Tracking Performance Of An Identical Master-Slave Teleoperation System Under Variable Time Delays

In this paper, the problem of stability and tracking performance of FRVF (Forbidden Region Virtual Fixture) for bilateral nonlinear teleoperation systems is studied in presence of varying time delay. It is proved that PD-like controllers can stabilize the teleoperation systems with FRVF in slave side and variable time delay in communication channels. It is also proved by proposed Lyapunov-Krasovskii's function that the mentioned problem of stability and tracking performance of FRVF is satisfied. Finally, the proficiency of this approach is demonstrated by simulating the method on a pair of 6-DOF (Degree of Freedom) PHANToM Omni robots with nonlinear dynamics. Keywords— Virtual fixture; variable delay; delayed teleoperation system; nonlinear teleoperation.

In a teleoperation system, providing force information to a human operator can improve task performance. When a communication block between a master and a slave has a transmission delay, the system is easily destabilized. Anderson and Spong guaranteed passivity in the communication block by using scattering transformation and overcame this instability caused by the time delay. But this method can be applied to the communication block with a constant time delay. In a traditional teleoperation system, its communication block has a constant time delay. But time delay irregularly changes in a computer network because many users share telecommunication lines. This paper shows that the variable time delay destabilizes bilateral master-slave manipulator with scattering transformation and a new compensation method which keeps the time delay constant. This new compensation method has been implemented in a single-axis master-slave manipulator.

This paper presents model-based predictive controllers that achieve a high level of transparency while maintaining stability in bilateral teleoperation under known constant or variable time delay. This goal is accomplished by utilizing available information on system model and time delay within an adaptive predictive control framework. The performance objectives are delay-free position tracking between the master and slave and the establishment of virtual mass-damper tool impedance between the user and environment. The controllers adapt to parameter changes in the user, environment as well as the master and slave dynamics. Delay reduction is accomplished based on a state observer and estimates of the system parameters. Using the delay-reduced dynamics, an adaptive output regulation problem is formulated and solved to obtain the control laws. A Lyapunov analysis of the performance and stability of the resulting system is presented. The proposed controllers are evaluated experimentally under constant and variable delay conditions.

Signal correlator with programmable variable time delay based on optical coherent transients

Teleoperation is a human control system enabling humans to interact with the remote environment through a dual robot system which includes a master robot and a slave robot operating in two different places. Wave variables and scattering approaches were proposed in [1],[2] with constant time delay, [3],[4] with varying time delays. This paper develops them based on different wave variables and new passivity control to guarantee the stability of the whole system against varying time delays without assumption that absolute derivative of time delays is smaller than one. The validity of the control law is based on passivity theory. In addition, force controller design is considered for increasing transparency of system. The simulation results demonstrate the good performance of the proposed controller for position synchronization.

An investigation is presented of insertion loss and constant variable delays in electronically variable magnetostatic-volume-wave delay lines. The delay line has a conductor-dielectric-YIG-dielectric-conductor structure. Variable delays up to 300 MHz bandwidth have been obtained in a single volume-wave delay line by adjusting the direction and magnitude of the biasing DC magnetic field in a plane containing the normal to the YIG film and the direction of wave propagation. Insertion loss as a function of frequency has been obtained for different biasing field angles and also for the angles corresponding to variable constant delays. Good agreement between theoretically obtained insertion loss and experimental results is found. Electronically variable magnetostatic-wave delay lines have promising applications in broadband phased-array antennas at 1-20 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A trigonometric approximation scheme for optimal periodic control problems with state and control dependent delays is considered. The formulation of approximate problems is here adapted to a specific form of state equation with variable time delays. Sufficient conditions for the sequence of nearly optimal solutions of approximate problems to be a generalized minimizing sequence for the basic problem are given. The application of the method proposed to a periodic control of chemical reactors with recycles and controlled piping is pointed out.

Improved stabilization criteria for Takagi–Sugeno fuzzy systems with variable delays

Foraging choice in laboratory rats: Constant vs. variable delay

The Turing (wave) instability is only possible in reaction-diffusion systems with more than one (two) components. Motivated by the fact that a time delay increases the dimension of a system, we investigate the presence of diffusion-driven instabilities in single-species reaction-diffusion systems with delay. The stability of arbitrary one-component systems with a single discrete delay, with distributed delay, or with a variable delay is systematically analyzed. We show that a wave instability can appear from an equilibrium of single-species reaction-diffusion systems with fluctuating or distributed delay, which is not possible in similar systems with constant discrete delay or without delay. More precisely, we show by basic analytic arguments and by numerical simulations that fast asymmetric delay fluctuations or asymmetrically distributed delays can lead to wave instabilities in these systems. Examples, for the resulting traveling waves are shown for a Fisher-KPP equation with distributed delay in the reaction term. In addition, we have studied diffusion-induced instabilities from homogeneous periodic orbits in the same systems with variable delay, where the homogeneous periodic orbits are attracting resonant periodic solutions of the system without diffusion, i.e., periodic orbits of the Hutchinson equation with time-varying delay. If diffusion is introduced, standing waves can emerge whose temporal period is equal to the period of the variable delay.

&lt;p style='text-indent:20px;'&gt;This paper presented a class of neural networks with time-varying delays to solve quadratic programming problems. Compared with previous papers, the neural networks proposed in this paper replaced the constant time delays &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ \tau $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; with variable time delays &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ \tau(t) $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; and had a more concise structure. There was an improvement of previous method in proving the existence and uniqueness of solutions of the neural networks in this paper. Further, this paper gave the conditions to be satisfied for the global exponential stability of the proposed neural networks. Through numerical examples, this paper verified that the proposed neural networks were accurate and efficient in solving the quadratic programming problems.&lt;/p&gt;

The Sixth International Symposium on Neural Networks (ISNN 2009)

We present sufficient conditions for robust relay delayed semiglobal stabilization of second order systems, which relate the upper bound to an uncertain time delay and the parameters of the plant. We also suggest an algorithm of delayed relay control gain adaptation for semiglobal stabilization, which is based on delayed information about the sign of the controlled variable only. The proposed algorithm suppresses bounded uncertainties in the time delay, that is, being designed for the upper bound of uncertainty in the time delay, the control law ensures semiglobal stabilization independently of any variable time delay obeying the given upper bound.

We present sufficient conditions for robust relay-delayed semiglobal stabilization of second order systems, which relate the upper bound to an uncertain time delay and the parameters of the plant. We also suggest an algorithm of delayed relay control gain adaptation for semiglobal stabilization, which is based on delayed information about the sign of the controlled variable only. The proposed algorithm suppresses bounded uncertainties in the time delay; that is, being designed for the upper bound of uncertainty in the time delay, the control law ensures semiglobal stabilization independently of any variable time delay obeying the given upper bound.

This document introduces a new Internal Multi-Model controller design method for a linear system with a limited variable time delay. This design method, is based on the use of a models collection to approximate the system functioning using Pade approximations; these models are inversed and multiplied by low pass filters in order to obtain a set of controllers that calculate the command value through a fusion procedure. These controllers are obtained by the multiplication of a low pass filter’s and Model’s inverse’s, in order to impose poles and zeros and to control the command robustness through the filter’s parameters, which shall confirm a compromise between stability and rapidity. In this paper the Multi-Model Command controller design method will be described through six sections; first section introduces the realized research in this paper, the second section describes Internal Model Control concepts, third section describes the effects of presence of a time delay on systems dynamics, the fourth section shows briefly Multi-Model concepts, the fifth section presents the new Internal Multi-Model controller design Method and finally section six deals with the obtained results of the new controller design method application for a system with a limited variable time delay and the filters parameters variation effects.