Multirate Strategy Research Articles

Distributed recursive filtering under random access protocols: A multirate strategy

AbstractThis article addresses the distributed recursive filtering problem for a class of time‐varying multirate systems in sensor networks with randomly occurring nonlinearities and the communication protocol. A multirate model is considered where the sampling period of the sensors is slower than the updating period of the system state. Accordingly, the lifting technique is proposed to transform the multirate system into a single‐rate system. In order to avoid data collisions, the random access protocol (RAP) scheduling is applied to determine which signal/packet selected by RAP scheduling can access the shared network for each sensor. Attention is focused on the design of a distributed recursive filter such that, in the simultaneous presence of randomly occurring nonlinearities, the multirate strategy and the RAP scheduling, an upper bound for the filtering error covariance is obtained with the help of the mathematical induction method. Furthermore, by utilizing a novel matrix simplification technique, the filter parameters are recursively calculated by minimizing the obtained upper bound. Finally, the effectiveness of the proposed distributed recursive filtering scheme is demonstrated via a numerical example.

Outlier-resistant observer-based [formula omitted]-consensus control for multi-Rate multi-agent systems

The H∞-consensus control problem is studied for a class of multi-rate multi-agent systems based on the outlier-resistant observers. To reduce the measurement cost and save the bandwidth resource, the multi-rate strategy is introduced to regulate the sampling rates of each agent. Next, the outlier-resistant observer is constructed for each agent, where the specific saturation function is introduced to restrain the adverse effect from the possible outliers. Then, the distributed consensus controller is designed for each agent by utilizing the available information from its own observer and its neighboring agents. The aim of this paper is to design the gain parameters for each agent such that the resulting augmented system can achieve the asymptotic stability as well as the H∞ disturbance attenuation constraint when encountering the possible measurement outliers. The sufficient condition is derived to guarantee the existence of the gain parameters, which are calculated by solving a semi-positive definite problem. Finally, an illustrative simulation example is employed to validate the feasibility of the consensus control scheme.

Energy Storage with Inclusion of Power Stability Improvement with Advanced Controls Based on VLSI

Multi rate strategy is fundamental for systems with different data and yield taking a gander at rates. Late advances in negligible figuring and correspondence applications deals low power and rapid VLSI DSP structures. This Paper presents Multi rate modules used for binding to offer sign overseeing in remote correspondence structure. Distinctive arranging made for the structure of low multifaceted nature, bit parallel Multiple Constant Multiplications improvement which principles the unusualness of DSP systems. In any case, basic hindrances of present approaches are either outrageously extravagant or not profitable enough. On the other hand, MCM and digit-consecutive snake offer elective low multifaceted nature plans, since digit-dynamic structure consolidate less space and are free of the data word length. Distinctive Constant Multiplications is capable way to deal with oversee decrease the proportion of enlargement and subtraction in poly stage channel execution. This Multi rate structure believing is purposeful and real to various issues. In this paper, thought has given to the MCM and digit dynamic structure with moving and including technique that offers elective low multifaceted nature in exercises. This paper what's more pivoted around Multi rate Signal Processing Modules using Voltage and Technology scaling. Lessening of intensity use is giant for VLSI system and moreover it ends up one of the most fundamental game-plan parameter.

Distributed Set-Membership Filtering for Multirate Systems Under the Round-Robin Scheduling Over Sensor Networks.

In this paper, the distributed set-membership filtering problem is dealt with for a class of time-varying multirate systems in sensor networks with the communication protocol. For relieving the communication burden, the round-Robin (RR) protocol is exploited to orchestrate the transmission order, under which each sensor node only broadcasts partial information to both the corresponding local filter and its neighboring nodes. In order to meet the practical transmission requirements as well as reduce communication cost, the multirate strategy is proposed to govern the sampling/update rate of the plant, the sensors, and the filters. By means of the lifting technique, the augmented filtering error system is established with a unified sampling rate. The main purpose of the addressed filtering problem is to design a set of distributed filters such that, in the simultaneous presence of the RR transmission protocol, the multirate mechanism, and the bounded noises, there exists a certain ellipsoid that includes all possible error states at each time instant. Then, the desired distributed filter gains are obtained by minimizing such an ellipsoid in the sense of the minimum trace of the weighted matrix. The proposed resource-efficient filtering algorithm is of a recursive form, thereby facilitating the online implementation. A numerical simulation example is given to demonstrate the effectiveness of the proposed protocol-based distributed filter design method.

A conservative implicit multirate method for hyperbolic problems

This work focuses on the improvement of a self-adjusting multirate strategy based on an implicit time discretization for the numerical solution of hyperbolic equations that allows to employ different time steps in different areas of the spatial domain. We propose a novel mass conservative multirate approach that can be generalized to various implicit time discretization methods. Mass conservation is achieved by flux partitioning, so that mass exchanges between a cell and its neighbors are exactly balanced. A number of numerical experiments on both nonlinear scalar problems and systems of hyperbolic equations have been carried out to test the efficiency and accuracy of the proposed approach.

An efficient parallel implementation of explicit multirate Runge–Kutta schemes for discontinuous Galerkin computations

Although explicit time integration schemes require small computational efforts per time step, their efficiency is severely restricted by their stability limits. Indeed, the multi-scale nature of some physical processes combined with highly unstructured meshes can lead some elements to impose a severely small stable time step for a global problem. Multirate methods offer a way to increase the global efficiency by gathering grid cells in appropriate groups under local stability conditions. These methods are well suited to the discontinuous Galerkin framework. The parallelization of the multirate strategy is challenging because grid cells have different workloads. The computational cost is different for each sub-time step depending on the elements involved and a classical partitioning strategy is not adequate any more. In this paper, we propose a solution that makes use of multi-constraint mesh partitioning. It tends to minimize the inter-processor communications, while ensuring that the workload is almost equally shared by every computer core at every stage of the algorithm. Particular attention is given to the simplicity of the parallel multirate algorithm while minimizing computational and communication overheads. Our implementation makes use of the MeTiS library for mesh partitioning and the Message Passing Interface for inter-processor communication. Performance analyses for two and three-dimensional practical applications confirm that multirate methods preserve important computational advantages of explicit methods up to a significant number of processors.

Extended Kalman filter based hand-shake detector for optical image stabilization using a low cost gyroscope

Application extended Kalman filter (EKF) based hand-shake detector to an optical image stabilization (OIS) stabilized by fuzzy sliding-mode controller (FSMC) is proposed in this paper to enhance the image sharpness and stabilization rate (SR) of digital cameras. A low-cost gyroscope is used to sense the hand-shake vibration independently in dual-axis and the EKF is designed to online tune the parameters of hand-shake detector for improving the phase-shift phenomenon. The proposed EKF based handshake detector determines the time-varying hand-shake vibration and adopts a multi-rate strategy to reduce the computational load. The developed OIS system equipped with the FSMC and EKF based hand-shake detector is implemented in a fixed-point 16-bit microcontroller. The OIS performance is improved by the EKF based hand-shake detector in the target frequency range 2-12 Hz, and the best SR is -30.46 dB at 8Hz and the largest improvement is 1.82 times (dB) at 2 Hz.

Vision-based navigation using multi-rate feedback from optic flow and scene reconstruction

AbstractVision-based control is being aggressively pursued for autonomous systems. Such control is particularly valuable for path planning to achieve mission objectives like target tracking and obstacle avoidance. This paper presents a multi-rate strategy that utilises a fast-rate optic flow approach and a slow-rate scene reconstruction approach. The vehicle uses scene reconstruction to generate an accurate map for path planning; however, optic flow is used to avoid obstacles while the scene reconstruction is computed. A switch element is used in the feedback path to determine whether information relating to the reconstructed map or the optical flow should be used for navigation. The resulting controller is able to generate flight trajectories and perform obstacle avoidance within a computational cost which is reasonable given performance demands and computational resources on a wide range of aircraft. A simulation demonstrates the performance of an aircraft that uses the multi-rate controller to avoid an obstacle which is only observed after a turn. Essentially, the fast-rate optic flow indicates the presence of the obstacle during the time that slow-rate scene reconstruction is being performed. The resulting flight path is able to follow mission objectives and avoid a collision.

A Multiple-Line Double Multirate Shooting Technique for the Simulation of Heterogeneous RF Circuits

This paper describes a computer-aided design tool especially conceived for the efficient time-domain simulation of strongly nonlinear mixed digital, baseband, and RF circuits operating in multiple time scales. The proposed numerical method is based on a 3-D envelope oriented technique over an innovative multiple-line double multirate shooting strategy, and is tested with an illustrative circuit example. Significant gains in computation speed over previous methods recently proposed for the simulation of this category of circuits are reported, as the technique was tailored to take advantage of the circuits' heterogeneity and stimulus time-rate disparity.

A multirate time stepping strategy for stiff ordinary differential equations

To solve ODE systems with different time scales which are localized over the components, multirate time stepping is examined. In this paper we introduce a self-adjusting multirate time stepping strategy, in which the step size for a particular component is determined by its own local temporal variation, instead of using a single step size for the whole system. We primarily consider implicit time stepping methods, suitable for stiff or mildly stiff ODEs. Numerical results with our multirate strategy are presented for several test problems. Comparisons with the corresponding single-rate schemes show that substantial gains in computational work and CPU times can be obtained.

Performance analysis of a wireless multirate direct-sequence CDMA using fast Walsh transform and decorrelating detection

We analyze the performance of a flexible multirate scheme for direct-sequence code division multiple-access (CDMA) mobile radio systems. The proposed scheme uses a variable processing gain serial pseudonoise modulation as a multirate strategy. To reduce the interference effects, the CDMA system utilizes the coherent fast Walsh transform transmission technique. The proposed scheme can be used in the reverse link (mobile-to-base station) of the upcoming third-generation wide-band CDMA system (has the feature of coherent reverse link). We analyze the system performance with and without using a decorrelating multiuser detector. The uncoded bit-error probability (BEP) with and without decorrelating detection on a multipath fading channel is derived analytically. In addition, the validity of the analysis results is demonstrated by computer simulations using the IMT-2000 vehicular multipath channel model. In order to make sure that the proposed processing techniques do not distort the soft values at the demodulator output, the proposed multirate scheme is also simulated in case of using turbo codes. The turbo-coded BEP is calculated for different user data rates and different number of decoding iterations.