被动冗余度空间机器人运动学综合

分析了“被动冗余度”空间机器人主,被动关节之间的运动学耦合,得到了可用于运动 学规划的耦合指标;分析了“被动冗余度”空间机器人的运动学奇异问题,以及与对应全主 动关节冗余度空间机器人的运动学奇异的区别,得到的新的可操作性指标同样可用于机器人 的运动规划;推导出了“被动冗余度”空间机器人的最佳最小二乘运动学优化方程,通过“ 准自运动”实现被动冗余度空间机器人优化控制;通过对平面3DOF空间站机器人的仿真证实 了分析得到的结论．     

水平运动的三自由度欠驱动机器人的位置控制

以水平运动的三自由度欠驱动机器人为研究对象,对其位置控制问题进行研究．基于分层控制思想提 出一种模糊控制系统,将欠驱动机器人末端位置控制问题进行分解,末端位置由主动关节的旋转与被动关节的伸展 或收缩组成．第1 关节按照规划的曲线运动,第2 关节和第3 关节通过动力学耦合作用运动到期望位置．主动关节 2 的控制力矩或控制电压通过对模糊逻辑控制器的输出量进行加权求和得到．采用该控制原理,通过数值仿真和实 验实现了3R 欠驱动机器人在操作空间中末端点到点的位置控制．     

基于PSO的空间机械臂轨迹规划技术研究

研究机器人的机械臂轨迹优化问题,空间机器人系统的机械臂和基座之间存在动力学耦合,基座姿态稳定性容易受到机械臂运动的反作用干扰.为了使空间机器人系统的姿态稳定性不受的影响,提出了一种基于PSO(粒子群优化算法)的参数化5-3-5轨迹规划方法.利用PSO的优化能力找到合适的参数组合,进行关节空间轨迹规划.通过对比实验,运用动力学仿真对方法的有效性进行了验证.仿真结果表明,方法规划出的轨迹运动光滑,且按段轨迹运动机械臂对基座姿态的扰动符合预期要求,证明规划轨迹的有效性.     

仿蛙跳跃机器人起跳任务规划与控制

研究跳跃机器人起跑规划问题,针对仿蛙跳跃机器人在起跳过程中脚掌与地面之间形成的欠驱动约束和特定的起跳任务,为提高系统性能,提出了一种在任务空间内实现给定起跳任务要求的路径运动规划控制.利用部分反馈线性化(PFL)将仿蛙跳跃机器人系统起跳动力学方程中的非线性部分线性化,设计了滑模变结构控制器对仿蛙跳跃机器人在起跳阶段的质心轨迹进行跟踪控制.结果表明滑模控制器能够使质心轨迹精确地跟踪给定轨迹,解决了仿蛙跳跃机器人的起跳任务优化控制问题,验证了提出的任务空间控制方法用于仿蛙跳跃机器人起跳任务规划的可行性.     

基于遗传算法的欠驱动机器人运动规划

研究了平面欠驱动机器人的非完整运动规划问题,建立欠驱动机器人系统动力学模型,提出了一种利用遗传算法(GA)解决欠驱动机器人运动规划的方法。引入部分稳定控制器的思想,提出基于能量最优的评价函数,利用遗传算法对评价函数进行离线优化,得到有关部分稳定控制器的切换规则。此方法可以推广到任意平面欠驱动机器人的规划问题上,以平面3R欠驱动机器人为研究对象进行了数值仿真,仿真结果验证了该方法的有效性。     

面向离散地形的欠驱动双足机器人平衡控制方法

欠驱动双足机器人在行走中为保持自身的平衡, 双脚需要不间断运动. 但在仅有特定立足点的离散地形上很难实现调整后的落脚点, 从而导致欠驱动双足机器人在复杂环境中的适应能力下降. 提出了基于虚拟约束(Virtual constraint, VC)的变步长调节与控制方法, 根据欠驱动双足机器人当前状态与参考落脚点设计了非时变尺度缩放因子, 能够实时重构适应当前环境的步态轨迹; 同时构建了全身动力学模型, 采用反馈线性化的模型预测控制 (Model predictive control, MPC) 滚动优化产生力矩控制量, 实现准确的轨迹跟踪控制. 最终进行了欠驱动双足机器人的随机离散地形稳定行走的仿真实验, 验证了所提方法的有效性与鲁棒性.     

机器人最佳轨迹规划和图形仿真的研究

本文介绍了基于 IBM-PC 微机的机器人轨迹规划的图形仿真系统.该系统可用于机器人运动学分析和最佳轨迹规划,并能产生机械手和广义物体组成的环境物的三维几何模型.系统以交互方式工作.在微机的 CRT 上,机械手连杆的运动具存动态效果.基于 MINIMAX 准则,我们提出了一种动力学性能指标用于轨迹规划.根据该指标所进行的轨迹规划可以获得最小的关节驱动力矩.最后,文中给出了 PUMA 560 机械手的仿真结果.     

基于执行时间约束的机器人关节空间轨迹优化

为在保证机器人运动轨迹的平滑性的条件下提高机器人工作效率,提出一种基于轨迹执行时间归一化处理的关节空间运动轨迹规划优化算法。对轨迹的执行时间进行归一化处理,分析关节空间位置、速度、加速度的运动轨迹相对于归一化时间的数学模型;考虑关节运动参数的约束条件,采用五次多项式拟合机器人在关节空间的运动轨迹,分析不同轨迹执行时间对关节位置运动轨迹的超调量的影响,实现机器人关节空间的位置轨迹优化;在M atlab环境里对机器人的运动轨迹进行仿真建模,完成机器人运动学仿真。多组仿真结果表明,该算法在保证机器人轨迹平滑的基础上,能保证轨迹执行时间最优,有效地提高机器人的运动效率。     

IVECO横梁焊接机器人轨迹规划及计算机仿真研究

机器人的轨迹规划可以在关节空间中进行 ,也可以在直角坐标空间中进行 .本文分析了这两种轨迹规划的特点 ,给出了基于关节空间的轨迹规划算法和基于直角坐标空间的轨迹规划算法 .针对 IVECO横梁的焊接 ,进行了机器人的轨迹规划研究 ,并进行了计算机仿真 ,该研究成果已应用于 IVECO横梁焊接工作站系统     

工业机器人时间最优轨迹规划及轨迹控制的理论与实验研究

提出了一种用于工业机器人时间最优轨迹规划及轨迹控制的新方法, 它可以确保在关节位移、速度、加速度以及二阶加速度边界值的约束下, 机器人手部沿笛卡尔空间中规定路径运动的时间最短. 在这种方法中, 所规划的关节轨迹都采用二次多项式加余弦函数的形式, 不仅可以保证各关节运动的位移、速度、加速度连续而且还可以保证各关节运动的二阶加速度连续. 采用这种方法, 既可以提高机器人的工作效率又可以延长机器人的工作寿命. 以PUMA 5 6 0机器人为对象进行了计算机仿真和机器人实验, 结果表明这种方法是正确和有效的. 它为工业机器人在非线性运动学约束条件下的时间最优轨迹规划及控制问题提供了一种较好的解决方案.     

Robust adaptive control of an underactuated free-flying space robot under a non-holonomic structure in joint space

This paper introduces a robust adaptive control scheme for an underactuated free-flying space robot under non-holonomic constraints. An underactuated robot manipulator is defined as a robot that has fewer joint actuators than the number of total joints. Because, if one of the joints is out of order, it is so hard to repair the joint, especially in space, the control of such a robot manipulator is important. However, it is difficult to control an underactuated robot manipulator because of the reduced dimension of the input space, i.e. the non-holonomic structure of the underactuated system. The proposed scheme does not need to assume that the exact dynamic parameters must be known. It is analysed in joint space to control the underactuated robot mounted on the space station under parametric uncertainties and external disturbances. The simulation results have shown that the proposed method is very feasible and robust for a two-link planar free-flying space robot with one passive joint.     

Disturbance observer-based robust control for underwater robotic systems with passive joints

Underwater exploration requires mobility and manipulation. Underwater robotic vehicles (URV) have been employed for mobility, and robot manipulators attached to the underwater vehicle (i.e. rover) perform the manipulation. Usually, the manipulation mode takes place when the rover is stationary. The URV is then modeled as a passive joint and joints of the manipulator are modeled as active joints. URV motions are determined by inherent dynamic couplings between active and passive joints. Furthermore, the control problem becomes complex since there are many hydrodynamic terms as well as intrinsic model uncertainties to be considered. Tocope with these difficulties, we propose a disturbance observer-based robust control algorithm for underwater manipulators with passive joints. The proposed control algorithm is able to treat an underactuated system as a pseudo-active system in which passive joints are eliminated. Also, to realize a robust control method, a non-linear feedback disturbance observer is applied to each active joint. A four-jointed underwater robotic system with one passive joint is considered as an illustrative example. Through simulation, it is shown that the proposed control algorithm has good position tracking performance even in the presence of several external disturbances and model uncertainties.     

The dexterity and singularities of an underactuated robot

Underactuated robots are robotic systems with more joints than actuators. A robot may be underactuated by design as in the case of a hyper‐redundant robot with passive joints or may become underactuated as a result of an actuator failure. In this article, we examine the dexterity of underactuated robots whose passive joints operate in either a locked or free‐swinging mode. The ability to an analyze the dexterity of an underactuated robot has important applications especially for the control of passive joints with brakes and for the fault tolerance analysis of an otherwise fully actuated kinematically redundant robot. The approach applied here is to use kinematics and dynamics‐based formulations of manipulator dexterity. We then characterize passive‐joint singularities, i.e., configurations where full end‐effector control is lost because one or more joints are passive instead of active. Lastly, we introduce a new characterization of joint‐limit singularities, which are configurations where full end‐effector control cannot be achieved because one or more joints are at their joint limits. © 2001 John Wiley & Sons, Inc.     

Time-scaling control of an underactuated manipulator

Position control of an underactuated manipulator that has one passive joint is investigated. The dynamic constraint caused by the passive joint is second-order nonholonomic. Time scaling of the active joint trajectory and bidirectional motion planning from the initial and the desired configurations provide an exact solution of the positioning trajectory. The active and passive joints can be positioned to the desired angles simultaneously by swinging the active joints only twice. Feedback control constrains the manipulator along the planned path in the configuration space. Simulation and experimental results show the validity of the proposed methods. © 1998 John Wiley & Sons, Inc.     

Robust robot manipulator control with autonomous consideration algorithm of torque saturation

As each joint actuator of a robot manipulator has a limit value of torque, the motion control system should consider the torque saturation. Conventional motion control based on robust acceleration controller cannot consider the torque saturation and it often causes an oscillated or wrong response. This paper proposes a new autonomous consideration method of joint torque saturation for robust manipulator motion control. The proposed method consists of three on-line autonomous algorithms. These algorithms are the torque limitation algorithm in joint space, the adjustment algorithm of motion control in Cartesian space, and the adjustment algorithm of motion reference in Cartesian space. The robot motion control using the proposed algorithms realizes smooth and robust robot motion response.     

基于轨迹规划的平面三连杆欠驱动机械臂位置控制

针对中间关节为欠驱动的二阶非完整平面三连杆机械臂,提出一种基于轨迹规划的末端点位置控制策略.首先,建立系统的动力学模型,并根据几何关系利用差分进化算法求取所有连杆与目标位置相对应的目标角度;然后,根据驱动关节与欠驱动关节的耦合关系,采用时间缩放法和双向法分别规划两根驱动连杆的两条轨迹,并利用遗传算法优化合适的第1连杆中间位置,将两条轨迹拼接成一条完整可达轨迹;最后,设计滑模变结构控制器以跟踪完整可达轨迹,实现系统从初始位置到目标位置的控制目标.数值仿真结果表明了所提出控制策略的有效性.     

基于免疫优化的平面Acrobot线性自抗扰鲁棒镇定

针对受不确定性影响的平面Acrobot机器人,提出一种基于免疫优化的线性自抗扰鲁棒控制设计方法,实现机器人末端点从任意初始位置到达并镇定在目标位置.首先,借助驱动关节与被动关节角度之间的状态约束获取机器人末端点位置与驱动关节角度的对应关系,使末端点的位置控制转换为驱动关节的角度控制;其次,为缩短运动路径加入最小角度位移限制条件,设计免疫算法求解目标位置所对应的驱动关节角度的最小期望值;再次,引入线性自抗扰控制技术,把机器人的模型不确定性、未知干扰等因素视为一个新的扩张状态变量,设计线性扩张状态观测器和基于状态误差的反馈控制器,在仅驱动关节角度可测的情况下实现Acrobot的鲁棒镇定;最后,通过仿真实验验证所提出方法具有更好的鲁棒控制性能.     

Differentially Flat Designs of Underactuated Open-Chain Planar Robots

A fully actuated system can execute any joint trajectory. However, if the system is underactuated, not all joint trajectories are attainable. For such systems, it is difficult to characterize attainable joint trajectories analytically. Numerical methods are generally used to characterize these. This paper investigates the property of differential flatness for underactuated planar open-chain robots and studies dependence on inertia distribution within the system. It is shown that certain choices of inertia distributions make an underactuated open-chain planar robot with revolute joints feedback linearizable, i.e., also differentially flat. Once this property is established, trajectory between any two points in the state space can be planned, and a controller can be developed to correct for errors. To demonstrate the proposed methodology in hardware, experiments with an underactuated 3-DOF planar robot are also presented.