一种基于EKF和ANN的车载组合导航方法

车载组合导航通常选用GPS和INS作为子系统,由于车载导航中实时性的要求,选用复杂度较低的扩展卡尔曼(EKF)作为组合导航滤波方法。提出了一种基于神经网络(ANN)和EKF相结合的方法进行组合导航。当GPS信号有效时,对ANN进行训练;当GPS发生间隔时,ANN的输出分量去修正INS输出偏差。同时考虑到GPS和INS信号中高频噪声的存在,采用小波变换方法进行预处理去噪,从而提高ANN训练样本的精度。跑车试验证明,所提出的车载组合导航方法,位置定位平均误差小于3.5 m,可满足车载导航的实际需求。     

基于LS-SVM和SVM的气动执行器故障诊断方法

为了解决自确认气动执行器的故障诊断问题,提出了一种基于最小二乘支持向量机(LS-SVM)回归建模和支持向量多分类机(SVM)的执行器故障诊断方法,该方法利用LS-SVM回归建立气动执行器的正常模型,将实际输出与模型输出比较,产生残差作为气动执行器的非线性故障特征向量。利用聚类方法设计了层次支持向量多分类机结构,以残差作为输入建立支持向量多分类机,判断气动执行器故障类型。利用DABLib生成的故障数据对所研究方法进行了验证,并与基于PCA-SVM的故障诊断方法进行了比较,结果表明该方法有效的解决了气动执行器故障诊断的小样本和非线性问题。     

LPV model-based robust diagnosis of flight actuator faults

A linear parameter-varying (LPV) model-based synthesis, tuning and assessment methodology is developed and applied for the design of a robust fault detection and diagnosis (FDD) system for several types of flight actuator faults such as jamming, runaway, oscillatory failure, or loss of efficiency. The robust fault detection is achieved by using a synthesis approach based on an accurate approximation of the nonlinear actuator–control surface dynamics via an LPV model and an optimal tuning of the free parameters of the FDD system using multi-objective optimization techniques. Real-time signal processing is employed for identification of different fault types. The assessment of the FDD system robustness has been performed using both standard Monte-Carlo methods as well as advanced worst-case search based optimization-driven robustness analysis. A supplementary industrial validation performed on the AIRBUS actuator test bench for the monitoring of jamming, confirmed the satisfactory performance of the FDD system in a true industrial setting.     

Modeling,diagnosis and estimation of actuator faults in vehicle suspensions

This paper deals with the modeling, diagnosis and estimation of faults in automotive Semi-Active (SA) dampers, particularly oil leakages in the actuator. An experimental multiplicative fault model is proposed and statistically validated with an index error of 15% for damper leakage. The fault model is used as design basis for two Fault Detection and Isolation (FDI) frameworks. The Frequency-based Fault Estimator (FFE) is based on the effect of the damper fault in the frequency domain and the Robust Parity Space (RPS) consists in a residual generator sensitive to the fault in the time domain. The model-based FDI systems were experimentally validated in a 1:5 scaled vehicle, fully instrumented and equipped with SA dampers. The experimental results show that, while both approaches represent suitable options for commercial applications, the RPS estimator has the fastest detection time and proportionality to the fault level. In addition, the RPS approach has better robustness to vehicle mass uncertainties. On the other hand, the FFE presents lower sensitivity to road profile and semi-active damper input variations. Additionally, this estimator requires a lower number of sensors and has a lower computational overhead.     

Sensor and actuator fault diagnosis of systems with discrete inputs and outputs

The paper describes a method for detecting and identifying faults that occur in the sensors or in the actuators of dynamical systems with discrete-valued inputs and outputs. The model used in the diagnosis is a stochastic automaton. The generalized observer scheme (GOS), which has been proposed for systems with continuous-variable inputs and outputs some years ago, are developed for discrete systems. This scheme solves the diagnostic problem as an observation problem, which is set up here for discrete-event systems. As the system under consideration is described by a stochastic automaton rather than a differential equation, the mathematical background and the diagnostic algorithms obtained are completely different from the well-known observers developed for continuous-variable systems. The GOS is extended here by a fault detection module to cope with plant faults that are different from actuator or sensor faults. The diagnostic algorithm consists of two steps, the first detecting the existence of a fault and the second isolating possible sensor or actuator faults or identifying plant faults. The results are applied to quantized systems whose discrete inputs and outputs result from a quantization of the continuous-variable input and output signals. Experimental results illustrate the proposed diagnostic method.     

压电陶瓷执行器的非光滑三明治模型辨识与内模控制

压电陶瓷执行器中含有非光滑、多值映射、频率依赖的非线性迟滞特性,然而在实际应用中,压电器件的输入输出信号无法直接测量,常规方法难以进行有效的辨识和控制.本文采用三明治模型来精确描述实际对象,并提出一种基于退化激励信号的两步辨识法解决三明治迟滞模型的辨识问题.最后,基于已辨识的三明治模型,设计一个内模控制器,解决压电陶瓷执行器的精密轨迹控制问题.实验结果表明所提出的辨识和控制方案取得了令人满意的结果.     

一种基于证据融合的执行器故障诊断方法

在工业过程闭环控制系统中,由于控制器的调节作用,执行器的故障特征在一定程度上受到掩盖和干扰,而单一的诊断方法总是存在误判现象.鉴于此,提出一种基于证据融合的诊断算法.首先,利用基于信号分析的方法计算表征故障特征的指标,针对“一票否决”现象对指标结果加以改进;然后,采用DS证据理论融合基于最小二乘支持向量机(LS-SVM)的概率分类特征实现优势互补,将指标表达的故障机理信息与概率分类挖掘的数据特征信息相结合,规避单一方法的局限性,从而提高诊断的准确率;最后,基于双容水箱系统的实验表明,所提出方法能够有效学习闭环系统中执行器的故障数据特征,提升诊断能力,克服单一方法的误判问题,具有较高的应用价值.     

Fuzzy control of a manipulator using an actuator and multibrakes

This paper is concerned with the control of a manipulator with n-degrees of freedom by one actuator and n ? 1 brakes using fuzzy inference. All the links of the manipulator are excited by a motor placed on the base link, and the excitation torque is successively transmitted through each link from the base link until the final link. The brakes on the joints act at identical frequency with different phases, and the phases of timing on the brakes are controlled by fuzzy inference such that all the joint angles of links are followed to the desired trajectories. The effectiveness of the proposed method is illustrated by a simple example.     

Modeling and characterization of a chemomechanical actuator using protein transporter

Plants and animal cells are naturally occurring actuators that exhibit force and motion driven by fluid transport through the cell membrane. The protein transporters embedded in the cell membrane serve as the selective gateway for ion and fluid transport. The actuator presented in this work generates force and motion from mass transport through an artificial membrane with protein transporters extracted from plant cell membranes. The artificial membrane is formed from purified 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-l-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphoethanolamine (POPE) lipids and supported on a porous substrate. The protein transporter used in the actuator membrane is a proton–sucrose cotransporter, SUT4, extracted from yeast cells genetically modified to grow the cotransporter in their cell membranes. The SUT4 transporter conducts proton and sucrose from the side of the membrane with higher concentration and carries water molecules across the membrane. It is observed from transport characterization experiments that fluid flux through the membrane varies with the applied sucrose concentration and hence is chosen as the control stimulus in the actuator. A modified four-state facilitated diffusion model is applied to the transport characterization data to compute the two characteristic parameters for fluid transport, saturation concentration and translocation rate, through the membrane. The flux rate through the membrane is observed to increase with the concentration until a particular value and saturates at a higher concentration. The saturation concentration for the actuator is experimentally found to be 6±0.6 mM sucrose on the side with lower pH. The corresponding maximum translocation rate is found to be 8.5±1.2 nl/ g cm² min. The maximum steady state deformation measured on the actuator is 60 m for 30 mM sucrose that corresponds to a force of 0.89 mN.     

非线性系统在线执行器故障诊断

针对一类含模型不确定性的非线性系统，提出了执行器故障检测与诊断的在线估计器设计方法．给出了故障诊断结构与算法，并分析了鲁棒性、灵敏度和稳定性．仿真结果验证了该方法的正确性．     

Interaction with the Boyer-Moore theorem prover: A tutorial study using the arithmetic-geometric mean theorem

There are many papers describing problems solved using the Boyer-Moore theorem prover, as well as papers describing new tools and functionalities added to it. Unfortunately, so far there has been no tutorial paper describing typical interactions that a user has with this system when trying to solve a nontrivial problem, including a discussion of issues that arise in these situations. In this paper we aim to fill this gap by illustrating how we have proved an interesting theorem with the Boyer-Moore theorem prover: a formalization of the assertion that the arithmetic mean of a sequence of natural numbers is greater than or equal to their geometric mean. We hope that this report will be of value not only for (non-expert) users of this system, who can learn some approaches (and tricks) to use when proving theorems with it, but also for implementors of automated deduction systems. Perhaps our main point is that, at least in the case of Nqthm, the user can interact with the system without knowing much about how it works inside. This perspective suggests the development of theorem provers that allow interaction that is user oriented and not system developer oriented. This research was supported in part by ONR Contract N00014-94-C-0193. The views and conclusions contained in this document are those of the author(s) and should not be interpreted as representing the official policies, either expressed or implied, of Computational Logic, Inc., the Office of Naval Research, or the U.S. government.     

Failure diagnosis of structured VLSI

The authors describe a method for diagnosing the failures observed in testing VLSI designs that use the scan-path structure. Diagnosis consists of simulating selected faults after testing using a fault simulator that allows the application of several patterns in parallel. The method is also suitable for signature-based random-pattern testing. The authors discuss diagnostic fault simulation, fault-list generation, relating faults to defects, diagnostic strategy, and random-pattern failures, and they report some experimental results to indicate the procedure's power     

Fault-tolerant control of linear systems using adaptive virtual actuator

In this paper, design and development of fault-tolerant control (FTC) is investigated for linear systems subject to loss of effectiveness and time-varying additive actuator faults as well as an external disturbance using the fault-hiding approach. The main aim of this approach is to keep the nominal controller and to design a virtual actuator that is inserted between the faulty plant and the nominal controller in order to hide actuator faults and disturbances from the nominal controller, and consequently the performance of the system before and after the occurrence of actuator faults is kept to be the same. The proposed adaptive virtual actuator does not require a separated fault detection, isolation and identification (FDII) unit and both state and output feedback cases are considered. An illustrative example is given to demonstrate the effectiveness of the proposed adaptive virtual actuator in both cases.     

压电谐振驱动三足机器人的平面运动

设计并实现了一类利用压电陶瓷片作动,由三条曲梁足支撑的振动驱动机器人.建立了在一条足共振驱动下机器人水平运动的动力学方程,数值计算解释了摩擦作用下的运动机理,寻找到异性摩擦对运动方向、速度的影响和压电激励频率与运动速度间的关系.通过建立圆弧曲梁控制方程求解圆弧型足面内振动的固有频率及振型,设计了三组不同频率的圆弧曲梁足参数,实验制作了机器人模型,利用压电控制三足间振动的共振切换,实现了预想的三个方向的运动以达到平面运动的效果,实验测量了机器人的运动速度与理论计算吻合得较好.     

Image compression and encryption using chinese remainder theorem

Multimedia Tools and Applications - The proposed encryption technique uses Chinese Remainder Theorem (CRT) and hash map to generate and distribute secret co-prime keys to participants. It utilizes...     

Development of self-healing linear actuator unit using thermoplastic resin*

High operational continuity in robots requires considerable ongoing manual maintenance, which can be replaced by enabling robots to self-heal. Extensive research on self-healing has been carried out toward the realization of this notion. The introduction of self-healing methods into mechanical systems has been investigated in recent years. However, these studies have been inadequate in terms of usage environment and self-healing efficiency. Therefore, in this work, we developed a self-healing actuator unit that can be applied to conventional mechanical systems by incorporating self-healing ability using a thermoplastic resin inserted at the actuator location. First, thermal simulation was performed to understand the design requirements to reduce healing time and ensure stable self-healing efficiency. Subsequently, experiments were performed with an actual machine, in which self-healing was consecutively carried out four times, resulting in an average self-healing efficiency of 110% and a maximum self-healing efficiency of 115%. These results show that it is possible to carry out healing without any reduction in the fracture strength of the healing mechanism, depending on the healing conditions and the designs of the parts in contact with the thermoplastic resin.     

Design of moving magnet type pickup actuator using inserted coil

Recently, the demand of the information storage devices with large storage capacity such as Blu-ray Disc and high-definition television is increased. In keeping with this trend, the optical storage devices are also required to have high data transfer rate and large storage capacity. To satisfy these requirements, the actuator for optical disc drive should have a high servo bandwidth to compensate the vibration of optical disc. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to make these frequencies of flexible modes to high frequency region. The frequency of flexible mode depends on materials and shape. Stiff materials and simple shape is useful to increase the frequency of flexible mode. In this paper, we suggested a moving magnet type actuator having flexible modes which are happened at high frequency region. Generally, the moving magnet type actuator has an advantage to increase the frequency of flexible mode because the moving magnet type actuator has simple structure and the Young’s modulus of magnet is high. However, large moving mass and inefficiency of Electromagnetic (EM) circuit cut down driving sensitivities of actuator. To improve driving sensitivities, we designed the model with the closed EM circuit for tracking actuation. The design of experiments (DOE) procedure is applied to get proper design parameters and the variable metric method (VMM) which is a technique of optimization is used to improve driving sensitivity. The lens holder is also improved based on the optimization result of EM circuit. And to make up for the low efficiency of EM circuit, the thermal stability is checked on condition that the input current is very high. At last, the final design of moving magnet type actuator is suggested and it is verified that the driving performance and the structural stiffness of the final design is sufficient.     

基于组合EKF的自主水下航行器SLAM

针对标准扩展卡尔曼滤波(EKF)在噪声统计特性不准确、系统模型与实际模型无法完全匹配情况下滤波精度严重下降的问题,提出了一种基于Sage-Husa自适应EKF和强跟踪EKF组合的SLAM(同步定位与地图构建)算法.首先建立了AUV(自主水下航行器)的动力学模型、特征模型以及传感器的测量模型,然后通过Hough变换进行特征提取,最终采用组合EKF实现了自主水下航行器的同步定位与地图构建.海试数据仿真试验表明本文所提方法降低了噪声统计特性时变以及模型不精确对系统的影响,提高了SLAM系统的精确性和鲁棒性.