全方位越障机构的设计

对一种具有越障功能的轮式全方位移动机构———车轮组机构进行了研究 ,详细论述了机构的组成和设计要求。该机构不仅能够实现平面上的轮式快速运动 ,而且能够越过一定高度的障碍。该机构不需要传感装置来检测障碍 ,不需要复杂的辅助机构来实现平面上运动和越障运动之间的转换 ,实现机构简单     

Evaluation of a radar-based proximity warning system for off-highway dump trucks

A radar-based proximity warning system was evaluated by researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health to determine if the system would be effective in detecting objects in the blind spots of an off-highway dump truck. An average of five fatalities occur each year in surface mines as a result of an equipment operator not being aware of a smaller vehicle, person or change in terrain near the equipment. Sensor technology that can detect such obstacles and that also is designed for surface mining applications is rare. Researchers worked closely with the radar system manufacturer to test and modify the system on large, off-highway dump trucks at a surface mine over a period of 2 years. The final system was thoroughly evaluated by recording video images from a camera on the rear of the truck and by recording all alarms from the rear-mounted radar. Data show that the system reliably detected small vehicles, berms, people and other equipment. However, alarms from objects that posed no immediate danger were common, supporting the assertion that sensor-based systems for proximity warning should be used in combination with other devices, such as cameras, that would allow the operator to check the source of any alarm.     

A full-scale solution to the rectilinear obstacle-avoiding Steiner problem

Routing is one of the important steps in very/ultra large-scale integration (VLSI/ULSI) physical design. Rectilinear Steiner minimal tree (RSMT) construction is an essential part of routing. Macro cells, IP blocks, and pre-routed nets are often regarded as obstacles in the routing phase. Obstacle-avoiding RSMT (OARSMT) algorithms are useful for practical routing applications. However, OARSMT algorithms for multi-terminal net routing still cannot meet the requirements of practical applications. This paper focuses on the OARSMT problem and gives a solution to full-scale nets based on two algorithms, namely An-OARSMan and FORSTer. (1) Based on ant colony optimization (ACO), An-OARSMan can be used for common scale nets with less than 100 terminals in a circuit. An heuristic, greedy obstacle penalty distance (OP-distance), is used in the algorithm and performed on the track graph. (2) FORSTer is a three-step heuristic used for large-scale nets with more than 100 terminals in a circuit. In Step 1, it first partitions all terminals into some subsets in the presence of obstacles. In Step 2, it then connects terminals in each connected graph with one or more trees, respectively. In Step 3, it finally connects the forest consisting of trees constructed in Step 2 into a complete Steiner tree spanning all terminals while avoiding all obstacles. (3) These two graph-based algorithms have been implemented and tested on different kinds of cases. Experimental results show that An-OARSMan can handle both convex and concave polygon obstacles with short wire length. It achieves the optimal solution in the cases with no more than seven terminals. The experimental results also show that FORSTer has short running time, which is suitable for routing large-scale nets among obstacles, even for routing a net with one thousand terminals in the presence of 100 rectangular obstacles.     

�ϰ����յ��Ŀ�ȼ���Ʊ�ըѹ������ʵ��ģ��

开敞空间可燃气云爆炸，尤其是在障碍物诱导下具有极大破坏力的爆炸，会造成巨大的经济损失和人员伤亡。因此，研究约束条件对气云爆炸场的影响，对进一步提出可行的防爆、抑爆方案提供理论依据具有重要意义。为此，建立了开敞空间可燃气云爆炸的实验系统，对半球形乙炔—空气预混气云内半球条栅形障碍物对爆炸威力的影响进行了实验研究。障碍物半径为0.1～0.3 m，条栅宽度为15～60 mm，空隙率为20%～75%，气云半径为0.25～1.25 m。通过对实验数据进行曲线拟合回归，并经方差检验，得到了对实际应用具有指导作用的拟合关系式。     

Algorithms for path planning, navigation and guidance of an AGV

Algorithms for path navigation and generation of guidance setpoints for an AGV are developed. Navigation is based on a simple flat world model of connected nodes using a suboptimal path solution for execution speed. The guidance algorithms use vision data from a stereo pair of linear image array cameras, which described an obstacle location and height where intersected by the vision system plane of view. The development of a map of the area on the AGV path allows the detection of obstacles, which may be passed subject to the aisle markings. The complete vision-guidance system can be implemented using inexpensive commercially available 16 bit microprocessors.     

On computational methods for variational inequalities

In this note, we focus on optimised mesh design for the Finite Element (FE) method for variational inequalities using global norm estimates for local error control. The strategies are based on the so called dual-weighted-residual (DWR) approach to a posteriori error control for FE-schemes (see, e.g., Rannacher et al. [19, 6, 2]), where error control for the primal problem is established by solving an auxiliary (dual) problem. In this context we blamed (cf. e.g., Rannacher and Suttmeier [18, 19]) global norm estimates being not that useful in applications. But having a closer look at the DWR-concept, one observes that in fact global (energy) error bounds can be employed to establish local error control. Our ideas and techniques are illustrated at the socalled obstacle problem.It turns out, that reliable and efficient energy error control is one main ingredient to establish useful a posteriori error bounds for local quantities. Therefore, in addition, we derive an unified approach to a posteriori error control in the energy norm for elliptic variational inequalities of first kind. Eventually, this framework is applied to Signorinis problem.     

PRIAMOS: An experimental platform for reflexive navigation

In this paper the new mobile robot system PRIAMOS is presented. The system emphasizes on fast navigation algorithms. In a (partially) unknown or changing environment fast perception and reaction is necessary for efficient task execution. Low level mapping and planning modules are used to span the period until higher control layers have enough time to react. The first part of this paper briefly describes the mechanical and technical construction of PRIAMOS. After an explanation of the software architecture the solutions for motion control and reflexive navigation, as realized in PRIAMOS, are given.     

An opportunistic global path planner

In this paper we describe a robot path-planning algorithm that constructs a global skeleton of free-space by incremental local methods. The curves of the skeleton are the loci of maxima of an artificial potential field that is directly proportional to distance of the robot from obstacles. Our method has the advantage of fast convergence of local methods in uncluttered environments, but it also has a deterministic and efficient method of escaping local extremal points of the potential function. We first describe a general roadmap algorithm, for configuration spaces of any dimension, and then describe specific applications of the algorithm for robots with two and three degrees of freedom.This research was supported by a David and Lucile Packard Foundation Fellowship and by NSF Presidential Young Investigator Grant number IRI-8958577.     

合肥地区大棚土壤肥力特征研究

通过采集大棚土壤样品研究合肥地区大棚土壤肥力状况,结果表明,该地区大棚土壤有效磷提高较快,而有机质、有效钾含量上升较慢,土壤有酸化的趋势,0~10 cm土层硝酸盐比露地提高5.9倍,水溶性盐含量增加54.8%,硝酸盐和水溶性盐表层积累作用最大,随着大棚种植年限延长次生盐渍化程度加重。解决这一问题需要从土壤管理、施肥、灌溉、耕作、政策等多方面采取措施。     

Monocular obstacle detection using reciprocal-polar rectification

Our obstacle detection method is applicable to deliberative translation motion of a mobile robot and, in such motion, the epipole of each image of an image pair is coincident and termed the focus of expansion (FOE). We present an accurate method for computing the FOE and then we use this to apply a novel rectification to each image, called a reciprocal-polar (RP) rectification. When robot translation is parallel to the ground, as with a mobile robot, ground plane image motion in RP-space is a pure shift along an RP image scan line and hence can be recovered by a process of 1D correlation, even over large image displacements and without the need for corner matches. Furthermore, we show that the magnitude of these shifts follows a sinusoidal form along the second (orientation) dimension of the RP image. This gives the main result that ground plane motion over RP image space forms a 3D sinusoidal manifold. Simultaneous ground plane pixel grouping and recovery of the ground plane motion thus amounts to finding the FOE and then robustly fitting a 3D sinusoid to shifts of maximum correlation in RP space. The phase of the recovered sinusoid corresponds to the orientation of the vanishing line of the ground plane and the amplitude is related to the magnitude of the robot/camera translation. Recovered FOE, vanishing line and sinusoid amplitude fully define the ground plane motion (homography) across a pair of images and thus obstacles and ground plane can be segmented without any explicit knowledge of either camera parameters or camera motion.