基于滑模的混联仿人空间机械臂轨迹跟踪控制

针对空间高速目标抓取任务中对手臂伸出定位基本动作的要求,提出一种4-DOF串并混联仿人机械臂。重点设计了以球面并联机构为机构原型的高承载力肩关节以及轻量化的驱动装置与低惯量的布置形式。考虑混联的结构特点,利用李群李代数法并结合虚功原理推导了机械臂的动力学方程,该方法可避免约束反力的处理与逻辑开链的划分以及大量的微分运算。在此基础上,针对混联结构的强非线性和强耦合性,使用滑模控制器对机械臂进行轨迹跟踪控制,验证了所提滑模控制器的有效性。

仿人机器人混联灵巧手臂设计及运动学逆解研究

以在轨服务仿人灵巧机械臂为研究背景,提出一种混联结构的仿人机器人灵巧手臂,并研究了具有自然姿态的运动学逆解方法。采用2-DOF球面并联机构前后串联转动低副的混联结构布置传动链,力图在载荷质量比、刚度及灵巧性上取得更好的性能。根据结构特点推导了正运动学解析解,并利用神经生理学感知运动模型联合在线PD补偿方法获得符合人类手臂自然姿态的逆运动学最优解。进行了轨迹跟踪仿真与手臂伸出定位试验,试验过程中机械臂样机近似保持着人类手臂的自然姿态,结果验证了运动学分析及所提方案的有效性与工程适用性。

探讨铁路联锁仿真实训系统方案实现

随着各地的铁路建设初有进展,对铁路的维护人员及相关工作人员的需求量剧增。对于相关人才的培养要符合铁路新技术的具体需求,这也是当前最为重要的任务之一。传统的授课方式及授课理念已经不能满足铁路人才需求,要进一步加大对设备的投资及对安全隐患进行排查。本文针对铁路联锁仿真实训系统进行实践证明,为今后的铁路建设奠定基础。

仿译与创译:英文广告仿拟翻译

仿拟翻译分仿译与创译,最佳关联原则具有很强的解释力,有四种基本翻译策略及在此基础上的动态优化组合策略。仿拟翻译要与广告创意与诉求相结合,译者要综合平衡多种因素,以实现最佳广告效果。

Vehicle and terrain interaction based on Adams-Matlab co-simulation

A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.

Design of hydraulic motor speed control system based on co-simulation of AMESim and Matlab_Simulink

In order to design an effective hydraulic motor speed control system, Matlab_Simiulink and AMESim co-simulation technology is adopted to establish more accurate model and reflect the actual system. The neural network proportion-integration-differentiation （PID） control parameters on-line adjustment is utilized to improve system accuracy, celerity and stability. Simulation results indicate that with the control system proposed in this paper, the system deviation is reduced, therefore accuracy is improved; response speed for step signal and sinusoidal signal gets faster, thus acceleration is rapidly improved; and the system can be restored to the control value in case of interfering, so stability is improved.

基于五点插值模型预测控制的车道保持系统研究

提出了一种车道保持系统(LKS)的控制器,其参考轨迹生成方法是对传感器获得的五个预览点进行插值。它的意义在于通过使用五个点来减少对传感器的需求。此外,这五个预览点之间的距离是由纵向速度决定的。随后,将跟踪问题的模型预测控制(MPC)转化为二次规划(QP)问题,实现了控制器的计算。通过Matlab/Simulink和CarSim在不同速度下的联合仿真,验证了该方法的有效性和鲁棒性。仿真结果表明,该控制器能有效地减小车辆的侧向位移,取得较好的控制效果。

Methods of Validating Simulation Model and Program Design

Validating simulation model is one of the important aspects for modeling and simulation. Some methods of validating model are compared and analyzed. Several typical methods, such as TIC’s inequality coefficient, gray interconnected analysis, direct spectrum estimation, maximum entropy spectral estimation based on Burg or Marple, are chosen and programmed in C language. Some examples by using the program are given. The results show that the program is available and it is best to adopt multi methods for validating models.

A co-simulation method for the train-track-bridge interaction analysis under earthquake using Simpack and OpenSees

Under high-level earthquakes,bridge piers and bearings are prone to be damaged and the elastoplastic state of bridge structural components is easily accessible in the train-track-bridge interaction(TTBI)system.Considering the complexity and structural non-linearity of the TTBI system under earthquakes,a single software is not adequate for the coupling analysis.Therefore,in this paper,an interactive method for the TTBI system is proposed by combining the multi-body dynamics software Simpack and the seismic simulation software OpenSees based on the Client-Server architecture,which takes full advantages of the powerful wheel-track contact analysis capabilities of Simpack and the sophisticated nonlinear analysis capabilities of OpenSees.Based on the proposed Simpack and OpenSees co-simulating train-track-bridge(SOTTB)method,a single-span bridge analysis under the earthquake was conducted and the accuracy of co-simulation method was verified by comparing it with results of the finite element model.Finally,the TTBI model is built utilizing the SOTTB method to further discuss the running safety of HST on multi-span simply supported bridges under earthquakes.The results show that the SOTTB method has the advantages of usability,high versatility and accuracy which can be further used to study the running safety of HST under earthquakes with high intensities.

Integrated yaw and rollover control based on differential braking for off-road vehicles with mechanical elastic wheel

Aiming at the issue of yaw and rollover stability control for off-road vehicles with non-pneumatic mechanical elastic wheel(MEW),an integrated control system based on fuzzy differential braking is developed.By simplifying the structure of the MEW,a corresponding fitting brush tire model is constructed and its longitudinal and lateral tire force expressions are set up,respectively.Then,a nonlinear vehicle simulation model with MEW is established to validate the proposed control scheme based on Carsim.The designed yaw and rollover control system is a two-level structure with the upper additional moment controller,which utilizes a predictive load transfer ratio(PLTR)as the rollover index.In order to design the upper integrated control algorithm,fuzzy proportional-integral-derivative(PID)is adopted to coordinate the yaw and rollover control,simultaneously.And the lower control allocator realizes the additional moment to the vehicle by differential braking.Finally,a Carsim-simulink co-simulation model is constructed,and simulation results show that the integrated control system could improve the vehicle yaw and roll stability,and prevent rollover happening.

An new representation for interconnection network structures

An important theoretic interest is to study the relations between different interconnection networks, and to compare the capability and performance of the network structures. The most popular way to do the investigation is network emulation. Based on the classical voltage graph theory, the authors develop a new representation scheme for interconnection network structures. The new approach is a combination of algebraic methods and combinatorial methods. The results demonstrate that the voltage graph theory is a powerful tool for representing well known interconnection networks and in implementing optimal network emulation algorithms, and in particular, show that all popular interconnection networks have very simple and intuitive representations under the new scheme. The new representation scheme also offers powerful tools for the study of network routings and emulations. For example, we present very simple constructions for optimal network emulations from the cube connected cycles networks to the butterfly networks, and from the butterfly networks to the hypercube networks. Compared with the most popular way of network emulation, this new scheme is intuitive and easy to realize, and easy to apply to other network structures.

TENSILE TEST AND PHYSICAL MODEL OF NiTi SHAPE MEMORY ALLOY

The tensile stress-strain curves of NiTi wires are obtained by tensile experiments under different heat treatments. A phenomenological physical model based on hysteresis element method is developed to describe the experimentally determined stress-strain curves of shape memory alloy (SMA) wires. Numerical simulations are made. Simulation results show that：(1) a series of unusual changes on physical and mechanical properties of SMA wires occur when martensitic, especially R (rhombohedral) phase transformation emerge. The stress-strain relation of SMA wires is highly non-linear; (2) there are no notable yielding phenomena before NiTi wires are broken; (3) numerical results obtained by the physical model are in good agreement with experimental data.

Simulation of Dynamic Electromagnetic Interference Environment for Unmanned Aerial Vehicle Data Link

In order to test the anti-interference ability of an Unmanned Aerial Vehicle(UAV) data link in a complex electromagnetic environment,a method for simulating the dynamic electromagnetic interference of an indoor wireless environment is proposed.This method can estimate the relational degree between the actual face of an UAV data link in an interface environment and the simulation scenarios in an anechoic chamber by using the Grey Relational Analysis(GRA) theory.The dynamic drive of the microwave instrument produces a real-time corresponding interference signal and realises scene mapping.The experimental results show that the maximal correlation between the interference signal in the real scene and the angular domain of the radiation antenna in the anechoic chamber is 0.959 3.Further,the relational degree of the Signal-toInterference Ratio(SIR) of the UAV at its reception terminal indoors and in the anechoic chamber is 0.996 8,and the time of instrument drive is only approximately 10 μs.All of the above illustrates that this method can achieve a simulation close to a real field dynamic electromagnetic interference signal of an indoor UAV data link.

An approach for QoS measurement and web service selection sureness

Web services have gained popularity m recent years anu prowue a new moue, u~ w^u, w,,,~,, ,^- cilitates interaction of scientific and business applications through the Internet. More often, several services with similar functionality are available from a large and changing number of service provid- ers. Quality of Service （QoS） is the dominant factor in service selection and is of great importance to users. In this paper, we propose a model for QoS measurement and web services selection. The model consists of QoS model, QoS monitoring, QoS comparison and service selection with a QoS feedback mechanism. The most suitable service is to take into account the agreed QoS, monitoring is done during invocation phase and if any deviation is recorded, next suitable service is selected. Fi- nally the model is proved to be feasible and effective by simulation experiments.

An Incremental LOD Method Based on Grid and Its Application in Distributed Terrain Visualization

Incremental LOD can be transmitted on the network as a stream, then users on the clients can easily catch the skeleton of terrain without downloading all the data from the server. Detailed information in a local part can be added gradually when users zoom it in without redundant data transmission in this procedure. To do this, an incremental LOD method is put forward according to the regular arrangement of grid. This method applies arbitrary sized grid terrains and is not restricted to square ones with a side measuring 2 k + 1 samples. Maximum height errors are recorded when the LOD is preprocessed and it can be visualized with the geometrical Mipmaps to reduce the screen error.

Realization of a Nine-Level Cascaded NPC/H-Bridge PWM Inverter Using Phase-Shifted Carrier PWM Technique

Cascaded H-Bridge inverter has been researched for the past two decades, but there are no explicit guidelines on how one can realize a cascaded NPC （neutral-point-clamped）/H-Bridge inverter. Past research has also concentrated on realizing a five-level NPC/H-Bridge inverter. This fails to address the principle of realizing a general cascaded N-level NPC/H-Bridge PWM inverter. This paper proposes an improved topology for achieving a nine-level cascaded NPC （neutral-point-clamped） H-Bridge inverter with reduced harmonic content. This new proposed topology requires a lesser number of separate dc sources as compared to conventional cascaded H-Bridge inverter. The whole system is considered as having four three level legs having two positive and two negative legs. By properly phase shifting the modulating wave and carriers, a nine-level output is achieved. A theoretical harmonic analysis of the proposed inverter is carried out based on double Fourier principle. The theoretical results are verified through MATLAB simulation.

Industry 5.0-The Relevance and Implications of Bionics and Synthetic Biology

Bionics （the imitation or abstraction of the ＂inventions＂ of nature） and, to an even greater extent, syn- thetic biology, will be as relevant to engineering development and industry as the silicon chip was over the last 50 years. Chemical industries already use so-called ＂white biotechnology＂ for new processes, new raw materials, and more sustainable use of resources. Synthetic biology is also used for the devel- opment of second-generation biofuels and for harvesting the sun＇s energy with the help of tailor-made microorganisms or biometrically designed catalysts. The market potential for bionics in medicine, en- gineering processes, and DNA storage is huge. ＂Moonshot＂ projects are already aggressively focusing on diseases and new materials, and a US-led competition is currently underway with the aim of creating a thousand new molecules. This article describes a timeline that starts with current projects and then moves on to code engineering projects and their implications, artificial DNA, signaling molecules, and biological circuitry. Beyond these projects, one of the next frontiers in bionics is the design of synthetic metabolisms that include artificial food chains and foods, and the bioengineering of raw materials; all of which will lead to new insights into biological principles. Bioengineering will be an innovation motor just as digitalization is today. This article discusses pertinent examples of bioengineering, particularly the use of alternative carbon-based biofuels and the techniques and perils of cell modification. Big data, analytics, and massive storage are important factors in this next frontier. Although synthetic biology will be as pervasive and transformative in the next 50 years as digitization and the Intemet are today, its ap- plications and impacts are still in nascent stages. This article provides a general taxonomy in which the development of bioengineering is classified in five stages （DNA analysis, bio-circuits, minimal genomes, protocells, xenobiology） from the familiar to the unknown, with implications for safety and security, in- dustrial development, and the development of bioengineering and biotechnology as an interdisciplinary field. Ethical issues and the importance of a public debate about the consequences of bionics and syn- thetic biology are discussed.

Affine Connections and Gauss-Bonnet Theorems in the Heisenberg Group

In this paper,we compute sub-Riemannian limits of Gaussian curvature associated to two kinds of Schouten-Van Kampen affine connections and the adapted connection for a Euclidean C2-smooth surface in the Heisenberg group away from characteristic points and signed geodesic curvature associated to two kinds of Schouten-Van Kampen affine connections and the adapted connection for Euclidean C2-smooth curves on surfaces.We get Gauss-Bonnet theorems associated to two kinds of Schouten-Van Kampen affine connections in the Heisenberg group.

Effect of Growing Size of Interaction Neighbors on the Evolution of Cooperation in Spatial Snowdrift Game

In this paper,we study the influence of the size of interaction neighbors(k) on the evolution of cooperation in the spatial snowdrift game.At first,we consider the effects of noise K and cost-to-benefit ratio r,the simulation results indicate that the evolution of cooperation depends on the combined action of noise and cost-to-benefit ratio.For a lower r,the cooperators are multitudinous and the cooperation frequency ultimately increases to 1 as the increase of noise.However,for a higher r,the defectors account for the majority of the game and dominate the game if the noise is large enough.Then we mainly investigate how k influences the evolution of cooperation by varying the noise in detail.We find that the frequency of cooperators is closely related to the size of neighborhood and cost-to-benefit ratio r.In the case of lower r,the augmentation of k plays no positive role in promoting the cooperation as compared with that of k = 4,while for higher r the cooperation is improved for a growing size of neighborhood.At last,based on the above discussions,we explore the cluster-forming mechanism among the cooperators.The current results are beneficial to further understand the evolution of cooperation in many natural,social and biological systems.

Comparative analysis on the performance of two concatenated codes for high-speed long-haul optical communication systems

After the development trend of high-speed long-haul optical communication systems and the theory of the concatenated code are analyzed,the comparative researches on the performances of the two concatenated codes of the inner-outer type and the improved interleaving type are performed in detail.The theoretical analyses and simulation results show that the inner-outer type concatenated code has the greater redundancy,and the improved interleaving type concatenated code is a superior concatenated code with the advantages of the better error correction performance,moderate redundancy and easy implementation.As a result,the improved interleaving type concatenated code can be better used in high-speed long-haul optical communication systems.