基于多模输入整形的柔性关节振动抑制研究

针对常规输入整形技术应用于具有非线性和时变特性的系统时振动抑制效果明显降低的局限性,提出多模Jerk-Limited输入整形算法。该方法通过引入振动频率在线辨识算法和设计延时补偿算法,提高输入整形算法的鲁棒性,并在不降低多模输入整形算法效果的基础上,减小输入整形引入的延时。结果表明:基于柔性关节的伺服系统仿真模型,多模输入整形算法对柔性系统的振动抑制程度可达90%左右,且延时时间降低87%左右。

多策略驱动的动态手势识别算法

在动态手势识别方法中,现有多模输入策略易忽略手势类别局部信息与全局信息的差异性,同时现有决策级融合对各通道数据预测结果采用均值操作,不能充分利用在识别中起关键性作用的特征信息.提出了一种多线索自适应驱动算法:采用多线索输入策略融合各模态数据的局部与全局信息,构建2D与3D卷积神经网络级联框架提取手势特征,设计自适应融合策略为各通道预测结果赋予不同的权重.在SKIG数据集和IsoGD公开数据集上的实验结果证明了该算法的有效性,取得了与当前主流算法相当的动态手势识别效果.

An Efficient MMI SOI Splitter with Multimode Input/Output Waveguides

A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for use in fiber optics communication systems.The fabricated device exhibits low loss and good coupling uniformity.The excess loss is lower than 0 8dB,and the uniformity is 0 45dB at the wavelength of 1550nm.Moreover,the polarization dependent loss is lower than 0 7dB at 1550nm.The device size is only 2mm×10mm.

Modeling of Isomerization of C_8 Aromatics by Online Least Squares Support Vector Machine

The least squares support vector regression (LS-SVR) is usually used for the modeling of single output system, but it is not well suitable for the actual multi-input-multi-output system. The paper aims at the modeling of multi-output systems by LS-SVR. The multi-output LS-SVR is derived in detail. To avoid the inversion of large matrix, the recursive algorithm of the parameters is given, which makes the online algorithm of LS-SVR practical. Since the computing time increases with the number of training samples, the sparseness is studied based on the pro-jection of online LS-SVR. The residual of projection less than a threshold is omitted, so that a lot of samples are kept out of the training set and the sparseness is obtained. The standard LS-SVR, nonsparse online LS-SVR and sparse online LS-SVR with different threshold are used for modeling the isomerization of C8 aromatics. The root-mean-square-error (RMSE), number of support vectors and running time of three algorithms are compared and the result indicates that the performance of sparse online LS-SVR is more favorable.

Modeling and Control of Nonlinear Discrete-time Systems Based on Compound Neural Networks

An adaptive inverse controller for nonliear discrete-time system is proposed in this paper. A compound neural network is constructed to identify the nonlinear system, which includes a linear part to approximate the nonlinear system and a recurrent neural network to minimize the difference between the linear model and the real nonlinear system. Because the current control input is not included in the input vector of recurrent neural network (RNN), the inverse control law can be calculated directly. This scheme can be used in real-time nonlinear single-input single-output (SISO) and multi-input multi-output (MIMO) system control with less computation work. Simulation studies have shown that this scheme is simple and affects good control accuracy and robustness.

Hybrid input shaping control scheme for reducing vibration of robot based on multi-mode control

The classic multi-mode input shapers(MMISs)are valid to decrease multi-mode residual vibration of manipulators or robots simultaneously.But these input shapers cannot suppress more residual vibration with a quick response time when the frequency bandwidth of each mode vibration is very different.The methodologies and various types of multi-mode classic and hybrid input shaping control schemes with positive impulses were introduced in this paper.Six types of two-mode hybrid input shapers with positive impulses of a 3 degree of freedom robot were established.The ability and robustness of these two-mode hybrid input shapers to suppress residual vibration were analyzed by vibration response curve and sensitivity curve via numerical simulation.The response time of the zero vibration-zero vibration and derivative(ZV-ZVD)input shaper is the fastest,but the robustness is the least.The robustness of the zero vibration and derivative-extra insensitive(ZVD-EI)input shaper is the best,while the response time is the longest.According to the frequency bandwidth at each mode and required system response time,the most appropriate multi-mode hybrid input shaper(MMHIS)can be selected in order to improve response time as much as possible under the condition of suppressing more residual vibration.

BLIND EQUALIZATION OF MIMO SYSTEMS BASED ON ORTHOGONAL CONSTANT MODULUS ALGORITHM

This paper investigates adaptive blind source separation and equalization for Multiple Input Multiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI) and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, then with the derived orthogonality between weight vectors of different input signals, a new orthogonal Constant Modulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance of the proposed method. Without channel identification, the proposed method can recover all the system inputs simultaneously and can be adaptive to channel changes without prior knowledge about signals.

Multi-loop Internal Model Controller Design Based on a Dynamic PLS Framework

In this paper,a multi-loop internal model control(IMC) scheme in conjunction with feed-forward strategy based on the dynamic partial least squares(DyPLS) framework is proposed.Unlike the traditional methods to decouple multi-input multi-output(MIMO) systems,the DyPLS framework automatically decomposes the MIMO process into a multi-loop system in the PLS subspace in the modeling stage.The dynamic filters with identical structure are used to build the dynamic PLS model,which retains the orthogonality among the latent variables.To address the model mismatch problem,an off-line least squares method is applied to obtain a set of optimal filter parameters in each latent space.Without losing the merits of model-based control,a simple and easy-tuned IMC structure is readily carried over to the dynamic PLS control framework.In addition,by projecting the measurable disturbance into the latent subspace,a multi-loop feed-forward control is yielded to achieve better performance for disturbance rejection.Simulation results of a distillation column are used to further demonstrate this new strategy outperforms conventional control schemes in servo behavior and disturbance rejection.

Dynamic analysis on methanation reactor using a double-input–multi-output linearized model

A double-input–multi-output linearized system is developed using the state-space method for dynamic analysis of methanation process of coke oven gas.The stability of reactor alone and reactor with feed-effluent heat exchanger is compared through the dominant poles of the system transfer functions.With single or double disturbance of temperature and CO concentration at the reactor inlet,typical dynamic behavior in the reactor,including fast concentration response,slow temperature response and inverse response,is revealed for further understanding of the counteraction and synergy effects caused by simultaneous variation of concentration and temperature.Analysis results show that the stability of the reactor loop is more sensitive than that of reactor alone due to the positive heat feedback.Remarkably,with the decrease of heat exchange efficiency,the reactor system may display limit cycle behavior for a pair of complex conjugate poles across the imaginary axis.

Study on intercarrier interference in mobile MIMO-OFDM based on the geometrical one-ring model

This paper investigates the distribution of intercarrier interference （ICI） in multiple-input multiple-output orthogonal frequency division multiplexing （MIMO-OFDM） systems based on the geometrical one-ring model. Using the spatial and temporal correlation of a geometrical one-ring model, a close-formed expression of intercarrier interference due to the Doppler effect caused by the movement of receiver is derived under the isotropic scattering conditions and non-isotropic scattering conditions. The analytical results are verified by Monte Carlo simulations. We use the generated channels to investigate MIMO-OFDM intercarrier interference under various channel parameters. It can be shown that more than 95% oflCI power comes from five neighboring subcarriers.

Modeling and characterization of novel magnetorheological(MR) cell with individual currents

Magnetorheological(MR) cell with multi-coil was designed to enlarge the range of controllable transmission torque by increasing the effective length. Individual input current was proposed to maximize its potential for reducing power consumption and generating large yield stress. Finite element analysis was performed to analyze magnetic field distribution, based on which a prototype MR cell was fabricated and tested to investigate the performance of various combinations of individual input currents. A good correlation was identified between experimental results and FEA predications. The results show that the power consumption can be reduced to 42.4%, maintaining large transmission torque, by distributing the total current(2 A) to three individual magnetic coils. In addition, optimal results of four input currents considering a multi-objective function are obtained by changing the weighting factor λ. The advantage of this design, such as lower power consumption and more control flexibility, makes it more competitive in engineering applications that require large energy consumption.

A non-stationary channel model for 5G massive MIMO systems

We propose a novel channel model for massive multiple-input multiple-out （MIMO） communication systems that incorporate the spherical wave-front assumption and non-stationary properties of clusters on both the array and time axes. Because of the large dimension of the antenna array in massive MIMO systems, the spherical wave-front is assumed to characterize near-field effects resulting in angle of arrival （AoA） shifts and Doppler frequency variations on the antenna array. Additionally, a novel visibility region method is proposed to capture the non-stationary properties of clusters at the receiver side. Combined with the birth-death process, a novel cluster evolution algorithm is proposed. The impacts of cluster evolution and the spherical wave-front assumption on the statistical properties of the channel model are investigated. Meanwhile, corresponding to the theoretical model, a simulation model with a finite number of rays that capture channel characteristics as accurately as possible is proposed. Finally, numerical analysis shows that our proposed non-stationary channel model is effective in capturing the characteristics of a massive MIMO channel.

Underwater three-dimensional imaging using narrowband MIMO array

To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the array physical size simultaneously, this paper proposes a new underwater 3-D acoustic imaging approach based on a novel multiple-input multiple-output (MIMO) array. Specifically, the MIMO array is composed of four uniform linear arrays (ULAs) located on four sides of a rectangle. The transmitting array composed of two ULAs is located on a pair of opposite sides, and the receiving array composed of another two ULAs is located on the other two sides. Furthermore, narrowband waveforms coded with orthogonal polyphase sequences are employed as transmitting waveforms. When the subcode numbers in the polyphase coded sequences are sufficient, the MIMO array has the same 3-D imaging ability as a rectangular array, which has a two-time bigger size than that of the former. Consequently, the MIMO array can not only save a great number of sensors, but halve the array size, when compared to a rectangular array with the same cross-range resolution. Computer simulations are provided to demonstrate the effectiveness of the proposed imaging approach.