Passivity based adaptive Jacobian tracking for free-floating space manipulators without using spacecraft acceleration

Most research so far on trajectory tracking of free-floating space manipulators has assumed that the kinematics of the space manipulator is exactly known. However, when a space manipulator picks up different tools of unknown lengths or unknown gripping points, its kinematics and dynamics change and are difficult to derive exactly. Thus, in this paper, we have proposed a passivity based adaptive Jacobian controller for free-floating space manipulators. The proposed controller consists of a transposed Jacobian feedback and a dynamic compensation term, and the parameter adaptation laws are derived by Lyapunov-like stability analysis tools. It is shown that the end-effector motion tracking errors converge asymptotically. To avoid using spacecraft acceleration, we define a new reference velocity, which is called spacecraft reference velocity. In addition, we have also conducted passivity interpretation of the proposed controller to obtain some physical insight into its properties. Simulation results are presented to show the performance of the proposed controller.     

Adaptive Jacobian position/force tracking control of free-flying manipulators

This paper solves the problem of position/force tracking control of a free-flying space manipulator with uncertain kinematics and dynamics. A free-flying manipulator interacting with an uncertain compliant surface is considered. To cope with the uncertainties arising from free-flyer’s kinematics, dynamics and surface stiffness and position, an adaptive Jacobian controller is devised. The convergence of the force and position tracking errors is proved based on Lyapunov stability analysis. Numerical simulation is presented to show the performance of the controller.     

Reaching a consensus in networks of high-order integral agents under switching directed topologies

Consensus problem of high-order integral multi-agent systems under switching directed topology is considered in this study. Depending on whether the agent’s full state is available or not, two distributed protocols are proposed to ensure that states of all agents can be convergent to a same stationary value. In the proposed protocols, the gain vector associated with the agent’s (estimated) state and the gain vector associated with the relative (estimated) states between agents are designed in a sophisticated way. By this particular design, the high-order integral multi-agent system can be transformed into a first-order integral multi-agent system. Also, the convergence of the transformed first-order integral agent’s state indicates the convergence of the original high-order integral agent’s state, if and only if all roots of the polynomial, whose coefficients are the entries of the gain vector associated with the relative (estimated) states between agents, are in the open left-half complex plane. Therefore, many analysis techniques in the first-order integral multi-agent system can be directly borrowed to solve the problems in the high-order integral multi-agent system. Due to this property, it is proved that to reach a consensus, the switching directed topology of multi-agent system is only required to be ‘uniformly jointly quasi-strongly connected’, which seems the mildest connectivity condition in the literature. In addition, the consensus problem of discrete-time high-order integral multi-agent systems is studied. The corresponding consensus protocol and performance analysis are presented. Finally, three simulation examples are provided to show the effectiveness of the proposed approach.     

一种温压炸药抛洒密度的间接测量方法

温压炸药在爆炸过程中的抛洒密度决定其毁伤性能,而目前尚未找到一种合适的方法对抛洒密度进行直接测量进而对炸药的毁伤性能进行评估。针对该问题,提出一种通过测量温度分布间接反映炸药抛洒密度的方法。为满足爆炸场高温、高压、迅速等恶劣条件,依据声温理论所定义的声速与温度之间的关系,提出利用声层析成像重建来测量温度分布。通过建立模型和模拟仿真验证,分别利用联合迭代重建法和最小二乘法重建并进行结果对比,得到的相对误差分别为7.2%,5.1%,5.6%,4.2%,基本达到测试准确度要求,说明该方法在研究爆炸场温度分布反映炸药抛洒密度的问题上有一定的实用性和有效性。     

抚顺东露天矿提高富矿资源采区回采率方法

资源可利用率的高低,是露天矿山开采活动中的一项重要内容,它对矿山建设及矿山正常生产过程中的技术经济效果影响巨大。东露天矿生产技术人员通过比选,采用具有针对性的施工方案,解决了油母页岩富矿倾斜矿体在台阶水平开采条件下富矿三角量无法选采这一技术难题,使受设备采掘规格限制自然贫化的富矿资源得以回收,提高富矿资源的采区回采率,取得了较好的技术经济成果。     

Adaptive task-space synchronisation of networked robotic agents without task-space velocity measurements

In this paper, we investigate the problem of task-space synchronisation of multiple robotic agents in the presence of uncertain kinematics and dynamics. Our control objective is to realise synchronisation without the measurements of task-space velocity. The communication topology is assumed to be directed graphs containing a spanning tree. A decentralised task-space observer with kinematic parameter updating is proposed to avoid the reliance of task-space velocity. Based on the observer, we propose the distributed adaptive synchronisation controller for two cases: (1) the leaderless consensus case and (2) the leader-follower case, where all the followers track the convex hull spanned by the virtual leaders and for each follower, it is required that there exists at least one leader that has a directed path to the follower. The asymptotic synchronisation is proved with Lyapunov analysis and input–output stability analysis tools. Simulations with multiple robotic agents are performed to show the effectiveness of the proposed schemes.     

基于模型预测方法的电网故障预测

电网诊断通常都是故障发生后,根据故障后产生的信息来推断故障。为了能在故障发生前进行预防,提出模型预测(ModelPrediction,MP)和溯因推理网络(AbductiveReasoningNetwork,ARN)方法预测电网故障。模型预测利用电力系统中历史数据来预测电网无故障运行时的数据,与电网实际运行时的数据作对比,计算差值,差值作为诊断系统的输入;溯因推理网络能够处理预测数据和相应的候选故障之间的复杂关系,被用来构建故障诊断系统。模型预测和溯因推理网络方法相结合,能在保护装置和断路器动作前进行故障定位,具有故障预警功能。仿真结果表明,溯因推理方法构成的预测系统比神经网络方法构成的预测系统诊断结果更快、更准确。     

Intelligent document-filling system on mobile devices by document classification and electronization

Both of an automatic classification method for original documents based on image feature and a layout analysis method based on rule hypothesis tree are proposed. Then an intelligent document-filling system by electronizing the original documents, which can be applied to cellphones and pads is designed. When users are filling documents online, information can be automatically input to the financial information system merely by taking photos of the original documents. By this means can not only save time but also ensure the accuracy between the data online and that on the original documents. Experiments show that the accuracy of document classification is 88.38%, the accuracy of document-filling is 87.22%, and it takes 5.042 seconds dealing with per document. The system can be applied to financial, government, libraries, electric power, enterprises and many other industries, which has high economic and application value.     

传感网中基于能量有效的多参数数据重构方法

为了更好地抵制网络能量快速消耗和降低不可靠链路对无线传感器网络系统数据收集的影响以提高数据重构精度,提出了一种基于能量有效的多参数数据重构方法（Multi-parameter Data Reconstruction Method based on Energy Efficient,MDR）。利用移动智能计算给出传感器节点之间多跳函数关系以确定传感器节点之间比例关系;通过稀疏矩阵设计一种低相干性的观测矩阵,抑制数据丢包率对整个传感网系统的影响,提高汇聚节点数据重构精度;通过基于数据转发策略确认机制实现簇间数据传输的高可靠性,完成了节点间多路径路由数据的可靠交付。仿真实验表明,在数据丢包率为40%的情况下,MDR的数据重构精度误差仍小于5%;在与其他算法比对时,其数据转发次数降低了10.36%,平均网络能耗降低了13.29%,从而验证了该算法的有效性和实效性。     

气缸头气门环带的密封性改进

以某厂HL125气缸头产品环带的加工为研究对象,简要介绍影响气缸头产品环带加工质量的因素,从产品结构、刀夹量具、加工工艺上加以制定解决措施,从而提高HL125气缸头气门环带的密封性,满足用户的需求.