遥操作机器人的新型力反馈算法*

在采用液压挖掘机改造的遥操作机器人双向伺服控制系统中,针对大臂和前臂两个自由度构建力反馈控制算法。以准确地获取从端机器人与环境的作用力,使反馈力能够更好地反映从端工作状况为目的,采用构建干扰力补偿项的方法消除干扰力对反馈力的影响;以机器人转角为输入,以空载时检测到的液压缸作用力为输出,通过径向基函数构建干扰力补偿项,此补偿项可对多种因机器人的机械本体动力学特性产生的干扰力之合力进行补偿。实验证明,在以液压机构为从手的双向力反馈系统中,通过构建干扰力补偿项的方法提高力反馈效果的方法是可行的,采用的带有干扰力     

侧向推搡下的四足机器人复合抗扰控制策略

针对四足机器人侧向推搡下的平衡恢复问题,提出了一种复合抗扰反应式鲁棒控制策略.该策略由摆动相的自适应侧摆规划策略和支撑相的关节抗扰控制构成.摆动相自适应侧摆规划策略通过四足机器人足端落地点的力平衡条件进行主动式步态规划以保证机器人在侧向推搡下的姿态稳定,并基于关节输出力矩给出了侧摆的启动条件.支撑相关节抗扰控制通过带扰动项的四足机器人完整动力学模型设计了基于干扰观测器的鲁棒滑模控制器,实现对侧向推搡扰动的补偿.最后,通过Matlab与ADAMS联合仿真验证了提出的控制策略的有效性.     

悬挂伸缩刀具的树障清理空中机器人飞行控制方法

针对输电线路附近的树障进行清理问题,本文提出了一种新型的悬挂伸缩刀具的树障清理空中机器人并进行了仿真和实物验证.首先,对悬挂伸缩刀具的空中机器人进行了伸缩刀具重心变化下的动力学、运动学建模及接触建模.其次,为避免空中机器人接触作业时机器人倾翻的问题,设计了力估计器用于力感知和导纳控制器用于力控制.针对空中机器人非线性强耦合、伸缩刀具时参数摄动及作业时扰动的问题,设计了线性自抗扰控制(LADRC)的机器人位姿控制器.再次,数值仿真验证了导纳控制能有效避免空中机器人接触作业时产生倾翻的问题,以及基于LADRC控制器的位姿控制具有良好的稳定性和抗扰性.最后,通过实物飞行和接触作业测试,进一步验证了本文悬挂伸缩刀具的树障清理空中机器人及其控制方法的有效性.     

A new adaptive learning rule

A method is presented for nonlinear function identification and application to learning control. The control objective is to identify and compensate for a nonlinear disturbance function. The nonlinear disturbance function is represented as an integral of a predefined kernel function multiplied by an unknown influence function. Sufficient conditions for the existence of such a representation are provided. Similarly, the nonlinear function estimate is generated by an integral of the predefined kernel multiplied by an influence function estimate. Using the time history of the plant, the learning rule indirectly estimates the unknown function by updating the influence function estimate. It is shown that the estimate function converges to the actual disturbance asymptotically. Consequently, the controller achieves the disturbance cancellation asymptotically. The method is extended to repetitive control applications. It is applied to the control of robot manipulators. Simulation and actual real-time implementation results using the Berkeley/NSK robot arm show that the proposed learning algorithm is more robust and converges at a faster rate than conventional repetitive controllers     

Robust Tracking Control for Self-balancing Mobile Robots Using Disturbance Observer

In this paper, a robust tracking control scheme based on nonlinear disturbance observer is developed for the self-balancing mobile robot with external unknown disturbances. A desired velocity control law is firstly designed using the Lyapunov analysis method and the arctan function. To improve the tracking control performance, a nonlinear disturbance observer is developed to estimate the unknown disturbance of the self-balancing mobile robot. Using the output of the designed disturbance observer, the robust tracking control scheme is presented employing the sliding mode method for the selfbalancing mobile robot. Numerical simulation results further demonstrate the effectiveness of the proposed robust tracking control scheme for the self-balancing mobile robot subject to external unknown disturbances.      

Cooperative localization and control of multiple heterogeneous robots using a string formation

This paper is on cooperative localization and control of multiple heterogeneous robots utilizing a string formation. This formation is preferred, since robots can move along a narrow passage utilizing this formation. Dead reckoning localization based on inertial measurement units leads to accumulated localization error. To avoid the error accumulation in dead reckoning localization, this paper introduces the last-move strategy for multiple heterogeneous robots. In the last-move strategy, a single robot is selected for maneuvering, and it turns on its bearing-range sensors for a short amount of time, in order to locate itself. While the selected robot moves, all other robots stop moving and perform as static landmarks for the moving robot. A robot may not maintain its desired course, in the case where environmental disturbance is severe. We thus develop a control strategy for avoiding obstacles while estimating the disturbance direction at a robot's location. To the best of our knowledge, this paper is novel in localization and control of a team of heterogeneous robots, considering the case where environmental disturbance is severe. The proposed localization process is energy-efficient, thus is suitable for practical applications. The performance of the proposed schemes is demonstrated utilizing MATLAB simulations.     

液压机器人的预测函数控制

针对液压机器人系统存在较大的不确定性及干扰 ,其特征参数将随工况的变化和外载及环境的影响产生大幅度变动的特点 ,提出一种预测函数控制 (PFC)和 PID相结合的新方法。该方法相当于一个 PFC- P控制结构 ,通过其本身内环来克服随机干扰 ,外环采用预测函数控制来获得优良的跟踪性能和鲁棒性 ,实现目标和控制的分层。仿真结果表明 ,该 PFC- P控制方法能兼顾跟踪性、鲁棒性和抗干扰性等性能指标 ,可获得满意的控制效果     

Stability analysis of robust adaptive hybrid position/force controller for robot manipulators using neural network with uncertainties

The aim of this paper is to design a robust adaptive neural network-based hybrid position/force control scheme for robot manipulators in the presence of model uncertainties and external disturbance. The feedforward neural network employed to learn a highly nonlinear function requires no preliminary learning. The control purposes are to achieve the stability in the sense of Lyapunov for desired interaction force between the end-effector and the environment and to regulate robot tip position in cartesian space. An adaptive compensator is also developed to eliminate the effect of disturbance term of neural network approximation error and external disturbance or unmodeled dynamics etc. A key feature of this compensator is that the prior information of the disturbance bound is not required. Finally, a comparative simulation study with a model-based robust control scheme for a two-link robot manipulator is presented.     

Reaction torque control of redundant free-floating space robot

This paper presents the reaction torque based satellite base reactionless control or base disturbance minimization of a redundant free-floating space robot. This subject is of vital importance in the study of the free-floating space robot because the base disturbance minimization will result in less energy consumption and prolonged control application. The analytical formulation of the reaction torque is derived in this article, and the reaction torque control can achieve reactionless control and satellite base disturbance minimization. Furthermore, we derive the reaction torque based control of the space robot for base disturbance minimization from both the non-strict task priority and strict task priority control strategy. The dynamics singularity in the proposed algorithm is avoided in this paper. Besides, a real time simulation system of the space robot under Linux/real time application interface (RTAI) is developed to verify and test the feasibility and reliability of the method. The experimental results demonstrate the feasibility of online reaction torque control of the redundant free-floating space robot.     

光伏阵列清洁机器人路径跟踪改进型自抗扰控制

针对光伏阵列清洁机器人清洁作业过程中存在路径跟踪精度低与外界不确定干扰等问题,提出了一种改进型自抗扰控制策略来控制驱动单元模型,实现驱动单元角速度（力矩）的高鲁棒性控制,从而提高了机器人的路径跟踪精度.通过分析机器人的运动状态,得到清洁机器人实际运动位姿与期望运动位姿之间的误差.由于外界环境以及其他不确定因素的干扰,通过建立清洁机器人移动底盘带不确定干扰因素的动力学控制模型,在传统自抗扰控制器的基础上通过改进fal函数,提出了一种运动学与动力学内外嵌套的改进型自抗扰策略.改进型扩张状态观测器来实时观测并补偿不确定干扰因素,从而实现清洁机器人高精度跟踪作业目标路径.通过多种目标路径的跟踪仿真实验,最终都表现出了较好的跟踪结果.证明了本文所设计的基于改进型自抗扰控制的光伏阵列清洁机器人路径跟踪控制算法的优越性与有效性,提高了光伏阵列清洁机器人的清洁作业路径跟踪精度.     

On the design of a disturbance observer for moving target tracking of an autonomous surveillance robot

This is a study of the design procedure establishment for an autonomous surveillance robot control system under continuous impulses. The purpose of the control system is to minimize vibration and misaiming when firing at a moving object from a gun installed on a surveillance robot. The surveillance robot was modeled using multi-body dynamic software (ADAMS and NASTRAN). In order to eliminate disturbances, the control system was designed by applying a disturbance observer. The designed control system effectively reduced 11Hz vibrations, and examined a control system required in high speed and high precision tracking. The simulation of the control algorithm used Matlab/Simulink. To examine whether the control results of the simulation and real control system program were the same, the inter-link of Matlab/Simulink and DSP is performed. Results of the disturbance observer function were satisfactory.     

一种新的双环结构机器人无标定自抗扰视觉伺服控制方法

在研究基于自抗扰控制器的机器人无标定视觉伺服方法的基础上，提出了一种新的双环结构机器人无标定自抗扰视觉伺服控制方法．内环采用Kalman滤波算法进行图像雅可比矩阵的在线辨识，可较好地逼近真实模型；外环采用自抗扰控制器，利用非线性观测器实时估计系统相对于当前估计模型的总扰动，并在控制中加以动态补偿．针对六自由度工业机器人进行了二维运动目标的跟踪实验，实验结果表明了该方法的可行性和有效性．     

基于动力学与控制统一模型的蛇形机器人速度跟踪控制方法研究

对带有被动轮的蛇形机器人进行速度跟踪控制时,利用传统的动力学建模方法得到的动力学方程复杂且不利于控制器的设计. 本文基于微分几何的方法将带有被动轮的蛇形机器人动力学投影到速度分布空间中, 得到了动力学与控制统一模型, 更有利于速度跟踪控制器的设计. 考虑到蛇形机器人在进行速度跟踪时容易出现奇异位形, 提出增加头部扰动速度的方法. 基于头部扰动速度和统一模型, 提出避免奇异位形的速度跟踪控制方法, 最后通过逆向动力学得到控制力矩. 文中对速度跟踪控制进行了数值仿真和实验验证. 仿真和实验结果表明, 提出的速度跟踪控制方法能够跟踪想要方向的速度, 并且在跟踪过程中可以有效地避免奇异位形.     

Lyapunov-Based Nonlinear Disturbance Observer for Serial n-Link Robot Manipulators

In this paper we extend the work done by Chen et al. (IEEE Trans Ind Electron 47(4):932–938, 2000) which proposed a nonlinear disturbance observer for two-link robot manipulators to n-link robot manipulators. A general form of dynamic equations of serial n-link robot manipulator is considered, and the stability analysis of the proposed observer is performed by using Lyapunov’s direct method. Although it seems that the formulation of disturbance observer is easy to derive, choosing the disturbance observer gain to guarantee stability is really hard. In this paper it is shown that the design parameter can be selected depends on the maximum velocity and physical parameters of robot manipulator to guarantee the global asymptotic stability of the disturbance observer. Using this nonlinear disturbance observer, no accurate dynamic model is required to achieve high precision motion control, because it makes the system robust against internal disturbances such as unmodeled dynamics and external disturbances such as friction in joints. The effectiveness of the proposed observer is investigated by numerical simulation for three-Dofs robot manipulator. In fact, controller with disturbance observer has more superior tracking performance, with a wide range of payloads and in the presence of friction in joints. It is also found that, although the proposed observer is designed for slow varying disturbances, it can estimate rapid time varying disturbances very well.     

立方体机器人自抗扰平衡控制方法

针对立方体机器人动力学模型多变量、强耦合的问题,提出一种基于自抗扰控制的平衡控制器设计方法.引入虚拟控制量,并在控制量与输出向量之间并行地嵌入多个自抗扰控制器,从而实现对多变量系统的解耦控制,将系统的动态耦合和外部扰动视为各自通道上的自抗扰控制器的总扰动,在为期望姿态安排过渡过程基础上,设计扩张状态观测器对总扰动进行估计并实时补偿.综合采用经验试凑法和带宽法对控制器参数进行整定,对自抗扰控制器系统进行稳定控制、姿态跟踪、抗扰性和鲁棒性实验,并与PID控制系统进行定量对比分析.仿真结果表明,所设计的自抗扰控制器不仅能有效实现立方体机器人的平衡控制,而且较PID控制器具有更好的响应速度、控制精度和强鲁棒性.     

时滞的非完整动力学系统滑模抗干扰跟踪控制

针对具有外部扰动和时滞的非完整轮式移动机器人系统,本文阐述了一种基于非线性扰动观测器的时滞滑模控制方法.首先,利用扰动观测器估计系统的外部扰动;然后,用极坐标转化移动机器人的姿态,并用计算转矩法对机器人的动力学方程进行反馈线性化.设计带时滞控制的滑模,目的是使移动机器人渐近稳定在期望轨迹上,并有效地减小控制增益的过高估计.最后,利用李雅普诺夫函数建立闭环系统的稳定性.仿真结果表明,该方案具有良好的跟踪精度和鲁棒性.     

Robust adaptive motion/force tracking control design for uncertain constrained robot manipulators

In the presence of uncertain constraint and robot model, an adaptive controller with robust motion/force tracking performance for constrained robot manipulators is proposed. First, robust motion and force tracking is considered, where a performance criterion containing disturbance and estimated parameter attenuations is presented. Then the proposed controller utilizes an adaptive scheme and an auxiliary control law to deal with the uncertain environmental constraint, disturbances, and robotic modeling uncertainties. After solving a simple linear matrix inequality for gain conditions, the effect from disturbance and estimated parameter errors to motion/force errors is attenuated to an arbitrary prescribed level. Moreover, if the disturbance and estimated parameter errors are square-integrable, then an asymptotic motion tracking is achieved while the force error is as small as the inversion of control gain. Finally, numerical simulation results for a constrained planar robot illustrate the expected performance.     

空间机器人分布式滑模变结构控制方法

针对空间机器人的动力学特性和星载控制系统的结构特点,分别基于干扰上确界和比例切换,设计了2种分布式滑模变结构控制方法,以实现在存在不确定干扰和关节摩擦力矩情况下基座姿态和关节运动的综合控制.首先给出了空间机器人的动力学模型和关节低速摩擦力矩模型,并以两自由度空间机器人为例,介绍了2种分布式滑模变结构控制方法的推导过程.通过仿真实验,对2种控制方法进行了对比,结果表明分布式变结构控制方法在简化算法的同时,能够保证系统控制性能,并对干扰和参数变化具有较强的鲁棒性.     

轮子打滑状态下全向移动机器人轨迹跟踪控制

针对全向移动机器人轨迹跟踪控制中存在未知轮子打滑干扰问题,设计自抗扰反步控制器.首先,建立存在轮子打滑扰动的全向移动机器人的运动学模型;然后,融合自抗扰控制技术与反步控制技术,设计基于全向移动机器人运动学模型的轨迹跟踪控制器,该控制器分别从纵向控制、横向控制及姿态控制上对打滑干扰进行实时估计与补偿;最后,利用Lyapunov定理分析闭环系统的稳定性并通过仿真实验验证了所提出控制算法的有效性和鲁棒性.     

一种新的机械手轨迹跟踪鲁棒控制

本文考虑存在外扰及参数不确定情况下机械手轨迹跟踪问题，通过利用机械手固有的结构特性，提出一种基于李雅普诺夫方法的新控制算法．该算法的新颖之处在于无需预先知道参数的不确定范围，并且减弱了对外扰的限制．该算法的渐近跟踪性已被证明．