This paper puts forward a new variable step size LMS adaptive algorithm based on variable region. The step size p(k) in the algorithm varies with the variation of the region of deviation e (k) to ensure the optimi...This paper puts forward a new variable step size LMS adaptive algorithm based on variable region. The step size p(k) in the algorithm varies with the variation of the region of deviation e (k) to ensure the optimization of the three performance objectives including initial convergent speed, trace ability of the time-varying system and steady disregulation. The paper demonstrates the convergence of the algorithm accompanied by random noise,展开更多
The contradiction of variable step size least mean square(LMS)algorithm between fast convergence speed and small steady-state error has always existed.So,a new algorithm based on the combination of logarithmic and sym...The contradiction of variable step size least mean square(LMS)algorithm between fast convergence speed and small steady-state error has always existed.So,a new algorithm based on the combination of logarithmic and symbolic function and step size factor is proposed.It establishes a new updating method of step factor that is related to step factor and error signal.This work makes an analysis from 3 aspects:theoretical analysis,theoretical verification and specific experiments.The experimental results show that the proposed algorithm is superior to other variable step size algorithms in convergence speed and steady-state error.展开更多
为了解决传统最小均方(Least Mean Square,LMS)算法因固定步长无法同时满足收敛速度快和稳态误差低的矛盾,提出了一种基于反双曲正弦函数的改进变步长LMS算法。该算法利用反双曲正弦函数和误差的自相关量构造了步长因子和误差信号的非...为了解决传统最小均方(Least Mean Square,LMS)算法因固定步长无法同时满足收敛速度快和稳态误差低的矛盾,提出了一种基于反双曲正弦函数的改进变步长LMS算法。该算法利用反双曲正弦函数和误差的自相关量构造了步长因子和误差信号的非线性函数,并从理论和仿真上验证了抗干扰能力以及参数选取对算法性能的影响。仿真结果表明:在系统辨识方面,与现有变步长LMS算法相比,该算法具有更低的稳态误差、更快的收敛速度;在通道校准方面的成功应用也说明了该算法的适用性。展开更多
针对传统超声信号时延估计(Time Delay Estimation,TDE)中固定步长最小均方(Least Mean Square,LMS)算法难以兼顾收敛速度与稳态精度,以及现有变步长算法依赖瞬时误差和固定函数模型导致在非平稳回波信号下适应性差的问题,提出一种基于...针对传统超声信号时延估计(Time Delay Estimation,TDE)中固定步长最小均方(Least Mean Square,LMS)算法难以兼顾收敛速度与稳态精度,以及现有变步长算法依赖瞬时误差和固定函数模型导致在非平稳回波信号下适应性差的问题,提出一种基于模糊变步长LMS的超声测厚信号TDE方法。分析超声回波信号的时变特性,摒弃单一误差反馈机制,提取输出信号与期望信号的局部相关系数误差及其变化量作为模糊控制器的双输入特征;设计零阶Sugeno模糊推理系统,建立输入特征与步长因子之间的非线性映射规则,实现步长因子的自适应动态调节。利用模拟回波信号进行不同信噪比下的仿真测试,结果表明:相较定步长LMS算法、双曲正切函数变步长LMS算法以及基于瞬时误差的模糊变步长LMS算法,所提方法的综合性能更优,在保证快速收敛的同时显著降低了稳态失调误差,具有更高的测量精度和抗噪性能。搭建超声测厚平台进行标准量块测量实验,结果表明:所提方法对不同厚度量块的测量相对误差均小于其他三种LMS算法,最大相对误差为0.710%。模糊变步长LMS时延估计方法为高精度超声飞行时间(Time of Flight,TOF)计算提供了重要技术支撑,有利于促进超声无损检测技术发展,具有一定的工程应用价值。展开更多
To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the...To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the view of minimizing mean squared error (MSE). The theorem reveals the one-to-one mapping between the optimal step-size and MSE. Following the theorem, optimal variable step-size LMS (OVS-LMS) model, describing the theoretical bound of the convergence rate of LMS algorithm, is constructed. Then we discuss the selection of initial optimal step-size and updating of optimal step-size at the time of unknown system changing. At last an optimal step-size LMS algorithm is proposed and tested in various environments. Simulation results show the proposed algorithm is very close to the theoretical bound.展开更多
为了改进现有的变步长最小均方误差(least mean square,LMS)算法在低信噪比时性能较差的缺陷,提出了一种基于改进的双曲正切函数的变步长LMS算法,从理论分析和仿真实验两方面讨论了引入参数对算法收敛性、跟踪性、稳定性的影响及算法的...为了改进现有的变步长最小均方误差(least mean square,LMS)算法在低信噪比时性能较差的缺陷,提出了一种基于改进的双曲正切函数的变步长LMS算法,从理论分析和仿真实验两方面讨论了引入参数对算法收敛性、跟踪性、稳定性的影响及算法的抗干扰性。理论分析和仿真实验表明该算法在高低信噪比时均具有较快的收敛速度和跟踪速度以及较小的稳态误差和稳态失调,并且在低信噪比时该算法的收敛性、跟踪性、稳态性均优于其他多种变步长算法。展开更多
针对固定步长最小均方(LMS,least mean square)算法以及变步长LMS算法在收敛速度与稳态误差性能方面的不足,本文提出了一种新的基于对数函数改进的LMS算法.由于该算法中不涉及指数的运算,使得算法的计算量大大下降,收敛速度更快.仿真结...针对固定步长最小均方(LMS,least mean square)算法以及变步长LMS算法在收敛速度与稳态误差性能方面的不足,本文提出了一种新的基于对数函数改进的LMS算法.由于该算法中不涉及指数的运算,使得算法的计算量大大下降,收敛速度更快.仿真结果表明,对数函数改进的LMS算法比基于反正切函数改进的LMS算法具有近似相同的稳态误差性能,然而本文算法收敛更快,速度平均提高1.5倍.并且比基于双曲正切函数改进的LMS算法中的稳态误差平均降低0.5倍,同时收敛速度平均提高1.0倍.展开更多
针对固定步长LMS(Least Mean Square)算法(FXSSLMS)不能同时满足快速收敛和小稳态失调误差的问题,该文提出了迭代变步长LMS算法(IVSSLMS)。与已有的变步长LMS算法(VSSLMS)不同,该算法的步长因子不再是由输出误差信号控制,而是建立了与...针对固定步长LMS(Least Mean Square)算法(FXSSLMS)不能同时满足快速收敛和小稳态失调误差的问题,该文提出了迭代变步长LMS算法(IVSSLMS)。与已有的变步长LMS算法(VSSLMS)不同,该算法的步长因子不再是由输出误差信号控制,而是建立了与迭代时间的改进Logistic函数非线性关系,克服了定步长算法收敛慢及已有变步长算法抗噪声干扰能力差的问题。最后从理论上分析了算法的性能,给出了其参数取值方法。理论分析和仿真均表明,所提算法能够在快速收敛情况下获得小的稳态失调误差,在有色噪声干扰下稳态失调误差比已有算法降低了约7 d B。展开更多
The variable structure control (VSC) theory is applied to the electro-hydraulic servo system here. The VSC control law is achieved using Lyapunov method and pole placement. To eliminate the chattering phenomena, a s...The variable structure control (VSC) theory is applied to the electro-hydraulic servo system here. The VSC control law is achieved using Lyapunov method and pole placement. To eliminate the chattering phenomena, a saturation function is adopted. The proposed VSC approach is fairly robust to load disturbance and system parameter variation. Since the distortion. including phase lag and amplitude attenuation occurs in the system sinusoid response, the amplitude and phase control (APC) algorithm, based on Adaline neural network and using LMS algorithm, is developed for distortion cancellation. The APC controller is simple and can on-line adjust, thus it gives accurate tracking.展开更多
基金Supported by Natural Science Foundation of Beijing of China (No.2005AA501140)
摘要This paper puts forward a new variable step size LMS adaptive algorithm based on variable region. The step size p(k) in the algorithm varies with the variation of the region of deviation e (k) to ensure the optimization of the three performance objectives including initial convergent speed, trace ability of the time-varying system and steady disregulation. The paper demonstrates the convergence of the algorithm accompanied by random noise,
基金the National Natural Science Foundation of China(No.51575328,61503232).
摘要The contradiction of variable step size least mean square(LMS)algorithm between fast convergence speed and small steady-state error has always existed.So,a new algorithm based on the combination of logarithmic and symbolic function and step size factor is proposed.It establishes a new updating method of step factor that is related to step factor and error signal.This work makes an analysis from 3 aspects:theoretical analysis,theoretical verification and specific experiments.The experimental results show that the proposed algorithm is superior to other variable step size algorithms in convergence speed and steady-state error.
摘要为了解决传统最小均方(Least Mean Square,LMS)算法因固定步长无法同时满足收敛速度快和稳态误差低的矛盾,提出了一种基于反双曲正弦函数的改进变步长LMS算法。该算法利用反双曲正弦函数和误差的自相关量构造了步长因子和误差信号的非线性函数,并从理论和仿真上验证了抗干扰能力以及参数选取对算法性能的影响。仿真结果表明:在系统辨识方面,与现有变步长LMS算法相比,该算法具有更低的稳态误差、更快的收敛速度;在通道校准方面的成功应用也说明了该算法的适用性。
摘要针对传统超声信号时延估计(Time Delay Estimation,TDE)中固定步长最小均方(Least Mean Square,LMS)算法难以兼顾收敛速度与稳态精度,以及现有变步长算法依赖瞬时误差和固定函数模型导致在非平稳回波信号下适应性差的问题,提出一种基于模糊变步长LMS的超声测厚信号TDE方法。分析超声回波信号的时变特性,摒弃单一误差反馈机制,提取输出信号与期望信号的局部相关系数误差及其变化量作为模糊控制器的双输入特征;设计零阶Sugeno模糊推理系统,建立输入特征与步长因子之间的非线性映射规则,实现步长因子的自适应动态调节。利用模拟回波信号进行不同信噪比下的仿真测试,结果表明:相较定步长LMS算法、双曲正切函数变步长LMS算法以及基于瞬时误差的模糊变步长LMS算法,所提方法的综合性能更优,在保证快速收敛的同时显著降低了稳态失调误差,具有更高的测量精度和抗噪性能。搭建超声测厚平台进行标准量块测量实验,结果表明:所提方法对不同厚度量块的测量相对误差均小于其他三种LMS算法,最大相对误差为0.710%。模糊变步长LMS时延估计方法为高精度超声飞行时间(Time of Flight,TOF)计算提供了重要技术支撑,有利于促进超声无损检测技术发展,具有一定的工程应用价值。
基金This work was supported in part by the National Fundamental Research Program(Grant No.G1998030406)the National Natural Science Foundation of China(Grant No.69972020)by the State Key Lab on Microwave and Digital Communications,Department of Electronics Engineering,Tsinghua University.
摘要To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the view of minimizing mean squared error (MSE). The theorem reveals the one-to-one mapping between the optimal step-size and MSE. Following the theorem, optimal variable step-size LMS (OVS-LMS) model, describing the theoretical bound of the convergence rate of LMS algorithm, is constructed. Then we discuss the selection of initial optimal step-size and updating of optimal step-size at the time of unknown system changing. At last an optimal step-size LMS algorithm is proposed and tested in various environments. Simulation results show the proposed algorithm is very close to the theoretical bound.
摘要为了改进现有的变步长最小均方误差(least mean square,LMS)算法在低信噪比时性能较差的缺陷,提出了一种基于改进的双曲正切函数的变步长LMS算法,从理论分析和仿真实验两方面讨论了引入参数对算法收敛性、跟踪性、稳定性的影响及算法的抗干扰性。理论分析和仿真实验表明该算法在高低信噪比时均具有较快的收敛速度和跟踪速度以及较小的稳态误差和稳态失调,并且在低信噪比时该算法的收敛性、跟踪性、稳态性均优于其他多种变步长算法。
摘要针对固定步长最小均方(LMS,least mean square)算法以及变步长LMS算法在收敛速度与稳态误差性能方面的不足,本文提出了一种新的基于对数函数改进的LMS算法.由于该算法中不涉及指数的运算,使得算法的计算量大大下降,收敛速度更快.仿真结果表明,对数函数改进的LMS算法比基于反正切函数改进的LMS算法具有近似相同的稳态误差性能,然而本文算法收敛更快,速度平均提高1.5倍.并且比基于双曲正切函数改进的LMS算法中的稳态误差平均降低0.5倍,同时收敛速度平均提高1.0倍.
摘要针对固定步长LMS(Least Mean Square)算法(FXSSLMS)不能同时满足快速收敛和小稳态失调误差的问题,该文提出了迭代变步长LMS算法(IVSSLMS)。与已有的变步长LMS算法(VSSLMS)不同,该算法的步长因子不再是由输出误差信号控制,而是建立了与迭代时间的改进Logistic函数非线性关系,克服了定步长算法收敛慢及已有变步长算法抗噪声干扰能力差的问题。最后从理论上分析了算法的性能,给出了其参数取值方法。理论分析和仿真均表明,所提算法能够在快速收敛情况下获得小的稳态失调误差,在有色噪声干扰下稳态失调误差比已有算法降低了约7 d B。
摘要The variable structure control (VSC) theory is applied to the electro-hydraulic servo system here. The VSC control law is achieved using Lyapunov method and pole placement. To eliminate the chattering phenomena, a saturation function is adopted. The proposed VSC approach is fairly robust to load disturbance and system parameter variation. Since the distortion. including phase lag and amplitude attenuation occurs in the system sinusoid response, the amplitude and phase control (APC) algorithm, based on Adaline neural network and using LMS algorithm, is developed for distortion cancellation. The APC controller is simple and can on-line adjust, thus it gives accurate tracking.