The kinematic design of spatial,hybrid closed chains including planar parallelograms

It is presented an integral approach for the kinematic design of spatial, hybrid closed chains which include planar parallelograms into their kinematic structure. It is based on a systematic application of recursive formulae intended for describing the evolution of screws through time. Due to the particular nature of the proposed approach, it can be closely related with Lie algebras and allows to overcome the lacking of group structure offered by a parallelogram when it is going to be considered as a component of a hybrid closed chain. Several application examples are presented in order to show the potential of the proposed approach.     

MEMS AC voltage reference for miniaturized instrumentation and metrology

This work explores MEMS (Micro-Electro-Mechanical Systems) potentialities to fabricate AC voltage references through mechanical-electrical transduction that could be used for high precision electrical metrology and for applications in miniaturized instrumentation. AC voltage reference ranging from 5 V to 90 V have been designed and fabricated using the same Epitaxial Silicon On Insulator (SOI) surface micromachining process allowing an accurate control of both dimensions and material properties. The measured MEMS AC voltage reference values have been found in a good agreement with CoventorWare calculations. These tests structures have also been used to develop the read-out electronics to drive the MEMS.     

Electro-thermal simulation and characterization of preconcentration membranes

We use electro-thermal simulations to design thermally insulated membranes that support thin film heaters as components of gas preconcentrators. These heaters provide a good thermal homogeneity ensuring a narrow desorption peak and, thus, a good sensor response. Temperature measurements have been carried out using an infrared camera and they are in agreement with the corresponding numerical predictions. Our model has been validated and it can be used in future designs.     

Pull-in-based μg-resolution accelerometer: Characterization and noise analysis

The pull-in time (t_pi) of electrostatically actuated parallel-plate microstructures enables the realization of a high-sensitivity accelerometer that uses time measurement as the transduction mechanism. The key feature is the existence of a metastable region that dominates pull-in behavior, thus making pull-in time very sensitive to external accelerations. Parallel-plate MEMS structures have been designed and fabricated using a SOI micromachining process (SOIMUMPS) for the implementation of the accelerometer. This paper presents the experimental characterization of the microdevices, validating the concept and the analytical models used. The accelerometer has a measured sensitivity of 0.25 μs/μg and a bandwidth that is directly related to the pull-in time, BW = 1/2t_pi ≈ 50 Hz. These specifications place this sensor between the state of the art accelerometers found both in the literature and commercially. More importantly, the resolution of the measurement method used is very high, making the mechanical-thermal noise the only factor limiting the resolution. The in-depth noise analysis to the system supports these conclusions. The total measured noise floor of 400 μg (100 μs) is mainly due to the contribution of the environmental noise, due to lack of isolation of the experimental setup from the building vibrations (estimated mechanical thermal noise of 2.8 μg/√Hz). The low requirements of the electronic readout circuit makes this an interesting approach for high-resolution accelerometers.     

Robust parametric CMAC with self-generating design for uncertain nonlinear systems

In this paper, a robust parametric cerebellar model articulation controller (RP-CMAC) with self-generating design, called RPCSGD, is proposed for uncertain nonlinear systems. The proposed controller consists of two parts: one is the parametric CMAC with self-generating design (PCSGD), which is utilized to approximate the ideal controller and the other is the robust controller, which is designed to achieve a specified H^∞ robust tracking performance of the system. The corresponding memory size of the proposed controller can be suitably constructed via the self-generating design. Thus, the useless or untrained memories will not take possession of the space. Besides, the concept of sliding-mode control (SMC) is adopted so that the proposed controller has more robustness against the approximated error and uncertainties. The stability of the system can be guaranteed surely due to the derivations of the adaptive laws of the proposed RPCSGD based on the Lyapunov function. Finally, the proposed controller is applied to the second-order chaotic system and the one-link rigid robotic manipulator. The tracking performance and effectiveness of the proposed controller are verified by simulations of the computer.     

Influences of haptic communication on a shared manual task

With the advent of new haptic feedback devices, researchers are giving serious consideration to the incorporation of haptic communication in collaborative virtual environments. For instance, haptic interactions based tools can be used for medical and related education whereby students can train in minimal invasive surgery using virtual reality before approaching human subjects. To design virtual environments that support haptic communication, a deeper understanding of humans′ haptic interactions is required. In this paper, human′s haptic collaboration is investigated. A collaborative virtual environment was designed to support performing a shared manual task. To evaluate this system, 60 medical students participated to an experimental study. Participants were asked to perform in dyads a needle insertion task after a training period. Results show that compared to conventional training methods, a visual-haptic training improves user′s collaborative performance. In addition, we found that haptic interaction influences the partners′ verbal communication when sharing haptic information. This indicates that the haptic communication training changes the nature of the users′ mental representations. Finally, we found that haptic interactions increased the sense of copresence in the virtual environment: haptic communication facilitates users′ collaboration in a shared manual task within a shared virtual environment. Design implications for including haptic communication in virtual environments are outlined.     

基于改进粒子群优化算法的IIR数字滤波器设计

针对粒子群优化(PSO)算法存在早熟收敛问题,提出了一种改进算法——带有柯西扰动的重分布粒子群优化(RPSO)算法,并应用于IIR数字滤波器的优化设计。RPSO在检测到粒子群早熟收敛时,自动触发粒子重分布机制,帮助粒子逃离局部收敛区域,同时在迭代过程中对种群的全局最优位置施加柯西扰动以保持种群的多样性。仿真实验结果表明,在对IIR数字滤波器设计时,RPSO算法的性能优于粒子群、量子粒子群以及基于混沌变异的粒子群优化等算法。     

政务信息资源中心框架设计及关键技术研究

目前国内有关政务信息资源共享的研究及应用还停留在网络互联互通、信息资源整合、点对点数据交换阶段,并没有达到"协同工作"的要求.鉴于此,提出了政务信息资源中心的概念,实现政务信息资源的统一获取、统一管理、规则化和规模化服务.结合工作实践,对其组成、总体框架、技术架构进行了设计,并就实现时需要解决的关键技术进行了研究.     

基于模型设计的处理器在回路联合仿真系统

运用基于模型设计方法开展处理器在回路联合仿真系统的设计研究.针对该方法在模型定点化重构及参数定标过程中存在的参数收敛不一致及工作量大等问题,提出一种迭代参数定标方法,设计了定标比较模块和迭代参数调整模块.建立了基于Matlab/Simulink联合仿真系统模型,以TMS320C6416为核心处理器建立联合仿真目标板平台...