Contact Stiffness Identification with Delay and Structural Compensation for Hardware-in-the-Loop Contact Simulator

The hardware-in-the-loop (HIL) simulation is necessary to test the contact dynamics of spacecraft in space. The stiffness parameter is important for the state recording and compliant control. A contact stiffness estimation method is proposed, where the force measurement delay and structural dynamics of the upper platform are compensated to guarantee the estimation accuracy. The force measurement delay and structural deformation of the upper platform lead to the delayed force signal and the position error respectively, and then the contact stiffness identification error. A phase lead based delay compensation is used to reconstruct the true contact force from the measured force. The structural deformation of the upper platform is compensated by a structural dynamics model to obtain the true contact position. Based on the compensated force and position signals, the stiffness identification is performed using the real time recursive least squares (RLS) method. The effectiveness of the proposed method is verified by simulations and experiments. In the experiments, the stiffness identification error is about ± 5 %, which is satisfactory for monitoring and control applications.     

Integrated design of fault reconstruction and fault-tolerant control against actuator faults using learning observers

This paper addresses the problem of integrated fault reconstruction and fault-tolerant control in linear systems subject to actuator faults via learning observers (LOs). A reconfigurable fault-tolerant controller is designed based on the constructed LO to compensate for the influence of actuator faults by stabilising the closed-loop system. An integrated design of the proposed LO and the fault-tolerant controller is explored such that their performance can be simultaneously considered and their coupling problem can be effectively solved. In addition, such an integrated design is formulated in terms of linear matrix inequalities (LMIs) that can be conveniently solved in a unified framework using LMI optimisation technique. At last, simulation studies on a micro-satellite attitude control system are provided to verify the effectiveness of the proposed approach.     

Smart product-service systems in interoperable logistics: Design and implementation prospects

To deal with the increasing complexity of customer demands, supply chain (SC) and logistics organisation and management have been constantly moving towards collaboration, intelligence, and service-orientation. The importance of service-oriented design for SC and logistics systems has been stressed, especially with regards to interoperability and sustainability. In this context, the recent intelligent interoperable logistics paradigm has been increasingly studied and the Smart Product-Service System (PSS) concept seems interesting for the paradigm. Smart PSS are characterised by their ability to collect and process information autonomously and subsequently make decisions and self-act/evolve. Interested in the potential for tackling complex logistics systems, this paper investigates how smart PSS could be considered and designed for service-oriented, intelligent interoperable logistics. A recent breakthrough logistics paradigm called the Physical Internet (PI) is taken as a practical example in this research. We present and discuss key design issues and innovative business models associated with smart PSS in PI. The results clearly indicate the promising potential of smart PSS in PI and the need for further research. Consequently, new research avenues leading to a new era of intelligent interoperable logistics are outlined. This paper intends to contribute to two main areas of research: the design and implementation of smart PSS in PI, and functional and conceptual research on PI and intelligent interoperable logistics.     

可翻滚移动空间四面体机构的运动学分析

提出可变四面体机构的翻滚式移动平台设计概念.该机构由6根伸缩杆和4个节点支座组成,通过伸缩杆的运动改变机构重心,使整个结构失稳,达到翻滚移动的目的.结合其运动形式进行机构的运动学分析,并在此基础上分析其稳定性.设计、制造原理样机,并进行性能测试.测试结果表明：该可变四面体机构能以翻滚步态实现全方位移动.     

基于SCPI的运载火箭遥测系统自动测试平台设计

针对目前火箭遥测系统专属测试设备操作复杂、通用性差等特点,提出一种基于SCPI指令的虚拟仪器智能测试方案,利用SCPI指令完成程序对智能设备的输出控制,结合TCP/IP通信技术、数据库访问技术以及在LabVIEW程序中完成Excel动态存储技术等,实现了火箭遥测系统电性能自动测试、闭环测试、在线监测等功能,测试结果表明,测试平台极大地提高了系统测试效率,测试数据可靠性好,可满足运载火箭遥测系统电性能测试工作,具有较好的推广价值。     

Effects of operational parameters on aeration on/off time in an intermittent aeration membrane bioreactor

This study was performed to evaluate the operational parameters on aeration on/off time in an intermittent aeration membrane bioreactor for wastewater treatment. The membrane bioreactor has 5.5 L of effective working volume including a microfiber membrane. The influent wastewater contained 133mg/L of BOD, 195 mg/L COD, 98 mg/L SS, 30 mg/L total nitrogen, and 3.8 mg/L total phosphorous. Operational conditions related to aeration on/off time were 8.8 h HRT, 10 LMH flux, 10 L/min air flow, and 6300 mg/L MLSS. For 2 h/cycle, aeration on/off time was operated for 12 cycles in three variations: 60/60 min, 50/70 min (I), and 40/80 min. Suction on/off time was 10/2 min, 8/2 min, and 8/2 min, respectively, but also 50/70 min (II) when aeration on/off time was operated at 8300 mg/L MLSS. The BOD removal efficiency rate of this process was higher than 97% regardless of the aeration on/off time distribution. To get higher than 82% total nitrogen removal efficiency rate, aeration off time in the reactor needs to be more than 70 min. The specific denitrification rate was 2.68 mgNO₃-N/gMv/h at 40/80 min on/off aeration times, which was 2.6 times more than at 60/60 min, and 1.4 times more than at 50/70 min (I) for 6300 mg/L MLSS. The specific nitrification rate was 1.96 mgNH₄-N/gMv/h at on/off aeration times of 50/70 min, 1.4 times less than at 40/80 min, but was ineffective for nitrification. Microbial activity was affected only a little by variation in aeration on/off time, though oxygen demand was reduced by aeration off time and allowed microbial concentration to increased. EPS (extracellular polymeric substance) per unit of microorganisms increased with aeration off time.     

支持向量分类器的模糊积分集成方法

针对常规的基于投票方法的支持向量分类器影响集成分类器的泛化能力的问题,提出一种基于模糊积分的支持向量分类器集成方法,不仅考虑各子支持向量分类器输出的客观信息,同时还考虑各子分类器输出对于最终决策的重要性,提高了集成分类器的泛化能力.仿真试验表明,该方法的分类准确率明显优于单一支持向量分类器和传统基于投票方法的支持向量分类器集成策略.     

基于IRN 神经网络的雷达天线伺服系统故障诊断

文中主要针对雷达天线伺服系统故障,提出了一种基于内部回归( Internally Recurrent Net,IRN)神经网络的故障诊断手段。通过分析雷达伺服系统的信号流程图,找到了导致天线故障的所有可能部件。利用故障树的分析手段对这些部件分类,发现同一故障部件可能引发不同的故障现象,同时对所有部件进行编号。建立适用于雷达天线伺服系统的IRN 神经网络,其中输入层共有23 个神经元对应23 个测试点,输出层共有4 个神经元对应所有故障的编号。对所建立的神经网络进行训练与测试,发现IRN 神经网络能够很好地完成对所有故障部件的分类。