Effective manipulation for a multi-DOF robot manipulator in laboratory environments

Robots are expected to enter human environments soon, and many challenging problems may then emerge when facing uncertain and varying environments. Among the challenges, one issue of great interest is how they can be effectively operated for task execution. If a robot is not to be controlled by detailed analysis and program coding, one appealing alternative is to provide a kind of manipulation system which enables the user to operate the robot naturally and efficiently. This idea has motivated us to develop an effective manipulation system for multi-degree of freedom (DOF) robot manipulators based on a 6-DOF haptic device. In this article, we focus on the laboratory environment, which is somewhat organized, but still demands sophisticated human manipulation. The proposed manipulation system, aimed for 3-D applications, provides two kinds of assistance. One is to enhance the linkage between the user and robot manipulator via the haptic clue. The other is to guide the movement of the user during task execution via a set of virtual tools, e.g., a ruler. We also propose a method for achieving smooth force rendering in manipulation, especially during the transition between two consecutive manipulations for guidance. For performance evaluation, this system is employed to conduct experiments in the chemical laboratory, which involve delicate and challenging maneuvers.     

Workstation planning for redundant manipulators

The use of redundant manipulators in assembly stations, where a number of pick-and-place tasks needs to be performed, is examined in this paper. The aim is to obtain optimum values for the location of the robot in the workstation, the sequence of tasks and the configuration of the robot at each task location, such that the total travel time is minimized. The location of the robot and the optimal configurations, for a given sequence of tasks, is obtained by formulating and solving a constrained nonlinear optimization problem using the sequential quadratic programming method. A near-optimum sequence of travel is then obtained using simulated annealing. The proposed techniques are illustrated using three numerical examples.     

机器人的运动时变可靠性分析

机器人系统存在的多种不确定性会导致其运动精度下降,为此开展机器人运动时变不确定性建模与分析,以期提高机器人运动精度。首先基于运动学分析建立了机器人末端执行器参考点位姿误差模型,随后基于机器人位姿误差模型提出了末端执行器位置精度的点（静态）可靠性、时变（区间）可靠性模型以及机器人运动的系统可靠性模型,最后给出了实现上述可靠性模型高效、高精度求解的包络方法,并以斯坦福机器人为实例验证了所提模型和求解方法的有效性。研究表明,所提出的可靠性模型能够有效获得机器人各坐标分量上的时变可靠度以及机器人运动的系统可靠度。研究工作为提高机器人运动精度提供了新方法。     

High performance loading robot design for a tool-delivery system

A concept of an ultrafast distributed material transfer system based upon linear induction motors (LIM) has been proposed in which vehicles can travel at velocities of up to 120 km/h. Performance and economic analysis of a high-speed tool-delivery system based on such a system has shown that the robot manipulator that loads and unloads the vehicles is the bottleneck. This paper presents a method to design a high-speed robot with cycle times comparable with the LIM material transfer system. A generic design methodology is developed for robot manipulators that integrates several key design issues such as kinematics, dynamics, structural mechanics, actuator sizing, assessing robustness to parameters and sensor errors, and vibration analysis. The methodology is computationally efficient and has been implemented using MATLAB for evaluating a number of 'rough-cut' feasible designs for the high-speed robot. A highly distributed architecture and distributed protocols are proposed for integrating the high-speed robot and the high-speed material transfer system.     

基于轴孔装配的机械操作臂逆向自律分散控制

 基于轴孔装配作业的特点,在自律分散控制的基础上,提出了一种逆向自律分散控制算法,用以规划机械操作臂的运动, 避免了求逆解的冗长过程,简化了对机械操作臂的控制。并通过对四自由度的平面机械手的运动仿真,验证了该算法的正确性。     

Effective Utilization of Industrial Robots—A Job and Skills Analysis Approach

The comparative abilities and limitations of industrial robots and humans are reviewed. This comparison leads to the development of a robot oriented job and skills analysis method with a two-fold objective: 1) to optimize a robot's task-performance, and 2) to guide the specification of the appropriate robot for given tasks. An example of water pump assembly by a robot is used to illustrate the proposed method and its usefulness.     

基于网络的空间机器人遥操作体系结构

提出了一种面向Ｉｎｔｅｒｎｅｔ的遥操作空间机器人共享控制体系模型,阐述了基于远端监控遥操作和近端智能自主控制相融合的遥操作控制结构,完成了时延情况下从Ｉｎｔｅｒｎｅｔ上操作拥有１５个自由度的智能机器人臂手集成系统。该系统采用基于国际互连网的主从控制结构,在多媒体交互和预测显示仿真技术的辅助下,实现了用户在广域网上控制实验室的机器人完成抓杯倒水等动作。     

Optimal-control approach to trajectory planning for a class of mobile robotic manipulations

Optimal-control theory is used in the manipulation planning for an ability-limited robot (i.e., a mobile robot with limited maneuverability). The goal of manipulation is to push an object from a given initial configuration to a goal configuration—a common task could be found in the application of mobile robots to manufacturing, in adaptive fixturing for robotic assembly and in robotic gaming. The ability-limited robot is restricted here to perform only two types of motion in a plane. One is pushing the object forward with a constant and fixed velocity, the other one is rotating the object counter-clockwise along a fixed-radius circle with a constant angular velocity. First, the controllability of the proposed manipulation system is proved. Then, the optimal-planning problem is studied within the framework of a switched system. By the aid of optimal-control theory, it is proved that an optimal trajectory involves at most two switchings between these two simple actions. After evaluating the existence and structure of the candidate optimal trajectories, an optimal planner is implemented to find the optimal trajectory. Finally, manipulation examples are provided to demonstrate the proposed manipulation method.     

The integration of manipulation and vision for assembly and quality control

The recent, development of industrial robots has produced quite powerful and cost-effective manipulators. Some crucial operations, as managing parts with random orientation or realigning pieces, can now be solved with the aid of vision systems connected with the manipulator. Quality control can be partially done during the assembly itself.

The solutions we may adopt to integrate manipulation and vision can be various. If we want to make it easy to program the system as a whole, with the same programming language, we should study solutions in which manipulation and vision use high-level languages To this end we will discuss how the choice of the programming language for the application programs is crucial.

The hardware and software structures of an operational example of such a system are presented. Examples of programs are given     

基于模糊自适应PID焊缝轨迹跟踪的机器人焊接前瞻控制方法

研究了机器人焊接的控制.针对当前传统焊接工业机器人通常仅按照示教点进行既定轨迹运动,不能适应小批量多品种的柔性与智能生产线的问题,将工业相机、图像处理技术与智能机器人相结合,提取出焊缝轨迹发送给机器人,同时为提高机器人焊接过程中的轨迹跟踪精度问题,提出了一种基于模糊自适应PID焊缝轨迹跟踪的前瞻控制方法.在工程大型薄壁结构件的焊接过程中,该方法将视觉检测与识别用于焊缝轨迹跟踪,以提高焊接机器人的作业精度.最后通过实验,验证了该方法具有良好的自适应性和控制精度,能够实现前瞻偏差补偿控制.     

Precision measurement and compensation of kinematic errors for industrial robots using artifact and machine learning

Industrial robots are widely used in various areas owing to their greater degrees of freedom (DOFs) and larger operation space compared with traditional frame movement systems involving sliding and rotational stages. However, the geometrical transfer of joint kinematic errors and the relatively weak rigidity of industrial robots compared with frame movement systems decrease their absolute kinematic accuracy, thereby limiting their further application in ultraprecision manufacturing. This imposes a stringent requirement for improving the absolute kinematic accuracy of industrial robots in terms of the position and orientation of the robot arm end. Current measurement and compensation methods for industrial robots either require expensive measuring systems, producing positioning or orientation errors, or offer low measurement accuracy. Herein, a kinematic calibration method for an industrial robot using an artifact with a hybrid spherical and ellipsoid surface is proposed. A system with submicrometric precision for measuring the position and orientation of the robot arm end is developed using laser displacement sensors. Subsequently, a novel kinematic error compensating method involving both a residual learning algorithm and a neural network is proposed to compensate for nonlinear errors. A six-layer recurrent neural network (RNN) is designed to compensate for the kinematic nonlinear errors of a six-DOF industrial robot. The results validate the feasibility of the proposed method for measuring the kinematic errors of industrial robots, and the compensation method based on the RNN improves the accuracy via parameter fitting. Experimental studies show that the measuring system and compensation method can reduce motion errors by more than 30%. The present study provides a feasible and economic approach for measuring and improving the motion accuracy of an industrial robot at the submicrometric measurement level.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00400-6     

A Robot Sensor for Measuring Thermal Properties of Gripped Objects

Robot manipulators will require a wide range of sensory systems if they are to become more widely useful. In this communication we describe a novel robot sensor designed to measure some of the thermal properties of a gripped object. A mathematical model of the sensor is proposed and validated by comparing predicted and measured sensor responses for a range of differing materials. The mathematical model can be used to analyze the sensor output and determine the thermal conductivity and thermal diffusivity of an unknown object held by the robot manipulator. This information will enable robot systems to discriminate between objects made of different materials and to aid recognition of unknown objects by providing information about their material structure.     

Six-Degree-of-Freedom Haptic Rendering in Virtual Teleoperation

Six-degree-of-freedom (6-DoF) haptic rendering of the telerobotic operation method using virtual joint coupling (VJC) is proposed. This algorithm couples six joints of a virtual robot with those of a 6-DoF haptic device based on a spring-damper model to render force and torque feedback to a user and drive the virtual robot in the teleoperation simulation. Our rigid body dynamics is decoupled from the haptic rendering loop with an open dynamic simulation library Open Dynamics Engine, which runs at a lower update rate, thereby alleviating computation demand and improving the stability of the system. To illustrate the role of haptics and physically based simulation in teleoperation, a path-following experiment with virtual constraints is carried out. An experiment of virtual assembly, in which a user performs assembly tasks by means of manipulation of a gripper mounted at the end of a virtual robot, is also implemented to verify the VJC algorithm.      

Scheduling and optimization of mixed-processing with multi-variety wafers in dual-armed cluster tools

ABSTRACT

To improve the efficiency of wafer fabrication, this work addresses the scheduling and control problems of mixed-processing with multiple wafer types in cluster tools. Then, based on a developed Petri net (PN) model, it presents a general model for cluster tools with multiple wafer types and the conventional swap strategy. By analyzing the coordination mechanism between wafers processing and robot tasks, necessary and sufficient conditions are established to check the schedulability of the system that is operated by using the conventional swap strategy. If the system is not schedulable checked by such schedulability conditions, a constraint-guided heuristic algorithm and a conflicts-avoiding algorithm are developed to obtain a reasonable schedule. Finally, illustrative examples are presented to show the applications of the proposed method.     

柔性仿人机械臂设计与动力学仿真

为优化仿人机器人手臂设计,基于Jourdain变分建立了刚柔耦合动力学模型;通过假设模态法对动力学方程进行解耦;编写了自适应变步长求解算法;在ADAMS虚拟样机和MATLAB上对水平面内的柔性手臂运动进行了仿真,人体手臂的运动仿真在虚拟样机进行．以人体手臂运动为参考,对比分析了变截面和等截面手臂的柔性变形,比较6种不同材质手臂运动中的末端横向变形量．仿真结果表明：等截面的仿人手臂运动可以近似等效为人体手臂的运动;柔性仿人手臂末端轴向变形量远小于横向变形量,对要求不高场合可以适当忽略柔性手臂的轴向变形;ABS材质的仿人机器人手臂柔性和人体手臂较为接近;改变ABS材质手臂的截面高度,可使得仿人手臂末端柔性和人体手臂一致,且振动主频和人体手臂固有频率不同．     

Safety and ergonomics evaluation of hybrid systems in Hong Kong.

This study is aimed at understanding common safety and ergonomics problems with robot installation in Hong Kong. Information was collected through direct observations and personal interviews with robot users from advanced hybrid manufacturing systems. The application areas of robots and types of safety devices employed were investigated. The ages, types of jobs, daily working hours and working conditions of personnel were examined. Fire precaution measures, types and varieties of training programs for users were analyzed. The results showed that although investments were made for installation of robots for improving production activity, limited attention was paid to the health, safety, and ergonomics aspects in the hybrid systems. There were also cases reported where no formal guidelines for robot manipulation and operation were provided. It seems that management and users paid attention to robot function and capability more than robot safety during robotization process. Conclusions were made by the authors that efforts should immediately be made to adopt recommendations on the safety devices and facilities and training requirements for improving users' health and safety before fatal accidents occur.     

Task proximity index: a novel measure for assessing the work-efficiency of assembly line balancing configurations

Assembly line balancing (ALB) aims at optimally partitioning the total work required to assemble a product to workstations. In this problem, precedence constraints must be observed on the sequence with which the distinct tasks of the assembly process may be carried out. In contrast to the strict mathematical posture employed in conventional ALB approaches, this paper provides a deep insight on the origin of precedence diagram which illustrates precedence constraints among the tasks. Our review on assembly planning methods reveals that these constraints are deduced from the geometry of the components to be attached, their position in the assembled product and even planner's expertise on the rational order with which the tasks are to be performed. Accordingly, it is explicitly shown through a case study of a real industrial product that the topology of tasks on the precedence diagram may be utilised to obtain more work-efficient ALB configurations. To this end, a metric system is developed to quantify the proximity of the tasks on the precedence diagram and a novel measure, namely the task proximity index, is proposed for assessing ALB solutions from a practical viewpoint.     

Base position planning of mobile manipulators for assembly tasks in construction environments

With good mobility and flexibility, mobile manipulators have shown broad applications in construction scenarios. Base position (BP) planning, which refers to the robot autonomously determining its working station in the environment, is an important technique for mobile manipulators when performing the construction assembly task, especially in a large-scale construction environment. However, the BP planning process is tedious and time-consuming for a human worker to carry out. Thus, to improve the efficiency of construction assembly tasks, a novel BP planning method is proposed in this paper, which can lead to appropriate BPs and minimize the number of BPs at the same time. Firstly, the feasible BP regions are generated based on the grid division and the variable workspace of the mobile manipulator. Then, the positioning uncertainties of the mobile manipulator are considered in calculating the preferred BP areas using clustering. Lastly, a set coverage optimization model is established to obtain the minimum number of BPs using an optimization algorithm according to the greedy principle. The simulated experiment based on a 9-degree of free (DoF) mobile manipulator has been performed. The results illustrated that the time for BP planning was significantly reduced and the number of BPs was reduced by 63.41% compared to existing manual planning, which demonstrated the effectiveness of the proposed method. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00411-3     

Curriculum Development and Instructional Design for “Industrial Robot Simulation Technology Training”based on Robot Studio

Taking the application of virtual simulation technology of industrial robot in teaching as the research object,a detailed research is conducted on the importance of course,principles of curriculum development,curriculum objectives,teaching content,teaching methods,teaching process and assessment methods in several aspects. And the actual teaching for a semester according to this research,through the virtual simulation teaching,improved teaching efficiency, improved the industrial robot application level and ability of the students,reduced the equipment failure rate,and laid a solid foundation for the subsequent course.     

用于室外道路环境综合理解的多种新型视觉传感技术和系统

针对室外智能移动机器人自主导航的要求，提出了基于多种新型视觉传感技术的室外道路环境综合理解方法，其基本原理是综合利用机器人四周360°景物的环视图象信息、机器人前方道路的双目注视图象信息以及机器人运行过程中形成的时空全景图象信息，综合完成实时机器人行驶方向确定、实时路面障碍物检测和机器人全局定位等视觉任务。