A novel AR-based robot programming and path planning methodology

This paper discusses the benefits of applying Augmented Reality (AR) to facilitate intuitive robot programming, and presents a novel methodology for planning collision-free paths for an n degree-of-freedom (DOF) manipulator in an unknown environment. The targeted applications are where the end-effector is constrained to move along a visible 3D path/curve, which position is unknown, at a particular orientation with respect to the path, such as arc welding and laser cutting. The methodology is interactive as the human is involved in obtaining the 3D data points of the desired curve to be followed through performing a number of demonstrations, defining the free space relevant to the task, and planning the orientations of the end-effector along the curve. A Piecewise Linear Parameterization (PLP) algorithm is used to parameterize the data points using an interactively generated piecewise linear approximation of the desired curve. A curve learning method based on Bayesian neural networks and reparameterization is used to learn and generate 3D parametric curves from the parameterized data points. Finally, the orientation of the end-effector along the learnt curve is planned with the aid of AR. Two case studies are presented and discussed.     

大型空间末端执行器在轨操作运输舱策略

针对空间运输舱具有较大的速度和惯量,在对运输舱的操作过程中存在着冲击和碰撞,严重的时候会影响系统的安全的问题,研制中国大型空间末端执行器,设计大容差柔性钢丝绳捕获机构和基于滚珠丝杠螺旋传动副的拖动机构,并且对其捕获传感器系统进行设计。根据末端执行器机构特点和工作原理,提出基于Loop/Contact控制模型的捕获控制策略,有效地减小了操作对系统的冲击。建立空间微重力环境下末端执行器系统和运输舱系统的动力学模型,推导大型末端执行器在轨操作运输舱的动力学方程。计算机仿真试验证明,捕获过程中捕获力较传统方式降低50%,试验证明捕获力小于700 N,二者验证了末端执行器的实用性和控制策略的可行性,对提高大型空间末端执行器的工作稳定性具有重要意义。     

Computation of the configuration degree of freedom of a spatial parallel mechanism by using reciprocal screw theory

In this paper, we propose a programmable algorithm to investigate the configuration degree of freedom (CDOF) of a spatial parallel mechanism in one Cartesian coordinate system with reciprocal screw theory. According to the physical meaning of reciprocal screws, we first obtain the terminal constraints of every kinematic chain which connects the end-effector with the fixed base, and then gain the free motion(s) of the end-effector and its degree of freedom (DOF). Through analyzing the controllability of the end-effector, we investigate the instantaneous screw expressions for the free motions of the end-effector of a spatial parallel mechanism and the CDOF of the mechanism. The whole mathematical analysis process can be directly embedded in a kind of CAD software, in which the imperfect Kutzbach Grübler formulas or its amendments are mostly utilized to analyze the DOF.     

新型平面直线驱动系统及其在机器人末端操作器中的应用

研制了一种机器人微驱动末端操作器用新型二自由度平面直线驱动系统 ,该二自由度电动机由于在X及Y方向采用共用永磁体的结构 ,与传统电机系统比较具有较高的性能体积比 ,应用于实际操作器系统中取得良好的效果     

Optimal actuator sizing and end point deformation for mobile robotic manipulators with elastic joint based on load criteria

Application of a numerical method to determine the maximum dynamic load carrying capacity (DLCC) for a robotic manipulator carrying an automobile petrol tank with joint elasticity subject to accuracy and actuator constraints is described in this paper. The maximum DLCC which can be achieved by a manipulator during a given trajectory is limited by a number of factors. The most important of which are the dynamic specification of the manipulator, the actuator limitations, and the elasticity of the joints such as reducers and servo drive system. Initially, the kinematic equations for carrying the automobile petrol tank by the robotic arm with 6 degrees of freedom (DOF) were calculated. The mechanical modeling was achieved via software programming. Dynamic modeling of the flexible joints manipulator was done simply for the three major axes. A method for determination of the dynamic load capacity with specific reference to both accuracy and actuator constraints is explained. The results obtained indicate the importance of both constraints and which constraint is more critical for accuracy and tracking.     

基于KUKA机器人的电热水器倒机系统的设计

根据电热水器的生产流程及工厂提出自动化生产的要求,提出了基于KUKA工业机器人的电热水器倒机系统的自动化设计方案。设计了机器人的末端执行器、输送线,搭建了以PLC为主控系统的电热水器倒机自动化控制系统。采用TCP/IP协议实现了PLC与KUKA工业机器人之间的通信,通过I/O接口实现了PLC与输送线的通信。利用KRL-KUKA Robot Language编写了机器人的程序,利用TIA PROTAL V11软件完成PLC与触摸屏连网的组态和系统监控界面的设计。该系统已在某电热水器生产车间得到应用,促进了该工厂的自动化建设,提高产品质量和生产效率,减轻员工繁重的体力劳动。在类似工艺和热水器制造行业中具有一定的参考价值。     

A compliant end-effector for microscribing

A new end-effector was designed and built for microscribing processes using principles of compliant mechanisms. Initial testing of a chemomechanical microscribing process showed that low forces produce lines that are significantly smoother, more uniform, and exhibit less material chipping. From the testing it is apparent that there is a need for a specialized precision end-effector that (1) is passively controlled, (2) has low axial stiffness, and (3) has high lateral stiffness. To meet these needs a three segment folded-beam compliant mechanism was chosen. This design is passively controlled, has a high axial/lateral stiffness ratio, is ideal for clean sensitive applications, and can be designed for a range of low forces. The axial stiffness of the end-effector was modeled using both the compliant mechanism pseudo-rigid body model and linear-elastic beam theory. The lateral stiffness was modeled using FEA techniques. Ratios of lateral stiffness to axial stiffness were found to be nearly 1000:1. A fatigue analysis was also performed and it was determined that the mechanism could reach approximately 1 billion cycles before failure. The compliant end-effector design is a significant improvement over existing scribing alternatives and can produce smooth and uniform scribed lines that exhibit less material chipping.     

工业机器人连续轨迹位置规划算法的研究

提出了一种工业机器人连续轨迹位置规划算法。此方法基于笛卡儿空间定时插补算法,包含四个方面内容:特征点提取、曲线拟合、通过位置插补和姿态插补确定插补点及利用逆运动学方程求出各关节转角。此方法可应用于各种工业机器人连续精确的路径规划。     

Collision-free control of mobile manipulators in a task space

This work offers the solution at the control feed-back level of the end-effector trajectory tracking problem for mobile manipulators subject to state equality and/or inequality constraints, suitably transformed into control dependent ones. Based on the Lyapunov stability theory, a class of controllers fulfilling the above constraints and generating a collision-free mobile manipulator trajectory with (instantaneous) minimal energy, is proposed. The problem of collision avoidance is solved here based on an exterior penalty function approach which results in continuous and bounded mobile manipulator controls even near boundaries of obstacles. The numerical simulation results carried out for a mobile manipulator consisting of a non-holonomic unicycle and a holonomic manipulator of two revolute kinematic pairs, operating both in a two-dimensional unconstrained task space and task space including the obstacles, illustrate the performance of the proposed controllers.     

基于传感器的操作臂惯性参数在线识别神经网络模型

机器人惯性参数识别是机器人精确建模以及机器人控制和仿真的关键问题之一。机器人腕力传感器的接入将影响机器人系统的动力学特性 ,同时腕力传感器的输出也真实地反映了机器人的力作用和机器人末端的动力学特性。本文基于腕力传感器的输出信号 ,对在线识别机器人操作臂末端的惯性参数的方法进行了分析和研究 ,并建立了惯性参数在线识别的神经网络模型 ,网络学习后其权值即为辨识的惯性参数。