Human-Robot Collaboration Framework Based on Impedance Control in Robotic Assembly

Human–robot(HR)collaboration(HRC)is an emerging research field because of the complementary advantages of humans and robots.An HRC framework for robotic assembly based on impedance control is proposed in this paper.In the HRC framework,the human is the decision maker,the robot acts as the executor,while the assembly environment provides constraints.The robot is the main executor to perform the assembly action,which has the position control,drag and drop,positive impedance control,and negative impedance control modes.To reveal the characteristics of the HRC framework,the switch condition map of different control modes and the stability analysis of the HR coupled system are discussed.In the end,HRC assembly experiments are conducted,where the HRC assembly task can be accomplished when the assembling tolerance is 0.08 mm or with the interference fit.Experiments show that the HRC assembly has the complementary advantages of humans and robots and is efficient in finishing complex assembly tasks.

Error Modeling and Sensitivity Analysis of a Parallel Robot with SCARA(Selective Compliance Assembly Robot Arm) Motions

Parallel robots with SCARA（selective compliance assembly robot arm） motions are utilized widely in the field of high speed pick-and-place manipulation. Error modeling for these robots generally simplifies the parallelogram structures included by the robots as a link. As the established error model fails to reflect the error feature of the parallelogram structures, the effect of accuracy design and kinematic calibration based on the error model come to be undermined. An error modeling methodology is proposed to establish an error model of parallel robots with parallelogram structures. The error model can embody the geometric errors of all joints, including the joints of parallelogram structures. Thus it can contain more exhaustively the factors that reduce the accuracy of the robot. Based on the error model and some sensitivity indices defined in the sense of statistics, sensitivity analysis is carried out. Accordingly, some atlases are depicted to express each geometric error’s influence on the moving platform’s pose errors. From these atlases, the geometric errors that have greater impact on the accuracy of the moving platform are identified, and some sensitive areas where the pose errors of the moving platform are extremely sensitive to the geometric errors are also figured out. By taking into account the error factors which are generally neglected in all existing modeling methods, the proposed modeling method can thoroughly disclose the process of error transmission and enhance the efficacy of accuracy design and calibration.

Design of Drilling and Riveting Multi-functional End Effector for CFRP and Aluminum Components in Robotic Aircraft Assembly

To fulfill the demands for higher quality,efficiency and flexibility in aviation industry,a multi-functional end effector is designed to automate the drilling and riveting processes in assembling carbon fiber reinforced polymer(CFRP)and aluminum components for a robotic aircraft assembly system.To meet the specific functional requirements for blind rivet installation on CFRP and aluminum materials,additional modules are incorporated on the end effector aside of the basic processing modules for drilling.And all of these processing modules allow for a onestep-drilling-countersinking process,hole inspection,automatic rivet feed,rivet geometry check,sealant application,rivet insertion and installation.Besides,to guarantee the better quality of the hole drilled and joints riveted,several online detection and adjustment measures are applied to this end effector,including the reference detection and perpendicular calibration,which could effectively ensure the positioning precision and perpendicular accuracy as demanded.Finally,the test result shows that this end effector is capable of producing each hole to a positioning precision within ±0.5 mm,aperpendicular accuracy within 0.3°,a diameter tolerance of H8,and a countersink depth tolerance of±0.01 mm.Moreover,it could drill and rivet up to three joints per minute,with acceptable shearing and tensile strength.

Voice Control for an Industrial Robot as a Combination of Various Robotic Assembly Process Models

Models for the design of assembly processes are considered. Various models for the voice control of an industrial robot are considered: a logical model, semantic networks, a frame model and Petri nets. It is shown that this set of models allows describing the process of designing the technological process for an industrial robot. The logical model of the technological process allows you to define logical relationships. A model based on semantic networks describes the relationship between assembly units in a detail. This allows you to determine the order and method of registration, as well as the mutual orientation of assembly units in the product. The frame model provides the ability to streamline the execution of the build process. A model based on Petri nets allows one to describe the type and sequence of technological transitions. Based on the proposed models, a method of voice control for an industrial robot is developed. The basic principles of voice control for an industrial robot are considered.

Sequence Planning for On-Orbit Assembly of Large Space Truss Structures in a Multirobot Environment

An approach to sequence planning for on-orbit assembly of large space truss structures in a multirobot environment is presented. A hierarchical representation of large space truss structures at the structural volume element level and strut level is adopted. The representation of connectivity matrix and directed graph is respectively presented at the strut level and SVE level. The multirobot environment that consists of autonomous space robots and struts is supposed. Then the multirobot serial assembly strategy,assembly states,assembly tasks and assembly sequences are described. The assembly sequence planning algorithms at the strut level and SVE level are respectively discussed. The results of the simulations show that this approach is feasible and efficient. Two extensions of this approach include more accurate assessment of the efficiency representation and improvements in planning algorithm. In the future,the assembly sequence planning of more large space truss structures and complex multirobot environments and assembly tasks will be considered.

Multi-agent robotic cooperative assembly system

Presents a multi robot cooperative assembly system (MRCAS) which is composed of an organizer computer, three industrial robots, PUMA 562 mounted on an omni directional vehicle, PUMA 760 and Adept I and organized into a hierarchical structure with the cooperation organization on the top and the coordination motion at the bottom to solve the main problem of coordination and cooperation among robots, and concludes with experimental results that MRCAS is reconfigurable and adaptable as the mission changes.

DFA Evaluation Considered Robotic Assembly Motion Stability

A method of DFAevaluation considered Robotic assembly motion stabilityis proposed .First the method of base assembly stability inferencesisintroduced ,then the concept ofstability cost, which showsthe dexterity ofrobots,and complexity of fixtures,is used to quantitatively repre sent the difficulty for clamping .

Uncalibrated Workpiece Positioning Method for Peg-in-hole Assembly Using an Industrial Robot

This paper proposes an uncalibrated workpiece positioning method for peg-in-hole assembly of a device using an industrial robot.Depth images are used to identify and locate the workpieces when a peg-in-hole assembly task is carried out by an industrial robot in a flexible production system.First,the depth image is thresholded according to the depth data of the workpiece surface so as to filter out the background interference.Second,a series of image processing and the feature recognition algorithms are executed to extract the outer contour features and locate the center point position.This image information,fed by the vision system,will drive the robot to achieve the positioning,approximately.Finally,the Hough circle detection algorithm is used to extract the features and the relevant parameters of the circular hole where the assembly would be done,on the color image,for accurate positioning.The experimental result shows that the positioning accuracy of this method is between 0.6-1.2 mm,in the used experimental system.The entire positioning process need not require complicated calibration,and the method is highly flexible.It is suitable for the automatic assembly tasks with multi-specification or in small batches,in a flexible production system.

Fuzzy reasoning model using fuzzy Petri Nets for the monitoring of robotic assembly

This paper presented a fuzzy Petri net model to deal with the monitoring of robotic assembly. Based on the fuzzy Petri net model, an efficient composite reasoning mode was proposed to perform fuzzy reasoning automatiealy. It can determine whether there exists an antecedent-consequence relationship between two contact states. Furthermore, various types of sensor signals can be converted to the same form of real values between zero and one, and the contradiction among large number, high degree of truth and importance of input conditions can be resolved very well by introducing the weight factors and priorities for sensor signals. Finally, a peg- in-the-hole example was given to illustrate the reasonability and feasibility of the proposed model.

Error Analysis of Robotic Assembly System Based on Screw Theory

Assembly errors have great influence on assembly quality in robotic assembly systems. Error analysis is directed to the propagations and accumula-tions of various errors and their effect on assembly success.Using the screw coordinates, assembly errors are represented as 'error twist', the extremely compact expression. According to the law of screw composition, relative position and orientation errors of mating parts are computed and the necessary condition of assembly success is concluded. A new simple method for measuring assembly errors is also proposed based on the transformation law of a screw.Because of the compact representation of error, the model presented for error analysis can be applied to various part- mating types and especially useful for error analysis of complexity assembly.

Research on Precision Assembly Robot's Joint Torque Control Based on Current Measurement

A set of new current sensing device is used to realize joint torque control based on current measurement in a precision assembly robot's third joint. The output torque's model of the joint's brushless DC motor is founded. Disturbance factors and the compensated effect of the torque's closed loop based on current measurement are analyzed. Related simulations and experiments show that the system has good current tracking and anti-disturbances performance, which improve the force control performance of the robot in assembly.

Bio-inspired Attachment Mechanism of Dynastes Hercules:Vertical Climbing for On-Orbit Assembly Legged Robots

With the increasing size of space facilities,on-orbit assembly requires robots to move on different heights of trusses.This paper proposes a bio-inspired attachment mechanism for robot feet to enable climbing on different heights of trusses.Inspired by the attachment and grasping abilities of Dynastes Hercules,we utilize its foot microstructures,such as microhooks and setae,to achieve efficient contact and firm grip with the surface.The morphology and arrangement of these structures can inspire the design of robot feet to improve their grasping and stability performance.We study the biological structure of Dynastes Hercules,design and optimize the bio-inspired structure,analyze the influence of various factors from theoretical and experimental perspectives,and verify the feasibility of the scheme through simulation.We propose an ideal climbing strategy that provides useful reference for robot applications in practice.Moreover,the influence laws of various factors in this paper can be applied to robot foot design to improve their operation ability and stability performance in the space environment.This bio-inspired mechanism can improve robot working range and efficiency,which is critical for on-orbit assemblyin space.

Robot trajectory planning for autonomous 3D reconstruction of cockpit in aircraft final assembly testing

The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.To address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization process.Smoothness metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D reconstruction.To ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision avoidance.By using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position path.Both orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and DVAO.The reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space trajectory.Simulation and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.

基于RobotStudio的工业机器人装配工作站仿真设计

随着“中国制造2025”强国战略的广泛开展与深入实施,制造业也正在经历从传统机械制造向数字化、智能化、网络化方向的转型,对生产效率和自动化程度提出了更高要求,机器换人成为必然趋势。本文利用RobotStudio软件对工业机器人装配工作站进行平台搭建,利用虚拟仿真技术对真实生产现场进行仿真模拟,并对工作站优缺点、解决方案以及未来发展方向进行讨论,为制造企业转型升级提供一定的理论依据和参考价值。

Accuracy Analysis of Assembly Success Rate with Monte Carlo Simulations

Monte Carlo simulation was applied to Assembly Success Bate (ASK) analyses. ASR of two peg-in-hole robot assemblies was used as an example by taking component parts' sizes, manufacturing tolerances and robot repeatability into account. A statistic arithmetic expression was proposed and deduced in this paper, which offers an alternative method of estimating the accuracy of ASR, without having to repeat the simulations. This statistic method also helps to choose a suitable sample size, if error reduction is desired. Monte Carlo simulation results demonstrated the feasibility of the method.

狭长空间内重载调姿装配机器人的设计与研究

针对舱体类狭长空间内部待安装设备种类多、批量大、载荷重、空间余量微小、装配路径复杂、装配风险高等问题,设计了一种重载调姿装配机器人。在机器人运动学研究的基础上,建立了误差模型,并以最小包围球半径为约束条件,通过遗传算法将误差参数的辨识结果补偿到机器人控制系统。以机柜装配为例,针对空间约束条件规划工作路径,基于动力学约束能耗函数模型,以时间、冲击和能耗为优化目标,得到多目标最优轨迹。样机实验验证了误差参数辨识的有效性,减小了机器人的绝对定位误差,且多目标最优轨迹的关节总冲击小、运动平稳,实现了机柜类设备高效、平稳、可靠的安装。

机器人人工拣选环境下混流装配线齐套物料配送优化

为了提高汽车制造企业配送的智能化水平、解决混流装配线齐套物料人工拣选效率低、成本高的问题,引入基于齐套物料配送策略的机器人人工拣选模式,通过优化自动拣选机器人、工人的配置数量及配送周期,使包含机器人使用成本、劳动力成本和在制品库存成本在内的总成本最小。为求解该配送优化问题,提出了改进量子蚁群算法,利用量子比特的叠加性增加种群多样性,避免算法陷入局部最优,同时设计了改进量子旋转门更新机制和基于差分进化操作的非最优个体优化策略,提高了算法收敛速度和寻优质量。最后,通过算例分析验证了模型的正确性与算法的有效性,并分析了拣选批量对总成本的影响。

机器人视觉示教技术在装配作业中的仿真研究

工件装配在工业制造中占有重要地位,实现机器人复杂而灵巧的装配动作,对于提升工业制造智能化水平具有重要意义。针对装配作业任务,将视觉示教与机器人技能学习相结合,首先搭建基于Kinect2相机和AR标签的机器人示教系统获取示教数据;接着设计了机器人装配技能学习算法生成新的运动轨迹;最后在Gazebo仿真平台完成了对上述方法的验证。该方法具有效率高、可操作性强等优点,在工业制造领域有着广阔的应用前景,同时对于机器人示教学习相关实践教学和应用研究具有重要意义。

人机协同装配多目标检测的改进YOLOv7算法

针对人机协同装配环境复杂多变且装配零件尺度差异大、部分零件相似度高的特征,为保证人机协作装配过程中机器人准确抓取装配零件,提出了一种改进的YOLOv7模型来提高装配场景中多零件目标检测效果。首先,采用ODConv(Omni-dimensional dynamic convolution)替换YOLOv7主干网络中的卷积层,使其能够自适应调整卷积核的权值,提取不同形状、大小的装配零件的特征。其次,在YOLOv7主干网络中引入SimAM(Selective image attention mechanism)模块来减轻复杂多变的装配环境背景对零件检测准确率的影响。最后,使用Efficient-IOU替换原始的CompleteIOU来加速收敛,同时降低部分装配零件相似度高对检测准确率的影响。实验结果表明,该模型的平均准确率为93.4%,改进后的网络优于原始网络和其他目标检测算法。所提出的改进YOLOv7算法在保持高精度的同时具有较高的FPS,模型参数和计算量也相对较低,适合动态人机协同装配场景下实时目标检测要求。

装配机器人的数字孪生虚实同步及抓取方法

针对工业机器人进行装配任务时对物料智能抓取精度差和数据处理难等问题,提出一种基于数字孪生的装配机器人虚实同步及抓取方法。以数字孪生为基础,设计了数字孪生装配机器人虚实同步及抓取架构。通过对多源异构数据的分类实现OPC UA服务器和客户端的信息模型搭建,并以OPC UA通信协议为桥梁进行装配机器人的数据通信,实现虚实同步。通过虚拟机器人对卷积神经网络进行进一步训练,提高对物料的抓取精度。在所开发的机器人数字孪生原型系统中验证所提方法的正确性和有效性,为实现装配机器人的数字孪生虚实同步和精确抓取提供新方案。