运动.仿真实验表明:该方法具有可行性.     

PID神经网络混沌优化及其在机械臂轨迹跟踪控制中的应用

针对BP优化PID神经网络（BP-PDNN）易陷入局部极小的不足,提出了一种变尺度混沌优化PID神经网络设计方法,即MSCOA-PIDNN,将其应用于机械臂轨迹跟踪控制中.利用混沌运动的遍历性优化网络权值,通过压缩优化变量取值区间提高搜索效率.采用MSCOA-PIDNN建立机械臂系统的预测模型,以多步预测性能指标为目标函数,优化PID神经网络控制器,从而实现机械臂系统轨迹跟踪的有效控制.仿真结果表明,MSCOA-PIDNN在机械臂轨迹跟踪控制中性能优于BP-PIDNN.     

机械臂系统任务空间同步的自适应间歇控制

针对由拉格朗日方程描述的参数不确定机械臂系统,提出了一种自适应间歇控制器使得机械臂系统在任务空间可以达到同步.即在任务空间中,对于给定的目标位置,机械臂末端执行器能够在间歇控制下到达目标位置.该控制器的设置与现有的大多数机械臂控制成果不同,控制器不用连续接收期望轨道信息而且考虑任务空间来取代关节空间,引入的推广的Bar...     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.