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.

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.

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.

Wave-Variable Based Force Feedback for a Space-Qualified Telerobot

2008 ◽  
Author(s):  
J. Scot Hart ◽  
Pete Shull ◽  
Diana Gentry ◽  
Gu¨nter Niemeyer ◽  
Stephen Roderick ◽  
...  
Keyword(s):  
Dynamic Capabilities ◽  
Force Feedback ◽  
Contact Forces ◽  
Stable Operation ◽  
Bilateral Teleoperation ◽  
Large Space ◽  
Wave Variable ◽  
Control Framework ◽  
Acceleration Feedback ◽  
Local Feedback

Bilateral teleoperation across significant time delays has been extensively studied and is posed to provide remote control of orbiting robots. Unfortunately, most standard approaches assume an impedance controlled, backdrivable robot. In this work, we apply wave variable control to Ranger, a large, space-qualified, geared robot. We incorporate local feedback of contact forces into the control framework to achieve backdrivable operation. In particular, this control framework imitates an idealized point mass to respect Ranger’s dynamic capabilities. Beyond perceiving steady state contact forces, the user’s perception can be enhanced with high-frequency acceleration feedback of contact transients. Experimental results from controlling Ranger using network communications show stable operation in free space and contact.

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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