The Fuzzy Neural Network Control Scheme With H∞ Tracking Characteristic of Space Robot System With Dual-arm After Capturing a Spin Spacecraft

In this paper,the dynamic evolution for a dualarm space robot capturing a spacecraft is studied,the impact effect and the coordinated stabilization control problem for postimpact closed chain system are discussed.At first,the pre-impact dynamic equations of open chain dual-arm space robot are established by Lagrangian approach,and the dynamic equations of a spacecraft are obtained by Newton-Euler method.Based on the results,with the process of integral and simplify,the response of the dual-arm space robot impacted by the spacecraft is analyzed by momentum conservation law and force transfer law.The closed chain system is formed in the post-impact phase.Closed chain constraint equations are obtained by the constraints of closed-loop geometry and kinematics.With the closed chain constraint equations,the composite system dynamic equations are derived.Secondly,the recurrent fuzzy neural network control scheme is designed for calm motion of unstable closed chain system with uncertain system parameter.In order to overcome the effects of uncertain system inertial parameters,the recurrent fuzzy neural network is used to approximate the unknown part,the control method with H∞tracking characteristic.According to the Lyapunov theory,the global stability is demonstrated.Meanwhile,the weighted minimum-norm theory is introduced to distribute torques guarantee that cooperative operation between manipulators.At last,numerical examples simulate the response of the collision,and the efficiency of the control scheme is verified by the simulation results.

Project Systems Engineering for Developing Space Robots

Space robots possess unique distinguishing features unlike general robots on earth, due to the particular environments in space. The developing of various practical space robots promoting the improvement of space science and technology is a complex man-machine-environment engineering problem. This paper analyses from the systems engineering viewpoint the space robot system in the scope of the architecture of robotics discipline, space environment characteristics, man-machine-environment system of space robots, the general methodology of project systems engineering and the process of space robot systems engineering.

Adaptive neural network control for coordinated motion of a dual-arm space robot system with uncertain parameters

Control of coordinated motion between the base attitude and the arm joints of a free-floating dual-arm space robot with uncertain parameters is discussed. By combining the relation of system linear momentum conversation with the Lagrangian approach, the dynamic equation of a robot is established. Based on the above results, the free-floating dual-arm space robot system is modeled with RBF neural networks, the GL matrix and its product operator. With all uncertain inertial system parameters, an adaptive RBF neural network control scheme is developed for coordinated motion between the base attitude and the arm joints. The proposed scheme does not need linear parameterization of the dynamic equation of the system and any accurate prior-knowledge of the actual inertial parameters. Also it does not need to train the neural network offline so that it would present real-time and online applications. A planar free-floating dual-arm space robot is simulated to show feasibility of the proposed scheme.

New coordination scheme for multi-robot systems based on state space models

A new coordination scheme for multi-robot systems is proposed. A state space model of the multi- robot system is defined and constructed in which the system＇s initial and goal states are included along with the task definition and the system＇s internal and external constraints. Task accomplishment is considered a transition of the system state in its state space （SS） under the system＇s constraints. Therefore, if there exists a connectable path within reachable area of the SS from the initial state to the goal state, the task is realizable. The optimal strategy for the task realization under constraints is investigated and reached by searching for the optimal state transition trajectory of the robot system in the SS. Moreover, if there is no connectable path, which means the task cannot be performed Successfully, the task could be transformed to be realizable by making the initial state and the goal state connectable and finding a path connecting them in the system＇s SS. This might be done via adjusting the system＇s configuration and/or task constraints. Experiments of multi-robot formation control with obstacles in the environment are conducted and simulation results show the validity of the proposed method.

Singular perturbation composite control of a free-floating flexible dual-arm space robot

The Free-floating Flexible Dual-arm Space Robot is a highly nonlinear and coupled dynamics system. In this paper, the dynamic model is derived of a Free-floating Flexible Dual-arm Space Robot holding a rigid payload. Furthermore, according to the singular perturbation method, the system is separated into a slow subsystem representing rigid body motion of the robot and a fast subsystem representing the flexible link dynamics. For the slow subsystem, based on the second method of Lyapunov, using simple quantitative bounds on the model uncertainties, a robust tracking controller design is used during the trajectory tracking phase. The optimal control method is designed in the fast subsystem to guarantee the exponential stability. With the combination of the two above, the system can track the expected trajectory accurately, even though with uncertainty in model parameters, and its flexible vibration gets suppressed, too. Finally, some simulation tests have been conducted to verify the effectiveness of the proposed methods.

多机器人系统PTCWA指标与布局优化

机器人协作系统是提高机械制造加工自动化与灵活性的有效方式,提出了一种基于协作工作空间与公共工作空间乘积(PTCWA)性能指标的机器人系统布局优化模型与方法。该方法采用解析法对多机械臂系统的公共工作空间和协同工作空间进行分析,研究系统布局与两种操作空间之间的耦合关系。基于机械臂D-H参数与机器人数量,对系统布局的极限位置进行分析。基于PTCWA性能指标与布局极限位置参数构建多臂系统布局优化模型,以系统性能指标最优为目标对优化模型进行优化求解。最后以由三个工业机器人组成的典型协作系统为实例进行仿真验证,结果表明以该优化模型进行优化求解可以得到机器人系统的最优系统布局参数。

空间站机械臂人机系统设计与验证

在充分调研国际空间站机械臂人机系统设计的基础上,结合中国空间站机械臂人机协同作业需求,建立了空间站机械臂“管理-设计-验证”全周期人机设计体系,通过人机项目规划、人机功能分配等管理要素,针对性地开展了空间机械臂人机系统详细设计,最后,从仿真分析、地面验证、在轨验证三大方面对人机系统进行了全要素全流程的验证,结果表明空间站机械臂人机系统设计合理,可应用于后续航天员出舱活动,保障航天员出舱活动安全、高效。研究结果将为空间机械臂人机系统设计与验证提供体系借鉴和工程指导。

Contact detumbling toward a nutating target through deformable effectors and prescribed performance controller

Detumbling operation toward a rotating target with nutation is meaningful for debris removal but challenging. In this study, a deformable end-effector is first designed based on the requirements for contacting the nutating target. A dual-arm robotic system installed with the deformable end-effectors is modeled and the movement of the end-tips is analyzed. The complex operation of the contact toward a nutating target places strict requirements on control accuracy and controller robustness. Thus, an improvement of the tracking error transformation is proposed and an adaptive sliding mode controller with prescribed performance is designed to guarantee the fast and precise motion of the effector during the contact detumbling.Finally, by employing the proposed effector and the controller,numerical simulations are carried out to verify the effectiveness and efficiency of the contact detumbling toward a nutating target.

基于KUKA重载机器人的柔性搅拌摩擦焊接系统开发与试验研究

为实现铝合金复杂结构产品的高效率高质量搅拌摩擦焊接成形,开展了基于KUKA重载机器人与新型搅拌摩擦焊技术结合的柔性焊接系统研究,通过自主研制多功能搅拌摩擦焊主机单元和试验工装,开发机器人柔性焊接专用控制系统实现集成控制,以此为基础开展了平板焊接试验试片接头组织性能研究及空间曲线轨迹的搅拌摩擦焊试验验证。研究结果表明:该重载机器人搅拌摩擦焊接系统可稳定实现6 mm厚2219 C10S铝合金平板试片和3 mm厚S形空间曲线焊接试验件的焊接,当搅拌头为转速n=800 r/min,焊接速度υ=200 mm/min时,试片接头抗拉强度和延伸率等力学性能较好,对试样焊缝进行超声相控阵及X光检测,未发现焊缝内部存在孔洞、裂纹等超标缺陷,验证了机器人搅拌摩擦焊接系统和工艺方法的适用性。

虚拟TCP设置及其在机器人数字化编程与加工中的应用

数字化制造中,机器人加工装备在数字化空间中实现轨迹生成、优化和加工仿真,需要利用TCP坐标系对轨迹进行转换并实现与实际加工一致的轨迹运动仿真,提高加工精度。当机器人采用工件在手的作业方式时,其TCP坐标系和轨迹点同时处于机器人末端,无法驱动机器人运动。通过设置虚拟TCP坐标系并利用虚拟TCP坐标系与轨迹点重合的约束条件,统一工件在手和工具在手的轨迹转换方法。在运行轨迹点时,机器人的TCP坐标系依次与转换后的轨迹点重合,保证仿真过程与机器人实际加工过程的一致。通过设置多个虚拟TCP坐标系,可以对相同轨迹点进行复用,提高编程效率。为验证虚拟TCP坐标系设置的正确性,分别在机器人铣削和磨削加工的数字化空间中设置虚拟TCP坐标系,通过对实际产品的加工,验证了两个空间中轨迹运行的一致性。通过调整数字化空间中的虚拟TCP位置,其磨削精度可以达到0.15 mm。

基于径向基函数神经网络的空间漂浮机械臂装配控制

针对空间漂浮机械臂在轨装配中动力学模型失准、待装配模块质量特性未知情况下的精确控制问题,本文提出了一种基于径向基函数神经网络补偿控制的装配方法。给出空间漂浮装配机械臂的构型设计及动力学模型描述,设计了一种基于径向基函数神经网络原理的补偿控制率,进行了稳定性与收敛性分析,推导出基于径向基函数神经网络神经网络的空间漂浮基座机械臂装配控制自适应律。不同工况下的在轨装配仿真案例表明:基于径向基函数神经网络原理补偿的控制方法能够控制机械臂末端执行器在未知特性大负载作用下快速准确地跟踪期望轨迹,而不进行补偿时控制器性能下降严重、甚至失效。所提出装配控制方法具有较强的工程实用价值,能为未来空间装配任务提供有效借鉴。

多机协调吊运系统综合多影响因子的位置稳定性评价方法

针对多机协调吊运系统由于欠约束特性导致的静平衡稳定性难以评价的问题,本文提出了综合多影响因子的位置稳定性评价方法。与传统方法不同,该方法将被吊运物中有运动任务需求的自由度定义为稳定自由度,其余自由度定义为欠稳定自由度,并将姿态自由度为稳定自由度时,影响稳定性的因素归结为位置自由度和各柔索拉力的差异2种因素;通过对这2种因素的量化,得到位置自由度影响因子、拉力大小影响因子和拉力均匀性影响因子,以3个影响因子的加权和作为每个位置点的稳定性评价指标。通过这种稳定性评价方法对系统的静平衡稳定位置工作空间进行了定义,并计算了系统不同稳定性裕度的静平衡稳定位置工作空间,为系统的可行轨迹规划和控制奠定了基础。

地月空间发展的若干工程与技术问题

针对地月空间发展的关键工程与技术问题,从地月空间运输、月球和小天体资源、月面机器人、地月空间经济圈等角度开展了研究。地月空间运输分为天地往返、地月转移和月面升降等阶段,需要根据不同阶段的环境特征发展不同的飞行器、运输方式和重复使用方案,并考虑地球空间站与载人月球探测的一体化设计。地球静止轨道是理想的地月空间工业园区,月球空间的真空、低重力、低温以及充足太阳能等条件为发展磁悬浮、太空电梯、天钩等电气化运输提供了便利;面对严酷的月面环境和稀缺的人力资源,月面机器人将发挥先导性和主力军作用,用于基础设施建设、航天员陪伴与辅助、人机协作等。地月空间发展不仅仅是载人登月,而是以建立地月空间经济圈为目标,促使国家利益从地面、海洋延伸至地月空间,推动太空产业从围绕地球向围绕地月空间发展,加速人类社会由地球文明向太阳系文明迈进。

复杂空间曲面焊接机器人自动编程系统

针对机器人在空间曲面焊接过程中需要保持焊接速度和焊炬位姿恒定的工艺要求,提出了一种适用于复杂空间曲面焊接机器人的运动规划方法,该方法采用NURBS曲线对三维点云描述的空间轨迹进行光顺逼近,建立机器人配合变位机组成的多自由度焊接系统运动学模型并进行逆运动学求解.开发了一套完整的复杂空间曲面焊接机器人自动编程系统.以翻领成型器为例进行了复杂空间曲面焊接机器人的自动编程及焊接试验.结果表明,文中提出的复杂空间曲面焊接机器人运动规划方法和自动编程系统能够顺利完成焊接任务,且运动平稳,具有良好的焊接轨迹精度.创新点:(1)研究一种NURBS曲线光顺逼近算法,兼顾焊接轨迹精度和系统运动平滑性.(2)构建了适用于多自由度机械臂配合变位机的复杂空间曲面焊接运动学模型.(3)设计了一套复杂空间曲面焊接机器人自动编程系统.

面向多机器人系统的元组空间协同模型

在多机器人协同领域,传统的协同模型虽然解决了协同实体间的信息交互、共享和通信问题,但复杂多变的协同环境所需要的决策机制并没有在模型层得到支持,只能通过应用程序来实现,导致协同系统开发困难并影响协同决策过程的执行效率。针对传统的协同模型存在无法灵活地支持用户决策的问题,本文提出一种基于事件具有决策能力的元组空间协同模型DEBC(Decision and Event Based Coordination)。DEBC模型在元组空间框架中引入决策机制,并对应用层的协同任务进行部分抽象,通过赋予元组空间一组支持决策的操作,使得协同应用程序开发具有高度的灵活性和适应性。同时引入事件机制,保证了协同实体间协同行为的灵活性和高效性。最后,对DEBC模型进行实例分析并与现有模型进行实验对比分析,验证了DEBC模型具有良好的表达能力和更高的执行效率,其提供的决策机制、事件机制具有广泛的适用性。

Area-oriented coordinated trajectory planning of dual-arm space robot for capturing a tumbling target

The growing amount of space debris poses a threat to operational spacecraft and the long-term sustainability of activities in outer space. According to the orbital mechanics, an uncontrolled space object will be tumbling, bringing great challenge to capture and remove it. In this paper, a dual-arm coordinated ‘‘Area-Oriented Capture'(AOC) method is proposed to capture a non-cooperative tumbling target. Firstly, the motion equation of the tumbling target is established, based on which, the dynamic properties are analyzed. Then, the ‘‘Area-Oriented Capture'concept is presented to deal with the problem of large pose(position and attitude) deviation and tumbling motion. An area rather than fixed points/devices is taken as the object to be tracked and captured. As long as the manipulators’ end-effectors move to a specified range of the objective areas(not fixed points on the target, but areas), the target satellite will be hugged by the two arms.At last, the proposed method and the traditional method(i.e. fixed-point oriented capture method)are compared and analyzed through simulation. The results show that the proposed method has larger pose tolerance and takes shorter time for capturing a tumbling target.

Detumbling strategy based on friction control of dual-arm space robot for capturing tumbling target

The rotational motion of a tumbling target brings great challenges to space robot on successfully capturing the tumbling target.Therefore,it is necessary to reduce the target's rotation to a rate at which capture can be accomplished by the space robot.In this paper,a detumbling strategy based on friction control of dual-arm space robot for capturing tumbling target is proposed.This strategy can reduce the target's rotational velocity while maintaining base attitude stability through the establishment of the rotation attenuation controller and base attitude adjustment controller.The rotation attenuation controller adopts the multi-space hybrid impedance control method to control the friction precisely.The base attitude adjustment controller applies the dual-arm extended Jacobian matrix to stabilize the base attitude.The main contributions of this paper are as follows:(1)The compliant control method is adopted to achieve a precise friction control,which can reduce the target angular velocity steadily;(2)The dual-arm extended Jacobian matrix is applied to stabilize the base attitude without affecting the target capture task;(3)The detumbling strategy of dualarm space robot is designed considering base attitude stabilization,realizing coordinated planning of the base attitude and the arms.The strategy is verified by a dual-arm space robot with two 7-DOF(degrees of freedom)arms.Simulation results show that,target with a rotation velocity of 20(°)/s can be effectively controlled to stop within 30 s,and the final deflection of the base attitude is less than 0.15°without affecting the target capture task,verifying the correctness and effectiveness of the strategy.Except to the tumbling target capture task,the control strategy can also be applied to other typical on-orbit operation tasks such as space debris removal and spacecraft maintenance.

基于神经网络的焊缝跟踪系统视觉标定方法

文中提出一种基于深度神经网络的焊缝跟踪系统机器人视觉标定方法,实现了机器人的简单快速标定。将焊缝跟踪传感器安装在机械臂末端,使用线激光器对被检测角点进行定位,工业相机拍摄对应的标定棋盘图像,用角点提取算法获取到相应棋盘格点的数字图像坐标,并通过示教器读取机械臂的各个关节角,利用神经网络极强的非线性映射能力,将其传入训练好的BP神经网络进行三维空间坐标的预测。此方法能够实现机器人的快速标定,避开传统标定方法中复杂的非线性运算,并减少坐标转换间的累积误差。实验结果表明,基于神经网络的标定方法具有较高的精度,且标定过程简单,为机器人视觉标定提供了一种新的方法。

浅析陕西广电融媒体集团融媒体新闻演播室升级改造

介绍陕西广电融媒体集团融媒体新闻演播室升级改造,重点阐述舞美空间的功能布局,以及轨道系统、灯光系统、LED屏播控系统的配置及工艺实施。

Reorientation and obstacle avoidance control of free-floating modular robots using sinusoidal oscillator

This paper presents that a serpentine curve-based controller can solve locomotion control problems for articulated space robots with extensive flight phases,such as obstacle avoidance during free floating or attitude adjustment before landing.The proposed algorithm achieves articulated robots to use closed paths in the joint space to accomplish the above tasks.Flying snakes,which can shuttle through gaps and adjust their landing posture by swinging their body during gliding in jungle environments,inspired the design of two maneuvers.The first maneuver generates a rotation of the system by varying the moment of inertia between the joints of the robot,with the magnitude of the net rotation depending on the controller parameters.This maneuver can be repeated to allow the robot to reach arbitrary reorientation.The second maneuver involves periodic undulations,allowing the robot to avoid collisions when the trajectory of the global Center of Mass(CM)passes through the obstacle.Both maneuvers are based on the improved serpenoid curve,which can adapt to redundant systems consisting of different numbers of modules.Finally,the simulation illustrates that combining the two maneuvers can help a free-floating chain-type robot traverse complex environments.Our proposed algorithm can be used with similar articulated robot models.