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

Robotica ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 859-875 ◽  
Author(s):  
Da Sun ◽  
Fazel Naghdy ◽  
Haiping Du
Keyword(s):  
Time Delays ◽  
Large Time ◽  
Wave Transformation ◽  
Bilateral Teleoperation ◽  
Bilateral Control ◽  
Wave Variable ◽  
Guarantee System ◽  
Remote Environment ◽  
The Stability ◽  
Teleoperation Systems

SUMMARYStability 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 operator's 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.

Design of a New Impedance Controller for a Time Delay Teleoperation System

2013 ◽  
Vol 392 ◽  
pp. 355-360
Author(s):  
Young Won Chang ◽  
Olga Kostiyukova ◽  
Kil To Chong
Keyword(s):  
Time Delays ◽  
Position Control ◽  
Control Architecture ◽  
Time Varying ◽  
Bilateral Teleoperation ◽  
Bilateral Control ◽  
Single Degree Of Freedom ◽  
Teleoperation System ◽  
The Stability ◽  
Teleoperation Systems

Bilateral teleoperation systems connected to computer networks such as the internet have to deal with varying time delays depending on several factors such as congestion, bandwidth, or distance. Such systems can easily become unstable due to irregular or varying time delays. A passivity concept has been used as the framework to solve the stability problem in bilateral control of teleoperation systems and we demonstrate in this paper how to recover both passivity and tracking performance using a novel control architecture that incorporates time varying gains into the transmission path, feedforward, and feedback position control. Simulation results for a single-degree of freedom master/ slave system are presented which demonstrates the performance of the resulting control architecture.

scholarly journals Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yuling Li
Keyword(s):  
Time Delays ◽  
Closed Loop ◽  
Internal Model Control ◽  
Bilateral Teleoperation ◽  
Closed Loop System ◽  
Teleoperation System ◽  
Model Control ◽  
The Stability ◽  
External Forces ◽  
Teleoperation Systems

The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC) design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

Adaptive Nonlinear Teleoperation with Time Delay Using Modified Wave Variable Based Controller

2011 ◽  
Vol 110-116 ◽  
pp. 2284-2295
Author(s):  
Wei Xiong ◽  
He Hua Ju ◽  
Hong Yun Liu
Keyword(s):  
Variable Method ◽  
Communication Delays ◽  
Bilateral Teleoperation ◽  
Wave Variable ◽  
Control Framework ◽  
Adaptive Motion ◽  
Key Issues ◽  
The Stability ◽  
Teleoperation Systems ◽  
Robotic Teleoperation

Transparency and stability are two key issues in bilateral teleoperation. In this paper, We propose a novel control framework for bilateral teleoperation of nonlinear robotic teleoperation systems under constant communication delays. The proposed approach utilizes the modified wave variable method based on the adaptive nonlinear control, the master and slave robots are directly connected over the delayed communication channels. To make the stability of the system independent of the communication delay, two nonlinear adaptive motion/force controllers are bilaterally designed for both master and slave manipulators and insured its passivity. To improve the transparency, a modified wave variable method based on Nimeyer-Slotine wave ways was used. Simulation results are presented which demonstrate the effectiveness of the proposed architecture.

A Simple Structure for Bilateral Transparent Teleoperation Systems With Time Delay

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Alireza Alfi ◽  
Mohammad Farrokhi
Keyword(s):  
Time Delay ◽  
Closed Loop ◽  
Simple Structure ◽  
Finite Impulse Response ◽  
Structure Design ◽  
Loop System ◽  
Bilateral Teleoperation ◽  
Closed Loop System ◽  
The Stability ◽  
Teleoperation Systems

This paper presents a simple structure design for bilateral teleoperation systems with uncertainties in time delay in communication channel. The goal is to achieve complete transparency and robust stability for the closed-loop system. For transparency, two local controllers are designed for the bilateral teleoperation systems. One local controller is responsible for tracking the master commands, and the other one is in charge of force tracking as well as guaranteeing the stability of the closed-loop system in the presence of uncertainties in time delay. The stability analysis will be shown analytically for two cases: (I) the possibly stability and (II) the intrinsically stability. Moreover, in Case II, in order to generate the proper inputs for the master controller in the presence of uncertainties in time delay, an adaptive finite impulse response (FIR) filter is designed to estimate the time delay. The advantages of the proposed method are threefold: (1) stability of the closed-loop system is guaranteed under some mild conditions, (2) the whole system is transparent, and (3) design of the local controllers is simple. Simulation results show good performance of the proposed method.

scholarly journals Stability Problem of Wave Variable Based Bilateral Control: Influence of the Force Source Design

2013 ◽  
Vol 2013 ◽  
pp. 1-11
Author(s):  
Dapeng Tian ◽  
Bao Zhang ◽  
Honghai Shen ◽  
Jiaquan Li
Keyword(s):  
Control System ◽  
Stability Analysis ◽  
Time Delay ◽  
Robust Stability ◽  
Scattering Theory ◽  
Stability Problem ◽  
Bilateral Control ◽  
Wave Variable ◽  
Small Gain ◽  
The Stability

The wave variable has been proposed to achieve robust stability against the time delay in bilateral control system. However, the influence of the force source on the overall system is still not clear. This paper analyzes this problem and proposes a supplement to the stability analysis for wave variable based bilateral control. Based on the scattering theory, it is pointed out that the design of force source decides the passivity of the two-port network of slave robot. This passivity influences the stability of overall system. Based on the characteristic equation and small gain theorem, it is clear that inappropriate designed force source in encoding the wave variable destroys the stability in the presence of time delay. A wave domain filter makes up for the broken stability. The principle of this reparation is explained in this paper. A reference is also provided by the analysis to design the parameter of the wave domain filter. Experiments prove the correctness and validity.

scholarly journals Extending model-mediation method to multi-degree-of-freedom teleoperation systems experiencing time delays in communication

Robotica ◽  
2015 ◽  
Vol 35 (5) ◽  
pp. 1121-1136 ◽  
Author(s):  
Emre Uzunoğlu ◽  
Mehmet İsmet Can Dede
Keyword(s):  
Time Delays ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Test Results ◽  
Bilateral Teleoperation ◽  
Extended Version ◽  
Teleoperation System ◽  
Teleoperation Systems ◽  
Three Degrees Of Freedom

SUMMARYIn this study, a bilateral teleoperation control algorithm is developed in which the model-mediation method is integrated with an impedance controller. The model-mediation method is also extended to three-degrees-of-freedom teleoperation. The aim of this controller is to compensate for instability issues and excessive forcing applied to the slave environment stemming from time delays in communication. The proposed control method is experimentally tested with two haptic desktop devices. Test results indicate that stability and passivity of the bilateral teleoperation system is preserved under variable time delays in communication. It is also observed that safer interactions of the slave system with its environment can be achieved by utilizing an extended version of the model-mediation method with an impedance controller.

Transparency Improvement by External Force Estimation in a Time-Delayed Nonlinear Bilateral Teleoperation System

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
H. Amini ◽  
S. M. Rezaei ◽  
Ahmed A. D. Sarhan ◽  
J. Akbari ◽  
N. A. Mardi
Keyword(s):  
Control Algorithm ◽  
Force Measurement ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Environmental Force ◽  
The Stability ◽  
External Forces ◽  
Teleoperation Systems

Teleoperation systems have been developed in order to manipulate objects in environments where the presence of humans is impossible, dangerous or less effective. One of the most attractive applications is micro telemanipulation with micropositioning actuators. Due to the sensitivity of this operation, task performance should be accurately considered. The presence of force signals in the control scheme could effectively improve transparency. However, the main restriction is force measurement in micromanipulation scales. A new modified strategy for estimating the external forces acting on the master and slave robots is the major contribution of this paper. The main advantage of this strategy is that the necessity for force sensors is eliminated, leading to lower cost and further applicability. A novel control algorithm with estimated force signals is proposed for a general nonlinear macro–micro bilateral teleoperation system with time delay. The stability condition in the macro–micro teleoperation system with the new control algorithm is verified by means of Lyapunov stability analysis. The designed control algorithm guarantees stability of the macro–micro teleoperation system in the presence of an estimated operator and environmental force. Experimental results confirm the efficiency of the novel control algorithm in position tracking and force reflection.

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