基于ADAMS的重载操作机的动力学仿真

通过对锻造操作机工作原理的分析,基于虚拟样机技术,在ADAMS软件中建立了重载操作机整机系统的虚拟样机,对操作机进行动力学仿真分析,得出典型工况下操作机的受力情况曲线.考虑了驱动力大小、大惯量构件、柔性体构件以及附加倾覆力矩等因素对操作机性能的影响,为设计操作机的结构设计提供了理论及数据依据.     

Output tracking control of mobile manipulators based on dynamical sliding-mode control

A dynamical sliding-mode controller is devised to track the output of mobile manipulators. During the investigation, firstly a reduced dynamic model considering the dynamics of the driving motor is developed for mobile manipulators. Then, the system is decomposed into four lower-dimensional subsystems by means of diffeomorphism and nonlinear input transformation. Moreover, a design method of the dynamical sliding-mode controller that is applied to the output tracking of mobile manipulators is proposed. The simulation results indicate that the dynamical sliding-mode controller can not only track the given trajectory correctly but also reduce the chattering of sliding-mode control system considerably. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(6): 29–33 [译自: 华南理工大学学报 (自然科学版)]     

Mathematical model of parallel retrial queueing of multiple requests

A model of parallel queueing of requests is developed for a queueing system consisting of two units with an unlimited number of servers in each unit and with retrial queueing in the units. An analytic expression is obtained for the generating function of the multi-dimensional state probability distribution of the random vector which characterizes the number of requests in each unit and the number of repeated calls to each unit in a nonstationary mode.     

Stability problem formulation of structurally compliant robot manipulators during contact task execution: A singular perturbation approach

Aspects of modelling, stability and control of robotic manipulators with structurally compliant links and joints during contact with a stiff work environment are presented in this paper. System models of n joint robotic manipulators are cast into multiple time-scale formulations. Several different models are developed, based on the relative differences in magnitude of the scaling parameters associated with the manipulator link, joint and environment stiffnesses. These stiffnesses, if greatly different, lead to a four time-scale system with virtually no interaction between these subsystems. In these models, as various subsystem stiffness coefficients become approximately equal, strong interaction among the subsystems is seen. Utilizing the theory of singularly perturbed dynamic systems, aspects of overall system stability are touched on, and possible use of a high speed stabilizing control is considered. It is seen from the analysis presented, that depending on the relative structural stiffness of the link, joint and work environment, is is not always possible to apply a corrective control for certain structural compliance effects. An example serves to illustrate some of the concepts discussed in the paper.

It is noted that this paper does not provide general stability conclusions, but rather forms a framework for stability investigation.     

Material analysis for artificial muscle and touch sensing of cooperative biomimetic manipulators

There is a need for material analysis that can comfort the innovations of human intelligence towards providing solution to human disabilities. Humans throughout history have always sought to mimic the appearance, mobility, functionality, intelligent operation, and thinking process of biological creatures. This field of biologically inspired technology, having the moniker biomimetics, has evolved from making static copies of human and animals in the form of statues to the emergence of robots that operate with realistic appearance and behavior. Technology evolution led to such fields as artificial muscles, artificial intelligence, artificial vision, and biomimetic capabilities in materials science, mechanics, electronics, computing science, information technology, and many others. One of the newest fields is the artificial muscles. To promote faster advancement in the field, there was a challenge to the research and engineering community to develop a robotic arm that would wrestle against human opponent and win. In this paper, we have proposed a material that can be used in making artificial human parts like hands, fingers, limbs, which can provide greater solutions to various problems that are being faced in recent developments.     

汽车驾驶机器人多机械手协调控制研究

汽车驾驶机器人研究中的一个关键问题就是多机械手的协调控制.为了实现驾驶机器人换档机械手和油门、离合、制动机械腿的综合协调控制,最终实现对给定循环行驶工况的车速跟踪,首先建立了基于Saridis G N三级控制架构的驾驶机器人递阶控制模型体系结构,然后在此基础上提出了驾驶机器人多机械于协调控制方法,并设计了油门/离合器协调控制器和油门/制动切换控制器.试验结果表明,本文提出的方法能合理协调控制汽车驾驶机器人油门、制动、离合机械腿和换挡机械手,实现了车辆的平稳起步,平顺换挡以及对给定车速的跟踪.     

基于伪刚体动力学模型的柔顺机构驱动特性研究

基于柔顺机构的等效伪刚体动力学模型,对柔顺曲柄滑块机构的驱动问题进行了研究.当给定从动件的运动规律时或者当从动件产生预期变形时候,分析了求解原动件驱动问题的一般方法,并与有限元分析方法进行了比较,结果表明该方法有效.     

On position/force tracking control problem of cooperative robot manipulators using adaptive fuzzy backstepping approach

In this paper, the position and force tracking control problem of cooperative robot manipulator system handling a common rigid object with unknown dynamical models and unknown external disturbances is investigated. The universal approximation properties of fuzzy logic systems are employed to estimate the unknown system dynamics. On the other hand, by defining new state variables based on the integral and differential of position and orientation errors of the grasped object, the error system of coordinated robot manipulators is constructed. Subsequently by defining the appropriate change of coordinates and using the backstepping design strategy, an adaptive fuzzy backstepping position tracking control scheme is proposed for multi-robot manipulator systems. By utilizing the properties of internal forces, extra terms are also added to the control signals to consider the force tracking problem. Moreover, it is shown that the proposed adaptive fuzzy backstepping position/force control approach ensures all the signals of the closed loop system uniformly ultimately bounded and tracking errors of both positions and forces can converge to small desired values by proper selection of the design parameters. Finally, the theoretic achievements are tested on the two three-link planar robot manipulators cooperatively handling a common object to illustrate the effectiveness of the proposed approach.     

面向协同设计的产品信息模型研究

论文提出了一种三层式的产品信息模型,重点研究了模型各层的信息交互问题.在数据层,采用模型驱动的方式以JavaBean为中间件建立数据库与XML之间的双向映射;在逻辑层,以结构树的方式组织管理产品零部件;在用户层中融入AJAX技术,赋予模型实时、同步的信息交互能力.基于AJAX4JSF开发了协同设计原型系统.利用论文提出的方法建立了GC1-2型缝纫机产品信息模型.实验表明,模型的实时同步信息交互能力有了一定的提高.     

企业数据协同管理模型研究

通过目前企业对数据管理需求的分析,提出结合计算机支持的协同工作(CSCW)和产品全牛命周期管理(PLM)思想的企业数据协同管理模型,并把该模型概括抽象成"一个规范、两个控制、三个模型",分别从信息、过程以及组织等角度分析数据协同管理机制.该模型构建的数据协同管理系统,比传统的数据管理系统更能适应目前以任务为驱动的生产经营模式,更能满足企业对数据管理集成性、动态性以及协同性的要求.     

A nonlinear finite element model for dynamics of flexible manipulators

A general nonlinear dynamics model is developed for three-dimensional flexible manipulators. A manipulator link is modelled as a beam undergoing both large gross rigid body motion and elastic deformation. The beam is discretized by the finite element method with its inertia lumped at the nodes of each element. A nonlinear strain-displacement relationship is developed to retain the geometric nonlinearity resulting from the large relative elastic deflections. The geometric nonlinearity is specifically treated so that the significance of the geometric nonlinear effects can be easily included not only in the fully nonlinear model, but also in the linearized model. Numerical results are presented to demonstrate the significant effects of geometric nonlinearity on the dynamic response of a flexible manipulator.     

Combining multiple Large Volume Metrology systems: Competitive versus cooperative data fusion

Large Volume Metrology (LVM) tasks can require the concurrent use of several measuring systems. These systems generally consist of set of sensors measuring the distances and/or angles with respect to a point of interest so as to determine its 3D position. When combining different measuring systems, characterized by sensors of different nature, competitive or cooperative methods can be adopted for fusing data. Competitive methods, which are by far the most diffused in LVM, basically perform a weighted mean of the 3D positions determined by the individual measuring systems. On the other hand, for cooperative methods, distance and/or angular measurements by sensors of different systems are combined together in order to determine a unique 3D position of the point of interest.This paper proposes a novel cooperative approach which takes account of the measurement uncertainty in distance and angular measurements of sensors of different nature. The proposed approach is compared with classical competitive approaches from the viewpoint of the metrological performance. The main advantages of the cooperative approach, with respect to the competitive one, are: (i) it is the only option when the individual LVM systems are not able to provide autonomous position measurements (e.g., laser interferometers or single cameras), (ii) it is the only option when only some of the sensors of autonomous systems work correctly (for instance, a laser tracker in which only distance – not angular – measurements are performed), (iii) when using systems with redundant sensors (i.e. photogrammetric systems with a large number of distributed cameras), point localization tends to be better than that using the competitive fusion approach.     

内燃机活塞拍击动力学模型研究

文中基于运动机构的振动响应分析方法,考虑活塞与连杆、曲轴及内燃机缸体的耦合振动对活塞拍击的影响,构建了内燃机活塞拍击动力学分析模型.应用本模型分析某型3.5L柴油发动机的活塞拍击现象,通过对比研究空载、满载工况下缸体的振动响应证明了动力学模型的有效性.理论分析了空载工况下内燃机零部件耦合振动特性对活塞拍击冲击力、活塞回转角度、连杆重心加速度及活塞拍击对连杆运动、曲轴扭转振动响应、主轴承座反力的影响机理.     

A cooperative robotic system based on multiple sensors to construct metallic structures

This paper describes a multisensorial robotic system to automatically construct metallic structures. Two robots must work cooperatively in the same workspace to perform the task. The robots are automatically guided using visual and force sensor information. A new time-independent visual force control system which guarantees the adequate robot behaviour during the construction of the structure is described. During the construction of the structure, a human operator works cooperatively with the robots in order to perform some tasks which cannot be automatically developed by the robots. To do so, a new human–robot cooperation approach is described in order to guarantee the human safety. The correct behaviour of the different subsystems proposed in the paper is demonstrated in Section 6 by the construction of a real structure composed of several metallic tubes and different types of pieces to join them.     

Cooperative manipulation of a virtual object by multiple remote users

In this paper, we explore the issues of force display in the cooperative virtual environment shared by multiple users distributed over the network with heterogeneous hardware platforms. The proposed method is to cope with the problem of small time delay and the difference of sampling rate in the distributed configuration. In the proposed approach the interaction forces of the participants are just treated as the independent sources of acceleration. Thus the action of a participant simply changes the acceleration of the virtual object and consequently the states of the virtual object will be updated. When the updated states are reported to all the participants, the information on the time of state changes is delivered, too. Employing the discrete state information updated by the other users, each user modifies his own virtual environment and pseudo-realtime simulation can be realized. Excluding the software interface and the communication technique, it is proposed the simulation method for the operation of respective users and the way of calculating the driving input to the display device. For experimental verification we construct a cooperative virtual environment shared by two remote users and outline the results of experiments.     

Synthesis of multiple degrees-of-freedom spatial-motion compliant parallel mechanisms with desired stiffness and dynamics characteristics

This paper presents a new design method to synthesize multiple degrees-of-freedom (DOF) spatial-motion compliant parallel mechanisms (CPMs). Termed as the beam-based structural optimization approach, a novel curved-and-twisted (C-T) beam configuration is used as the basic design module to optimize the design parameters of the CPMs so as to achieve the targeted stiffness and dynamic characteristics. To derive well-defined fitness (objective) functions for the optimization algorithm, a new analytical approach is introduced to normalize the differences in the units, e.g., N/m or N m/rad, etc., for every component within the stiffness matrix. To evaluate the effectiveness of this design method, it was used to synthesize a 3-DOF spatial-motion (θ_x − θ_y − Z) CPM that delivers an optimized stiffness characteristics with a desired natural frequency of 100 Hz. A working prototype was developed and the experimental investigations show that the synthesized 3-DOF CPM can achieved a large workspace of 8°×8°×5.5 mm, high stiffness ratios, i.e., >200 for non-actuating over actuating stiffness, and a measured natural frequency of 84.4 Hz.     

Study of path loss and data transmission error of IEEE 802.15.4 compliant wireless sensors in small-scale manufacturing environments

Wireless sensors emerge as a promising candidate for supporting a wide range of plant floor monitoring applications in manufacturing; nevertheless, manufacturing environments are notoriously harsh for radio propagation. Usually abundant of stationary and moving objects, manufacturing environments may cause transmission errors among wireless sensors due to blocking, scattering, and multipath effects. This study aims to experimentally investigate the nature of such transmission errors due to common stationary and moving obstacles in small-scale manufacturing environments inside a machine shop and with a moving forklift, respectively. The measurement study was performed using the commonly adopted IEEE 802.15.4-based 2.4 GHz Zigbee radio. The measurements show that the occurrence of transmission errors closely depends on the received signal strength in both stationary and moving settings, and the transmission errors can be mostly avoided by controlling the transmit power to assure the received signal strength above the radio receiving sensitivity level. It is also found that electromagnetic noise due to the typical machinery has negligible effects on the transmission error.     

Fuzzy force control of constrained robot manipulators based on impedance model in an unknown environment

To precisely implement the force control of robot manipulators in an unknown environment, a control strategy based on fuzzy prediction of the reference trajectory in the impedance model is developed. The force tracking experiments are executed in an open-architecture control system with different tracking velocities, different desired forces, different contact stiffnesses and different surface figurations. The corresponding force control results are compared and analyzed. The influences of unknown parameters of the environment on the contact force are analyzed based on experimental data, and the tunings of predictive scale factors are illustrated. The experimental results show that the desired trajectory in the impedance model is predicted exactly and rapidly in the cases that the contact surface is unknown, the contact stiffness changes, and the fuzzy force control algorithm has high adaptability to the unknown environment. Translated from Journal of Northeastern University (Natural Science), 2005, 26(8): 766–769 [译自: 东北大学学报 (自然科学版)]     

基于动态角色的多机器鱼协作顶球研究

机器鱼水球比赛是进行多机器鱼协作研究的标准平台。考虑在机器鱼水球比赛中的协作顶球策略问题,以行为机制理论为基础,根据机器鱼与球之间的距离及机器鱼的方向,通过引入进攻与防守函数来确定各机器鱼的动态角色分配。进一步将多机器鱼协作顶球任务划分为4个子任务层,分别对4个子任务层的行为机制与算法加以规划。最后,通过实验验证了多机器鱼协作顶球策略的可行性和有效性。