Minimum-Energy Translational Trajectory Generation for Differential-Driven Wheeled Mobile Robots

Mobile robots can be used in many applications, such as exploration, search and rescue, reconnaissance, security, and cleaning. Mobile robots usually carry batteries as their energy source and their operational time is restricted by the finite energy available from the batteries. Therefore, energy constraints are critical to the service time of mobile robots. This paper investigates the minimum-energy control problem for translational trajectory generation, which minimizes the energy drawn from the batteries. Optimal control theory is used to find the optimal velocity trajectory in analytic form. To demonstrate energy efficiency obtainable, we performed simulations of minimum-energy velocity control and compared the results with loss-minimization control and energy-optimal trapezoidal velocity profiles. Simulation results showed that significant energy savings can be achieved, of up to 9% compared with loss-minimization control and up to 10% compared with energy-optimal trapezoidal velocity profile. We also performed an actual robot experiment using Pioneer 3-AT platform to show the validity of the proposed minimum-energy velocity control. The experimental results revealed that the proposed minimum-energy velocity control can save the battery energy up to 10% compared with loss-minimization control. Categories (3): Robot control, (5): RobotMotion Planning     

Global Level Path Planning for Mobile Robots in Dynamic Environments

This paper presents a self-adapting approach to global level path planning in dynamic environments. The aim of this work is to minimize risk and delays in possible applications of mobile robots (e.g., in industrial processes). We introduce a hybrid system that uses case-based reasoning as well as grid-based maps for decision-making. Maps are used to suggest several alternative paths between specific start and goal point. The casebase stores these solutions and remembers their characteristics. Environment representation and casebase design are discussed. To solve the problem of exploration vs. exploitation, a decision-making strategy is proposed that is based on the irreversibility of decisions. Forgetting strategies are discussed and evaluated in the context of case-based maintenance. The adaptability of the system is evaluated in a domain based on real sensor data with simulated occupancy probabilities. Forgetting strategies and decision-making strategies are evaluated in simulated environments. Experiments show that a robot is able to adapt in dynamic environments and can learn to use paths that are less risky to follow.     

牵引一制动型液力变矩器原始特性研究

 基于束流理论建立了牵引一制动型液力变矩器原始特性参数计算数学模型．对以D430型液力变矩器为原
型设计的牵引一制动型液力变矩器进行了原始特性参数计算，并将计算结果同D430型液力变矩器原始特性参数进
行了比较分析，结论合理． 对设计牵引一制动型液力变矩器具有一定的指导意义．     

轧机锁紧油缸泄漏原因分析及系统改进

济钢第一小型轧钢厂轧机液压换槽系统因工作压力增高，蓄能器压力油长期作用于锁紧缸，引起密封圈击穿、泄漏和机架不稳。通过增设定值减压阀控制油压，改进锁紧油缸结构，解决了锁紧油缸的泄漏问题，保证了轧制线的稳定，轧机作业率由85％提高到87％。     

微型液压钻的应用

介绍国外在特殊场所采用的先进钻孔技术的微型液压钻。它具有可手控的永久磁性基座、独特的刀具结构、有效的火花控制和极大的便携性,适用于特殊环境下的钻孔作业。     

水工隧洞内消能工的研究及应用进展

对于高水头、大流量的水电工程,以往的消能工具有一定的局限性,研究表明,把大面积遭受高速水流作用改为局部承受的消能方式,是高坝泄洪消能的一条有效途径。内消能工主要有孔板(洞塞)式消能工、旋流式消能工、消力井等3种形式。实践表明,内消能工对改善大坝下游水流流态,保护下游环境,保障下游边坡稳定等有积极作用,综合考虑,旋流式消能工具有较大优越性。对水工隧洞内部消能技术尚需开展进一步的研究与实践。     

机械臂的动态混合控制

本文研究当机械臂的终端受有约束时的控制问题,其中心内容是给出“任务规范投影算子”的概念,利用它首先将机械臂的动态方程解耦为两组方程,它们分别描述了运动与约束力,在此基础上给出了机械臂的控制律,使闭环系统跟踪期望的速度与约束力。     

液压启闭机CAD系统研究

简要介绍了在引进支撑环境下独立开发的专用ＣＡＤ系统应用软件－“液压启闭机ＣＡＤ系统”的运行环境、结构特点，主要功能模块的功能、开发过程中碰到的关键技术难点及解决办法。     

Coupling GIS with Hydrologic and Hydraulic Flood Modelling

Geographic Information Systems (GIS) have been recognised as a powerful means to integrate and analyse data from various sources in the context of comprehensive floodplain management. As part of this comprehensive approach to floodplain management, it is very important to be able to predict the consequences of different scenarios in terms of flooded areas and associated risk. Hydrologic and hydraulic modelling plays a crucial role and there is much to gain in incorporating these modelling capabilities in GIS. This is still a rather complex task and research is being done on the full integration of these models. Interfacing between these models and GIS may be a very efficient way of overcoming the difficulties and getting very good results in terms of engineering practice. This paper presents results based on the use of Intergraph GIS coupled with Idrisi GIS. Using these two systems substantially increased the flexibility of using GIS as a tool for flood studies. A lumped (XSRAIN) and a distributed (OMEGA) hydrologic models were used to simulate flood hydrographs. The well known HEC-2 Hydraulic model was used to compute flooded areas. These models were applied in the Livramento catchment with very good results. The computation of flooded areas for different flood scenarios, and its representation in GIS, can be used in the assessment of affected property and associated damages. This is a very useful GIS-based approach to floodplain management.     

SIMILARITY LAW OF FLUCTUATING PRESSURE WITHIN HYDRAULIC JUMP AREA

Through a series of model tests of five scales for 2-D free hydraulic jump, the da-ta of fluctuating pressure acting on the floor level within the hydraulic jump were obtained. Dur-ing the experiments, Froude number varied from 2.94 to 8.61, and Reynolds number rangedfrom 2×10~4 to 6×10~5. Experiment results indicate that the amplitude scale of fluctuating pres-sure is the length scale of model, i. e. P'=L, which agrees with gravity similarity law: Thefrequency scale of the fluctuating pressure is a unity i. e., f=1, which does not satisfy thegravity similarity law.