Da Sun

Application of wave-variable control to bilateral teleoperation systems: A survey

Abstract Teleoperation systems allow an operator to perform complex tasks in a remote environment. Stability of a bilateral teleoperation system is quite sensitive to time delays. One of the methods to guarantee the stability of bilateral telerobotics in the presence of time delays is wave variable control. A review of various applications of wave variable methods in telerobotics has been conducted. An evaluation of different methods proposed to compensate for the intrinsic problems associated with wave variable methods, including position drift, wave reflection and time varying delay, has also been carried out. In addition, different techniques developed to enhance the performance of the wave-based systems are also identified and reviewed. The research gaps in this field are identified and future directions for further research are proposed.

Wave-Variable-Based Passivity Control of Four-Channel Nonlinear Bilateral Teleoperation System Under Time Delays

An innovative wave-based time-domain passivity approach applied to a four-channel nonlinear teleoperation system is proposed. The primary objective of this approach is to enhance system transparency while maintaining stability in the presence of random time delays. The system stability for different scenarios of human and environment condition is analyzed. The method is validated through experimental work based on a 3-DOF bilateral teleoperation system. The experimental results show that the proposed control algorithm can robustly guarantee the system stability, and simultaneously provide better performance than methods developed in previous work.

Neural Network-Based Passivity Control of Teleoperation System Under Time-Varying Delays

In this paper, a novel neural network (NN)-based four-channel wave-based time domain passivity approach (TDPA) is proposed for a teleoperation system with time-varying delays. The designed wave-based TDPA aims to robustly guarantee the channels passivity and provide higher transparency than the previous power-based TDPA. The applied NN is used to estimate and eliminate the system’s dynamic uncertainties. The system stability with linearity assumption on human and environment has been analyzed using Lyapunov method. The proposed algorithm is validated through experimental work based on a 3-DOF bilateral teleoperation platform in the presence of different time delays.

Transparent four-channel bilateral control architecture using modified wave variable controllers under time delays

Stability and transparency are two critical indices of bilateral teleoperation systems. The wave variable method is a conservative approach to robustly guarantee system passivity under arbitrary constant time delays. However, the wave-variable-based reflection is an intrinsic problem in this method because it can significantly degrade system transparency and disorient the operators perception of the remote environment. In order to enhance both the transparency and the stability of bilateral teleoperation systems in the presence of large time delays, a new four-channel (4-CH) architecture is proposed which applies two modified wave-transformation controllers to reduce wave-based reflections. Transparency and stability of the proposed system are analyzed and the improvement in these when using this method is measured experimentally. Results clearly demonstrate that the proposed method can produce high transparency and stability even in the presence of large time delays.

Enhancing flexibility of the dual-master-dual-slave multilateral teleoperation system

A flexible dual-master-dual-slave teleoperation system is proposed. On the master side, a new control law with a variable dominance factor is proposed to offer the system high flexibility and ease of training. A new wave-based Time Domain Passivity Approach (TDPA) is deployed to guarantee the channel passivity and high transparency in the presence of random time delays. The proposed algorithm is validated by applying it to a multilateral teleoperation platform consisting of four 3-DOF haptic devices configured as two masters and two slaves. The results demonstrate the feasibility of the proposed system in different complex tasks and its superior performance compared to previous work.

Stability control of force-reflected nonlinear multilateral teleoperation system under time-varying delays

A novel control algorithm based on the modified wave-variable controllers is proposed to achieve accurate position synchronization and reasonable force tracking of the nonlinear single-master-multiple-slave teleoperation system and simultaneously guarantee overall system’s stability in the presence of large time-varying delays. The system stability in different scenarios of human and environment situations has been analyzed. The proposed method is validated through experimental work based on the 3-DOF trilateral teleoperation system consisting of three different manipulators. The experimental results clearly demonstrate the feasibility of the proposed algorithm to achieve high transparency and robust stability in nonlinear single-master-multiple-slave teleoperation system in the presence of time-varying delays.

Type-2 Fuzzy Logic based Time-delayed Shared Control in Online-switching Tele-operated and Autonomous Systems

This paper develops a novel shared control scheme for online-switching tele-operated and autonomous system with time-varying delays. Type-2 Takagi-Sugeno (T-S) fuzzy model is used to describe the d ...

Interaction Measures for Control Configuration Selection Based on Interval Type-2 Takagi–Sugeno Fuzzy Model

Interaction measure determines decentralized and sparse control configurations for a multivariable process control. This paper investigates interval type-2 Takagi–Sugeno fuzzy (IT2TSF) model based interaction measures using two different criteria, one is controllability and observability gramians, the other is relative normalized gain array (RNGA). The main contributions are: first, a data-driven IT2TSF modeling method is introduced; second, explicit formulas to execute the two measures based on IT2TSF models are given; third, two interaction indexes are defined from RNGA to select sparse control configuration; fourth, the calculations to derive sensitivities of the two measures with respect to parametric variations in the IT2TSF models are developed; and fifth, the discussion to compare the two measures is presented. Three multivariable processes are used as examples to show that the results calculated from IT2TSF models are more accurate than that from their type-1 counterparts, and compared to gramian-based measure, RNGA selects more reasonable control configurations and is more robust to the parametric uncertainties.