On the implementation and control of a pneumatic power active lower-limb orthosis

This paper develops a pneumatic power active lower-limb orthosis (PPALO) to be a controlled plant. Due to the use of pneumatic actuators, the PPALO inherently possesses non-smooth nonlinearities, such as asymmetric dynamics, friction, and dead zone. In order to eliminate the influence of these nonlinearities on the pneumatic actuators and the dynamic coupling terms included in the dynamics of the lower-limb orthosis, an inner-loop PI controller with a differential pressure feedback and an outer-loop filter-based iterative learning control (FILC) scheme which consists of an outer PD feedback controller as well as a feedforward filter are used. Finally, a trajectory tracking control experiment is conducted to validate that the proposed method can effectively control the system to track the desired trajectory and reduce the vibration caused by nonlinearities of the pneumatic actuators.     

基于通行优先的单交叉口感应控制优化设计

感应控制适用于一些交通流量较小,随机波动性较大的路口。在经典感应控制的基础上,引入一个通行优先权的概念,利用检测器进行数据采集,对于车辆的排队长度和车辆延误进行计算,通过权值计算来确定各个交通方向的交通需求,最后设置优先级来进行交通信号相位的顺序控制。该方法可以有效提高经典感应信号控制的效率,并在仿真实验结果中得到证实。     

Position control of an Ionic Polymer Metal Composite actuated rotary joint using Iterative Feedback Tuning

Ionic Polymer Metal Composites (IPMCs) are a novel material that has been the subject of considerable interest over recent decades because of their unique electrochemical and mechanical properties which allow them to be used as smart transducers. However, there has been insufficient research to determine if the electro-active polymer can reliably actuate common engineering mechanisms due to its nonlinear and time-variant nature. This paper explores a model-free approach for controlling the position of an IPMC actuated rotary linkage for micro-manipulation. The mechanism was developed based on the mechanical characteristics of the IPMC actuators. A Proportional, Integral (PI) controller was initially developed and tested to control the tip displacement of the mechanism. Test results show that this classical controller is capable of actuating the rotary mechanism to microscopic deflections but would not completely stabilise at the steady state position. An adaptive, nonlinear tuning method called Iterative Feedback Tuning (IFT) was developed to tune the performance of the PI controller. Empirical results show that the new control scheme improved the steady state response. However, the enhancement of the transient response could not be definitively validated as solely the work of the IFT algorithm due to the time-variant and variable response behaviour of IPMCs.     

Fuzzy error governor: A practical approach to counter actuator saturation on flexible joint robots

In this paper, a practical method to counter actuator saturation based on a fuzzy error governor is developed and a complete case study is considered. In addition to good performance, the method has two attracting properties: It does not change the structure of the main controller, and therefore, the theoretically proven characteristics of the system are untouched, and it is simply implementable in practice. The proposed controller structure is applied on a flexible joint robot (FJR). The robust stability of the closed loop system for an n-DOF FJR is thoroughly analyzed and the proposed controller is implemented on a laboratory setup to show the ease of implementation and the resulting closed-loop performance. The main controller used for the n-DOF FJR consists of a composite structure, with a PD controller on the fast dynamics and a PID controller on the slow dynamics. The bandwidth of the fast controller is decreased during critical occasions with the fuzzy logic supervisor, which adjusts the loop gain to a proper level. Using Lyapunov direct method, the robust stability of the overall system is analyzed in presence of modeling uncertainties, and it is shown that if the PD and the PID gains are tuned to satisfy certain conditions, the closed loop system becomes UUB stable.     

经股四头肌腱关节腔内注射玻璃酸钠治疗膝骨关节炎的疗效观察

目的观察经股四头肌腱行关节腔内注射玻璃酸钠治疗膝骨关节炎(Knee Osteoarthritis,KOA)的疗效。方法对48例KOA患者(70膝)于髌骨上缘经股四头肌腱膝关节腔穿刺注射玻璃酸钠,分别于治疗前及治疗后1月行Hss评分。结果经股四头肌腱膝关节腔穿刺可做到一针穿刺成功。治疗后Hss评分较治疗前明显升高(P<0.01),其中疼痛项、功能项差异有统计学意义。结论经股四头肌腱膝关节腔内注射玻璃酸钠对改善KOA患者临床症状疗效确切、持久,操作简便、成功率高、病人痛苦小。     

认知网中感知时间和功率控制的联合优化机制

针对认知无线网中为了最大化认知用户的吞吐量问题,提出了一种感知时间和功率控制的联合优化机制。该机制保证认知系统在低于一定干扰限制下,将认知用户吞吐量描述成为一个多约束优化问题,从理论上分析了最优功率分配方案与最优感知时间分配方案。根据理论分析结果,设计了联合迭代机制通过确定合适的感知参数从而达到最大化认知用户吞吐量的目的。仿真结果表明：提出的联合优化机制复杂度较低,并且该方案的认知吞吐量性能最接近理论最优方案的性能。     

Event driven sliding mode control of a lower limb exoskeleton based on a continuous neural network electromyographic signal classifier

This study presents an event driven automatic controller to regulate the movement of a mobile lower limb active orthosis (LLAO) triggered with the information obtained from electromyographic (EMG) signals, which are captured from the user’s triceps and biceps muscles. The proposed controller has an output feedback realization including a velocity estimator algorithm based on a high order sliding mode observer. The output feedback controller implements a class of decentralized super-twisting algorithm. The controller must enforce the movement of the orthosis articulations following some defined reference trajectories. This strategy realizes a time-window dependent event driven controller for the active orthosis. The controller selects among four different routines to be executed by a patient. A differential neural network classifies the different patterns of muscle movements. This classifier succeeds in defining the correct EMG class in a 95% of the tested signals. This work senses the EMG signals from the biceps and triceps, considering a possible injury in the patient to be obtained from the quadriceps. Therefore, four upper limb routines are established to generate the corresponding classes and the four different main therapies for the LLAO. A fully instrumented and self-designed orthosis is constructed to evaluate the proposed controller including three rotational joints per leg and a mobile robot to execute translation movements.     

Iterative learning control of a pneumatically actuated lung tumour mimic model for an improvement of PET/CT-imaging

In this paper, a model-based tracking control is proposed for a mechanism dedicated to accurately reproduce the breathing-induced motion of a human lung tumour. In former work, a 3-dimensional mechanism equipped with three pneumatically driven axes has been developed and constructed for this purpose. The overall control structure consists of decentralised axis controller for each pneumatic cylinder with a cascaded structure: A fast inner control loop governs the pressure induced drive force using backstepping techniques, whereas the outer control loop is related to an optimal, robust position control of the cylinder. Additionally, discrete-time iterative learning controllers are utilised to compensate lumped disturbance forces and model uncertainties. The suggested overall control structure has been implemented on the innovative test rig and successfully validated in a clinical framework. The given work represents the basis for future improvements of algorithms regarding PET/CT-imaging as well as radiotherapy.     

Control of an air pressure actuated disposable bioreactor for cultivating heart valves

A disposable injection molded bioreactor for growing tissue-engineered heart valves is controlled to mimic the physiological heart cycle. Tissue-engineered heart valves, cultured from human stem cells, are a possible alternative for replacing failing aortic heart valves, where nowadays biological and mechanical heart valves are used. Growing and conditioning is done by mechanically stimulating the tissue in a bioreactor. The disposable injection molded bioreactor uses flexible membranes and steering valves to mimic a physiological heart cycle. In this work, an air pressure actuation control system for this bioreactor is designed. One membrane is position controlled to achieve a desired flow through the heart valve, while another membrane controls the aortic pressure. A third actuator controls a steering valve used to impose a resistance on the flow back to the first membrane, in order to control the heart valve closing pressure. Due to the repetitive character of the setpoints, repetitive controllers are designed and implemented. A high position tracking performance is achieved and pressure setpoints are mimicked successfully, while preventing large pressure oscillations and suppressing disturbances that could be damaging for the tissue heart valve. The control system allows full adjustability of operating conditions needed for the growing, conditioning and testing phases of tissue engineered heart valves.     

基于模糊控制参数自整定的舰载雷达三轴稳定控制

在舰载雷达三轴稳定控制中,采用经典PID控制算法难以取得较高的控制精度且参数整定繁琐。本文采用了将经典PID控制与模糊控制相结合的方法,利用模糊理论进行PID参数的自动整定,并将其应用于舰载雷达三轴稳定控制中,取得了较好的控制效果。     

PDAVQ：一种基于PD控制的自适应虚拟队列管理算法

提出了一种新的基于比例差分控制的自适应虚拟队列管理(AVQ)算法—PDAVQ,用于对网络链路中产生的拥塞进行控制,以达到有效利用网络带宽,使整个网络系统达到稳定,缓解网络拥塞的目的。而且本文对所提算法运用控制理论对系统的稳定性进行了证明,给出了满足系统稳定性条件的参数选择方法和 PDAVQ 算法的具体描述。最后,通过 ns2 仿真实验与现有的 AVQ 算法比较,结果表明,所提 PDAVQ 算法具有较高的吞吐率、较低的链路延迟和数据丢失率,并能更快的使整个网络系统达到稳定,具有较好的网络性能。     

两颗中继卫星共用测站协同控制研究

中继卫星地面应用系统建设周期长、建设造价昂贵。处于相近轨位的两颗中继卫星使用同一个测站进行测控和数据中继应用,能够有效降低系统建设成本。通过梳理卫星各平台测控事件之间的时间约束关系及其对地面应用系统的设备的使用约束,分析了测定轨精度、位置保持、星蚀期能源管理、地敏探头干扰保护对共用测站的影响,提出了两颗中继卫星分时测定轨、位置保持分别进行地敏探头干扰保护的方法,以及平台应急条件下共用测站控制支持模式。最后,就共用测站执行数据中继任务提出了建简易备份站降速使用的建议,为中继卫星地面应用系统建设提供有益的参考。     

基于不同策略的联合接纳控制算法综述

无线通信网络中多种接入技术将长期并存且协同工作,传统的接纳控制方法无法满足现有用户与网络需求.联合接纳控制是联合无线资源管理的重要组成部分,接纳控制策略的好坏直接影响到用户的服务质量.通过对不同接纳控制策略进行分类并建立相应策略库,设定策略选择机制,以提高阻塞率、中断率、用户满意率及网络资源利用率等指标.以此为指导,分别讨论了不同策略的联合接纳控制算法的性能,并对现有的联合接纳控制算法进行了总结.最后,给出了联合接纳控制下一步需要解决的问题及研究发展方向.     

Adaptive power control and beam-forming joint optimization in cognitive radio networks

A novel adaptive power control and beam-forming joint optimization algorithm is proposed in cognitive radio(CR) underlay networks,where cognitive network share spectrum with primary network which spectrum is licensed.In this paper,both primary base station(PBS) and cognitive base station(CBS) are all equipped with multi antennas,while each primary user(PU) and cognitive user(CU) has only one antenna.Different from traditional algorithms,an adaptive weight factor generating solution is supplied to different access users(both PUs and CUs) in this paper,and the different priority of users is also considered,because PUs have higher priority,the weight factor of PUs is fixed as constant and signal-to-interference and noise ratio(SINR) threshold is unchanged,while for CUs,it is set adaptively and SINR threshold is also changed accordingly.Using this algorithm,the transmit power is decreased,which relax the strict requirements for power amplifier in communication systems.And moreover,owing to PUS has fixed SINR threshold,the calculated SINR at receiver is nearly unchanged,but for CUs,the SINR is changing with the adaptive weight factor.Under the assurance of quality of service(QoS) of PUs,the solution in this paper can enable CRs access to the CR network according to adaptive SINR threshold,therefore which supplies higher spectrum utilization efficiency.     

联合变换用于指纹鉴定

一、引言 联合变换是基于相关运算的一种光学技术,它为特征识别提供了简便实用的方法。文 献[2]用联合变换原理分析并实现了汉字字符的特征识别。由于在实际应用中可以在输入平面内调整特征函数以及被识别信号的方位乃至尺寸,这种方法具有很大的灵活性,有着广泛的应用前景。本文给出这种方法用于指纹鉴定的实验结果。由于指纹鉴定自身的一些特点,联合变换方法显得特别适合这类工作。     

Stability of discrete-time systems joined with a saturation operator on the state-space: Yet another version of Liu-Michel's criterion

A novel criterion for the global asymptotic stability of fixed-point state-space digital filters using saturation arithmetic is presented. The criterion, which is basically a new version of an earlier criterion due to Liu and Michel, is a generalization and improvement over a recently reported criterion. The generalization is due to the fact that the use of even unsymmetric Lyapunov matrix P is permitted. An example illustrating the improvement realized from the present criterion is given.     

New approach to stability of 2-D discrete systems with state saturation

A new criterion for the global asymptotic stability of 2-D discrete systems described by the Roesser model using saturation arithmetic is presented. The criterion is a generalization over an earlier criterion due to Liu and Michel. The generalized criterion has the feature that Lyapunov matrix P is not restricted to be symmetric, i.e., P can be even unsymmetric. A modified form of the criterion is also presented. Two examples showing the effectiveness of the generalized approach to yield new 2-D stability results are provided. To the best of author's knowledge, the use of unsymmetric P to obtain new 2-D stability conditions (i.e., conditions which are outside the scope of symmetric P) is demonstrated, for first time, in this paper.     

Stability analysis in an AVQ model of Intemet congestion control algorithm

This paper focuses on the local stability of a classical congestion control model in the Internet,namely adaptive virtual queue(AVQ) algorithm with feedback delay.Firstly,necessary and sufficient stability conditions in terms of key tuning parameters are given,which can provide exact guidelines for setting system parameters.Furthermore,by computing the rightmost characteristic root,the optimal parameter configuration for AVQ is derived,which can guarantee superior stability performance.Finally,some simulation examples are given to illustrate the correctness of the theoretical analysis.     

预测控制主动队列管理算法的设计与分析

针对Intemet时滞网络系统,提出了基于模型预测控制的主动队列管理算法MPAQM.首先考虑时滞系统的因果性来定义预测输出,然后根据拥塞控制的要求描述优化问题,求得路由器缓冲区的分组丢失率;另外分析给出保证闭环时滞系统稳定的充分条件,为算法的参数调节提供理论指导,使得队列能快速、稳定地到达期望值.在单瓶颈和多瓶颈网络拓...