以弹跳机器人为背景的弹性环弹跳运动能量转换

文章以弹性环作为弹跳机器人的简单物理模型,研究弹性环对胡克定律的适用性以及弹性势能与初始动能的关系,在此基础上得出忽略空气阻力以及考虑空气阻力的理论弹起高度.文章利用高速摄像系统对弹性环运动过程进行观测,数据分析结果表明理论值与实验结果吻合较好.本文对于弹性环这种简单弹跳模型所得的研究结果有助于为弹跳机器人的能量转换效率及控制弹跳高度提供参考.     

改进蚁群算法在移动机器人路径规划中的研究

移动机器人合理的路径规划是进行探索任务的前提,针对移动机器人路径规划的复杂性,把蚁群算法引入到机器人路径规划中;普通的蚁群算法存在收敛速度慢、效率低和容易陷入局部最优等缺陷,难以直接应用于机器人路径规划中;提出一种在蚁群算法中改进信息素的更新方式、引入最大最小蚁群系统以及改进状态转移规则的移动机器人路径规划方法,在栅格环境下对移动机器人的路径规划进行仿真测试,仿真结果表明该方法能缩小最优路径的查找范围,降低发现最优路径所需的循环次数,能有效提高最优路径的搜索效率,整体性能优于普通蚁群算法。     

Texture gradient studies of a Cu‐tube by the robot at STRESS‐SPEC

The handling of larger samples for texture studies is limited when we using the Eulerian cradle. The robot Stäubli RX160 installed at STRESS‐SPEC offers much more freedom in sample manipulation on one hand to perform pole figure scanning and on the other hand to position the sample for a texture mapping. A key problem is that slit systems cannot be positioned close to large samples due to safety reasons which makes corrections more important. A very simple solution was tested to correct the scattered intensity for each pole figure point for constant volume and anisotropic absorption. A simple method to make these corrections is needed because engineering samples such as semi‐finished products have a large variety of shapes and weights and an ideal slit system is only seldomly available. The test sample was a Cu‐tube of 140 mm in diameter with an average wall thickness of 10 mm. To compare the corrections three kind of samples were measured, first a cube of 10 × 10 × 11 mm³ without any correction, second an 11 mm long tube segment and third a tube segment of 250 mm (12 kg weight) in length. Orientation Distribution Function (ODF) analysis of the average texture over the tube wall by the iterative series expansion method has shown that sufficient intensity corrections can be done to describe the texture gradient around the circumference of the Cu‐tube related to low ovality and eccentricity of the Cu‐tube.     

Utilization of nonlinear vibrations of soft pipe conveying fluid for driving underwater bio-inspired robot

Creatures with longer bodies in nature like snakes and eels moving in water commonly generate a large swaying of their bodies or tails, with the purpose of producing significant frictions and collisions between body and fluid to provide the power of consecutive forward force. This swaying can be idealized by considering oscillations of a soft beam immersed in water when waves of vibration travel down at a constant speed. The present study employs a kind of large deformations induced by nonlinear vibrations of a soft pipe conveying fluid to design an underwater bio-inspired snake robot that consists of a rigid head and a soft tail. When the head is fixed, experiments show that a second mode vibration of the tail in water occurs as the internal flow velocity is beyond a critical value. Then the corresponding theoretical model based on the absolute nodal coordinate formulation (ANCF) is established to describe nonlinear vibrations of the tail. As the head is free, the theoretical modeling is combined with the computational fluid dynamics (CFD) analysis to construct a fluid-structure interaction (FSI) simulation model. The swimming speed and swaying shape of the snake robot are obtained through the FSI simulation model. They are in good agreement with experimental results. Most importantly, it is demonstrated that the propulsion speed can be improved by 21% for the robot with vibrations of the tail compared with that without oscillations in the pure jet mode. This research provides a new thought to design driving devices by using nonlinear flow-induced vibrations.

     

An asymptotically stable collision-avoidance system

Artificial potential fields, which are widely used in robotics for path planning and collision avoidance, are normally beset by difficulties arising from the existence of local minima. This article proposes a solution that involves an asymptotically stable point-mass system governed by differential equations. The system represents a planar point robot moving from its initial position to the desired goal whilst avoiding a static obstacle. Because the system is asymptotically stable, its Lyapunov function, which produces artificial potential fields around the goal and the obstacle, has no local minima other than the goal configuration in the pathwise-connected proper subset of free space which contains the goal configuration. As an application, we consider the point stabilization of a planar mobile car-like robot moving in the presence of a static obstacle.     

旋量法在机器人动力学分析中的应用

本文用旋量方法研究机器人的动力学模型，将速度和角速度，力和力矩的内在联系有机地融合为一体，使Ｎｅｗｔｏｎ－Ｅｕｌｅｒ方法更加简明有效率．文中相对于机器人各臂质心建立参考系，使惯性张量和质心加速度计算简化，进一步减少计算量，达到快速实时计算．     

基于多层多道焊的弧焊机器人视觉信息提取及处理

介绍爬行式弧焊机器人三维视觉信息的传感原理。研究了拉普拉斯锐化、细化等措施对图像处理的效果。给出型坡口多层多道焊边缘坐标的确定以及纠偏量和深度值的计算方法，实验说明效果较好。     

Control of Wheeled Robots

A nonholonomic model of a wheeled robot with one steering wheel is considered. The model accounts for dynamic effects. The motion-planning problem for this model is solved by reducing it to a linear two-point boundary-value problem__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 4, pp. 117–125, April 2005.     

两自由度并联机器人控制系统设计

针对机电装配、医药包装等行业自动化抓取和放置实际应用的需求,设计了一种采用直线伺服驱动技术的两自由度高速并联机器人。首先进行了机器人的机械结构设计,并且通过运动学分析,结合运用蒙特卡洛法与几何法求解出并联机器人的工作空间;其次采用MCU+CPLD(STM32F103+MaxⅡ)的双控制架构,根据工作空间结构在MCU中设计出高效的运动轨迹生成算法,并在CPLD中运用DDS技术将伺服运动参数转换成脉冲经一级差分后输出到伺服驱动器。在双控制器的通信方面合理利用CPLD中的状态机提出了双级数据缓冲方式,使得MCU写与CPLD读交错进行,可以实现数据的无缝刷新。最后进行了并联机器人系统样机的制作与调试,分析结果表明所研制的机器人控制系统能够使机器人快速抓放金属小球,实现稳定可靠运行。     

Optimal vehicle suspension characteristics for increased structural fatigue life

Heavy off-road vehicle suspension systems face unique challenges. The ride comfort versus handling compromise in these vehicles has been frequently investigated using mathematical optimisation. Further challenges exist due to the large variations in vehicle sprung mass. A passive suspension system can only provide optimal isolation at a single payload. The designer of such a suspension system must therefore make a compromise between designing for a fully-laden or unladen payload state. This work deals with suspension optimisation for vehicle structural life. The paper mainly addresses two questions: (1) What are the suspension characteristics required to ensure optimal isolation of the vehicle structure from road loads? and (2) If such optimal suspension characteristics can be found, how sensitive are they to changes in vehicle payload? The study aims to answer these questions by examining a Land Rover Defender 110 as test vehicle. An experimentally validated non-linear seven degree-of-freedom mathematical model of the test vehicle is constructed for the use in sensitivity studies. Mathematical optimisation is performed using the model in order to find the suspension characteristics for optimal structural life for the vehicle under consideration. Sensitivity studies are conducted to determine the robustness of the optimal characteristics and their sensitivity to vehicle payload variation. Recommendations are made for suspension characteristic selection for optimal structural life.