Tracking control system using image sensor for arc welding

A highly accurate and widely applicable tracking control system which guides a welding torch along a joint line is described. The control system includes a servomechanism, a solid-state image sensor, and an image processor. The solid-state image sensor detects the cross-sectional pattern of the welding groove with a He-Ne gas laser. The image processor, consisting mainly of a microcomputer, processes video information and estimates the position of the welding groove center using a statistical technique. This method of tracking control has been employed in the welding apparatus for penstocks with good practical results.     

Energy scavenging and power management in networks of autonomous microsensors

Networks of autonomous microsensors promise to revolutionize the way people interact with electronics, enabling ambient intelligence. In this paper we investigate different energy scavenging options in real applications to find out which devices are more suitable to power a microsensor having a volume of only 100 mm³. Photovoltaic cells are the most promising power generators when a power level of 100 μW is required. If the power consumption can be reduced to about 10 μW, MEMS-based vibration-driven scavengers and thermoelectric generators can also be used.

The paper presents as well a power management architecture that enables the use of a scavenger as power source, and discusses some consequences of the limited available volume on power electronics.     

The Demeter System for Automated Harvesting

Automation of agricultural harvesting equipment in the near term appears both economically viable and technically feasible. This paper describes the Demeter system for automated harvesting. Demeter is a computer-controlled speedrowing machine, equipped with a pair of video cameras and a global positioning sensor for navigation. Demeter is capable of planning harvesting operations for an entire field, and then executing its plan by cutting crop rows, turning to cut successive rows, repositioning itself in the field, and detecting unexpected obstacles. In August of 1997, the Demeter system autonomously harvested 40 hectares (100 acres) of crop in a continuous run (excluding stops for refueling). During 1998, the Demeter system harvested in excess of 48.5 hectares (120 acres) of crop, cutting in a variety of fields.     

Modular Robot Motion Planning Using Similarity Metrics

In order for a modular self-reconfigurable robotic system to autonomously change from its current state to a desired one, it is critical to have a cost function (or metric) that reflects the effort required to reconfigure. A reconfiguration sequence can consist of single module motions, or the motion of a branch of modules. For single module motions, the minimization of metrics on the set of sets of module center locations serves as the driving force for reconfiguration. For branch motions, the question becomes which branches should be moved so as to minimize overall effort. Another way to view this is as a pattern matching problem in which the desired configuration is viewed as a void, and we seek branch motions that best fill the void. A precise definition of goodness of fit is therefore required. In this paper, we address the fundamental question of how closely geometric figures can be made to match under a given group of transformations (e.g., rigid-body motions), and what it means to bisect two shapes. We illustrate these ideas in the context of applications in modular robot motion planning.     

飞行器在直角坐标系中定位方法研究

本文提出仅用星敏感器进行自主导航定位方法。通过大气折射数据确定飞行器高度,用星敏感器间接测量飞行器到地心的方向矢量,从而确定飞行器在地球直角坐标系中三维坐标。     

A requirements-based programming approach to developing a NASA autonomous ground control system

A new requirements-based programming approach to the engineering of computer-based systems offers not only an underlying formalism, but also full formal development from requirements capture through to the automatic generation of provably-correct code. The method, Requirements-to-Design-to-Code (R2D2C), is directly applicable to the development of autonomous systems and systems having autonomic properties. We describe both the R2D2C method and a prototype tool that embodies the method, and illustrate the applicability of the method by describing how the prototype tool could be used in the development of LOGOS, a NASA autonomous ground control system that exhibits autonomic behavior. Finally, we briefly discuss other possible areas of application of the approach.     

Cable-Direct-Driven Robot (CDDR) with Passive SCARA Support: Theory and Simulation

This article presents a new planar translational cable-direct-driven robot (CDDR) with actuation redundancy and supported against loading normal to the motion plane with a passive planar two-degree-of-freedom SCARA-type (Selective Compliance Assembly Robot Arm) serial manipulator. This allows the robot to resist cable sag without being supported on the motion plane. The proposed robot architecture may assure high payload-to-weight ratio, resistance to forces normal to the plane of motion, and a potentially large workspace. Another benefit is that the passive SCARA has structure to provide end-effector moment resistance, which is not possible with many proposed translational CDDRs. Moreover, the passive robot can also serve as an independent Cartesian metrology system. This article derives the kinematics and dynamics models for the proposed hybrid serial/parallel architecture. Additionally it proposes a dynamic Cartesian controller always ensuring positive cable tensions while minimizing the sum of all the torques exerted by the actuators. Simulation examples are also presented to demonstrate the novel CDDR concept, dynamics, and controller.Category (7) – System Modelling/Simulation/Control/Computer–Aided Design/Robot Control/Teleoperation/Moving Robots     

一种改进势场法在多移动机器人避碰规划中的应用

基于人工势场法原理建立了移动机器人避障模型,对人工势场法的“势场陷阱”问题进行了重点分析,对动态停止“势场陷阱”和徘徊抖动“势场陷阱”问题分别采用“随机扰动法”和“动态步长折半法”处理,并把它用到多移动机器人避碰规划中,仿真结果表明改进效果明显。     

REAL-TIME MOTION PLANNING METHOD BASED ON NEURAL NETWORKS FOR MULTIPLE MOBILE ROBOTS

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基于压电陶瓷驱动的腹腔手术微型机器人

介绍了一个基于压电陶瓷驱动的多节蛇型游动腹腔手术微型机器人,其特点是响应速度快,运动精度高,作用力与动作范围大,每一节均可实现两个自由度方向上±60°范围内迅捷而灵活的动作.对设计中的两个