力觉临场感遥操作机器人系统的预测无源控制

针对力觉临场感遥操作机器人系统传输通道中存在大的通信时延，造成系统不稳定和操作性能降低，利用前向神经网络建立从机械手和环境的模型。通过神经网络模型预测从机械手受力，并结合无源控制算法进行控制切换，消除或减少通信时延对系统的影响。文中的实验结果表明了该方法的有效性。     

具有H_∞性能的机械手神经自适应跟踪控制

针对非线性不确定机械手系统的轨迹跟踪控制问题,提出一种具有H∞性能的神经自适应控制算法;该算法为机械手系统分别设计了主控制器和监督控制器;主控制器由神经网络控制为基础,基于滑模控制原理得到神经网络权值的自适应律;基于李亚普诺夫稳定性理论和鲁棒控制设计的监督控制器,补偿自适应神经网络对系统不确定项学习的误差,同时使系统具有H∞性能;通过二自由度机械手模型进行仿真实验,仿真结果验证了方法的有效性。     

基于RBF神经网络逆系统的机械手解耦控制策略

针对机械手系统具有非线性时变、多变量、强耦合的特点,提出一种基于RBF神经网络逆系统的机械手解耦控制策略。首先证明了系统的可逆性,进一步通过神经网络在线逆辨识建立机械手的神经网络逆系统模型,并将辨识得到的逆模型作为控制器模型与机械手系统串联,构成伪线性复合系统,实现了将具有强耦合特性的多变量输入/输出机械手系统解耦成单个独立的伪线性对象。最后以两关节机械手为仿真对象进行了仿真,仿真结果验证了本方案的有效性和可行性。     

基于快速学习型神经网络的机器人运动学模型辨识及运动控制

该文提出一种快速学习型神经网络，它不仅符合生物神经网络的基本特征，而且算法简单，学习收敛速度快，有线性，非线性系统辨识精度高优异特点。因此，此类神经网络非常适合于机器人运动学模型辨识及运动控制，仿真结果表明，基于快速学习型神经网络进行机械手运动学模型辨识有运动控制是合适的。     

考虑驱动系统动态的机械手神经网络控制及应用

针对结构和参数均未知的机械手控制问题, 提出了考虑驱动系统动态的机械手神经网络控制方法, 采用稳定的径向基(Radial basis function, RBF)神经网络辨识机械手未知动态, 而附加的鲁棒控制可以保证存在神经网络的建模误差和外部干扰时系统的稳定性和性能, 并且该方法使机械手闭环系统一致最终有界. 同时开发了基于半实物仿真技术的机械手控制系统, 最后, 将本文方法与经典的PD控制器和自适应控制器在同一机械手平台上进行了实验验证与分析, 实验结果表明该方法具有良好的控制性能.     

带有力觉和触觉临场感的灵巧手主从系统的设计

针对遥控作业中控制者操作时缺乏力觉和触觉临场感等问题，介绍了设计的带有力觉和触觉临场感主、从灵巧手系统，讨论了在从机械手上触觉和力觉的感知以及在主机械手上触觉和力觉的再现等问题，提出了利用模糊控制实现触觉再现以及改进的力反馈－位置型结构来实现力觉再现的新方法，最后进行了实验验证．     

基于神经网络的内模控制在机械手控制中的研究

采用内模控制与神经网络相结合的方法来解决机械手的控制问题,使机械手沿着一定的期望轨迹运行。神经网络对机械手建模,使其作为内模控制中的模型,训练方法采用前馈网络的BP学习算法。单个神经元使用静态模型,输入神经元之间的延迟引入系统的动态。仿真结果表明,该方法具有有效性和实用性。     

机器人的柔性关节机械手控制研究

研究柔性关节机械手的自适应控制策略,当机械手系统参数准确已知时,传统的反演控制算法可以根据状态反馈对柔性关节机械手进行控制.但是机械于模型参数存在误差时,传统的控制方法需要关爷加速度反馈,这将对柔性关节机械手的控制信号将引入噪声,能够破坏系统的动态品质.为解决上述问题,在反演控制算法的基础上引入鲁棒性,提出了鲁棒自适应反演控制算法.在已知模型误差界的条件下,通过神经网络对误差在线自学习,实现了无需模型的柔性关节自适应控制.与传统算法相比,新方法对未知扰动等模型具有鲁棒性及全局稳定性,同时不需要关节加速度信息反馈.     

基于RTW的空间机器人遥操作实时仿真系统

搭建了一套实时仿真系统以作为空间机器人遥操作的研究平台.系统以两台PC机分别模拟主从端的运行情况,主端PC连接通用力反馈游戏手柄作为主手输入设备,从端PC挂接嵌入式处理器(PC/104)用作空间机械手的实时仿真;主从端信号传输时延根据TCP/IP协议由软件模拟产生.利用Madab中的RTW/xPC Target工具箱将空间机械手模型编译为实时可执行代码,下载到嵌入式处理器(PC/104)实时执行,保证了手柄输入和空间机械手Simulink模型间的时钟同步.结合给定模型数据,完成了空问机械手实时位置跟踪实验,证明了系统搭建方案的可行性.系统对空间机器人遥操作的研究起到了很好的支撑作用.     

基于Internet的遥操作系统带观测器的反馈控制

通常遥操作系统主、从机械手间存在通信时延,影响了系统的稳定性和操作性能.在基于Internet的遥操作系统中,时延是时变的,对系统的影响尤为剧烈.为了解决这个问题,在环境模型未知的条件下,首先提出在本地控制端用主手状态、预测的从手状态及接触力设计反馈控制器;接着用时间前向观测器预测从机械手的状态,并将时延变化率建模为系统不确定参数,最终得到稳定性和透明性条件.仿真结果表明了该方法的有效性.     

Adaptive passive control with varying time delay

This paper presents a passive control scheme for a force reflecting bilateral teleoperation system with a varying time communication delay. To improve the stability and performance of the system, the master and slave must be coupled dynamically via a transmission network through which the force and velocity are communicated bilaterally. However, the time delay caused by various factors, such as the transmission distance, network congestion, and communication bandwidth, is a long-standing impediment to bilateral control that can destabilize the system. In this study, we investigated how a varying time delay affects the stability of a teleoperation system. A new optimal adaptive approach based on a passive control scheme was designed bilaterally for both the master and slave sites. Extra variables were transmitted together with the wave variables in the scattering system. The proposed scheme achieved both passive control, and an acceptable tracking performance. The tracking performance was demonstrated using a computer simulation of varying time delays in a bilateral teleoperation system.     

Bilateral Teleoperation of Multiple Agents with Formation Control

This paper studies the formation problem for multislave teleoperation system over general communication networks, where multiple mobile slave agents are coupled with a single master robot. The forward and backward network transmission time delays are assumed to be asymmetric and time-varying. Due to the quantization in the network, a dynamic quantization strategy is provided to quantize the output signals of the master robot and slave agents before transmitting. Then, a novel masterslave protocol is designed to achieve the formation task under variable time delays and quantization. Additionally, the sufficient conditions for stability are presented to show that the formation protocol can stabilize the master-slave system under variable time delays and quantization. Finally, simulation are performed to show effectiveness of the main results.      

Experimental comparison of backdrivability for time-delayed telerobotics

After stability, transparency is the major goal in teleoperation system design. This transparency goal of the overall system depends on the master/slave manipulator backdrivability. However, time delay in communication channel severely affects the backdrivability of a bilateral teleoperation system in practice. This study investigates the effects of communication delays on the backdrivability of a teleoperation system for wave-variable-based control techniques. The controllers are compared on position and force tracking performance using two identical linear robots coupled via network model that allowed random transmission round-trip delays. Overall, the comparison study reports a deteriorating effect in the system backdrivable performance (i.e., larger position errors and lower fidelity of contact information) from delays. In addition, wave-variable-based controller with position compensation is shown to make better system backdrivability.     

High-fidelity bilateral teleoperation systems and the effect of multimodal haptics.

In master-slave teleoperation applications that deal with a delicate and sensitive environment, it is important to provide haptic feedback of slave/environment interactions to the user's hand as it improves task performance and teleoperation transparency (fidelity), which is the extent of telepresence of the remote environment available to the user through the master-slave system. For haptic teleoperation, in addition to a haptics-capable master interface, often one or more force sensors are also used, which warrant new bilateral control architectures while increasing the cost and the complexity of the teleoperation system. In this paper, we investigate the added benefits of using force sensors that measure hand/master and slave/environment interactions and of utilizing local feedback loops on the teleoperation transparency. We compare the two-channel and the four-channel bilateral control systems in terms of stability and transparency, and study the stability and performance robustness of the four-channel method against nonidealities that arise during bilateral control implementation, which include master-slave communication latency and changes in the environment dynamics. The next issue addressed in the paper deals with the case where the master interface is not haptics capable, but the slave is equipped with a force sensor. In the context of robotics-assisted soft-tissue surgical applications, we explore through human factors experiments whether slave/environment force measurements can be of any help with regard to improving task performance. The last problem we study is whether slave/environment force information, with and without haptic capability in the master interface, can help improve outcomes under degraded visual conditions.     

A Composite State Convergence Scheme for Bilateral Teleoperation Systems

State convergence is a novel control algorithm for bilateral teleoperation of robotic systems. First, it models the teleoperation system on state space and considers all the possible interactions between the master and slave systems. Second, it presents an elegant design procedure which requires a set of equations to be solved in order to compute the control gains of the bilateral loop. These design conditions are obtained by turning the master-slave error into an autonomous system and imposing the desired dynamic behavior of the teleoperation system. Resultantly, the convergence of master and slave states is achieved in a well-defined manner. The present study aims at achieving a similar convergence behavior offered by state convergence controller while reducing the number of variables sent across the communication channel. The proposal suggests transmitting composite master and slave variables instead of full master and slave states while keeping the operator’s force channel intact. We show that, with these composite and force variables; it is indeed possible to achieve the convergence of states in a desired way by strictly following the method of state convergence. The proposal leads to a reduced complexity state convergence algorithm which is termed as composite state convergence controller. In order to validate the proposed scheme in the absence and presence of communication time delays, MATLAB simulations and semi-real time experiments are performed on a single degree-of-freedom teleoperation system.      

An overlapping communication protocol using improved time-slot leasing for Bluetooth WPANs

In this paper, we propose an overlapping communication protocol using improved time-slot leasing in the Bluetooth WPANS. One or many slave–master–slave communications usually exist in a piconet of the Bluetooth network. A fatal communication bottleneck is incurred in the master node if many slave–master–slave communications are required at the same time. To alleviate the problem, an overlapping communication scheme is presented to allow slave node directly and simultaneously communicates with another slave node to replace with the original slave–master–slave communication works in a piconet. This overlapping communication scheme is based on the improved time-slot leasing (TSL) scheme which modified from the original TSL, while the original TSL scheme only provides the slave-to-slave communication capability. The key contribution of our improved TSL scheme is to offer the overlapping communication capability. With the overlapping communication scheme, we developed an overlapping communication protocol in a Bluetooth WPANs. Finally, simulation results demonstrate that our developed communication protocol achieves the performance improvements on bandwidth utilization, transmission delay time, network congestion, and energy consumption.     

Teleoperation Control of a Position‐Based Impedance Force Controlled Mobile Robot by Neural Network Learning: Experimental Studies

Effective haptic performance in teleoperation control systems can be achieved by solving two major problems: the time‐delay in communication channels and the transparency of force control. The time‐delay in communication channels causes poor performance and even instability in a system. The transparency of force feedback is important for an operator to improve the performance of a given task. This article suggests a possible solution for these two problems through the implementation of a teleoperation control system between the master haptic device and the slave mobile robot. Regulation of the contact force in the slave mobile robot is achieved by introducing a position‐based impedance force control scheme in the slave robot. The time‐delay problem is addressed by forming a Smith predictor configuration in the teleoperation control environment. The configuration of the Smith predictor structure takes the time‐delay term out of the characteristic equation in order to make the system stable when the system model is given a priori. Since the Smith predictor is formulated from exact linear modeling, a neural network is employed to identify and model the slave robot system as a nonlinear model estimator. Simulation studies of several control schemes are performed. Experimental studies are conducted to verify the performance of the proposed control scheme by regulating the contact force of a mobile robot through the master haptic device.     

Integrated adaptive robust control for multilateral teleoperation systems under arbitrary time delays

With the increasing industrial requirements such as bigger size object, stable operation, and complex task, multilateral teleoperation systems extended from traditional bilateral teleoperation are widely developed. In this paper, the integrated control design is developed for multilateral teleoperation systems, where n master manipulators are operated by human to remotely control n slave manipulators cooperatively handling a target object. For the first time, the control objectives of multilateral teleoperation including stability, synchronization, transparency, and internal force distribution are clarified systematically. A novel communication architecture is proposed to cope with communication delays, where the estimated environmental parameters are transmitted from the slave side to the master, to replace the traditional environmental force measurement in the communication channel. A kind of nonlinear adaptive robust control technique is used to deal with nonlinearities, unknown parameters, and modeling uncertainties existing in the master, slave, and environmental dynamics, so that the excellent tracking performance is achieved in both master and slave sides. The coordinated motion/force control is designed in the slave side by the optimal internal force distribution among n slave manipulators, and the impedance control is designed in the master side to realize the target transparency behavior. In summary, the proposed control algorithm can achieve the guaranteed robust stability, the excellent synchronization and transparency performance, and the optimal internal force distribution simultaneously for multilateral teleoperation systems under arbitrary time delays and various modeling uncertainties. The simulation is carried out on a 2‐master/2‐slave teleoperation system, and the results show the effectiveness of the proposed control design. Copyright © 2015 John Wiley & Sons, Ltd.     

遥操作旋转运动梁系统多目标优化控制研究

本文以旋转运动柔性梁为对象,采用基于胞映射的多目标优化方法进行遥操作系统双边控制研究.首先建立遥操作旋转运动柔性梁系统动力学方程,其次考虑信号传输时滞和系统主从端跟踪误差信号设计主端控制器和从端控制器,并利用Lyapunov稳定性理论获得保证闭环控制系统稳定的控制增益所需要满足的条件.由于满足稳定性条件并不意味着好的控制性能,最后利用基于胞映射的多目标优化方法进行优化控制设计,得到同时满足多个不同目标的控制增益的Pareto最优解集.仿真结果表明所获得的控制增益能够有效实现遥操作系统主从端的信号跟踪,并且操作者能够及时感受到从端环境的变化.     

Control gain adaptation in virtual reality mediated human–telerobot interaction

The Internet connects millions of computers worldwide, and provides a new potential working environment for remote‐controlled telerobotic systems. The main limitation of using the Internet in this application is random delays between communicating nodes, which can cause disturbances in human–machine interaction and affect telepresence experiences. This is particularly important in systems integrating virtual reality technology to present interfaces. Telepresence, or the sense of presence in a remote environment, hypothetically is positively related to teleoperation task performance. This research evaluated the effect of constant and random network (communication) delays on remote‐controlled telerover performance, operator workload, and telepresence experiences. The research also assessed the effect of using a system gain adaptation algorithm to offset the negative impact of communication delays on the various response measures. It was expected that with gain adaptation, system stability, performance, and user telepresence experiences would improve with a corresponding decrease in workload. Results indicated that gain adaptation had a significant effect on the performance measures. The study demonstrated that gain adaptation could reduce deterioration in telepresence experiences and improve user performance in teleoperated and telerobotic control. © 2005 Wiley Periodicals, Inc. Hum Factors Man 15: 259–274, 2005.