Robots in radioactive environments

With improving technology and the growing perception of the need to keep human workers away from high radiation areas, more competitive robotic systems are increasingly becoming available. This article describes our ten years of experience in developing telerobotic systems for maintenance operations in the Spanish nuclear industry. It also describes a teleoperation platform that can be used with standard robots or with specially designed service robots. The modular architecture of this teleoperation platform has allowed the reuse of software components designed for very different applications and drastically reduce development lead time.     

A novel approach for stability and transparency control of nonlinear bilateral teleoperation system with time delays

In this paper, a novel control approach is presented to improve the stability and transparency of the nonlinear bilateral teleoperation system with time delays, where a four-channel (4-CH) architecture using modified wave reflection reduction transformation is explored in order to guarantee the passivity of the communication channels in the nonlinear bilateral teleoperation system; a sliding-mode controller is proposed to compensate for the dynamic uncertainties and enhance the system synchronization performance in finite time. The system stability has been analyzed using Lyapunov functions. The proposed method is validated through experimental work based on a 3-DOF bilateral teleoperation platform in the presence of time delays. The experimental results clearly demonstrate that the proposed control algorithm has superiority on system transparency over other wave-based systems.     

Sliding-mode bilateral teleoperation control design for master–slave pneumatic servo systems

This paper presents a novel bilateral control design scheme for pneumatic master–slave teleoperation systems that are actuated by low-cost solenoid valves. The motivation for using pneumatic actuators in lieu of electrical actuators is that the former has higher force to mass ratio than the latter and is inert to magnetic fields, which is crucial in certain teleoperation applications such as MRI-guided, robot-assisted surgery. A sliding mode approach, called the three-mode control scheme, is incorporated into a two-channel bilateral teleoperation architecture, which can implement a position–position, force–force, or force–position scheme. An analysis of stability and transparency of the closed-loop teleoperation system is carried out. The proposed control design performance is experimentally verified on a single-degree-of-freedom pneumatic teleoperation system actuated by on/off valves. Experimental results show high accuracies in terms of position and force tracking under free-space motion and hard-contact motion in the teleoperation system. Another purpose of this paper is to demonstrate the possibility to improve the valve lifetime by increasing the number of control levels. To do this, a new control design, called the five-mode control scheme, is developed and compared with the three-mode scheme in time domain as well as in frequency domain.     

建立分布式多媒体系统的体系结构参考模型

分布式多媒体系统具有广阔的应用前景。但由于缺乏一致的体系结构，其研究和开发均受到了很大的限制。本文首先给出分布式多媒体系统的资源配置模型和一般功能需求，引入虚拟设备、虚拟连接、ＱｏＳ等概念，最后描述了我们所使用的分布式多媒体系统体系结构参考模型。该模型对理解分布式多媒体系统的特点和工作原理亦有相当帮助。     

电缆管道巡检机器人远程测控系统的研究与实现

采用图形化编程语言LabVIEW,通过构建多循环应用程序框架,开发了一种用于电缆管道巡检遥操作机器人的新型远程测控系统.该系统能够远程控制机器人在电缆管道内的运动并实时监测机器人沿管内行进时的位置和姿态,能通过机器人获取管内视频信息并进行Canny算子边缘处理以及对管内敷设电缆的温度监测.实际运行结果表明,该测控系统设计新颖、运行可靠、功能实用,对类似遥操作机器人的远程监测与控制系统开发有较好的参考作用.     

High-fidelity sliding mode control of a pneumatic haptic teleoperation system

For a pneumatic teleoperation system with on/off solenoid valves, sliding mode control laws for position and force ensuring low switching (open/close) activity of the valves are developed. Since each pneumatic actuator has two pneumatic chambers with a total of four on/off valves, 16 possible combinations (‘operating modes’) for the valves’ on/off positions exist, but only seven of which are both functional and unique. While previous work has focused on three-mode sliding-based position control of one pneumatic actuator, this paper develops the seven-mode sliding-based bilateral control of a teleoperation system comprising a pair of pneumatic actuators. The proposed bilateral sliding control schemes are experimentally validated on a pair of actuators utilizing position-position and force-position teleoperation architectures. The results demonstrate that leveraging the additional modes of operation leads to more efficient and smoother control of the pneumatic teleoperation system. It was found that viscous friction forces were crippling haptic feedback in the position-position architecture. Through the use of force sensors, the force-position architecture was able to compensate for the heavy viscous friction forces.     

Sharing control [multiple miniature robots]

Presents a framework for the operation and coordination of multiple miniature robots. Simple teleoperation can be useful in many situations, but the operator's attention must be completely dedicated to controlling the robot. This may be difficult when the task requires the use of multiple robots. This article introduces a layered system that has been developed to facilitate multimodal control. This system includes user interfaces (UI) for teleoperation clients and robust sensor interpretation algorithms for autonomous control clients. A distributed software control architecture dynamically coordinates hardware resources and shares them between the various clients, allowing for simultaneous control of multiple robots.     

4‐Channel Sliding Mode Control of Teleoperation Systems with Disturbances

Sliding mode control can effectively account for the disturbances of a system. Among the different teleoperation architectures, 4‐channel architecture is the most successful for fulfilling transparency. In this paper, two sliding mode controllers are designed for nonlinear master and slave with external disturbances and are incorporated into a 4‐channel structure to achieve transparency. To this end, each of the controllers consists of a sliding mode position feedback law, a force feedback law, and two supplementary terms regarding gravity and contact force compensation. Stability and transparency of the overall system is studied via a Lyapunov function analysis. Simulations compared with the conventional adaptive control on teleoperation systems demonstrate the effectiveness of the proposed scheme.     

Application of wave-variable control to bilateral teleoperation systems: A survey

Teleoperation systems allow an operator to perform complex tasks in a remote environment. Stability of a bilateral teleoperation system is quite sensitive to time delays. One of the methods to guarantee the stability of bilateral telerobotics in the presence of time delays is wave variable control. A review of various applications of wave variable methods in telerobotics has been conducted. An evaluation of different methods proposed to compensate for the intrinsic problems associated with wave variable methods, including position drift, wave reflection and time varying delay, has also been carried out. In addition, different techniques developed to enhance the performance of the wave-based systems are also identified and reviewed. The research gaps in this field are identified and future directions for further research are proposed.     

A novel adaptive bilateral control scheme using similar closed‐loop dynamic characteristics of master/slave manipulators

This article presents a novel adaptive bilateral control scheme for obtaining ideal responses for teleoperation systems with uncertainties. A condition that is equivalent to getting an ideal response in teleoperation has been found to be making the closed‐loop dynamics of master and slave manipulators a similar form. An adaptive approach is applied to achieve similarity for the uncertain master and slave manipulators. Using the similar closed‐loop dynamic characteristics of master/slave teleoperation systems, excellent position and force tracking performance has been obtained without estimating the impedance of human and environment. The validity of the theoretical results is verified by experiments. © 2001 John Wiley & Sons, Inc.     

不确定遥操作系统带干扰观测器的自适应控制

遥操作系统受到不同类型的不确定性因素影响, 这些不确定性会降低系统的透明性, 甚至会使得系统不稳定. 本文提出了一种带干扰观测器的自适应控制器(adaptive controller with disturbance observer, ACWDO) 用来处理遥操作系统中同时受到的外部干扰和内部动力学参数不确定性. 首先建立了受外部干扰的遥操作系统的非线性动力学模型; 然后分别对主机器人和从机器人设计非线性干扰观测器用来对外部干扰进行估计和补偿; 之后在干扰观测器基础之上分别对主机器人和从机器人设计自适应控制器用来处理内部不确定的动力学参数; 最后再将所设计的ACWDO融入到四通道遥操作系统结构中. 理论分析和仿真结果表明, 所设计的控制器可以取得良好的位置跟踪和力跟踪效果, 确保了遥操作系统的透明性.     

Absolute stability analysis of sampled-data scaled bilateral teleoperation systems

Stability of a bilateral teleoperation system may be jeopardized by controller discretization, which has been shown to involve energy leaks. This paper proposes a novel approach to analyzing the absolute stability of sampled-data bilateral teleoperation systems consisting of discrete-time controllers and continuous-time master, slave, operator, and environment. The proposed stability analysis permits scaling and delay in the master and the slave positions and forces. The absolute stability conditions reported here impose bounds on the gains of the discrete-time controller, the damping terms of the master and the slave, and the sampling time. A design-related application of these results is in proper selection of various control parameters and the sampling rate for stable teleoperation under discrete-time control. To explore the trade-off between the control gains and the sampling time, it is studied that how large sampling times, which require low control gains for maintaining stability, can lead to unacceptable teleoperation transparency and human task performance in a teleoperated switching task. This shows that the effect of sampling time must be taken into account because neglecting it (as in the absolute stability literature) undermines both stability and transparency of teleoperation. The resulting absolute stability condition has been verified via experiments with two Phantom Omni robots.     

A generic natural language interface for task planning — application to a mobile robot

This paper presents a generic natural language interface that can be applied to the teleoperation of different kinds of complex interactive systems. Through this interface the operators can ask for simple actions or more complex tasks to be executed by the system. Complex tasks will be decomposed into simpler actions generating a network of actions whose execution will result in the accomplishment of the required task. As a practical application, the system has been applied to the teleoperation of a real mobile robot, allowing the operator to move the robot in a partially structured environment through natural language sentences.     

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.     

Adaptive wavenet controller design for teleoperation systems with variable time delays using singular perturbation method

The main goal of controller design in teleoperation systems is to achieve stability and optimal operation in presence of factors such as time delays, system disturbances and modeling errors. This paper proposes a new method of controller design based on wavenet with singular perturbation method for the bilateral teleoperation of robots through the internet. The wavenet controller could overcome the variable time delay in teleoperation system. This new method introduces a reduced-order structure for control and stability of teleoperation systems. By using singular perturbation method, teleoperation system is decomposed into two fast and slow subsystems. This method is a step towards reduced-order modeling. In this method, we use a feedback linearization method in master subsystem and a wavenet controller for slave subsystem. In wavenet controller, we used a learning method so that the system was Lyapunov stable. As the stability of the model is highly dependent on the learning of the system, we use Lyapunov stability in this method. It has been tried to reduce the tracking error between the master and the slave subsystems. In this structure the position of master-slave are compared together and controlling signal is applied to the slave so that they can track each other in the least possible time. In all schemes the effectiveness of the system is shown through the simulations and they have been compared with each other.     

Applying telepresence and augmented reality to teleoperate field robots

In many real-world teleoperation applications like mining, advanced teleoperation techniques will be needed in the near future. Full telepresence provides the best possible resources for controlling a moving machine. Unfortunately, full telepresence is expensive to implement and may be technically motivated only when really needed.In this paper different complexity of telepresence systems are compared. All systems were installed on the same vehicle by using the same teleoperation system by configuring it differently. Different kinds of tasks like corridor driving, loading, etc. were performed with all systems by several users. The comparison was made by timing the executions, registering errors, and interviewing the operators.     

适用于空间机器人遥操作系统数据通信的纠错编码

本文首先介绍了一般机器人遥操作系统在通信中使用的差错控制技术,接着根据空间机器人遥操作系统中通信信道的特点,提出采用Reed-Solomon（RS）码作为空间机器人遥操作系统的遥测数据和遥控数据的纠错编码,用软件实现了基于有限域GF(2^8) 的通用编译码算法,最后分析了在空间遥操作原型系统中应用RS码后的误码性能。     

基于Internet多操作者多机器人的遥操作系统的研究

近年来基于Internet多操作者多机器人MOMR(Multi-Operator-Multi-Robot)协作成 为许多学者关注的对象．相对于单操作者单机器人SOSR(Single-Operator-Single-Robot )遥操作任务的单一性和局限性，MOMR在群体作业如：设备维护、建筑建造、外科手术等许 多场合具有明显的优势．对于危险或难以到达的环境，MOMR遥操作系统的控制成为一个主要 问题． 本文综述了基于Internet 的MOMR系统的结构、概念以及国内外的研究现状，并讨论了MOMR 系统存在的主要问题和各种协调(或协作)控制方法．     

Modeling and control of cooperative teleoperation systems

This paper presents a multilateral control architecture for teleoperation in multimaster/multislave environments. The proposed framework incorporates flow of position and force information between all master and slave robots, rather than merely between corresponding units. Within this architecture, cooperative performance measures are defined to enhance coordination among the operators and the robots for achieving the task objectives. A /spl mu/-synthesis-based methodology for cooperative teleoperation control is also introduced. This approach guarantees robust stability of cooperative teleoperation in the presence of dynamic interaction between slave robots, as well as unknown passive operators and environment dynamics. It also improves task coordination by optimizing relevant performance objectives. Experiments carried out with a two-master/two-slave single-axis system demonstrate the effectiveness of the proposed approach.