Master-slave Teleoperation System Research Articles

Robust Adaptive-Sliding-Mode Control for Teleoperation Systems with Time-Varying Delays and Uncertainties

Master–slave teleoperation systems with haptic feedback enable human operators to interact with objects or perform tasks in remote environments. This paper presents a sliding-mode control scheme tailored for bilateral teleoperation systems operating in the presence of unknown uncertainties and time-varying delays. To address unknown but bounded uncertainties, adaptive laws are derived alongside controller design. Additionally, a linear matrix inequality is solved to determine the allowable bound of delays. Stability of the closed-loop system is ensured through Lyapunov–Krasovskii functional analysis. Two-degree-of-freedom mechanisms are self-built as haptic devices. Free-motion and force-perception scenarios are examined, with experimental results validating and comparing performances. The proposed adaptive-sliding-control method increases the position performance from 58.48% to 82.55% and the force performance from 83.48% to 99.77%. The proposed control scheme demonstrates enhanced position tracking and force perception in bilateral teleoperation systems.

A master-slave teleoperation system control model based on model predictive control with fast dynamic response

A master-slave teleoperation system control model based on model predictive control with fast dynamic response

A master-slave teleoperation system control model based on model predictive control with fast dynamic response

Robot technology is advancing with constantly expanding applications. Teleoperation system demonstrates its potential to extend human capabilities in unstructured and hazardous environments as an important branch of robotics. However, there are still issues involving insufficient position tracking accuracy and dynamic response capabilities. This article proposes a master-slave teleoperation system control model based on model predictive control (MPC) with a real-time dynamic adaptive parameter adjustment algorithm. We establish a model based on the integral barrier Lyapunov function and construct a dynamic optimization model based on MPC. Then we carry out rolling optimization and feedback correction at each moment to feed the predicted values generated by MPC back to correct the actual tracking trajectories in real-time. Additionally, we utilize an adaptive neural network and robust term compensation to adjust dynamic parameters and eliminate the effects of time delays, external disturbances, and model uncertainties. Theoretical simulation experiments are conducted on the Simulink platform, analyzing position tracking error and dynamic response capabilities of the master-slave robot respectively to verify the proposed model. The results indicate a reduction in the position tracking errors of the master with 10% and slave with 11%, while also showing an improvement in their dynamic response capabilities. The speed error ranges of the master and slave are shortened with 6% and 7% respectively.

Bilateral coordination quantisation control for master-slave flexible manipulators based on PDE dynamic model

This paper investigates a tracking adaptive control issue of the master-slave flexible system with input signal quantisation. Considering the distributed parameter characteristics of the flexible manipulator, the master-slave teleoperation system is a dynamic model described by partial differential equations. In this work, an adaptive boundary bilateral coordination quantisation control scheme is developed such that input signal quantisation can be achieved by applying random quantiser. Based on such control strategy, all signals of the closed-loop system are bounded and Lyapunov method is used to prove uniform ultimate boundedness of the control system. The proposed control law can not only effectively eliminate the deflection of the flexible link but also realise angle coordination. The numerical simulation results are provided for illustrating the control effectiveness.

画像情報に基づく情報拡張機能を有するバイラテラル遠隔制御システム

Master-slave teleoperation robots are useful for tasks that require human judgments and skills. Haptic sensation can be transmitted between a master and a slave by implementing bilateral control. Besides, visual information of the slave side that cannot be directly seen from the master side is presented by devices such as cameras, endoscopes, and displays. Therefore, advanced support of the teleoperation robots for operators can be expected by utilizing extended visual and haptic information. In this paper, a master-slave teleoperation system with ability to extend information transmitted to operators is proposed. The teleoperation system consists of one degree of freedom master-slave system implementing bilateral control based on robust acceleration control and an image processing system. To support operators, visual and haptic augmented reality is generated by image processing, micro-macro bilateral control, and compliance control. In addition, a design method of position and force scaling for micro-macro bilateral control according to magnification ratio of image is presented. The utility of the proposed bilateral teleoperation system is verified by experiments.

Stabilization of bilateral teleoperators with asymmetric stochastic delay

Abstract In this paper we consider the problem of position tracking and error boundedness for a master–slave teleoperation system when the communication channel is characterized by a time-varying stochastic delay. In particular, we assume the delay to be a time-varying Markov regime switching process. Our solution is based on a suitable proportional–derivative (PD) like controller. Exploiting a Lyapunov–Krasovskii functional approach, we are able to show that the velocity and position errors remain bounded, provided specific inequality is satisfied. Moreover, zero steady-state position error is achieved when the human operator and the environment do not interact with the system. In order to be able to exploit Lyapunov–Krasovskii approach we need to lift the underlying process to an infinite-dimensional process taking values in a suitable Banach space so that, in the new space, the process is a Markov process. Our conditions for guaranteeing boundedness and the zero steady-state position tracking error are the natural generalization of the deterministic counterparts available in the literature, i.e. when considering the trivial case of a single-state Markov process previous results are recovered. Simulation results show the effectiveness of the proposed approach.

Bilateral coordination control of flexible master–slave manipulators using a partial differential equation model

In this study, we evaluate the coordination tracking control problem of a flexible master–slave teleoperation system. The system under consideration is based on a dynamic model described by a set of partial differential equations. Existing research on bilateral controllers is based on teleoperation systems composed of rigid master robots and rigid or flexible slave robots. In this work, we consider teleoperation systems with flexible master and slave robots. We dynamically model flexible master–slave manipulators using partial differential equations. Based on the dynamic model, a bilateral coordination controller is developed to realize the coordination angle tracking and vibration suppression of flexible master–slave manipulators. The teleoperation system is proven to be asymptotically stable under the control scheme. Numerical simulation results illustrate that the proposed controller is effective.

Experimental Assessment of Absolute Stability in Bilateral Teleoperation.

Absolute stability analysis of bilateral teleoperation systems are typically model-based. Under borderline conditions of absolute stability, depending on the degree of uncertainty in the dynamic model of the teleoperator and existing noise, the system may behave as potentially unstable when the model-based analysis predicts otherwise. In this article, we propose a methodology to experimentally verify the absolute stability of master-slave teleoperation systems. Since absolute stability demands bounds of all possible environments, we achieve this by conducting only three experiments that are often experienced in teleoperation: free slave, mass-carrying slave and locked slave (rigid environment). We will validate and compare our proposed method with the benchmark Llewellyns absolute stability criterion. Furthermore, we will examine the robustness of the proposed method and will provide guidelines for choosing the mass for the mass-carrying load condition.

Autonomy for Surgical Robots: Concepts and Paradigms

Robot-assisted and computer-integrated surgery provides innovative, minimally invasive solutions to heal complex injuries and diseases. The dominant portion of these surgical interventions has been performed with master–slave teleoperation systems, which are not capable of autonomous task execution or cognitive decision making. Much of the most advanced technologies foundered on the drawing boards or at the research labs for a long time, partially due to the fact that the surgical domain is resistant to the introduction of new hazards via the increased complexity of novel solutions. It has been seen with similar heavily regulated areas that internationally accepted standards can facilitate the adoption of new technologies in a safe manner. This paper reviews the existing autonomous capabilities of surgical robots, and investigates the major barriers of development presented by the lack of autonomy benchmarks and standards. The emerging safety standard environment is presented, as a key enabling factor to the commercialization of autonomous surgical robots. A practical scale is introduced to assess the level of autonomy of current and future surgical robots. Regarding the forthcoming robotic platforms, it is crucial to improve the transparency of the regulatory environment, streamline the standardization framework, and increase the social acceptance.

Composite Adaptive Control of Teleoperators With Joint Flexibility, Uncertain Parameters, and Time-Delays

This paper is focused on composite adaptive control design for master-slave teleoperation systems with a flexible-joint manipulator as the slave. Gravity compensation and time-varying delays are considered. For the master manipulator, the composite adaptive controller with a novel adaptation law is designed to guarantee the parameter estimation error and the tracking error converging to zero. For the slave manipulator with joint flexibility, the proportional plus damping control with gravity compensation is proposed. The stability criteria of the closed-loop teleoperation system are given in terms of linear matrix inequalities. Comprehensive simulation studies are provided to demonstrate the effectiveness of the proposed control scheme.

Hardware-in-the-loop simulation of massive-payload manipulation on orbit

This paper describes a hardware-in-the-loop simulation of massive-payload manipulation on orbit using a master–slave teleoperation system. The main problems in teleoperating a space robot arm from the earth to manipulate a massive payload are communication delay, unexpected excessive force generated between the slave arm and the payload, and geometric/dynamic modeling error. In order to overcome those problems, a teleoperation system using mixed force and motion commands is discussed. The teleoperation system is verified by performing hardware-in-the-loop simulations.

Bilateral Adaptive Control of Nonlinear Teleoperation Systems With Uncertain Dynamics and Dead-Zone

Dead-zone is one of the most common hard nonlinearities ubiquitous in master–slave teleoperation systems, particularly in the slave robot joints. However, adaptive control techniques applied in teleoperation systems usually deal with dynamic uncertainty but ignore the presence of dead-zone. Dead-zone has the potential to remarkably deteriorate the transparency of a teleoperation system in the sense of position and force tracking performance or even destabilizing the system if not compensated for in the control scheme. In this paper, an adaptive bilateral control scheme is proposed for nonlinear teleoperation systems in the presence of both uncertain dynamics and dead-zone. An adaptive controller is designed for the master robot with dynamic uncertainties and the other is developed for the slave robot with both dynamic uncertainties and unknown dead-zone. The two controllers are incorporated into the four-channel bilateral teleoperation control framework to achieve transparency. The transparency and stability of the closed-loop teleoperation system is studied via a Lyapunov function analysis. Comparisons with the conventional adaptive control which merely deal with dynamic uncertainties in the simulations demonstrate the validity of the proposed approach.

Discrete-time control of bilateral teleoperation systems: a review

SUMMARYThe possibility of operating in remote environments using teleoperation systems has been considered widely in the control literature. This paper presents a review on the discrete-time teleoperation systems, including issues such as stability, passivity and time delays. Using discrete-time methods for a master-slave teleoperation system can simplify control implementation. Varieties of control schemes have been proposed for these systems and major concerns such as passivity, stability and transparency have been studied. Recently, unreliable communication networks affected by packet loss and variable transmission delays have been received much attention. Thus, it is worth considering discrete-time theories for bilateral teleoperation architectures, which are formulated on the same lines as the continuous-time systems. Despite the extensive amount of researches concerning continuous-time teleoperation systems, only a few papers have been published on the analysis and controller design for discrete bilateral forms. This paper takes into account the challenges for the discrete structure of bilateral teleoperation systems and notifies the recent contributions in this area. The effect of sampling time on the stability-transparency trade-off and the task performance is taken into consideration in this review. These studies can help to design guidelines to have better transparency and stable teleoperation systems.

Transparent bilateral teleoperation interacting with unknown remote surfaces with a force/velocity observer design

ABSTRACTA master–slave teleoperation system is considered, in which the slave manipulator is interacting with a rigid surface with unknown geometry. It is assumed that neither force nor velocity measurements at the slave side are available. To deal with this problem, an extended-state high-gain observer is proposed to estimate in an arbitrary close manner the velocity and force signals. At the same time, the gradient vector for the remote surface is online estimated and employed into an hybrid position/force controller based on the orthogonal decomposition of the task space. A formal proof is presented, which guarantees ultimate boundedness of the state of the system, with arbitrarily small ultimate bound. Furthermore, it is established the transparency of the teleoperation system that, roughly speaking, gives the human operator the sensation of being interacting directly with the remote surface. The proposed scheme is validated through numerical simulations and experiments.

An MRI-Guided Telesurgery System Using a Fabry-Perot Interferometry Force Sensor and a Pneumatic Haptic Device.

This paper presents a surgical master-slave teleoperation system for percutaneous interventional procedures under continuous magnetic resonance imaging (MRI) guidance. The slave robot consists of a piezoelectrically actuated 6-degree-of-freedom (DOF) robot for needle placement with an integrated fiber optic force sensor (1-DOF axial force measurement) using the Fabry-Perot interferometry (FPI) sensing principle; it is configured to operate inside the bore of the MRI scanner during imaging. By leveraging the advantages of pneumatic and piezoelectric actuation in force and position control respectively, we have designed a pneumatically actuated master robot (haptic device) with strain gauge based force sensing that is configured to operate the slave from within the scanner room during imaging. The slave robot follows the insertion motion of the haptic device while the haptic device displays the needle insertion force as measured by the FPI sensor. Image interference evaluation demonstrates that the telesurgery system presents a signal to noise ratio reduction of less than 17% and less than 1% geometric distortion during simultaneous robot motion and imaging. Teleoperated needle insertion and rotation experiments were performed to reach 10 targets in a soft tissue-mimicking phantom with 0.70 ± 0.35 mm Cartesian space error.

Design and Performance Assessment of 2-DOF Teleoperation Device with Force Telepresence

Teleoperation device is a man-machine interface of robot master-slave teleoperation system which is important for the operator to perceive the robots’ working condition and control them. Its performance will directly influence the work efficiency, accuracy and mechanical operation of the teleoperation system. Taking the self-designed 2-DOF teleoperation device with force telepresence as the research object, analyze its key technology from the structure pattern, operating performance and other aspects, which can realize the accurate position control and force telepresence of the teleoperation system, providing a certain reference for the design.

Robotic assistance for children with cerebral palsy based on learning from tele-cooperative demonstration

Physical interaction with the environment and object manipulation, play an important role in the development of children’s cognitive and perceptual skills. For children who have severe physical impairments, one of the biggest concerns is the loss of opportunities for meaningful play. Assistive robots can enable children to engage in play activities. In this paper, we focus on robotic assistance for position-following play activities such as pick-and-place. This task is done via a master–slave teleoperation system with the master robot in the child’s hand and the slave robot performing the task in the environment. In the demonstration phase, a therapist (or, in general, a helper such as a parent) holds the slave robot in the task environment to modify and assist the child’s movements as the child controls the master robot. A learning from demonstration (LfD) technique, which utilizes Gaussian mixture models (GMM) and Gaussian mixture regression (GMR), is used to learn the helper-administered assistance to the child for completing the task. These probabilistic models provide insight into how the helper assisted the child by analyzing the multiple trials of demonstration in the presence of the helper. In the robotic assistance phase, the robot will utilize the learned data to assist the child in the helper’s absence and on a child-specific and as-needed basis. The efficacy of this framework is validated through experiments conducted, involving a two-dimensional (2D) play environment.

Output-Feedback Adaptive Control of Networked Teleoperation System With Time-Varying Delay and Bounded Inputs

The output-feedback based controller design problem is investigated for the networked teleoperation system in this paper. A new control scheme is proposed to guarantee the global asymptotic stability of the bilateral teleoperation system with time-varying delays and bounded inputs. First, a new fast terminal sliding-mode velocity observer is proposed to estimate the unknown velocity signals for the teleoperation system. Then, by considering the unknown gravity term, an adaptive SP+Sd-type (saturated proportion plus saturated damping) controller is designed based on the estimated velocity. In the new controllers, the specific sigmoidal function is not used, and any one on a set of saturation functions can be applied. Furthermore, by choosing Lypunov–Krasovskii functional, we show that the master–slave teleoperation system is stable under specific linear matrix inequality conditions. With the given controller design parameters and the upper bound of the input, the allowable maximal transmission delay can be computed by using the proposed stability criteria. Finally, both simulations and experiments are performed to show the effectiveness of the proposed methods.

Bilateral teleoperation with delayed force feedback using time domain passivity controller

Time delay is a long standing impediment of bilateral control and can destabilize the system evidently. This paper presents a mode-based approach to alleviate some of the problems associated with time delays in a master-slave robot system. The originality of the approach proposed mainly lies in its capacity to take into account explicitly the slave force feedback modified according to the output of Passivity Observer (PO). This method consists of a virtual slave environment model together with a PO to calculate the system energy on the master side. The local environment model is built by the parameters that are identified online at the slave side. Simulation results show the superior performance of the proposed control scheme in the presence of time delays. Experimental results, using a 1-DOF master-slave teleoperation system, support this conclusion. Parameters of remote slave environment can be accurately identified by the RLS method.Passivity observer (PO) together with a virtual environment model is built on the local master side and the system passivity can be judged by the PO.Stable force tracking is achieved by the proposed method with time delay.The proposed method is robust to random communication time delay.

Synchronization control for a class of tele-operation system with stochastically time-varying communication delays

Synchronization control methods for a class of tele-operation system with stochastically time-varying communication delays are surveyed, aiming at the existing communication delays, packet loss, and so on, during the ground-based tele-operation of unmanned aerial vehicles. A control model for this class of master-slave tele-operation system with communication time delays is established. Then, the time delays within the remote control communication network are depicted by a time-varying-delay function, of which the modal parameters are transferred based on an ergodic Markov process. After that, the synchronization control problem of the system is solved by stability analysis of the mean square within the framework of the stochastic systems. Finally, the semi-physical simulation platforms of an unmanned micro-quadrotor are carried out to verify the methods presented in this paper; and the elementary simulation results show that the loci of the master-slave sides are all bounded through designing the controllers by the feedback linearization separately in the methods.