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.     

Design-by-Optimization and Control of Redundantly Actuated Parallel Kinematics Sliding Star

The paper deals with the design and control of an example of redundantly actuated parallel kinematic structure that can be a machine tool. The principle of redundant actuation brings parallel kinematic structures which do not have singular positions in workspace and which has increased dynamic, stiffness and accuracy properties. There is proposed a parallel kinematic structure called Sliding Star that has promising dynamic and stiffness properties. The conceptual design-by-optimization of this structure is briefly described. The redundantly actuated parallel kinematics have control problem due to mutual fighting of redundant drives. There is described the solution of this problem. Based on the investigated redundantly actuated parallel kinematics there has been built a laboratory prototype. The experimental results from the control of this prototype are briefly presented.     

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.     

Consequences of Geometric Imperfections for the Control of Redundantly Actuated Parallel Manipulators

Actuation redundancy increases and homogenizes the kinematic dexterity and stiffness as well as the force distribution among the actuators of parallel-kinematics machines (PKMs). It also allows for internal prestresses within the PKM without affecting the environment that can potentially be used to account for secondary tasks, such as active stiffness and backlash-avoiding control. However, in the presence of geometric uncertainties, this feature can become a serious problem, since then, control forces may be annihilated, or even some of the intentional prestress components may interfere with the environment. While model uncertainties can generally be tackled with robust-control concepts, actuation redundancy of PKM impedes the use of established robust-control schemes. The effect of such uncertainties and the applicability of standard model-based control schemes are analyzed in this paper. It is shown that geometric uncertainties lead to parasitic perturbation forces that cannot be compensated by adjustment of the controls. An amended version of the augmented PD and computed torque-control scheme is proposed that does not suffer from such effects.      

Performance Analysis and Application of a Redundantly Actuated Parallel Manipulator for Milling

This paper deals with the performance analysis of a 3-degree-of-freedom (3-DOF) planar parallel manipulator with actuation redundancy. Closed-form solutions are developed for both the inverse and direct kinematics about the redundant parallel manipulator. In performance analysis phase, the dexterity is analyzed, three kinds of singularities are investigated, and the stiffness is estimated. Compared with the corresponding non-redundant parallel manipulator with the redundant link removed, the redundantly actuated one has better dexterity, litter singular configurations and higher stiffness. The redundantly actuated parallel manipulator was applied to the design of a 4-DOF hybrid machine tool which also includes a feed worktable to demonstrate its applicability.     

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.     

冗余驱动仿下颌运动机器人的机构设计及轨迹规划

为实现人体下颌的运动,针对下颌系统的冗余特性和颞下颌关节运动的独特性,提出一种新型的冗余驱动的仿下颌运动机器人.首先,根据人体下颌运动机理以及仿生设计参数对仿下颌运动机器人进行样机设计.然后,基于虚拟仿真软件,对冗余驱动的仿下颌运动机器人进行轨迹规划.最后,在样机上进行下颌功能运动实验,分别模拟下颌的开闭、前后和侧方运动.结果证明该仿下颌运动机器人能够实现人体下颌的运动,特别是颞下颌关节的运动.     

Type Synthesis and Dynamics Performance Evaluation of a Class of 5-DOF Redundantly Actuated Parallel Mechanisms

Machine Intelligence Research - This paper presents a five degree of freedom (5-DOF) redundantly actuated parallel mechanism (PM) for the parallel machining head of a machine tool. A 5-DOF single...     

基于并行自学习的神经网络内模控制及其应用研究

基于在线并行自学习的神经网络内模控制,该方法是借助于神经网络对复杂系统的辩识能力对被控对象进行正模型及逆模型的辩识,用NNM辩识对象的正模型,通过一个并行自学习系统训练的NNC辩识对象的逆模型,然后用做内模控制器去控制对象。将该种控制策略应用于火电厂热工对象中具有大迟延、大惯性和时变等特性的主汽温对象,仿真研究表明,该控制方案适应对象参数的变化并表现出良好的控制特性,具有较强的鲁棒性和自适应能力。在实际应用中具有一定的实用价值。     

Dynamics and Optimized Torque Distribution Based Force/position Hybrid Control of a 4-DOF Redundantly Actuated Parallel Robot with Two Point-contact Constraints

International Journal of Control, Automation and Systems - A 4-DOF redundantly actuated parallel robot (RAPR) for jaw movement achieved by adding two point-contact constraints...     

Robust Control of Spacecraft: Application to an Actuated Simulator

International Journal of Control, Automation and Systems - In this article, a hardware-in-the-loop implementation of two robust controllers based on high-order sliding mode and μ-synthesis...     

气动人工肌肉驱动的并联平台模糊PID控制

为了提高气动人工肌肉(PAM)驱动的3自由度并联平台的位置跟踪控制精度,提出一种基于Prandtl-Ishlinskii(P-I)逆模型的模糊PID(比例-积分-微分)控制算法.首先通过动态试验分析单根PAM的迟滞特性,建立P-I逆模型.接着搭建PAM驱动的3自由度并联试验平台,设计模糊PID控制器.试验结果显示模型最大误差为0.3904 mm,平均误差为0.0793 mm,验证了所提控制算法能够很大程度地减小PAM迟滞特性对动态控制精度的影响.3自由度平台的γ角误差能保持在0.13?以内,基于P-I逆模型的模糊PID控制器整体误差波动小,表明动态轨迹跟踪效果较好.     

自适应内模控制方法在磨矿过程中的应用

针对磨矿生产过程中球磨机给矿环节存在的大滞后、大惯性、参数时变等特性,提出了一种增益自适应内模控制方法,将内模控制和对象增益参数辨识算法相结合,通过在线辨识被控对象模型的增益参数,对内模控制器和被控时象模型进行校正,以减少模型参数变化和各种干扰对系统的影响.计算机仿真和实际应用效果均表明,与常规PID控制及IMC控制效果相比,该控制方法对于阶跃响应具有超调小、响应时间快、鲁棒性能好等特点,满足磨矿生产过程对控制器性能的要求,实现了球磨机给矿环节的稳定化控制,为选矿过程综合自动化系统的实施奠定了基础.     

模糊内模PID控制及应用

工业控制系统经常存在时滞现象,且含有一定程度的非线性环节,采用常规控制方法很难满足控制要求.内模控制对时滞系统具有较好的控制作用.当内模与系统实际模型相差较大时,控制效果将会下降.根据影响系统参数的主要因素,预先确定在不同条件下系统的传递函数.当系统运行时,借助模糊控制理论,直接调用相应的系统参数,并采用内模PID进行控制.实际应用表明,该方法具有很好的控制效果.     

气动人工肌肉驱动球面并联机器人关节的力控制研究

分析了具有柔索冗余驱动特点的静力关系，研究了力控制的智能控制算法及策略，在建立的实验样机上达到了良好的力伺服性能．将气动人工肌肉的被动柔顺性与位置控制到力控制过渡的主动柔顺控制策略结合，有效避免了机器人在与环境接触时的碰撞与冲击．     

基于奇异值分解的内模控制方法及在非方系统中的应用

针对复杂工业生产过程中常常出现的输入与输出变量数目不相等的非方系统, 首次提出一种基于奇异值分解(Singular value decomposition, SVD)的内模控制(Internal model control, IMC)新方法. 该方法通过添加补偿项实现对非方系统的解耦并消除不可实现因素, 并应用SVD矩阵理论设计一种非对角型滤波器, 使控制系统不仅具备良好的高维解耦能力和响应速度快的优点, 而且因设置新型滤波结构而具备极强的鲁棒性. 仿真结果表明了这种方法的有效性和可靠性.     

CAT4 (Cable Actuated Truss—4 Degrees of Freedom): A Novel 4 DOF Cable Actuated Parallel Manipulator

The CAT4 (Cable Actuated Truss—4 degrees of freedom) robot is a novel, passively jointed, parallel robot utilizing six control cables for actuation. The architecture has been under development at the Queen's University Robotics Laboratory. The robot utilizes a passive jointed linkage with 18 revolute joints to constrain the end effector motion and provide the desired structural stability, restricting the end effector to 3 translational degrees of freedom (DOF) and 1 DOF for end effector pitch. This central mechanism together with winched cable actuation gives a number of important benefits for applications where the advantages of a parallel robot are required in conjunction with light weight. Six electric motor driven winches control the length of the cable actuators that extend from the top frame to points on the end effector raft and jointed linkage to create a stiff, but lightweight, actuated robot. Simulation work on the robot is presented giving the kinematics, including a computational estimate of the workspace for a specific configuration. Results of computational simulation of the motion of the manipulator and a discussion of the advantages and potential difficulties are also presented. © 2002 Wiley Periodicals, Inc.     

模糊控制在摆缸位置伺服系统中的应用

由于摆动气缸的摩擦转矩、空气可压缩性、比例阀的压力特性等非线性因素的存在,要得到摆缸伺服系统精确的数学模型十分困难,而且气动系统易受周围环境因素的影响,当采用传统PID控制时,很难使系统长时间保持良好的控制效果,尤其是当有一定的外界干扰之后会导致系统工作不稳定.利用Matlab实时仿真模块的功能,把模糊自适应整定PID的控制算法引入到伺服系统的控制器设计中,搭建的半实物仿真模型,对系统进行半实物仿真实验,并通过不断地在线修改控制规则,提高控制器的控制性能,实验结果表明,模糊PID控制效果良好.