Slave Subsystems Research Articles

A realistic approach to treatment design based on impulsive synchronization

Motivated by the need for a systematic methodology for treatment design, especially considering the fact that drugs are consumed in specific dosages at a time(not continuously), the aim of this work is to design an impulsive treatment plan which is applicable in real world. In this study, an innovative methodology for designing an impulsive treatment program is proposed which synchronizes the dynamics of the patient as the slave subsystem with those of the healthy person as the master subsystem. It is generally accepted that controllers based on impulsive synchronization have great performance on chaotic systems; however, this article suggests an innovative approach for synchronizing two non-chaotic systems with different dynamics. It is mathematically proved that the proposed method successfully synchronizes the two systems. An algorithm is then provided to design treatment based on synchronization. To validate the viability of the proposed method, design parameters are adjusted for diseases, and diabetes and cancer treatment are considered as case studies. The performance of the treating plan is demonstrated via simulations.

Incomplete Orientation Mapping for Teleoperation With One DoF Master-Slave Asymmetry

Teleoperation systems require a human-centered approach in which the kinematic mapping is intuitive and straightforward for the operators. However, a mismatch in the degrees-of-freedom (DoFs) between master and slave could result in an asymmetrical teleoperation system. That is an obstacle for intuitive kinematic mapping. In particular, it is even more challenging when the missing DoF is a pure rotational DoF, since the rotation group SO(3) is a nonlinear Riemannian manifold. This letter is concerned with an asymmetric teleoperation system, where the master subsystem can provide 6-DoF pose sensing while the slave subsystem only has 5 DoFs. The rotation along the missing DoF, which is configuration-dependent, is mapped to a geodesic curve in SO(3). We define and prove the closed-form solution of the perpendicular curve to the geodesic curve. Based on the perpendicular curve, we develop a novel Incomplete Orientation Mapping (IOM) approach to avoid the motion in the missing DoF. By comparing with two baseline methods, the experimental results demonstrate that the proposed method can discard the rotational motion along the missing DoF for all configurations, while preserving the remaining rotations.

A Generalized Scattering Framework for Teleoperation with Communication Delays

Abstract The scattering (wave) based teleoperation is currently one of the most popular approaches to bilateral teleoperation with communication delays. Limitations of the conventional scattering-based teleoperation are mostly related to the underlying passivity requirements imposed on the master-human and slave-environment subsystems. In this paper, a generalized scattering framework for bilateral teleoperation with communication delays is outlined, and basic stability results for generalized scattering-based teleoperator systems with delays are established. The proposed framework removes many limitations of the existing scattering-based teleoperation, and allows for much higher flexibility in the control design for the master and slave subsystems.

Lyapunov Stable Teleoperation Controllers Using Passivity Analysis

Teleoperated robots are helpful in handling distant objects, and is being increasingly relied upon in nuclear centers, space travel, etc. Control of teleoperated systems are plagued by the trade-off between its two objectives, namely stability and transparency. This paper proposes novel controllers for the master and slave sub-systems of the teleoperation system, in order to simultaneously meet both these performance objectives. Passivity analysis is done to guarantee the stability of the system. The uniqueness of the proposed controllers lies in circumventing the problems of gain tuning. Both simulations and experiments are carried out on a 1-degree of freedom teleoperated system, and the performance objectives are observed to be satisfactorily met.

Functional Mock-Up Interface-Based Approach for Parallel and Multistep Simulation of Electromagnetic Transients

This paper presents a new simulation approach based on the functional mock-up interface standard for parallel and multistep simulation of electromagnetic transients in power grids with computationally expensive control systems. The control systems are represented by slave subsystems, which are decoupled in memory from the power network and encapsulated in functional mock-up units. The simulation modes are either asynchronous or synchronous. In the asynchronous mode, the subsystems are simulated in parallel, whereas in the synchronous mode, the simulation of each subsystem is executed in a sequential multistep environment. Considerable computation time gains in both modes have been observed in power system protection studies on large-scale networks with accuracy properly maintained.

Nonlinear Model-Mediated Teleoperation for Surgical Applications under Time Variant Communication Delay

Robot-assisted surgery is often carried out through master-slave teleoperation. With the progress of robotic technology and development of novel surgical procedures, new challenges emerge like need for haptic feedback and time delay in teleoperation communication channels, etc. Most existing bilateral teleoperation works in literature emphasize more on maintaining system stability at the cost of degraded transparency, with time variant communication delay further worsening the situation. In this paper, we present a nonlinear Hunt-Crossley model-mediated bilateral teleoperation scheme with targeted applications in robot-assisted surgery. The system stability is guaranteed by decoupling the master and slave subsystems and the system transparency is enhanced with online environment parameter estimation using recursive least squares (RLS) technique. Simulation studies have been carried out for both constant and time varying interaction environments. The proposed teleoperation scheme is shown to be efficient in providing stable and transparent performance and robust against communication delay and environment parameter variance.

Teleoperation Systems Design Using Singular Perturbation Method and Sliding Mode Controllers

The purpose of designing a controller for a teleoperation system is to achieve stability and optimal operation in the presence of factors such as time-delay, system disturbance, and modeling errors. This paper proposes a new method of controller design based on singular perturbation for the bilateral teleoperation of robots through Internet. This study provides sliding mode controller based on the singular perturbation model which is robust on time-varying delay. Using singular perturbation method, the teleoperation system is decomposed into fast and slow subsystems. Teleoperation systems usually have complex dynamic and controller designing is difficult for them. This method is a novel step toward reducing order modeling. In this paper, teleoperation system dynamic was decomposed into two states, slave and error (different from master and slave) and a sliding mode controller was designed for each state. Despite the communication channel in teleoperation systems, it is difficult and almost impossible to design controller based on full-order system. Therefore, many researchers have focused on controller design based on master and slave subsystems. This study shows that the singular perturbation is a proper method for controller design in master or slave, based on slave and error subsystem models with the effect on the total system. It is intended here to reduce the tracking error between the master and the slave. For different values of time-delay, the positions of master-slave were compared. This comparison was also applied for master and slave control signals based on singular perturbation. In all schemes, the effectiveness of the system was shown through simulations and comparisons between the various schemes were presented.

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.

Research of the Precision Clock Synchronization Based on IEEE 1588

In distributed measurement and control system, it is the key to need a global time to determine the order of events happened in system, to achieve the effectiveness of monitoring and control data which is various information transmissions or operation state，therefore the clock synchronization technology is required to synchronize the every slave subsystem. IEEE 1588 precision clock synchronization protocol can effectively solve the time synchronization problem in distributed measurement and control system. First, the basic principles of the IEEE 1588 precision clock synchronization protocol and related program flow are introduced in this article. Second, two algorithms applied to clock synchronization including DS comparison algorithm and State decision algorithm was further proposed and discussed. Meanwhile, the clock synchronization with PTP (Precision Time Protocol) between two devices communication was implemented on the platform of embedded Linux operating system. Finally test showed the accuracy of synchronization was reached less than dozens of microseconds.

操作性向上のための機能分離による異自由度ロボット間バイラテラル制御

This paper proposes a bilateral control for master and slave systems with different degrees of freedom (DOF). In this paper, it is assumed that the number of DOF on the master side is smaller than that on the slave side. In addition, the slave system is divided into slave subsystems according to the number of DOF on the master side. Each slave subsystem accomplishes two kinds of distinctive functions; “task realization by bilateral control between a master robot and a slave subsystem” and “adaptation to environment in contact with a slave subsystem by automation control.” The task realization is achieved within the range of the number of DOF on the master side. On the other hand, the adaptation to environment in contact with the slave subsystem is achieved by using the DOF not to be utilized for the task realization. In the results, the proposed controller actualizes both functions. In addition, a human operator can carry out the desired task of the slave system without the consideration of environmental surface. The validity of the proposed method is confirmed by experimental results.

A novel structure for the optimal control of bilateral teleoperation systems with variable time delay

The purpose of designing a controller for a teleoperation system is achieving stability and optimal operation in the presence of factors such as time delay, system disturbance and modeling errors. In this article three new schemes for teleoperation systems are suggested using an optimal control to reduce the error of tracking between the master and slave systems. In the first scheme optimal controller has been designed in both the master and slave subsystems and by a suitable combination of the output signals of both controllers and exerting it to the slave, it has tried to create the best performance with regard to tracking. In the second scheme, as in the first one, optimal controller is applied to both the master and slave systems and the output of each controller is then applied to its own system, and by changing the system parameters and weighting factors, it has tried to reduce the tracking error between the master and the slave subsystems. In the third structure optimal control is applied to the master. In all three structures the positions of master–slave are compared together and controlling signals are applied to the master or 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 are compared with each other.

A novel order reduction method for nonlinear dynamical system under external periodic excitations

The concept of approximate inertial manifold (AIM) is extended to develop a kind of nonlinear order reduction technique for non-autonomous nonlinear systems in second-order form in this paper. Using the modal transformation, a large nonlinear dynamical system is split into a ‘master’ subsystem, a ‘slave’ subsystem, and a ‘negligible’ subsystem. Accordingly, a novel order reduction method (Method I) is developed to construct a low order subsystem by neglecting the ‘negligible’ subsystem and slaving the ‘slave’ subsystem into the ‘master’ subsystem using the extended AIM. As a comparison, Method II accounting for the effects of both ‘slave’ subsystem and the ‘negligible’ subsystem is also applied to obtain the reduced order subsystem. Then, a typical 5-degree-of-freedom nonlinear dynamical system is given to compare the accuracy and efficiency of the traditional Galerkin truncation (ignoring the contributions of the slave and negligible subsystems), Method I and Method II. It is shown that Method I gives a considerable increase in accuracy for little computational cost in comparison with the standard Galerkin method, and produces almost the same accuracy as Method II. Finally, a 3-degree-of-freedom nonlinear dynamical system is analyzed by using the analytic method for showing predominance and convenience of Method I to obtain the analytically reduced order system.

Periodic chaos synchronization in slave subsystems using optical fiber ring resonators

Synchronization characteristics of chaos generated in optical fiber ring resonators are analyzed numerically for slave subsystems. It is found that highly synchronized chaos appears periodically with the period of one wavelength in a difference in resonator length between the two slave subsystems. It is remarkable that the difference in system parameters included in the phase results in the periodic synchronization whose period corresponds to 2π phase shift. The correlation coefficient degrades gradually with an increase in a much wide range in the phase parameter difference. In addition, synchronization characteristics become worse monotonically as the difference in other system parameters not included in phase increase.

Chaos synchronization characteristics in erbium-doped fiber laser systems

Chaos synchronization characteristics in the master–slave and slave–slave systems with modulated erbium-doped fiber lasers are investigated numerically. We find that synchronization state of chaos becomes better, i.e., the correlation coefficient between the two outputs reaches unity, as the difference in the input power between the two subsystems decreases and is not dependent strongly upon the difference in the modulation index in both the master–slave and slave–slave systems. In the master–slave system, the highest correlation coefficient is attained at the smaller pump power and the larger modulation index in the slave subsystem than those in the master subsystem. On the other hand, the correlation coefficient equal to unity is achieved with the identical parameters in the slave 1 and 2 subsystems in the slave–slave system.

Controlling the global behavior of coupled chaotic systems by means of energy regulation

This paper addresses the problem of partially controlling a set of two unidirectionally coupled, nonlinear (possibly chaotic) subsystems in order that the whole system performs some stable behaviors of interest. In this purpose, the proposed approach mainly consists in regulating the whole system energy (implicitly related to system trajectories), by means of an Energy based Sliding Mode Control scheme (ESMC for short), so that this energy converges towards a neighborhood of a selected magnitude. A major point is that the designed control inputs are directly applied to the master system, contrarily to usual approaches which generally consider the control of slave subsystems (or both master and slave subsystems). In this paper, we introduce some theoretical results related to the proposed approach. Then, an example involving two unidirectionally coupled Chua's circuits is presented.

Scaling properties of bicritical dynamics in unidirectionally coupled period-doubling systems in the presence of noise.

We study scaling regularities associated with the effects of additive noise on the bicritical behavior of a system of two unidirectionally coupled quadratic maps. A renormalization group analysis of the effects of noise is developed. We outline the qualitative and quantitative differences between the response of the system to random perturbations added to the master subsystem or the slave subsystem. The universal constants determining the rescaling rules for the intensity of the noise sources in the master and slave subsystems are found to be gamma=6.619036... and nu=2.713708..., respectively. A number of computer graphical illustrations for the scaling regularities is presented. We discuss the smearing of the fine structure of the bicritical attractor and the Fourier spectra in the presence of noise, the self-similar structure of the Lyapunov charts on the parameter plane near the bicritical point, and the shift of the threshold of hyperchaos in dependence of the noise intensity.

Dynamic analysis of a heavy vehicle using a condensation technique

For conducting dynamic design studies on commercial heavy vehicles, finite element analysis is usually required. Existing dynamic analysis techniques involve significant computation time. In order to reduce the computation time, a dynamic condensation method is proposed in this paper. The condensation technique involves sub-dividing the system under consideration into master and slave sub-systems; usually the number of master degrees-of-freedom (DOF) is significantly smaller than the slave sub-system DOF. A heavy vehicle ride comfort analysis is carried out using the proposed condensation technique and the results are shown to be as accurate as the complete model simulation. A saving in computation time is also demonstrated. However, there are issues such as modal truncation errors that occur when using this technique. The paper briefly addresses guidelines to overcome such issues.

A Teleoperated Microsurgical Robot and Associated Virtual Environment for Eye Surgery

We have developed a prototype teleoperated microsurgical robot (MSR-1) and associated virtual environment for eye surgery. Bidirectional pathways relay visual, auditory, and mechanical information between the MSR-1 master and slave. The surgeon wears a helmet (visual master) that is used to control the orientation of a stereo camera system (visual slave) observing the surgery. Images from the stereo camera system are relayed back to the helmet (or adjacent screen) where they are viewed by the surgeon. In each hand the surgeon holds a pseudotool (a shaft shaped like a microsurgical scalpel) that projects from the left and right limbs of a force reflecting interface (mechanical master). Movements of the left and right pseudotools cause corresponding movements (scaled down by 1 to 100 times) in the microsurgical tools held by the left and right limbs of the micromotion robot (mechanical slave) that performs the surgery. Forces exerted on the left and right limbs of the slave microsurgical robot via the microtools are reflected back (after being scaled up by 1 to 100 times) to the pseudotools and hence surgeon via actuators in the left and right limbs of the mechanical master. This system enables tissue cutting forces to be felt including those that would normally be imperceptible if they were transmitted directly to the surgeon's hands. The master and slave subsystems (visual, auditory, and mechanical) communicate through a computer system which serves to enhance and augment images, filter hand tremor, perform coordinate transformations, and perform safety checks. The computer system consists of master and slave computers that communicate via an optical fiber connection. As a result, the MSR-1 master and slave may be located at different sites, which permits remote robotic microsurgery to become a reality. MSR-1 is being used as an experimental testbed for studying the effects of feedforward and feedback delays on remote surgery and is used in research on enhancing the accuracy and dexterity of microsurgeons by creating mechanical and visual telepresence.

Asymptotic Stability for Force Reflecting Teleoperators with Time Delay

A bilateral system consists of a local master manipulator and a remotely located slave manipulator. Velocity commands are sent forward from the master to the slave, and force information is "re flected "back from the slave to the master. Often there is a transmission delay when communicating between the two subsys tems, which causes instability in the force-reflecting teleoperator. Recently, a solution for this instability problem was found, based on mimicking the behavior of a lossless transmission line. Al though the resulting control law was shown to stabilize an actual single-DOF teleoperator system, and although the control law is intuitively stable because of its passivity properties, stability for the system has not yet been proven. In this article we extend these results to a nonlinear n-DOF system and prove its stability. Non linear, multidimensional networks are used to characterize the nonlinear equations for the master and slave manipulators, the time-delayed communication systems, the human operator, and the environment. Tellegen's theorem and the Lyapunov theory are then applied to prove that the master and slave subsystems have asymp totically stable velocities. In addition, we show how gain scaling can be used without disturbing the stability of the system.