Chapter 7: Robustness of Linear Constant-Delay Predictors to Time-Varying Delay Perturbations

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Farzad Hashemzadeh ◽  
Iraj Hassanzadeh ◽  
Mahdi Tavakoli ◽  
Ghasem Alizadeh

A new framework is proposed to mitigate the adverse effect of time-varying time delays on the passivity of a teleoperation system. To this end, the communication channel with time-varying delays is modeled as a constant-delay channel along with additive output disturbances. Then, disturbance estimator blocks are added in each of the feedforward and feedback paths to estimate these disturbances and to compensate for them. In the disturbance estimator block, there is a need for a virtual time-varying delay block such that the overall communication channel can be seen as one with a constant delay. We also propose a method for determining this virtual delay. Two PHANToM haptic devices connected through a communication channel with time-varying delays are considered for a case study. Simulation and experimental results confirm the efficiency of the proposed method in terms of passivating the teleoperation system in the presence of time-varying delays.


Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 661
Author(s):  
Huansen Fu ◽  
Baotong Cui ◽  
Bo Zhuang ◽  
Jianzhong Zhang

This work proposes a state estimation strategy over mobile sensor–actuator networks with missing measurements for a class of distributed parameter systems (DPSs) with time-varying delay. Initially, taking advantage of the abstract development equation theory and operator semigroup method, this kind of delayed DPSs described by partial differential equations (PDEs) is derived for evolution equations. Subsequently, the distributed state estimators including consistency component and gain component are designed; the purpose is to estimate the original state distribution of the delayed DPSs with missing measurements. Then, a delay-dependent guidance approach is presented in the form of mobile control forces by constructing an appropriate Lyapunov function candidate. Furthermore, by applying Lyapunov stability theorem, operator semigroup theory, and a stochastic analysis approach, the estimation error systems have been proved asymptotically stable in the mean square sense, which indicates the estimators can approximate the original system states effectively when this kind of DPS has time-delay and the mobile sensors occur missing measurements. Finally, the correctness of control strategy is illustrated by numerical simulation results.


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