Stochastic scheduling based formation control of underwater teleoperator with time-varying delay

Abstract

Most, if not all, research in single-master-multiple-slave (SMMS) underwater teleoperator formation control has assumed that continuous-time signal transmission is available among master and slaves. Unfortunately, the inherent challenges posed by limited bandwidth and time-varying delays in the underwater medium complicate effective transmission. In addition, slaves working in underwater inevitably suffer from external disturbances. To address these issues, this paper introduces a scheme wherein only one neighboring slave is permitted to exchange its current information to the master according to specifically designed stochastic scheduling protocols. These protocols are modeled as independent and identically distributed (i.i.d) sequences, as well as Markov sequences. During the data transmission process, a logarithmic quantizer is employed to convert the continuous signal to piecewise continuous signal taking values in a finite set. Furthermore, a fixed-time disturbance observer is constructed to estimate the external disturbances affecting the system. Based on novel Lyapunov–Krasovskii functionals, formation stability criteria are derived, which establish the relationship among system stability, control parameters, and communication conditions, such as stochastic scheduling, time delay, and quantization parameters. Numerical simulations and experiments are performed to illustrate the efficiency of the proposed methods.