基于变阻抗控制的冗余驱动并联机器人多目标内力优化

由于冗余驱动的存在,冗余驱动并联机器人系统逆动力学模型存在无限组可跟踪期望轨迹的控制力矩解,这使得机器人在运行过程中具有完成附加任务的能力.以实现骨科机器人的安全精准操控为目的,提出了基于变阻抗控制的冗余驱动并联机器人多目标内力优化方法.首先,采用支链分解法对冗余驱动并联机器人的动力学进行建模.其次,为实现机器人的安全操作,设计了冗余驱动并联机器人时变阻抗控制器,利用李雅普诺夫理论分析了系统的稳定性;在此基础上,以消除冗余驱动并联机器人运动过程中的传动间隙为附加任务,提出了一种以力矩传递性能、驱动功率和控制力为优化目标的多目标融合驱动力优化方法.最后,通过仿真实验与对比分析,验证了所提方法的有效性,实现了机器人系统传动间隙的消除.     

冗余驱动并联机械手的混合位置/力自适应控制

针对冗余驱动并联机构研究一种自适应的混合位置/力控制算法.基于并联机构中约束 子流形的几何性质,将冗余驱动并联机构的逆动力学自然投影到位形空间和约束力空间.基于投 影方程,提出一种统一的具有渐进稳定性的自适应混合位置/力控制算法.采用最小二范数准则 求解冗余解问题,实现了实际驱动关节力矩的优化.仿真结果验证了控制方法的有效性.     

冗余驱动仿下颌运动机器人工作空间分析及试验验证

根据人类下颌系统冗余驱动的生理特性,即下颌受颞下颌关节约束且受多于本身自由度数目的下颌肌肉驱动的特点,介绍了一种采用点接触高副模拟人体颞下颌关节的6PUS-2HKP(higher kinematic pair)冗余驱动并联机构来完成下颌运动,该机构可应用于牙科义齿性能测试.首先,建立机器人的坐标系,针对机构存在点接触高副的特点,分析和推导了冗余并联机构的独立位置参数和运动学方程.然后,采用下颌运动轨迹描记仪对实验对象下颌切点边缘性运动进行了采集.通过分析各驱动机构及点接触高副的运动范围,采用数值分析的方法获得了机器人的工作空间.最后,采用实验的方法,测量了仿下颌运动机器人做最大运动时下颌切点的运动轨迹.通过对比实验对象切点边缘性运动和工作空间仿真结果可知,该仿下颌运动机器人能够满足人类下颌运动空间要求.     

含被动高副的冗余驱动并联机器人优化设计

针对具有平移和旋转混合自由度的冗余驱动并联机器人,提出一种优化设计方法.首先,介绍了仿人类口颌设计的并联机器人,由6-PUS(prismatic-universal-spherical)并联机构模拟6条主要咀嚼肌,2个被动高副模拟下颌关节.针对机构含被动高副的特点,利用末端执行器上的3点描述位姿,建立其量纲一致的雅可比矩阵.基于机器人结构和尺寸对速度误差传递性能的影响的分析,给出了该冗余驱动并联机器人的优化方法.设置性能参数对该冗余驱动并联机器人进行了尺寸优化设计,与优化前机器人机构相比全局误差标准差下降了39.83％.结果表明所提出的优化设计方法提高了并联机构的速度传递性能,并可以扩展用于其他机器人的优化设计.     

基于AutoCAD平台的六自由度并联机器人

本文研究基于AutoCAD平台的六自由度并联机器人在姿态给定情况下工作空间(即位置工作空 间)的几何确定方法,该方法以机器人的运动学反解为基础,得出Stewart并联机器人和6-R TS并联机器人位置工作空间的边界方程,从而得出Stewart并联机器人的位置工作空 间是6个球体的交集,6-RTS并联机器人在姿态给定时其工作空间是6个相同的规则曲面体 的交集．基于AutoCAD平台,其交集以及交集的容积可以很容易的得出,该方法是确定六自 由度并联机器人工作空间的一种简单、有效方法．     

智能材料DE 驱动的两态串并联机器人系统的运动特性

本文利用电活性绝缘弹胶体DE 的机电驱动特点,结合两态驱动的概念,设计了一种包含3 个两态驱 动器件的并联机构,将其作为串—并联离散驱动机器人系统的基本单元,并据此构建多个单元串联组成的多级离散 驱动系统．文中首先利用智能DE 材料制作满足这一驱动特性的圆柱形两态驱动器件,先测试其直线驱动特性,即 变形值．其次,将该变形值作为并联机构数学模型的驱动值,分析单级及多级并联机构的运动状态、特性及工作空 间的特点．最后,利用数学工具Mathematica 描绘出上述两态驱动并联机构系统所能达到的工作空间分布点云图, 分析了结构参数与驱动量对系统工作空间的范围、精度的影响．     

气动3-UPU机器人的神经网络监督控制仿真

以基于气浮无摩擦缸驱动的3-UPU并联机器人为研究对象,对其进行运动学、工作空间仿真分析以及气动比例位置系统数学建模与控制仿真.由于气动比例位置系统具有很强的非线性,而且易受环境因素影响,当采用传统PID控制时,很难使系统保持良好的控制效果.考虑到神经网络具有很强的逼近特性,于是引入RBF神经网络监督控制算法进行仿真分析.仿真结果表明,上述机器人具有较大的工作空间,同时在气动比例位置系统中,RBF神经网络监督控制具有更优的控制效果,在保证系统稳定的前提下提高了输出响应速度.     

线驱动模块化七自由度机器人轨迹跟踪控制

阐述了一种线驱动与常规串联驱动相结合的混合设计方法．这种设计方法融合了线驱动并联机构和模块化串联机构的优点，而且混合驱动机器人的工作空间大于完全线驱动机器人的工作空间．文章首先介绍了混合驱动机器人的机构设计，也就是机器人的肩关节采用模块化串联结构，而肘、腕关节采用线驱动结构．然后利用几何分析的方法来解机器人前向运动学问题．在分析驱动线长与关节角之间变换关系的基础上，分别利用速度法和关节角增量法来计算机器人逆向运动学解．最后，使用VC++实现混合驱动机器人对直线运动轨迹进行跟踪的仿真，从而证明了文章所描述的设计方法的正确性．     

绳索牵引康复机器人控制及仿真研究

康复机器人是典型的人机合作系统.人与机器人在同一物理空间,因此对机器人的柔顺性、安全性提出了严格要求.绳索驱动具有柔顺性好、占空间小、重量轻等特点,不会与人体产生刚性碰撞、冲击,非常适合于康复机器人的驱动控制.由于绳索的柔性使其只能承受拉力,其牵引构成冗余驱动系统,因此绳索位置伺服系统须引入力控制,保证工作时绳索具有一定的张力.针对康复训练机器人的人体骨盆控制问题,设计了基于绳索驱动的伺服控制系统,通过Matlab提供的sisotool进行PI和PD控制器的设计,并对张紧力、位置和二者之间的相互影响进行了仿真分析,证明了绳索驱动适合对骨盆规律的控制,并且可以在其他绳索牵引控制技术上得到应用和推广.     

面向精密调整的6-HTRT并联机器人

为实现光学精密调整,研制出了由交流伺服电机驱动的6-HTRT并联机器人,它具有6个自由度,其结构特点决定了该机器人可以完成高精度定位调整。分析了机器人的位置逆解,并对不同位姿下的工作空间进行了仿真。控制系统采用基于ISA总线的闭环控制方式,测试结果显示:该并联机器人工作空间较大、分辨率高、重复定位精度高,说明机器人结构和控制系统设计的合理性。最后应用此并联机器人成功完成了光学精密装配试验。     

A geometric approach to solving the stable workspace of quadruped bionic robot with hand–foot-integrated function

This paper discusses stable workspace of a hand–foot-integrated quadruped walking robot, which is an important issue for stable operation of the robot. This robot was provided with combined structure of parallel and serial mechanisms, whose stable workspace was the subspace of the workspace in which the system was considered stable. The reachable region was formed under structural conditions, while the stable space was formed by the overall conditions of stability which changed with the robot's pose and the mass of grabbed object. In this paper, based on the robot's main structure, the key issues in solving the robot's workspace are discussed in detail, including searching steady conditions of operation of the robot. To research the robot's workspace, working leg's motion curve needed to be solved by kinematics analysis. Due to the redundant drive, it was problematic to deal analytically with the kinematics of the quadruped walking robot. A geometric method of kinematic analysis was proposed as well. Based on the geometric method, the workspace of the robot under varying postures was analyzed by the method of grid partition and in combination with Matlab, VB and Solidworks software programs. An automated computational system of the stable workspace was developed and an example was given to illustrate the whole process in detail. The theory and analysis procedures were also verified by simulation of the robot and its actual grabbing of an object.     

Path-constrained control of a redundant manipulator in a task space

This study addresses the problem of controlling a redundant manipulator with both state and control dependent constraints. The task of the robot is to follow by the end-effector a prescribed geometric path given in the task space. The control constraints resulting from the physical abilities of robot actuators are also taken into account during the robot movement. Provided that a solution to the aforementioned robot task exists, the Lyapunov stability theory is used to derive the control scheme. The numerical simulation results, carried out for a planar manipulator whose end-effector follows a prescribed geometric path given in a task space, illustrate the trajectory performance of the proposed control scheme.     

Path following by the end-effector of a redundant manipulator operating in a dynamic environment

This paper addresses the problem of generating at the control-loop level a collision-free trajectory for a redundant manipulator operating in dynamic environments which include moving obstacles. The task of the robot is to follow, by the end-effector, a prescribed geometric path given in the work space. The control constraints resulting from the physical abilities of robot actuators are also taken into account during the robot movement. Provided that a solution to the aforementioned robot task exists, the Lyapunov stability theory is used to derive the control scheme. The numerical simulation results for a planar manipulator whose end-effector follows a prescribed geometric path, given in both an obstacle-free work space and a work space including the moving obstacles, illustrate the trajectory performance of the proposed control scheme.     

Reliability-based approach to the inverse kinematics solution of robots using Elman's networks

The solution of inverse kinematics problem of redundant manipulators is a fundamental problem in robot control. The inverse kinematics problem in robotics is the determination of joint angles for a desired cartesian position of the end effector. For the solution of this problem, many traditional solutions such as geometric, iterative and algebraic are inadequate if the joint structure of the manipulator is more complex. Furthermore, many neural network approaches have been done to this problem. But the neural network-based solutions are not much reliable due to the error at the end of learning. Therefore, a reliability-based neural network inverse kinematics solution approach has been presented, and applied to a six-degrees of freedom (dof) robot manipulator in this paper. The structure of the proposed method is based on using three networks designed parallel to minimize the error of the whole system. Elman network, which has a profound impact on the learning capability and performance of the network, is chosen and designed according to the proposed solution method. At the end of parallel implementation, the results of each network are evaluated using direct kinematics equations to obtain the network with best result.     

欠驱动冗余度空间机器人优化控制

欠驱动控制是空间技术中容错技术的重要方面.本文研究了被动关节中有制动器的欠驱动冗余度空间机器人系统的运动优化控制问题.从系统动力学方程出发,分析了欠驱动冗余度空间机器人的优化能力和控制方法;给出了主、被动关节间的耦合度指标;提出了欠驱动冗余度空间机器人系统的“虚拟模型引导控制”方法,在这种方法中采用与欠驱动机器人机构等价的全驱动机器人作为模型来规划机器人的运动,使欠驱动系统在关节空间中逼近给出的规划轨迹,实现了机器人末端运动的连续轨迹运动优化控制;通过末关节为被动关节的平面三连杆机器人进行了仿真,仿真的结果证明了提出算法的有效性.     

八足步行机器人参数的仿真计算

通过对八足步行机器人的研究,希望建立一个对复杂地形高度适应、有一定承载能力的步行机器人平台。该机器人在行走过程中,摆动腿为串联结构,而支撑腿则与地面、躯体形成具有冗余输入的多环并联机构,由于分析困难,因此借助先进的动力学仿真软件ADANS对其进行仿真计算。该文在八足步行机器人初始结构参数基础上,建立了三维机器人仿真模型,以灵活度为评价指标对机器人结构进行优化,并对优化后的模型作了运动学仿真分析,最后关于角度值的测量对原理样机的控制起到指导作用。研究表明ADAMS／VIEW模块可以方便、直观、准确地计算步行机器人运动情况。     

基于运动性能分析的双臂冗余度机器人协调运动研究

为了提高双臂冗余度机器人在其交互工作空间中的协调运动能力,以ABB YuMi为例,提出了一种计算简便并且能够有效反映双臂协调运动灵活性的性能指标。利用D-H法建立了YuMi机器人的运动学模型,分析了双臂可操作度的分布情况,分别研究了两种协调运动方式的运动学约束关系以及相应的运动控制规律,基于灵活性分析构建了双臂协调装配电机转子与轴承以及字母绘制的任务,通过仿真和实验验证了本文双臂可操作度指标的有效性及协调运动规划方法的正确性。     

Experiences and results from designing and developing a 6 DoF underwater parallel robot

REMO I Robot is a novel application of a parallel structure as an underwater robot of 6 DoF. Compared to other underwater robots, navigation of REMO I Robot is performed by the capability of its parallel structure to modify its geometric structure (thruster and front ring) and to displace by itself. This kinematic property of the parallel platform allows vectorial formation of thrusting forces to take place. Remo I Robot has just one single thruster in its rear ring, therefore the vectorial navigation gives maneuverability, flexibility, and holonomic capabilities for its navigation and positioning. The latter is important for intervention and manipulation tasks. That is why it gives a solid alternative when compared to traditional submarine robots such as shown in the simulation results and experiments performed using a real prototype. In conclusion, this paper proposes a conceptual frame for the development of underwater parallel robots. Moreover, it also points out the experience acquired from the development of the underwater Remo I Robot.     

Present and future robot control development—An industrial perspective

Robot control is a key competence for robot manufacturers and a lot of development is made to increase robot performance, reduce robot cost and introduce new functionalities. Examples of development areas that get big attention today are multi robot control, safe control, force control, 3D vision, remote robot supervision and wireless communication. The application benefits from these developments are discussed as well as the technical challenges that the robot manufacturers meet. Model-based control is now a key technology for the control of industrial robots and models and control schemes are continuously refined to meet the requirements on higher performance even when the cost pressure leads to the design of robot mechanics that is more difficult to control. Driving forces for the future development of robots can be found in, for example, new robot applications in the automotive industry, especially for the final assembly, in small and medium size enterprises, in foundries, in food industry and in the processing and assembly of large structures. Some scenarios on future robot control development are proposed. One scenario is that light-weight robot concepts could have an impact on future car manufacturing and on future automation of small and medium size enterprises (SMEs). Such a development could result in modular robots and in control schemes using sensors in the robot arm structure, sensors that could also be used for the implementation of redundant safe control. Introducing highly modular robots will increase the need of robot installation support, making Plug and Play functionality even more important. One possibility to obtain a highly modular robot program could be to use a recently developed new type of parallel kinematic robot structure with large work space in relation to the robot foot print. For further efficient use of robots, the scenario of adaptive robot performance is introduced. This means that the robot control is optimised with respect to the thermal and fatigue load on the robot for the specific program that the robot performs. The main conclusion of the presentation is that industrial robot development is far away from its limits and that a lot of research and development is needed to obtain a more widely use of robot automation in industry.     

平面三自由度并联冗余机器人的位置分析

由于机构的结构复杂 ,对并联机器人进行位置分析 ,尤其是并联冗余机器人 ,要比串联机器人复杂得多 .本文提出一种新的平面三自由度并联冗余机器人位置分析方法 ,运用这种方法进行了位置正解和位置反解分析 .对于位置正解 ,其中方程的解最多为 4 ,说明这种平面并联机构可以有 4种不同的位姿 .对于位置反解 ,可以有16组解 .最后用数值实例进行了验证 ,给出了计算结果 .本文所提出的方法也为求解其它并联冗余机器人提供了新的途径