共查询到20条相似文献，搜索用时 546 毫秒
1.
Dynamic model and control strategy of parallel mechanism have always been a problem in robotics research. In this paper,different dynamics formulation methods are discussed first, A model of redundant driven parallel mechanism with a planar parallel manipulator is then constructed as an example. A nonlinear adaptive control method is introduced. Matrix pseudo-inversion is used to get a desired actuator torque from a desired end-effector coordinate while the feedback torque is directly calculated in the actuator space. This treatment avoids forward kinematics computation that is very difficult in a parallel mechanism. Experiments with PID together with the descibed adaptive control strategy were carried out for a planar parallel mechanism. The results show that the proposed adaptive controller outperforms conventional PID methods in tracking desired input at a high speed, 相似文献
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ＲｅｍｏｔｅＣｏｍｍｕｎｉｃａｔｉｏｎａｎｄＣｏｎｔｒｏｌｏｆａＲｏｂｏｔＵｓｉｎｇＭＭＳＤｉｎｇＸｉｎｑｕａｎ（丁心泉）（ＤｅｐａｒｔｍｅｎｔｏｆＣｏｍｐｕｔｅｒＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，ＳｏｕｔｈｅａｓｔＵｎｉｖｅｒｓｉｔｙ，... 相似文献
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WUBin 《重庆大学学报(英文版)》2002,1(1):56-60
In order to plow an access to low cost automation,the method to set up the most economical and optimized control system is studied.Such a system is achieved by adopting the field bus technologies based on net connection to form the hierarchical architecture and employing genetic algorithm to intelliently optimize the parameters of the topology structure at the field execution level and the parameters of a local controller,Praxios has proved that this realization can shorten the system development cycle,improve the systtem‘s reliability,and achieve conspicuous social economic benefits. 相似文献
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Mark R. van den Bunt Margriet A. Groen Steve Frost Airey Lau Jonathan L. Preston Vincent L. Gracco 《Scientific Studies of Reading》2018,22(6):503-516
Studies of the role of phonological representations in learning to read have almost exclusively focused on speech perception. In the current study, we examined links between sensorimotor control of speech, reading, and reading-related abilities. We studied two languages, English and Dutch, which vary in the regularity of their spelling-to-sound mappings. There were 236 American and Dutch children, 4 to 8 years old, who performed an altered auditory feedback task in which the first formant of the /?/ vowel was altered. A stronger response to altered feedback for literate relative to preliterate children was observed, and this was particularly the case for the Dutch children. Moreover, the magnitude of the responses was related to precursors of reading in preliterate children and to reading skill in literate children. We propose that these findings could be related to changes in children’s speech production skills that facilitate the integration of orthographic and phonemic information. 相似文献
5.
WUBin 《重庆大学学报(英文版)》2002,1(1):56-60
In order to plow an access to low cost automation, the method to set up the most economical and optimized control system is studied. Such a system is achieved by adopting the field bus technologies based on net connection to form the hierarchical architecture and employing genetic algorithm to intelligently optimize the parameters of the topology structure at the field execution level and the parameters of a local controller. Praxis has proved that this realization can shorten the system development cycle, improve the system's reliability, and achieve conspicuous social economic benefits. 相似文献
6.
To improve the machining precision of a surface grinding machine, a micropositioning workpiece table with high performance was used as auxiliary infeed mechanism to implement nanometer level positioning and dynamic compensation. To better understand the characteristics of the grinding machine modulated with micropositioning workpiece table, the dynamic model of the grinding system was established with modal synthesis and Lagrange's equation methods. The grinding system was divided into five subsystems. For each subsystem, the generalized kinematic and potential energies were obtained. Accordingly the dynamic model of the grinding system was given in the modal domain. The waviness of the grinding process was achieved based on the wheel and workpiece vibration. A nonlinear proportional integral derivative (PID) controller with differential trackers was developed to realize dynamic control. The simulation results show that the machining accuracy of the workpiece can be effectively improved by utilizing the micropositioning workpiece table to implement dynamic compensation. An experimental test was carried out to verify the proposed method, and the waviness of the workpiece can be reduced from 0.46 μm to 0.10 μm. 相似文献
7.
Software has been developed for digital control of WDW series testing machine and the measurement of fracture toughness by modularized design. Development of the software makes use of multi-thread and serial communication techniques, which can accurately control the testing machine and measure the fracture toughness in real-time. Three-point bending specimens were used in the measurement. The software operates stably and reliably, expanding the function of WDW series testing machine. 相似文献
8.
Li Xiufeng 《五邑大学学报(社会科学版)》1989,(Z1)
The problem of modeling one-link flexible manipulators is considered.The dynamic model is derived from an inhomogeneouo fourth-order partial differential equation under the zero boundary conditions. The correspondence between the values of the poles of the transfer function and the values of the natural frequencies shows that the modeling is reasonable. To manipulate the cumbersome formulae the REDUCE language has been extensively used.##属性不符 相似文献
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In recent times, spiritual gurus in the West have advocated a simple yet interesting idea: people should sit on the floor instead of chairs. Their main argument is that sitting on the floor is good for health and promotes humility. 相似文献
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《实用翻译教程》一书中谈到Not…and…句型时是这样说的:“Nor…+形容词(副词)+and+形容词(副词)这一结构有时也可表示部分否定。即只否定and后面的词。1)This film is not instruc tive and interesting.这部影片颇有教育意义,但没有趣味。2)He did not answer this question correctly and concisely. 相似文献
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方立 《暨南大学华文学院学报》2002,(4)
This article treats the chunk 'lian...dou' as a complex conjunction on the ground that the sentence thatfollows the sentence in which the chunk' lian...dou' occurs is often incomplete. The interpretation of theincomplete sentence, or the sentence fragment, calls for the restoration of the elided constituents by re-construction. Moreover, the proposition expressed by the sentence fragment is entailed by the propositionexpressed by the sentence in which the chunk 'lian...dou' occurs. Following Montague's rule-to-rulehypothesis, we can take the entailment inherent in the whole construction as the syntactic reflex in its se-mantics. Since the entailment is obviously induced by the chunk 'lian...dou', we treat it as a complexconjunction.Section 1 demonstrates that the sentence that follows the sentence in which the chunk 'lian...dou' occursis not independent and in many ways is similar to the 'ruguo...(name)' construction.Section 2 develops a scalar model based on Fillmore et al (1988) for the semantic inter 相似文献
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Miranda Rocksén 《Scandinavian Journal of Educational Research》2017,61(4):377-393
This study investigates classroom organisation and interaction focusing on phases of activity. The detailed in-depth case study is based on video recordings of 1 science unit consisting of 11 lessons about biological evolution in a Swedish ninth-grade class (aged 15). The study illuminates the temporality of student participation as a fundamental and practical concern for the science teaching profession. Through multiple scale analysis an activity pattern and students' contrasting positions are identified. Movements of control and agency between teacher and students in small-groups provide opportunities for the teacher to coordinate the teaching and the pace of students' participation. The implications point to challenges involved in providing all students with the learning opportunities that participation in the school science discourse affords. 相似文献
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INTRODUCTION The problem of minimal surface is an old and active problem in the field of differential geometry. The minimal surface has been employed in many areas such as architecture, material science, aviation, ship manufacture, biology, crystallogeny, and so on. The history of minimal surface began with La- grange in 1762 (Nitsche, 1989). Many literature on the minimal surface exist in the last two hundred years (Nitsche, 1989; Osserman, 1986), but few on the minimal surface from the… 相似文献
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1 Introduction Withtherapiddevelopmentofcomputertechnology,digitalcontrolsystemsarewidelyusedinengineeringandresearch.InsomedigitalcontroldevicessuchasaGermanmadeWDWtestingmachineequippedwiththeDOLIsystem,however,duetoproblemsinsoftwareupdatingandlocalization,thefunctionareinsufficient.Forexample,thesystemsoftwareislimitedtothemeasurementofconventionalmechanicalproperty,incapableofmeasuringfracturetoughnessKICofmaterials.Asfracturetoughnessofmaterialsisanimportantparameterformaterialsev… 相似文献
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This qualitative study explored the intertwining relationships among the concepts of parental autonomy support, parental control, and cultural values for Mexican American families. The study was guided by the following questions: (1) What elements of parental autonomy support are identified in Mexican American parents’ involvement in their children’s academic performance? (2) How do Mexican American parents conceptualize “autonomy support” and “parental control”? Sixteen Mexican American mothers expressed their own goals and strategies for home-based parental involvement to support their adolescents’ academic performance, and responded to the prototypes of autonomy support parenting and use of psychological control. Four themes emerged from the data to explain the participants’ practice: (1) Explain the expectations for behavioral and academic pursuit through persistent “telling” and “reminding”; (2) Respond to children’s feelings from parents’ perspectives; (3) Encourage with provisions, praises, and criticisms; and (4) Allow choices upon trust in child’s sense of responsibility. Discussion is focused on how Mexican-American mothers’ conceptualization of “autonomy support” and “parental control” is influenced by the cultural values of educación and respeto. Culturally appropriate autonomy support training is suggested for effective intervention programs for Mexican-American parents. 相似文献
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《Journal of moral education》2012,41(3):186-191
Abstract The present study compares Israeli adolescents from Eastern, i.e., African‐Asiatic descent and Western, i.e., European‐American descent, with respect to locus of control (LOC) and moral judgement. It was assumed that the differential patterns of socialization that characterize the two ethnic groups, would be reflected by the subjects’ LOC and moral judgement. It was hypothesized that more internal LOC orientation and more relativistic moral judgement would be associated with Western than with Eastern patterns of socialization. The results confirmed the general hypothesis. Israeli adolescents of Eastern descent were found to be more externally oriented and their moral judgement to be more realistic than adolescents of Western descent. No relationship between LOC and moral judgement within each of the origin groups was found. The results are discussed in terms of socialization patterns and child‐rearing practices. 相似文献
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lIntroductionTheflexiblemanulhcturingtechnology(FMT)originatedinUSAinthemid1960s',sincethenithasspreadtomanyothercountries.Duringthelastfewyears,theflexiblemanufacturingsystem(FMS)hasdemonstratednotonlypopularintheindustrializedcountries,butalsofindsitsap… 相似文献