Two-time scale control and observer design for trajectory tracking of two cooperating robot manipulators moving a flexible beam

In this paper, we present two-time scale control design for trajectory tracking of two cooperating planar rigid robots moving a flexible beam, which does not require vibration measurement for the beam. First, the kinematics and dynamics of the robots and the object are derived. Then, using the relations between different forces acting on the object by the manipulators’ end-effectors, dynamics equations of the robots and the object are combined. The resulting equations show that the coupled dynamics including beam vibration and the rigid motion take place in two different time domains. By applying two-time scale control theory on the combined dynamics, a composite control scheme is elaborated which makes the beam orientation and its center of mass position track a desired trajectory while suppressing the beam vibration. For the controller algorithm, first a slow controller is utilized for the slow (rigid) subsystem and then a fast stabilizing controller is considered for the fast (flexible) subsystem. To avoid requiring measurement of beam vibration for the fast control law, a linear observer is also designed. The simulation results show the efficiency of the proposed control scheme.     

Intelligent control of multi-fingered hands

This paper is concerned with intelligent control for grasping and manipulation of an object by multi-fingered robot hands with rigid or soft hemispheric finger ends that induce rolling contacts with the object. Even in the case of 2D motion like pinching by means of a pair of multi-degrees of freedom robot fingers, there arises an interesting family of Lagrange’s equations of motion with many geometric constraints, which are under-actuated, redundant, and non-holonomic in some sense. Regardless of underactuation of dynamics, it is possible to find a class of sensory feedback signals that realize secure grasp of an object together with control of object orientation. In regard to the secure grasping, a problem of force/torque closure for 2D objects in a dynamic sense plays a crucial role. It is shown that proposed sensory feedback signals satisfying the dynamic force/torque closure can be constructed without knowing object kinematic parameters and location of the mass center. To prove the convergence of motion of the overall fingers–object system under the circumstance of redundancy of joints, new concepts called “stability on a manifold” and “asymptotic stability on a manifold” are introduced. Based on the results found for intelligent control of robotic hands, the last two sections attempt to discuss why human multi-fingered hands can become so dexterous at grasping and object manipulation.     

基于积分流形的柔性机械手组合控制

为解决柔性机械手非最小相位的控制问题以及克服运动中的抖振,采用积分流形和奇异摄动理论,将柔性机械手系统分解为快慢两个子系统.对于慢变子系统,设计一种基于一阶鲁棒微分估计器的二阶滑模控制策略,使其轨迹跟踪期望值;对于快变子系统,采用频率成形滤波器设计动态补偿器来抑制弹性振动,并基于线性二次型最优控制方法给出相应的最优控制规律,使系统的输出快速趋于稳定.仿真结果表明了该控制策略的有效性.     

On the robust control of two manipulators holding a rigid object

In this paper, a control architecture is developed for the closed chain motion of two six-joint manipulators holding a rigid object in a three-dimensional workspace. Dynamic and kinematic constraints are combined with the equations of motion of the manipulators to obtain a dynamical model of the entire system in the joint space. Reduced-order dynamic equations are then developed with regard to the position and force control variables. Robust control laws are then determined such that the force and position control design is decoupled. The control laws that will be discussed are: a robust position tracking controller that yields an exponentially stable position tracking error result, and a robust force tracking controller that yields adjustable bounds on the force tracking error.     

RoboCup足球赛彩色视觉系统及其滤波算法

为了满足机器人足球赛对视觉识别子系统高精确度的要求 ,介绍了一种参加RoboCup小型组比赛的计算机视觉子系统和滤波算法。为了快速地识别场上信息,本文采用了一种基于HSI色彩空间利用阈值向量分割图象的方法,这种方法先用阈值法将HSI色彩空间分成若干个子集,通过象素点与子集的位 “与”运算确定象素点的颜色。由于噪声的影响,总伴随目标识别不出来的情况,本文基于航迹预测的原理,提出了一种快速的动态窗口图像滤波方法。实验结果表明该方法可以有效地提高视觉系统的识别精度。     

轻型无人机飞行控制系统适航安全性研究

随着技术的发展,起飞飞全重25公斤至150公斤的轻型无人机飞行空域可完全融入民航空域,本文试着从适航审定角度讨论其适航安全性。采用民机事故概率统计结果与适航安全水平对比方法,确定了该型无人机系统定量化的期望安全水平。然后以最关键的飞控分系统为对象,在某型无人机上进行了飞行控制功能危险分析和故障模式影响分析,获得飞控分系统安全关键清单。最后基于SAE ARP4754A和RPAS 1309,对飞控分系统部件的期望安全水平进行了定量化规定,和研制保证等级的分配。研究结果对全重25公斤至150公斤轻型无人机的适航审定管理实践有参考借鉴意义。     

高精度二极管粘片机控制系统的设计与实现

本文介绍了一种高精度二极管粘片机控制系统的设计方案,并具体阐述了其设计思想。在分析系统结构及工作原理的基础上,提出了视觉定位系统、上位控制系统、执行机构等各分系统的设计。研制的高精度二极管粘片机已应用于具体项目中,实验表明其具有结构合理、速度快、精度高、界面直观等优点。     

Two-time scale visual servoing of eye-in-hand flexible manipulators

Visual servoing of eye-in-hand flexible manipulators is addressed in this paper. Dynamic effects of both the rigid and the flexible motion of the manipulator are fully taken into account in a control solution where the two-time scale nature of the problem is exploited. The visual information is used in the "slow" subsystem for a task-space-oriented control law, where computationally expensive operations, such as inverse and time derivative of the Jacobian, are avoided. A constructive proof of stability of this control scheme, based on Lyapunov theory, is also presented. The effectiveness of the proposed controller is shown by means of a numerical simulation concerning a trajectory tracking problem. Some experimental results finally demonstrate the precision enhancement achieved by the proposed algorithm on a single-link flexible manipulator.     

足球机器人决策子系统设计与分析

足球机器人系统目前已成为人工智能应用技术研究的重要实验平台,系统的核心部分就是决策子系统。本文介绍了一种决策子系统的分层控制结构设计,它由协调层,运动规划层和基本动作层组成,这三层在逻辑上紧密联系又相对独立,使该决策子系统具有适应性强,扩展性好等特点。     

基于运动空间相关性和时间连续性的运动估算快速算法

运动估算是视频信号的帧间预测编码中的一个重要环节,其效率和精度直接影响到编码器的性能。由于全搜索算法搜索速度较低,而很少采用,故目前普遍采用三步法、交叉法等各种快速近似算法,但是这些算法匹配精度较低,而且某些情况下应用效果不好。为解决上述算法存在的问题,在对视频编码中运动物体的空间相关性和时间连续性进行分析的基础上,给出了一种利用运动物体的空间相关性和时间连续性来进行运动估算的快速算法。实验结果表明,该算法计算每个宏块运动矢量所需的平均搜索次数低于三步法,而匹配精度则非常接近于全搜索算法,并且采用该算法的编码器,其总的编码输出位数少于采用全搜索算法的编码器。     

Stability and control aspects of flexible link robot manipulators during constrained motion tasks

The effect of robotic manipulator structural compliance on system stability and trajectory tracking performance and the compensation of this structural compliance has been the subject of a number of publications for the case of robotic manipulator noncontact task execution. The subject of this article is the examination of dynamics and stability issues of a robotic manipulator modeled with link structural flexibility during execution of a task that requires the robot tip to contact fixed rigid objects in the work environment. The dynamic behavior of a general n degree of freedom flexible link manipulator is investigated with a previously proposed nonlinear computed torque constrained motion control applied, computed based on the rigid link equations of motion. Through the use of techniques from the theory of singular perturbations, the analysis of the system stability is investigated by examining the stability of the “slow” and “fast” subsystem dynamics. The conditions under which the fast subsystem dynamics exhibit a stable response are examined. It is shown that if certain conditions are satisfied a control based on only the rigid link equations of motion will lead to asymptotic trajectory tracking of the desired generalized position and force trajectories during constrained motion. Experiments reported here have been carried out to investigate the performance of the nonlinear computed torque control law during constrained motion of the manipulator. While based only on the rigid link equations of motion, experimental results confirm that high-frequency structural link modes, exhibited in the response of the robot, are asymptotically stable and do not destabilize the slow subsystem dynamics, leading to asymptotic trajectory tracking of the overall system. © 1992 John Wiley & Sons, Inc.     

基于神经滑模的柔性连杆机械手末端位置控制

：为了提高柔性机械手末端位置控制的鲁棒性和精度,提出了一种基于神经滑模的控制策略．首先采 用输入/输出线性化方法将动力学模型部分线性化,使之分成输入/输出子系统与内动态子系统．输入/输出子系统 采用神经滑模控制,内动态子系统采用状态反馈控制器镇定．随后,对控制系统内动态稳定性进行了分析,并在 两自由度柔性连杆机械手控制的仿真试验中得到了满意的结果．试验结果表明,在存在模型不确定性时,该控制 策略提高了控制系统的鲁棒性和控制精度．     

连续跟踪状态下基于可分性特征的目标优化分类

针对拥塞复杂监控场景中目标的准确分类问题,提出了一种连续跟踪状态下基于可分性特征的目标优化分类方法。首先对整个场景中所有目标提取简单的颜色、形状和位置特征建立初始目标匹配,利用目标的运动方向及速率预测下帧中优先搜索区域以提高目标匹配效率,减少运算量,并对未建立对应关系的遮挡目标采用外观特征模型进行再匹配。为了提高目标分类的准确率,系统利用连续跟踪状态下目标特征的不间断提取和匹配,根据匹配最大概率决定最优分类结果。通过多种场景的实验结果表明,该方法的分类准确度比未利用连续跟踪信息的方案获得了更好分类准确度,平均达到了97%,有效改善了复杂场景中目标分类精度。     

Performance analysis of opto-mechatronic image stabilization for a compact space camera

The paper presents new performance results for the enhanced concept of an opto-mechatronic camera stabilization assembly consisting of a high-speed onboard optical processor for real-time image motion measurement and a 2-axis piezo-drive assembly for high precision positioning of the focal plane assembly. The proposed visual servoing concept allows minimizing the size of the optics and the sensitivity to attitude disturbances. The image motion measurement is based on 2D spatial correlation of sequential images recorded from an in situ motion matrix sensor in the focal plane of the camera. The demanding computational requirements for the real-time 2D-correlation are covered by an embedded optical correlation processor (joint transform type). The paper presents briefly the system concept and fundamental working principles and it focuses on a detailed performance and error analysis of the image motion tracking subsystem. Simulation results of the end-to-end image motion compensation performance and first functional hardware-in-the-loop test results conclude the paper.     

基于力反馈的脊柱外科机器人系统的设计与实现

本文针对脊柱椎管狭窄症减压手术中椎管壁磨削不安全这一问题，介绍一种基于力反馈控制策略的脊柱外科机器人系统，包括监控磨削过程的检测子系统、完成磨削手术操作的运动驱动子系统和再现磨削信息状况的控制显示子系统。利用脊柱磨削手术过程中磨削力的变化特点，提出基于力反馈的脊柱外科机器人控制策略，辅助医生实现安全的脊柱手术操作。最后通过仿真实验和模拟骨实验，验证了此基于力反馈控制策略的脊柱外科机器人系统的可行性。     

移动机器人THMR-V遥控系统的设计与实现

介绍了基于视觉的移动机器人THMR-V遥控系统的设计及实施。重点介绍了指挥站测控与监控系统、方向盘力反馈技术、无缝隙切换技术,以及数据与图象无线通信系统。     

非线性仿射控制系统的高阶滑模控制

研究非线性仿射系统的高阶滑模控制问题.通过适当的输入及非线性状态变换将系 统分解为一个关于切换变量及其高阶导数的低阶线性子系统和一个关于滑模的低阶非线性子 系统,进而给出了其高阶滑模控制器的设计方法.最后,对两轮驱动的非完整移动机器人进行 了数值仿真,结果表明高阶滑模控制在抖振减弱方面确实具有一定的作用.     

An ultraprecision six-axis visual servo-control system

This paper presents the development of a novel active visual measurement technique, laterally sampled white-light interferometry (L-SWLI), which is capable of real-time visual tracking of six-degree-of-freedom (6-DOF) rigid body motion with near-nanometer precision. The visual tracking system is integrated with a 6-DOF motion stage to realize an ultraprecision six-axis visual servo-control system. Contrary to conventional interferometric techniques, L-SWLI obtains the complete pose of the target object from a single image frame, therefore allowing real-time tracking. Six-DOF motions are obtained from measuring the fringe pattern on multiple surfaces of the object or from a single surface with additional information gained from conventional image-processing techniques. The feasibility of the visually servoed motion scheme was demonstrated on a micro cantilever. The cantilever was maneuvered in a three-dimensional space with near-nanometer motion resolution in all three translational axes.     

弹性基和弹性关节空间机器人的自适应鲁棒抗扰控制及振动抑制

研究不确定弹性基和弹性关节空间机器人的抗扰运动控制及基座和关节弹性振动同步抑制问题.在对基座和关节弹性进行等效线性弹簧假设的基础上,建立了弹性基和弹性关节空间机器人的动力学方程,并推导了基于等效刚度思想的奇异摄动慢、快变子系统.对传统参数自适应控制律进行σ修正并与鲁棒抗扰控制相结合,对不确定参数和有界外部扰动影响下的慢变子系统提出了基座姿态和臂杆关节刚性运动轨迹跟踪的改进自适应鲁棒抗扰控制方案.使用高增益线性状态观测器对快变高阶量进行实时观测,针对快变子系统设计了基座和关节弹性振动同步抑制的改进最优控制方案.仿真示例分析,表明了所提混合控制方案在空间机器人抗扰运动控制及振动抑制上的有效性.     

Real-Time Iterative Compensation Framework for Precision Mechatronic Motion Control Systems

With regard to precision/ultra-precision motion systems, it is important to achieve excellent tracking performance for various trajectory tracking tasks even under uncertain external disturbances. In this paper, to overcome the limitation of robustness to trajectory variations and external disturbances in offline feedforward compensation strategies such as iterative learning control (ILC), a novel real-time iterative compensation (RIC) control framework is proposed for precision motion systems without changing the inner closed-loop controller. Specifically, the RIC method can be divided into two parts, i.e., accurate model prediction and real-time iterative compensation. An accurate prediction model considering lumped disturbances is firstly established to predict tracking errors at future sampling times. In light of predicted errors, a feedforward compensation term is developed to modify the following reference trajectory by real-time iterative calculation. Both the prediction and compensation processes are finished in a real-time motion control sampling period. The stability and convergence of the entire control system after real-time iterative compensation is analyzed for different conditions. Various simulation results consistently demonstrate that the proposed RIC framework possesses satisfactory dynamic regulation capability, which contributes to high tracking accuracy comparable to ILC or even better and strong robustness.