Risk assessment of satellite launch with reusable launch vehicle

A new methodology is developed for assessing the risk associated with launching satellites in space by use of Reusable Launch Vehicles (RLVs). The objective is to assess the Maximum Probable Loss (MPL) for third party insurance purposes, which is a requirement for licensing of private operators. Launch industry convention has been to execute an MPL analysis for each and every flight. With the advent of commercial, reusable launch vehicle services, much higher flight rates are anticipated. Consequently a method for developing a conservative, ‘once-and-for-all’ MPL value is desirable. Failures during the boost, orbital vehicle, and return phases of the flight that could lead to impact of the rocket or its stages on the ground are considered. Simple geometric models are used to evaluate an upper bound to the probability that assets of various form and size on the ground will be hit by a stray rocket or vehicle stage. Models for the loss resulting from hitting an asset are also developed. The methodology is applied to a proposed launch site in Southern Australia.     

欠驱动水下机器人三维轨迹跟踪有限时间预设性能控制

本文研究了具有不确定动态和未知时变海洋环境扰动的欠驱动水下机器人(AUVs)三维轨迹跟踪有限时间预设性能控制问题,提出新型预设性能函数和误差映射函数,将受预设性能限制的轨迹跟踪误差转变为非受限的变换后误差;构造新的超螺旋(ST)扩张状态观测器,在有限时间内实时估计AUV不确定动态和未知时变海洋环境扰动引起的总扰动;基于...     

高速转向工况下的无人驾驶车辆路径跟踪

为提高无人驾驶车辆在高速转向工况下的路径跟踪精度与行驶稳定性,基于三自由度单轨车辆模型与模型预测控制理论,分析前轮转角约束对车辆跟踪精度与行驶稳定性的影响,提出一种自适应于侧向附着力的路径跟踪控制方法.以Pacejka'89魔术公式轮胎模型为基础,分析轮胎纵向受力,以此推算轮胎的侧向附着力,从而建立前轮转角约束随车辆状...     

选择性催化氧化除去甲醇燃料电池电动车上富氢气中CO的研究进展

评述了间接甲醇燃料电池电动车中存在的甲醇转化的富氢气中CO的净化技术 ,介绍了选择性氧化除去富氢气中CO的研究进展。     

环境保护和电动车的开发

21世纪将是环保的世纪,人们对环境和能源问题日益关注,各国政府对空气污染的控制要求日趋严格,因而电动车的开发备受关注。本文从分析当前各国开发电动车的形势和电动车的基本概念出发,进一步探讨开发电动车的总体策略及关键技术,特别是先进的车体技术、电力驱动技术和电池技术。开发电动车的总体策略应该是：a）集中汽车技术、电机技术、电子技术、材料技术等的优势,进行系统集成和优化;b）集中政府、工业、电力、交通、用户的优势,进行大协作,共同分担风险和享受成果。文中列出了最近各国开发的主要电动车样车。     

Movement time and guidance accuracy in teleoperation of robotic vehicles

Two experiments are reported on the steering of a tracked vehicle through straight-line courses and corners to determine the relationships between movement time and control accuracy with the geometry of the course, such as the vehicle width, the track width and the type of corner. For straight line tracking, Drury’s law in which movement time (MT) is linear with the tracking task difficulty measure [A/(W???d)] is found to hold, where A is the distance traveled, ‘W’ is the track width and ‘d’ is the vehicle width. Performance in three types of corners (right angle, cut angle and circular) varied little, with the most important factor being the clearance (W???d) available to the operator. Collisions with boundary walls were also highly related to this factor. The reported research has strong relevance to the training of operators for urban search and rescue robots.

Practitioner summary: Data for steering a real vehicle in a simulated environment of straight paths and different corner geometries showed that Drury’s law holds for straight line tracking and the clearance between the widths of vehicle and track is important in steering corners. Data show clear need for training of USAR (Urban Search and Rescue) operators.     

平巷人车运行速度的研究

平巷人车是煤矿运输人员的主要工具,要求使用时巷道坡度≤14‰。重点阐述了平巷人车运行速度的要求,指出此指标的来源和依据,分析其合理性,得出普遍适用的规律。运行速度直接影响制动距离和最小水平曲率半径的取值,如何平衡它们之间的关系,也是关注的问题。     

Status quo and open challenges in vision-based sensing and tracking of temporary resources on infrastructure construction sites

Modern construction projects require sufficient planning and management of resources to become successful. Core issues are tasks that deal with maintaining the schedule, such as procuring materials, guaranteeing the supply chain, controlling the work status, and monitoring safety and quality. Timely feedback of project status aids project management by providing accurate percentages of task completions and appropriately allocating resources (workforce, equipment, material) to coordinate the next work packages. However, current methods for measuring project status or progress, especially on large infrastructure projects, are mostly based on manual assessments. Recent academic research and commercial development has focused on semi- or fully-automated approaches to collect and process images of evolving worksites. Preliminary results are promising and show capturing, analyzing, and documenting construction progress and linking to information models is possible. This article presents first an overview to vision-based sensing technology available for temporary resource tracking at infrastructure construction sites. Second, it provides the status quo of research applications by highlighting exemplary case. Third, a discussion follows on existing advantages and current limitations of vision based sensing and tracking. Open challenges that need to be addressed in future research efforts conclude this paper.     

Cooperative target pursuit by multiple UAVs in an adversarial environment

This paper presents the development of a cooperation strategy for multiple UAVs to pursue a target moving in an adversarial environment where threat exposure should be minimized, and obstacles and restricted areas should be avoided. A probabilistic approach is used to model the adversarial environment. A cost function is defined to quantify placement of UAVs around the target in formation in terms of threat exposure level and distance to the target. The cost function is used to develop a cooperation strategy for a team of UAVs to follow the target such that the total threat exposure of the team and the average distance to the target throughout the pursuit are minimized according to the weighting coefficients specified. The cooperation strategy has the feature of collision avoidance as well as data-fusion-based estimation of the target trajectory based on noisy measurements. Simulation results have demonstrated that the cooperation reduces the risk of losing the target during the pursuit while avoiding obstacles and restricted areas. Further, the UAVs guided by the cooperation strategy can follow the target closer without increasing the total threat exposure level as compared to cases where the UAVs pursue the target without cooperation.     

Supervisory control of hybrid powertrains: An experimental benchmark of offline optimization and online energy management

The paper describes a chain of tools aimed at the development and validation of energy management strategies (EMS) for hybrid powertrains. These tools comprise an offline optimizer based on Pontryagin minimum principle (PMP) and the online equivalent consumption minimization strategy (ECMS), both implemented in a dynamic simulation platform and as a real-time controller in a semi-physical testing equipment. The results presented are aimed at illustrating the continuity of the various approaches by comparing the offline-generated energy management laws with their online counterparts, both in terms of trajectories over time and in terms of global results (fuel consumption, state-of-charge deviations).