The current trends in development and deployment of advanced micro- and miniscale electromechanical systems (MEMS) have facilitated the unified fundamental, applied, and experimental research activities in the analysi...
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The current trends in development and deployment of advanced micro- and miniscale electromechanical systems (MEMS) have facilitated the unified fundamental, applied, and experimental research activities in the analysis and design of state-of-the-art motion devices (rotational and translational electromechanical motion devices), integrated circuits (ICs), and controllers. The objectives of this paper are to design, develop, and compare different control algorithms for high-performance MEMS with permanent-magnet rotational servo-motors controlled by ICs (VLSI driver-controller is fabricated using CMOS technology). The problems to be solved are very challenging because a number of long-standing issues in design, hardware integration, control, nonlinear analysis, and robustness have to be solved. The major emphases of this paper are the analysis and design of robust servo-systems, as well as the comparison of the dynamic performance of closed-loop MEMS with different control algorithms. We. synthesize, verify, and test proportional-integral, integral with state feedback extension, relay, and sliding mode controllers. It is illustrated that the sliding mode control laws drive the states and tracking error to the switching surface and maintain (keep) the states and tracking error within this nonlinear switching surface in spite of different references, disturbances, parameter variations, and uncertainties. That is, robust tracking, desired accuracy, and disturbance attenuation are achieved. We report the experimental setup which was built to perform the advanced studies of high-performance MEMS. The testbed was built to integrate permanent-magnet microscale servo-motor and ICs (driver-controller). (C) 2002 Published by Elsevier Science Ltd.
This paper proposes an adaptive boundary control to an axially moving string system, which couples with a mass-damper-spring (MDS) controller at its right-hand-side (RHS) boundary. Unknown parameters appearing in the ...
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This paper proposes an adaptive boundary control to an axially moving string system, which couples with a mass-damper-spring (MDS) controller at its right-hand-side (RHS) boundary. Unknown parameters appearing in the system equation are assumed constant and estimated on-line by using adaptation laws. The adaptive computed-torque control algorithm applied to robot manipulators of lumped systems is extended to design the adaptive boundary controller for the coupling system. It is found that the control force and update laws depend only on the displacement, velocity and slope of the string at the RHS boundary. Lyapunov stability guarantees the convergence of the tracking error to zero. Finally, the performance of the proposed controller is demonstrated by numerical simulations.
This paper proposes an innovative simultaneous localization and mapping (SLAM) algorithm which combines a strong tracking filter (STF), an unscented Kalman filter (UKF), and a particle filter (PF) to deal with the low...
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This paper proposes an innovative simultaneous localization and mapping (SLAM) algorithm which combines a strong tracking filter (STF), an unscented Kalman filter (UKF), and a particle filter (PF) to deal with the low accuracy of unscented FastSLAM (UFastSLAM). UFastSLAM lacks the capacity for online self-adaptive adjustment, and it is easily influenced by uncertain noise. The new algorithm updates each Sigma point in UFastSLAM by an adaptive algorithm and obtains optimized filter gain by the STF adjustment factor. It restrains the influence of uncertain noise and initial selection. Therefore, the state estimation would converge to the true value rapidly and the accuracy of system state estimation would be improved eventually. The results of simulations and practical tests show that strong tracking unscented FastSLAM (STUFastSLAM) has a significant improvement in accuracy and robustness.
A topological method for the design and optimization of planar circularly polarized (CP) directional antenna with low profile was presented. By inserting two parasitic layers, generated by particle swarm optimization,...
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A topological method for the design and optimization of planar circularly polarized (CP) directional antenna with low profile was presented. By inserting two parasitic layers, generated by particle swarm optimization, between the equiangular spiral antenna and the ground, a low-profile wideband CP antenna with directional radiation pattern and high gain is achieved. The optimized antenna shows an impedance matching band (|S-11| < 10dB) of 4-12 GHz with a whole-band stable directional pattern in 4-11.5 GHz, and the antenna gain peak is 8 dBi, which work well in the available band. Measured return loss, antenna gain, and far field patterns agree well with simulation results.
We present a deterministic black box solution for online approximate matching. Given a pattern of length m and a streaming text of length n that arrives one character at a time, the task is to report the distance betw...
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We present a deterministic black box solution for online approximate matching. Given a pattern of length m and a streaming text of length n that arrives one character at a time, the task is to report the distance between the pattern and a sliding window of the text as soon as the new character arrives. Our solution requires 0(Sigma(log)(m)(j=1)(2)(n, 2(j-1))/n) time for each input character, where T(n, m) is the total running time of the best offline algorithm. The types of approximation that are supported include exact matching with wildcards, matching under the Hamming norm, approximating the Hamming norm, k-mismatch and numerical measures such as the L-2 and L-1 norms. For these examples, the resulting online algorithms take O(log(2) m), O(root m log m), O(log(2) m/epsilon(2)), O(root k log k log m), O(log(2) m) and O(root m log to) time per character, respectively. The space overhead is linear in the pattern size, which we show is optimal for any deterministic algorithm. (C) 2011 Elsevier Inc. All rights reserved.
Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multi-antenna transmission modes are addre...
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Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multi-antenna transmission modes are addressed in this article for UTRAN long-term evolution. First, a high-level system overview of LTE is given, with special emphasis on the important components related to RRM. The quality of service parameter framework is outlined, as one of the main objectives for the families of RRM algorithms is to maximize system capacity while serving all users according to their minimum QoS constraints. It is demonstrated how the collocation of the RRM algorithms at the base station with easy access to air interface measurements offers opportunities for efficient cross-functional optimization between layers 1, 2, and 3. Examples of performance results for different traffic mixes and antenna transmission schemes are also presented, and the article is concluded with recommendations-on how to operate the various RRM options under different load and traffic conditions.
As model checking becomes increasingly used in industry, there is a big need for efficient new methods to deal with the large real-size designs. The author presents a novel method for improving the performance of mode...
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As model checking becomes increasingly used in industry, there is a big need for efficient new methods to deal with the large real-size designs. The author presents a novel method for improving the performance of model checking using parallelisation techniques. The model checking is performed on a distributed-memory environment consisting of a network of machines. The important two keys to focus on are the memory balance and communication reduction. A new algorithm for partitioning the large state space modelling industrial designs with hundreds of millions of states and transitions is proposed. The state space is supposed to be represented by a weighted Kripke structure (this is an extension of the Kripke structure where weights are associated with the states and with the transitions). This algorithm partitions the weighted Kripke structure by performing a combination of abstraction-partition-refinement on this structure. The CTL model checking algorithm is distributed on processes located on different network machines. Each one owns a partition and executes the algorithm on it. The algorithm for CTL model checking is designed to reduce the communication overhead between the processes. The experimental results on large real designs show that this method improves the quality of partitions, the communication overhead and then the overall performance of the model checking.
In this work, the problem of a spacecraft's rendezvous is considered in the radial coordinate system, taking into consideration the effect of the difference gravitational acceleration, using a control algorithm wi...
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In this work, the problem of a spacecraft's rendezvous is considered in the radial coordinate system, taking into consideration the effect of the difference gravitational acceleration, using a control algorithm with the prediction model based on the minimization of the generalized work functional. The analytical formulas have been derived to compute the control actions when the motion of the center of mass and the motion about the center of mass, when solving the parametric optimization problem, are considered in a unified terminal formulation. The analytical solution is based on a special prediction model that has an analytical solution in the advanced modeling of the rendezvous process. The results of modeling a spacecraft's rendezvous are presented.
The IETF has recently advanced the IPsec protocols to draft standard status. These protocols include mechanisms for the establishment of a secure channel, via cryptographic key exchange, over an insecure medium. Such ...
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The IETF has recently advanced the IPsec protocols to draft standard status. These protocols include mechanisms for the establishment of a secure channel, via cryptographic key exchange, over an insecure medium. Such a channel can then be used for ensuring the confidentiality, authentication, and/or integrity of the communications between two parties. In this article we explain the algorithms and protocols of IPsec's Internet Key Exchange and discuss the types of security that the various IKE modes provide.
This paper describes a modified particle swarm optimization (MPSO) for the synthesis of the low sidelobe concentric ring arrays. The MPSO has been utilized to optimize the element placement in a concentric ring array ...
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This paper describes a modified particle swarm optimization (MPSO) for the synthesis of the low sidelobe concentric ring arrays. The MPSO has been utilized to optimize the element placement in a concentric ring array to obtain the lowest peak sidelobe level (PSLL). And here the multiple optimization constraints include the array aperture, the minimum ring spacing and the element spacing in each ring. Unlike standard PSO using fixed corresponding relationship between the optimal variables and their coding, the MPSO utilized the coding resetting of optimal variables to avoid infeasible solution during the optimization process. Also, the proposed approach has reduced the size of the searching area of the PSO by means of indirect description of individual. The simulated results confirming the great efficiency and robustness of this algorithm are provided in this paper.
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