预估控制下的实时网络遥操作移动机器人

构建了能使操作者通过Internet远程实时控制的移动机器人系统．为了补偿网络时延和抵消其对遥操作系统的影响，基于我们以前提出的改进型Smith预估器原理，采用了预估控制策略．为了保证系统稳定性和透明性，基于主从端的传感器信息交换，设计了一个动态模型管理器，其中模型和力反馈误差调节通过模糊控制实现．除了力反馈外，为了增强遥操作的实时性，引入了预估的虚拟显示．为了精确地预测网络时延，提出了一个新颖的时钟同步算法．为了降低时延抖动，结合我们提出的两个算法，实现了数据缓冲策略．最后，通过长距离的网络遥操作实验验证了系统和控制策略的实用性和有效性．     

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 haptic interface for computer-integrated endoscopic surgery and training

Haptic feedback has the potential to provide superior performance in computer-integrated surgery and training. This paper discusses the design of a user interface that is capable of providing force feedback in all the degrees of freedom (DOFs) available during endoscopic surgery. Using the Jacobian matrix of the haptic interface and its singular values, methods are proposed for analysis and optimization of the interface performance with regard to the accuracy of force feedback, the range of applicable forces, and the accuracy of control. The haptic user interface is used with a sensorized slave robot to form a master–slave test-bed for studying haptic interaction in a minimally invasive environment. Using the master–slave test-bed, teleoperation experiments involving a single degree of freedom surgical task (palpation) are conducted. Different bilateral control methods are compared based on the transparency of the master–slave system in terms of transmitting the critical task-related information to the user in the context of soft-tissue surgical applications.     

空间遥操作机器人主从双边自适应内模控制

天地大时延严重破坏具有力反馈的空间遥操作机器人系统的稳定性和透明性;针对天地大时延和未知的从手操作环境,基于内模控制和自适应控制思想设计一种自适应内模控制器;推导从手环境参数辨识模型,基于带遗忘因子的递推最小二乘滤波辨识环境模型,并利用辨识信息构建自适应内模控制器;基于单参数SNPIDC算法分别设计主手和从手自适应控制器;大量的仿真结果证明,在设计的主从双边自适应内模控制器作用下,空间遥操作机器人系统稳定性好,对未知环境适应能力强,系统透明性好,阻抗匹配程度高,且操作人员临场感强。     

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.     

面向双操作者的六足机器人共享遥操作

随着六足机器人遥操作系统研究工作的日趋深入,针对其操控系统的开发也将面临诸多挑战.为了实现双人操控条件下各操作者的控制权重实时分配,设计一种基于透明性及控制状态(TCS)的六足机器人双用户控制权重分配方法.其双主端与单从端采取位置-速度的交互模式,通过分析系统实时透明性与当前控制状态,构建三边遥操作控制律,实时计算共享因子,采用速度跟踪模式设计基于触觉力反馈的系统控制架构,并利用三端口绝对稳定定理确定控制律参数的稳定范围.最后,搭建半物理仿真实验平台并验证所设计的三边共享遥操作方法能够在兼顾系统安全性与透明性的同时以较高的效率与安全性实现六足机器人的双用户操控,并能充分考虑双用户的控制意图.     

PD-like controller for delayed bilateral teleoperation of wheeled robots

This paper proposes a proportional derivative (PD)-like controller applied to the delayed bilateral teleoperation of wheeled robots with force feedback in face of asymmetric and varying-time delays. In contrast to bilateral teleoperation of manipulator robots, in these systems, there is a mismatch between the models of the master and slave (mobile robot), problem that is approached in this work, where the system stability is analysed. From this study, it is possible to infer the control parameters, depending on the time delay, necessary to assure stability. Finally, the performance of the delayed teleoperation system is evaluated through tests where a human operator drives a 3D simulator as well as a mobile robot for pushing objects.     

Semi-Autonomous Bilateral Teleoperation of Hexapod Robot Based on Haptic Force Feedback

With the widespread use of multi-legged robots in various applications, new challenges have arisen in terms of designing their control systems, one of which is posed by the multiple degrees of freedom of the robotic legs. This paper proposes a novel method for the bilateral teleoperation control of a hexapod robot by using a semi-autonomous strategy. In this teleoperation system, the body velocities of the slave robot and the displacements of the master robot are mapped to each other. The angular velocities of the joints of the legs rely on independent planning to achieve a horizontal movement. A controller is designed based on the difference between the expected velocity and the actual velocity of the body, and the difference is fed back to the operator in the form of haptic force. Therefore, the transparency of the control system is guaranteed by increasing the damping compensation both in the master and slave robots. In addition, the stability of the bilateral teleoperation control system of the hexapod robot is guaranteed by passivity theory, and the proposed method is verified by conducting semi-physical simulation experiments.     

A novel adaptive robust control architecture for bilateral teleoperation systems under time‐varying delays

Bilateral teleoperation technology has caused wide attentions due to its applications in various remote operation systems. The communication delay becomes one of the main challenging issues in the teleoperation control design. Meanwhile, various nonlinearities, parameter variations, and modeling uncertainties existing in manipulator and environment dynamics need to be considered carefully in order to achieve good control performance. In this paper, a globally stable nonlinear adaptive robust control algorithm is developed for bilateral teleoperation systems to deal with these control issues. Namely, the unknown dynamical parameters of the environmental force are estimated online by the improved least square adaptation law. A novel communication structure is proposed where only the master position signal is transmitted to the slave side for the tracking design, and the online estimators of the environmental parameters are transmitted from the slave to the master to replace the traditional environmental force measurement. Because the estimated environmental parameters are not power signals, the passivity problem of the communication channel and the trade‐off limitation between the transparency performance and robust stability in traditional teleoperation control are essentially avoided. The nonlinear adaptive robust control is subsequently developed to deal with nonlinearities, unknown parameters, and modeling uncertainties of the master, slave, and environmental dynamics, so that the guaranteed transient and steady‐state transparency performance can be achieved. The experiments on two voice‐coil motor‐driven manipulators are carried out, and the comparative results verify that the proposed control algorithm achieves the excellent control performance and the guaranteed robust stability simultaneously under time delays. Copyright © 2014 John Wiley & Sons, Ltd.     

遥操作系统基于观测器的预测控制

在遥操作系统中需要主、从机械手间进行通信,但通信通道中存在较大的通讯时延,这会降低系统操作性能,甚至会使系统不稳定.为了解决这个问题,首先建立系统的状态空间模型,接着提出用时间前向观测器预测从机械手状态,并结合力、位置和速度反馈消除或减小时延对系统影响.系统反馈参数可方便地通过线性矩阵不等式求解.该方法能使系统渐近稳定而且具有良好的透明性.仿真结果表明该方法是有效的.     

Explicit time‐delay compensation in teleoperation: An adaptive control approach

This paper proposes a control framework that addresses the destabilizing effect of communication time delays and system uncertainties in telerobotics, in the presence of force feedback. Force feedback is necessary to obtain transparency, which is providing the human operator as close a feel as possible of the environment where the slave robot is operating. Achieving stability and providing transparency are conflicting goals. This is the major reason why, currently, a very few, if at all, fully operational force feedback teleoperation devices exist except for research environments. The proposed framework handles system uncertainty with adaptation and communication time delays with explicit delay compensation. The technology that allows this explicit adaptive time‐delay compensation is inspired by Massachusetts Institute of Technology (MIT)'s Adaptive Posicast Controller. We provide simulation results that demonstrate stable explicit adaptive delay compensation in a force‐reflecting teleoperation set up. Copyright © 2016 John Wiley & Sons, Ltd.     

基于手眼双模态人机接口的移动机器人编队共享控制

传统的基于手控器单模态人机接口的移动机器人编队控制系统在进行队形变换和局部避障等复杂运动控制时效果较差。本文针对此问题提出了一种基于力反馈手控器和眼动仪双模态人机接口的编队共享控制方法。首先,将操作员的手部输入信号和视线跟踪信号分别映射为编队行进和队形切换命令。然后,设计一个由主端遥操作控制器和从端自主控制器组成的共享控制框架。主端遥操作控制器负责接收分发操作员的控制命令并接管编队行进运动控制和队形切换控制,从端自主控制器负责根据系统状态自主完成队形保持、外部避障和内部避碰等任务。最后,通过避障实验、队形切换实验和单双模态对比实验来证明该控制方法的有效性。实验结果表明,相对于传统的单模态双边遥操作控制,本文提出的控制方法降低了操作负荷,控制效率提升了17.42%。     

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.     

Bilateral teleoperation of a group of mobile robots for cooperative tasks

A visual and force feedback-based teleoperation scheme is proposed for cooperative tasks. The bilateral teleoperation system includes a haptic device, an overhead camera and a group of wheeled robots. The commands of formation and average velocities of the multiple robots are generated by the operator through the haptic device. The state of the multiple robots and the working environment is sent to the human operator. The received information contains the feedback force through the haptic device and visual information returned by a depth camera. The feedback force based on the difference between the desired and actual average velocities is presented. The wave variable method is employed in the bilateral teleoperation of multiple mobile robots with time delays. The effectiveness of the bilateral teleoperation system is demonstrated by experiments. The robots in the slave side are able to follow the commands from the master side to interact with the environments, including moving in different formations and pushing a box. The results show that the scheme enables the operator to manipulate a group of robots to complete cooperative tasks freely.     

Robust Output Feedback Controller Design for Time‐Delayed Teleoperation: Experimental Results

In this paper, a robust output feedback control strategy is proposed for a nonlinear teleoperation system which can deal with stability as well as transparency despite the variable time‐delay and uncertain dynamics. The proposed approach is composed of two steps. First, local Lyapunov based adaptive controllers are applied to both master and slave sides in order to suppress the nonlinearities in the system dynamics. Afterwards, a new observer‐based controller scheme is proposed to achieve stability and performance (transparency) of the teleoperation system. Using the Lyapunov techniques, stability and performance objectives are cast as some linear matrix inequality (LMI) feasibility conditions. To evaluate the performance of the proposed controller, a set of simulations and experiments are performed. Through simulation results, it is demonstrated that the proposed approach significantly outperforms the existing methodologies reported in the literature.     

A teleoperation system for micro positioning with haptic feedback

This paper presents the research work on a 1 Degree of Freedom (DOF) macro-micro teleoperation system which enables human operator to perform complex task in micro environment such as cell insertion with the capability of haptic feedback. To reach submicron resolution, a nano-motion piezo actuator was used as the slave robot and a servo DC motor was used as the master robot. Force sensors were implemented at both ends for haptic feedback and a microscope equipped with camera was employed for real-time visual feedback. The hysteresis nonlinearity of the piezo motor was modeled using LuGre friction model and compensated for. A Sliding Mode Based Impedance Controller (SMBIC) was designed at the slave side to ensure position tracking while an impedance force controller was designed at the master side to ascertain tracking of the force. Control parameters were chosen based on Llewellyn stability criteria such that the entire system stays stable against parameter uncertainties and constant time delay. The experimental results demonstrated capability of the proposed control frameworks in desirable tracking of the position and force signals while the entire system remained stable. The results of this study can be used for complex tasks in micron environment such as cell insertion.     

Scaled teleoperation system for nano-scale interaction and manipulation

In this paper, a visual and haptic human–machine interface is proposed for teleoperated nano-scale object interaction and manipulation. Design specifications for a bilateral scaled tele-operation system with slave and master robots, sensors, actuators and control are discussed. The Phantom? haptic device is utilized as the master manipulator, and a piezoresistive atomic force microscope probe is selected as the slave manipulator and as topography and force sensors. Using the teleoperation control system, initial experiments are realized for interacting with nano-scale surfaces. It is shown that fine structures can be felt on the operator's finger successfully, and improved nano-scale interaction and manipulation using visual and haptic feedback can be achieved.     

无源散射变换的双边移动机器人网络遥操作

网络遥操作系统的随机时延给控制器设计带来巨大挑战,严重时破坏系统的稳定性。首先对遥操作无源理论及其波变量控制方法做了简单综述,然后提出直接无源散射变换方法,它将无源双边控制方法推广到具有随机时延的网络遥操作系统中去,保证网络遥操作系统在任何不对称随机网络时延情况下稳定。最后基于此变换方法设计了一个虚拟主从手双边移动机器人网络遥操作方案,并进行了仿真验证,结果表明结出的设计方法能满足系统性能要求。     

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.     

Adaptive controller of a master–slave system for transparent teleoperation

This article presents an adaptive control scheme based on position-force architecture to achieve the stability and transparency for teleoperation in unknown or varying environments. Without any knowledge about the parameters of the slave robot and environment dynamics, the proposed scheme guarantees the robustness to the parameter uncertainties of the master robot as well as the stability of the whole teleoperation system. Numerical simulations are presented to demonstrate the transparency and robustness to the parameter uncertainties of the master robot. Experimental results to a master–slave system show the validity of the proposed scheme. © 1998 John Wiley & Sons, Inc.