北极冰下自主/遥控机器人控制系统设计与实现

自主/遥控水下机器人是近年来出现的一种新型水下机器人，其自带能源，通过微光缆与水面支持系统相连接，既具有自治水下机器人大范围自主航行的能力，又具有遥控水下机器人定点操作能力，提高了自治水下机器人实时获取数据的能力，扩大了遥控水下机器人的作业范围。由于自主/遥控水下机器人工作方式的灵活性和多样性，其必将会在海洋监测、军事等方面有越来越广泛的应用。 北极是反映全球气候变化的敏感地区，目前世界各国对北极的考察规模越来越大，对极地海洋的探索力度也大幅度增加。由于自主/遥控水下机器人具有灵活的工作方式，将其应用到北极冰下海洋环境监测中，便于满足北极科考的需求。本论文以科考需求为背景，将自主/遥控水下机器人应用到北极海洋环境监测中，为搭载的测量设备提供一个基本的运动平台。 本论文以实现自主/遥控水下机器人控制系统功能为目的，在深入研究已有水下机器人控制系统结构的基础上，开展自主/遥控水下机器人的控制系统软件和硬件设计与实现工作。将CAN总线与PC/104总线应用到自主/遥控水下机器人控制系统中，实现了一种分布式与集中式相结合的控制系统体系结构，将控制系统的可扩展性、实时性、可靠性等结合在一起。 以作者的实际工作为基础，介绍了自主/遥控水下机器人控制系统软、硬件的设计与实现。采用基于CAN总线技术的分布式控制系统体系结构；采用基于PC104嵌入式计算机的数字控制方案进行航行控制系统硬件设计与系统配置；采用嵌入式单片机做为分系统的控制器；在QNX操作系统下用C语言编写水下控制系统软件，采用模块化和标准化的设计思想，将水下控制系统软件分化多个功能模块，每个模块由不同的进程来实现。 实际实验结果表明，本文所设计的控制系统能够达到预期目标；所设计底层硬件系统和底层驱动软件能够给机器人的上层控制软件提供一个稳定基础。

北极冰下自主/遥控水下机器人导航与轨迹跟踪研究

将水下机器人用于极地科考，可以通过其携带的多种传感器和设备进行大范围、长时间的冰下观测作业，并取得重要的极地科考资料，如冰下水纹，海冰厚度等。而这些观测数据必须与准确的浮冰位置信息相结合才有实用价值，但北极高纬度特性和长期覆盖的大范围海冰使得一些传统水下机器人导航技术难以有效实施，所以需要研究一种能在北极冰下具有良好性能和高可靠性的导航系统。同时，对北极海冰进行的一系列科学考察，需要载体能够沿着浮冰上预定轨迹航行，但由于海流等外界影响的存在，浮冰处于实时运动中，所以要顺利完成科考任务，必须有相应的轨迹跟踪算法作为支撑。 本文正是针对以上这两点需求，在充分考虑环境特殊性的情况下，研究了水下机器人在北极冰下的导航与轨迹跟踪问题，提出了基于GPS测向仪冰面修正的水下机器人自主导航技术和基于制导控制器的浮冰轨迹跟踪方法，并进行了仿真和实物测试，试验结果表明本文所研究的导航设计方案和浮冰轨迹跟踪方法合理，可以达到北极冰下科考的定位精度和作业要求。 主要工作包括：（1）ARV导航系统设计。详细研究了各导航传感器的输出信息；坐标系定义、坐标变换、相对于浮冰的航位推算以及绝对坐标的求解；最后详细研究了整个冰下导航系统。（2）ARV导航系统误差分析。首先对各传感器的误差进行了详细分析；接着通过分析整个导航算法，建立了浮冰坐标系下ARV位置误差传递方程；最后通过引入具体传感器的参数指标，数值计算了整个导航系统的精度。（3）浮冰轨迹跟踪系统设计。首先对水下机器人在冰下的航迹进行了描述；接着分析了两种冰下制导控制器，视线法制导和横向轨迹误差法制导；最后详细研究了整个ARV航迹控制系统。（4）浮冰轨迹跟踪算法仿真。详细讨论了北极“ARV”的水平面动力学模型。并结合模型对浮冰轨迹跟踪算法进行了Matlab和视景仿真，验证了算法的合理性。（5）湖试和海试结果分析。通过对ARV棋盘山湖试和北极冰下海试数据分析，定量说明了导航误差和轨迹跟踪性能。

越野移动机器人自动驾驶专家系统的研究

本文研究越野移动机器人驾驶专家系统等有关问题．首先介绍了系统的硬件支持环境，然后阐述了自动驾驶专家系统的总体结构，有关知识库的内容以及使用知识的各功能模块的作用与运行机理．该系统已部分得以应用，能够完全代替驾驶员完成各种驾驶操作，并能进行自主导航、运动规划、自动绕障、动态跟踪目标、原路返回以及示教再现等复杂任务。

一种先进的轻型水下机器人——金鱼Ⅲ号

本文叙及一种新的轻型水下机器人(亦称无人遥控潜水器或ROV)——金鱼Ⅱ号。概要地描述了它的主要技术特点,系统总体结构,简要工作原理,及其适用范围。文中以在丰满电站进行实际作业为例,说明了该型水下机器人的应用前景。

动态补偿的水下机器人路径规划

本文研究水下机器人在障碍位置未知条件下,进行路径规划的方法,使自治水下机器人以最短的行程距离,避开障碍,达到预定目标.针对变化的、复杂的海洋情况,本文采用动态与静态相结合、规划与控制相结合的手段,应用人工势场理论,引入距离误差做动态反馈补偿,实现全局规划控制.本文提出的这种适于自治水下机器人导航的动态路径规划-控制方法,可以解决障碍环境参数已知、未知的路径规划问题.仿真结果表明该方法具有较强的稳定性和适应性.

Towards Autonomous Motion Vision

Earlier, we introduced a direct method called fixation for the recovery of shape and motion in the general case. The method uses neither feature correspondence nor optical flow. Instead, it directly employs the spatiotemporal gradients of image brightness. This work reports the experimental results of applying some of our fixation algorithms to a sequence of real images where the motion is a combination of translation and rotation. These results show that parameters such as the fization patch size have crucial effects on the estimation of some motion parameters. Some of the critical issues involved in the implementaion of our autonomous motion vision system are also discussed here. Among those are the criteria for automatic choice of an optimum size for the fixation patch, and an appropriate location for the fixation point which result in good estimates for important motion parameters. Finally, a calibration method is described for identifying the real location of the rotation axis in imaging systems.

Robust Agent Control of an Autonomous Robot with Many Sensors and Actuators

This thesis presents methods for implementing robust hexpod locomotion on an autonomous robot with many sensors and actuators. The controller is based on the Subsumption Architecture and is fully distributed over approximately 1500 simple, concurrent processes. The robot, Hannibal, weighs approximately 6 pounds and is equipped with over 100 physical sensors, 19 degrees of freedom, and 8 on board computers. We investigate the following topics in depth: distributed control of a complex robot, insect-inspired locomotion control for gait generation and rough terrain mobility, and fault tolerance. The controller was implemented, debugged, and tested on Hannibal. Through a series of experiments, we examined Hannibal's gait generation, rough terrain locomotion, and fault tolerance performance. These results demonstrate that Hannibal exhibits robust, flexible, real-time locomotion over a variety of terrain and tolerates a multitude of hardware failures.

Time-dependent Hyperstar algorithm for robust vehicle navigation in time-dependent stochastic road networks.

The vehicle navigation problem studied in Bell (2009) is revisited and a time-dependent reverse Hyperstar algorithm is presented. This minimises the expected time of arrival at the destination, and all intermediate nodes, where expectation is based on a pessimistic (or risk-averse) view of unknown link delays. This may also be regarded as a hyperpath version of the Chabini and Lan (2002) algorithm, which itself is a time-dependent A* algorithm. Links are assigned undelayed travel times and maximum delays, both of which are potentially functions of the time of arrival at the respective link. The driver seeks probabilities for link use that minimise his/her maximum exposure to delay on the approach to each node, leading to the determination of the pessimistic expected time of arrival. Since the context considered is vehicle navigation where the driver is not making repeated trips, the probability of link use may be interpreted as a measure of link attractiveness, so a link with a zero probability of use is unattractive while a link with a probability of use equal to one will have no attractive alternatives. A solution algorithm is presented and proven to solve the problem provided the node potentials are feasible and a FIFO condition applies for undelayed link travel times. The paper concludes with a numerical example.

Roll Project Rich Vehicle Routing benchmark problems.

This document describes a large set of Benchmark Problem Instances for the Rich Vehicle Routing Problem. All files are supplied as a single compressed (zipped) archive containing the instances, in XML format, an Object-Oriented Model supplied in XSD format, documentation and an XML parser written in Java to ease use.

Telerobotic Sheepdogs: how useful is autonomous behaviour?

Wilson,M.S. and Neal,M.J., 'Telerobotic Sheepdogs: how useful is autonomous behaviour?', Proceedings of the 6th International Conference on Simulation of Adaptive Behaviour, ed. Meyer,J.A. and Berthoz,A. and Floreano,D. and Roitblat,H.L. and Wilson,S.W., pp 125-134, 2000, MIT Press

An Autonomous Sailing Robot for Ocean Observation

Sauze, C. and Neal, M. 'An Autonomous Sailing Robot for Ocean Observation', in proceedings of TAROS 2006, Guildford, UK, Sept 4-6th 2006, pages 190-197.

Developmental Learning for Autonomous Robots

M.H. Lee, Q. Meng and F. Chao, 'Developmental Learning for Autonomous Robots', Robotics and Autonomous Systems, 55(9), pp 750-759, 2007.

Nonlinear Acoustics in Underwater and Biomedical Applications: Array Performance Degradation and Time Reversal Invariance

This dissertation describes a model for acoustic propagation in inhomogeneous flu- ids, and explores the focusing by arrays onto targets under various conditions. The work explores the use of arrays, in particular the time reversal array, for underwater and biomedical applications. Aspects of propagation and phasing which can lead to reduced focusing effectiveness are described. An acoustic wave equation was derived for the propagation of finite-amplitude waves in lossy time-varying inhomogeneous fluid media. The equation was solved numerically in both Cartesian and cylindrical geometries using the finite-difference time-domain (FDTD) method. It was found that time reversal arrays are sensitive to several debilitating factors. Focusing ability was determined to be adequate in the presence of temporal jitter in the time reversed signal only up to about one-sixth of a period. Thermoviscous absorption also had a debilitating effect on focal pressure for both linear and nonlinear propagation. It was also found that nonlinearity leads to degradation of focal pressure through amplification of the received signal at the array, and enhanced absorption in the shocked waveforms. This dissertation also examined the heating effects of focused ultrasound in a tissue-like medium. The application considered is therapeutic heating for hyperther- mia. The acoustic model and a thermal model for tissue were coupled to solve for transient and steady temperature profiles in tissue-like media. The Pennes bioheat equation was solved using the FDTD method to calculate the temperature fields in tissue-like media from focused acoustic sources. It was found that the temperature-dependence of the medium's background prop- erties can play an important role in the temperature predictions. Finite-amplitude effects contributed excess heat when source conditions were provided for nonlinear ef- fects to manifest themselves. The effect of medium heterogeneity was also found to be important in redistributing the acoustic and temperature fields, creating regions with hotter and colder temperatures than the mean by local scattering and lensing action. These temperature excursions from the mean were found to increase monotonically with increasing contrast in the medium's properties.

On the Size Distribution of Autonomous Systems

This paper explores reasons for the high degree of variability in the sizes of ASes that have recently been observed, and the processes by which this variable distribution develops. AS size distribution is important for a number of reasons. First, when modeling network topologies, an AS size distribution assists in labeling routers with an associated AS. Second, AS size has been found to be positively correlated with the degree of the AS (number of peering links), so understanding the distribution of AS sizes has implications for AS connectivity properties. Our model accounts for AS births, growth, and mergers. We analyze two models: one incorporates only the growth of hosts and ASes, and a second extends that model to include mergers of ASes. We show analytically that, given reasonable assumptions about the nature of mergers, the resulting size distribution exhibits a power law tail with the exponent independent of the details of the merging process. We estimate parameters of the models from measurements obtained from Internet registries and from BGP tables. We then compare the models solutions to empirical AS size distribution taken from Mercator and Skitter datasets, and find that the simple growth-based model yields general agreement with empirical data. Our analysis of the model in which mergers occur in a manner independent of the size of the merging ASes suggests that more detailed analysis of merger processes is needed.