A GENERAL FREQUENCY DEPENDENT DIGITAL OPTIMAL PREVIEW SERVO SYSTEM

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Application of Modelica/MWorks on modeling,simulation and optimization for electro-hydraulic servo valve system

Electro-hydraulic servo valve is a typical complicated multi-domain system constituted by mechanical, electric, hydraulic and magnetic components, which is widely used in electro-hydraulic servo systems such as construction machinery, heavy equipment, weapon and so forth. The traditional method of modeling and simulation of servo valve is based on block diagram or signal flow, which cannot describe the servo valve system from components level nor be used in modeling and simulation of overall servo systems. In the procedure of traditional method, computational causality must be involved in modeling of servo valve, which is inconvenient to execute modification on components or parameters. Modelica is an object-oriented modeling language which is suited for large, complex, heterogeneous and multi-domain systems. The key features of Modelica are multi-domain, object-oriented and non-causal, which are suitable for modeling of servo valve and make the model readable, reusable, and easy to modify. The simulation results show similar curves with traditional method. This new servo valve modeling and simulation method can provide the engineers a more efficient way to design and optimize a servo valve and an overall servo system.     

基于DSP和CPLD的数字化转台伺服系统的设计与实现

介绍了一种数字化转台伺服系统的设计及其实现．在设计中使用了数字信号处理器(DSP)以及复杂可编程逻辑器件(CPLD)，有效地降低了模拟电路中噪声、漂移等固有因素的影响，使得系统具有较高的精度。实验证明了该方案的实用性和有效性。     

调宽控制平台稳定系统对陀螺漂移影响的研究

介绍了在平台式惯导系统中,由脉冲调宽加矩方式控制的惯性稳定平台的角振动对陀螺漂移的因素,通过对平台稳定系统的动态仿真,得出了它螺漂移与采用脉宽调制工作的稳定回路参数之间的关系,为惯性平台稳定回路的设计提供重要的数据依据。     

机器人无标定视觉伺服控制研究进展

视觉伺服控制是机器人系统重要的控制手段. 相比传统的在标定条件下使用的视觉伺服系统,无标定视觉伺服系统具有更高的灵活性与适应性,是机器人伺服控制系统未来重要的发展方向和研究热点. 本文从目标函数选择、控制器设计、运动轨迹规划三方面综述了无标定视觉伺服控制系统近年来的主要研究进展. 首先根据目标函数的形式,分析了基于位置的视觉伺服、基于图像的视觉伺服以及混合视觉伺服各自的特点与应用;在控制器设计方面,根据是否在设计过程中考虑机器人的非线性动力学特性,分别介绍了考虑机器人运动学与考虑机器人动力学的无标定视觉伺服控制器的设计,重点突出了雅克比矩阵的构造与估计方法;针对无标定视觉伺服系统运动轨迹可能存在的问题,从空间轨迹优化与障碍规避的角度,阐述了已有的可行解决方案. 最后,基于当前的研究进展展望了无标定视觉伺服的未来研究方向.      

转子系统振动的CSFDB主动控制实验研究

采用可控挤压油膜阻尼器作为主控元件,进行转子系统振动主动控制研究,设计开发了锥形可控挤压油膜阻尼器（Controllable Squeeze Film Damping Bearing,CSFDB).CSFDB的外环轴向位置通过专门设计的电液伺服系统来调节其平淡同的轴向位置对应不同的油膜间隙,使转子系统、CSFDB、电液伺 服系统形成一个闭环控制系统,即主动控制转子系统的振动,本文的实验研究工作内容有,CSFDB-转子系统振动特性实验研究;CSFDB-转子系统加、减速振动特性试验研究;转子系统振动的CSFDB主动控制实验研究。转子模型为一单盘悬臂转子,研究结果表明,CSFDB控制效果明显,所研制的控制仪工作可靠,能满足实时必研究;CSFDB外环位置调节系统设计思路可行,性能可靠避孕药推广应用前景。     

Ride quality analysis of a tracked vehicle suspension with a preview control

The feasibility of a preview control is examined for tracked vehicle’s suspension systems to improve the performance of tracked vehicle systems. Numerical results are compared with LQ, robust H_∞, reference model tracking and hybrid preview control methods. The ride quality analysis is performed based on the vertical acceleration at the driver’s position. On the simulations, it is proven that the hybrid preview controller is the most efficient and practical method.     

静电陀螺测试转台电气部分方案设计

叙述了静电陀螺三环测试转台电气部分的方案设计要点。该电气部分包括静电陀螺启动与控制系统，转台控制系统，计算机三大部分，测角分系统采用粗精耦合式角位置传感器。双轴伺服分系统采用带有纯积分环节的一阶无差控制系统，三轴位置控制分系统采用一阶无差数字控制的方案，从而确保转台满足精度指标。     

On the frequency bandwidth change of a servo system with a gear reducer due to backlash and motor input voltage

Summary The paper analyzes how the frequency bandwidth of a servo system is affected by the input voltage of its motor and the magnitude of the total backlash. The bandwidth of the system is defined as the set of antiresonance frequencies, which appears in the frequency-response characteristic. The change in the frequency-response characteristics is investigated depending on motor input voltage and the magnitude of the total backlash. It is shown that at infinite motor input voltage, the servo system has a bandwidth equivalent to that of a backlash-free system. The amount of the systems bandwidth reduction due to the backlash changes greatly with the motor input voltage. It becomes possible then to determine the necessary maximum input voltage of the motor and the admissible magnitude of the total backlash to satisfy the desired bandwidth for a servo system with a gear reducer.     

Design of multi-degree motion haptic mechanisms using smart fluid-based devices

This article presents two different types of haptic masters capable of 4-degree- of-freedom (DOF) force feedback utilizing magnetorheological fluid (MR) and electrorheological (ER) fluid. The proposed ER master consists of a spherical joint for 3-DOF rotational motion and a linear device for 1-DOF translational motion, the MR haptic master consists bi-directional clutches associated with a planetary gear system and one-directional clutch with a bevel gear system. After showing the configuration of each haptic mechanism, the torque and force models of the actuators are derived based on the field-dependent Bingham model. After undertaking optimal design with spatial limitation and desired torque level, two different types of haptic master systems are manufactured. The torque and force responses are experimentally evaluated to validate practical feasibility of the proposed haptic masters for medical application.     

双边沿鉴频鉴相器的设计

一本文提出了用ＥＰＬＤ芯片实现高分辨率的双边沿鉴频鉴相器，从而解决了锁相伺服系统的高精度问题。     

三轴转台陀螺伺服系统的模型分析与解耦设计

本文对三轴陀螺伺服转台模型进行了较为详细的分析,并进行了适当的简化,在此基础 上对系统进行了解耦设计。     

哈密顿系统正则变换在时变最优控制中的应用

利用哈密顿系统正则变换和生成函数理论求解线性时变最优控制问题,构造了新的最优控制律形式并提出了控制增益计算的保结构算法. 利用生成函数求解最优控制导出的哈密顿系统两端边值问题,并构造线性时变系统的最优控制律,由第2类生成函数所构造的最优控制律避免了末端时刻出现无穷大反馈增益. 控制系统设计中需求解生成函数满足的时变矩阵微分方程组. 根据生成函数与哈密顿系统状态转移矩阵之间的关系,从正则变换的辛矩阵描述出发,导出了求解这组微分方程组的保结构递推算法.为了保持递推计算中的辛矩阵结构,哈密顿系统状态转移矩阵的计算中利用了Magnus级数.      

Optimal nonlinear observers for chaotic synchronization with message embedded

This paper presents an optimal nonlinear observer for synchronizing the transmitter-receiver pair with guaranteed optimal performance. In the proposed scheme, a generalized nonlinear state-space observer via uniform matrix transformations is constructed to estimate the transmitter state and the information signal, simultaneously. A nonlinear optimal design approach is used to synchronize chaotic systems. Solving the Hamilton–Jacobi–Bellman (H–J–B) equations we can obtain a linear optimal feedback scheme for piecewise-linear chaotic systems. Moreover, a robust scheme derived from the H _∞ optimization theory improves the synchronization performance of general nonlinear chaotic systems by suppressing the influence of their high order residual terms. Finally, two numerical simulation examples are illustrated by the chaotic Chua’s circuit system and the Lorenz chaotic system to demonstrate the effectiveness of our scheme.     

拟哈密顿系统非线性随机最优控制

主要介绍近十几年来拟哈密顿系统非线性随机最优控制理论方法及其应用的研究成果, 包括基于拟哈密顿系统随机平均法与随机动态规划原理的非线性随机最优控制基本策略, 即响应极小化控制、随机稳定化、首次穿越损坏最小化控制、以概率密度为目标的控制, 为将它们应用于工程实际而作的部分可观测系统最优控制、有界控制、时滞控制、半主动控制、极小极大控制的进一步研究, 以及综合考虑这些实际问题的非线性随机最优控制的综合策略, 非线性随机最优控制在滞迟系统、分数维系统等中的若干应用, 介绍与这些研究有关的背景, 并指出今后有待进一步研究的问题.     

The optimal truncated low-dimensional dynamical systems based on flow databases

A new theory on the construction of optimal truncated Low-Dimensional Dynamical Systems (LDDSs) with different physical meanings has been developed. The physical properties of the optimal bases are reflected in the user-defined optimal conditions. Through the analysis of linear and nonlinear examples, it is shown that the LDDSs constructed by using the Proper Orthogonal Decomposition (POD) method are not the optimum. After comparing the errors of LDDSs based on the new theory, POD and Fourier methods, it is concluded that the LDDSs based on the new theory are optimally truncated and catch the desired physical properties of the systems. The project supported by the National Natural Science Foundation of China and LNM, Institute of Mechanics, CAS     

Characterizing the anticipating chaotic synchronization of RCL-shunted Josephson junctions

This study addresses the problem of anticipating synchronization of two chaotic RCL-shunted Josephson junctions (RCLSJ) based on time-delayed feedback control. The error dynamical system can be dealt with in virtue of non-linear pendulum-like system methods, through which we establish sufficient conditions to guarantee the existence of anticipating synchronizing slave systems. The design of a desired feedback controller can be achieved by solving a group of linear matrix inequalities (LMIs) by utilizing available numerical software. In the presence of parameter uncertainties, we further explore the robust anticipating synchronization, and propose corresponding criteria as well. These results are demonstrated through numerical simulations that under the derived conditions, the slave RCLSJ model could respond in exactly the same way as the master would do in the future, hence it allow us to anticipate the non-linear chaotic dynamics.     

海洋重力传感器伺服回路分析与设计

海洋重力仪是改善舰船惯导系统精度的重要设备，其重力传感器的伺服回路决定着仪器的精度和动态性能。作在介绍零长弹簧海洋重力传感器结构原理的基础上，研究其伺服回路的结构组成和设计方法，分析了其主要环节参数对系统性能的影响，考察了其时域性能，对海洋重力仪的研制具有重要指导作用。     

Partially saturated nonlinear control for gantry cranes with hardware experiments

Gantry cranes are typically underactuated nonlinear dynamic systems with highly coupled system states. We propose in this paper a partially saturated nonlinear controller for gantry crane systems by converting the crane model into an objective (i.e., desired closed-loop) system. The presented scheme guarantees “soft” cart start by introducing a smooth saturated function into the controller. In particular, we first establish an objective system with desired signal convergence and stability performance. Then, on the basis of the objective dynamics’ structure, we derive a partially saturated control law straightforwardly by solving one partial differential equation, without necessity of performing partial feedback linearization operations to the original crane model. The convergence and stability performance of the objective system is assured with Lyapunov-based methods. In order to verify the practical control performance of the proposed method, we implement both numerical simulation and hardware experiments to illustrate that the new method achieves increased performance with respect to existing methods, with lessened control efforts.     

Adaptive intelligence learning for nonlinear chaotic systems

In this paper, a reinforcement learning algorithm is proposed for a class of nonlinear differential chaotic systems. The nonlinear function of the chaotic systems is assumed to be bounded but the bounds are unknown. The unknown bounds need to be on-line adjusted. An adaptive optimal (or near optimal) control input with the reinforcement signal can be obtained compared with the current adaptive control for chaotic systems. The reinforcement signal is approximated by the neural networks. Based on Lyapunov analysis theory and by using Young’s inequalities, the closed-loop system is guaranteed to be stable. Finally, the simulation results are given to illustrate the effectiveness of the approach.