卫星激光通信粗跟踪系统复合控制策略

针对卫星激光通信粗跟踪系统的跟踪稳定精度指标要求高的特点,建立了基于永磁同步电机直接驱动的粗跟踪系统模型并进行了跟踪稳定误差分析。在采用传统PID控制策略存在跟踪误差较大、动态性能较差等不足的基础上,提出了一种基于粗跟踪系统的改进型前馈复合控制策略。从理论上分析了前馈复合控制策略提高了粗跟踪系统的动态性能,为降低跟踪稳定误差提供了改善方案。地面实验验证结果表明,与传统控制策略相比,改进型复合控制策略极大地降低了系统的动态跟踪误差,动态跟踪误差由606μrad降低至13μrad(1δ)。进一步的在轨实验也验证了改进型复合控制策略的合理性和先进性,总体指标满足了卫星激光通信终端的极高精度要求。本文所提出的控制策略对其他高性能跟踪伺服系统设计也具有较大的借鉴意义。     

Sliding mode based fault detection,reconstruction and fault tolerant control scheme for motor systems

The fault-tolerant control problem belongs to the domain of complex control systems in which inter-control-disciplinary information and expertise are required. This paper proposes an improved faults detection, reconstruction and fault-tolerant control (FTC) scheme for motor systems (MS) with typical faults. For this purpose, a sliding mode controller (SMC) with an integral sliding surface is adopted. This controller can make the output of system to track the desired position reference signal in finite-time and obtain a better dynamic response and anti-disturbance performance. But this controller cannot deal directly with total system failures. However an appropriate combination of the adopted SMC and sliding mode observer (SMO), later it is designed to on-line detect and reconstruct the faults and also to give a sensorless control strategy which can achieve tolerance to a wide class of total additive failures. The closed-loop stability is proved, using the Lyapunov stability theory. Simulation results in healthy and faulty conditions confirm the reliability of the suggested framework.     

Traumatic brain injury,driver aggression and motor vehicle collisions in Canadian adults

ObjectiveThis study examines the associations between lifetime traumatic brain injury (TBI), driver aggression, and motor vehicle collisions among a population sample of adults who reside in the province of Ontario, Canada.MethodA cross-sectional sample of 3993 Ontario adults, aged 18–97 were surveyed by telephone in 2011 and 2012 as part of Center for Addiction and Mental Health’s ongoing representative survey of adult mental health and substance use in Canada. TBI was defined as trauma to the head that resulted in loss of consciousness for at least five minutes or overnight hospitalization.ResultsAn estimated 91% (95% CI: 90.0, 91.9) of individuals in this sample held a valid Ontario driver’s license at the time of testing. Among those, 16.7% reported a history of lifetime TBI and 83.3% reported no TBI. The prevalence of TBI was higher among men than women. Relative to licensed adults without TBI, adults with a history of TBI had significantly higher odds of engaging in serious driver aggression in the past 12 months, such as making threats to hurt another driver, passenger or their vehicle (AOR = 4.39). These individuals also reported significantly higher odds (AOR = 1.74) of being involved in a motor vehicle collision that resulted in hurting themselves, their passenger(s) or their vehicle.ConclusionThis is the first population-based study to demonstrate a relationship between a history of TBI and higher rates of serious driver aggression and collision involvement. Given the large proportion of adult drivers with a history of TBI, these individuals may account for a disproportion burden of all traffic safety problems. Whether the increased road safety risk of adults with a history of TBI is reflective of neurocognitive deficits or is merely evidence of a cluster of unsafe activities produced by a higher risk lifestyles requires further research attention.     

154吨电动轮汽车主发电机保护

主发电机是电动轮汽车的主要部件之一,而由于矿山的使用环境条件极为恶劣,这就有可能发生各种危害主发电机的故障。为确保车辆运行的经济性和安全性,MK-36型154吨矿用电动轮汽车装设了一套主发电机保护装置。本文初步分析了该套保护装置各部分的原理、结构及作用,并作了初步评价。     

高岭土露天矿技改设计中运输系统的选择

介绍了龙岩高岭土公司矿石和废石运输的原设计方案、生产现状和技改设计中须解决的问题。根据矿山的实际情况,推荐了矿石和废石运输的可行方案,并阐述了它们的优缺点。同时,从工艺技术、征地、基建投资、运行费用等技术经济方面分别对可行的矿石和废石运输系统进行了详细的比较。最终确定,公路-胶带联合运输和公路运输分别为矿石和废石运输的最佳方案。     

双梁起重机滑触线粉尘清扫装置

在永磁铁氧体生产环境中 ,铁氧体粉尘在双梁起重机滑触线上沉积 ,造成起重机电机缺相运行事故的发生。在起重机天车上设计、安装了滑触线粉尘清扫装置 ,该装置由清扫刷、悬臂板、连结架等组合而成。随着起重机的运行 ,清扫装置自动进行滑触线的清扫作业 ,保证了起重机电机的安全     

软启动器在鼠笼型异步电动机启动控制中的应用

软启动器是应用于鼠笼型异步电动机启动控制的一种新型装备。它可以使启动电流以恒定的斜率平衡上升，并且不受电网波动的影响，减少启动转矩对负载的影响。本文介绍了软启动器的基本原理、技术特性、以及在特定负载情况下所具有的节能效果；指出了在不同负载情况下的控制方案。     

上海通用汽车展示厅及办公楼

本文从环境、功能、材料和技术几个层面,介绍了上海浦东通用汽车展示厅及办公楼的设计创意和建筑形象。     

基于Elman神经网络的电机故障诊断

通过Elman神经网络训练采集到的电机特征频率振动信号,建立电机故障的模型.并以转子故障为对象,在电机实验台上分别采集水平和垂直方向上的振动信号,通过放大、滤波和A/D转换后,进行频谱分析.为验证网络对故障判断的效果,对故障电机采集振动信号后,代入网络检验.验证表明该网络模型可有效识别电机常见故障.     

基于自适应滑模观测器无位置传感器PMSM控制方法研究

针对无位置传感器永磁同步电机控制存在的转子位置与转速估计精度不高的问题,结合自适应算法设计了一种新型的自适应滑模观测器。滑模自身机制引起的系统抖振问题是影响电机转子位置与转速估计的最大因素。为了降抖减振,采用连续的sigmoid阈值函数代替sign符号函数;提出一个反电动势自适应估计环节代替传统的低通滤波器,提高反电动势估计精度;此外为了降低转子位置及其转速的估计误差,采用锁相环对其进行估计。最后,基于200W的PMSM搭建实验平台对上述改进算法进行验证。结果表明:电机转子位置与转速估计稳态误差分别为0.129 rad、79 r/min,能够实现无位置传感器PMSM高精度控制。