Performance analysis in delayed nonlinear bilateral teleoperation systems by force estimation algorithm

2017 ◽  
Vol 40 (5) ◽  
pp. 1637-1644
Author(s):  
Farhad Azimifar ◽  
Kamran Hassani ◽  
Amir Hossein Saveh ◽  
Farhad Tabatabai Ghomshe
Keyword(s):  
Closed Loop ◽  
Force Measurement ◽  
Estimation Algorithm ◽  
Lyapunov Theory ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Teleoperation Systems ◽  
System With Time Delay

This paper establishes a novel control strategy for a nonlinear bilateral teleoperation system with time delay. Besides position and velocity signals, force signals are additionally utilized in the control scheme. This modification significantly improves the poor transparency during contact with the environment. To eliminate the external force measurement, a force estimation algorithm is proposed for the master and slave robots. The closed loop stability of the nonlinear teleoperation system with the proposed control scheme is investigated through the Lyapunov theory. Furthermore, it is theoretically and experimentally proved that force reflection occurs and transparency is enhanced simultaneously. Consequently, experimental results verify the efficiency of the new control scheme in free motion and during collision of the slave robot with the environment.

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.

Transparency performance improvement for multi-master multi-slave teleoperation systems with external force estimation

2017 ◽  
Vol 40 (13) ◽  
pp. 3851-3859 ◽  
Author(s):  
Farhad Azimifar ◽  
Saman Ahmadkhosravi Rozi ◽  
Ahmad Saleh ◽  
Iman Afyouni
Keyword(s):  
Control Strategy ◽  
Closed Loop ◽  
Estimation Algorithm ◽  
Lyapunov Theory ◽  
Shared Environment ◽  
Force Estimation ◽  
Teleoperation System ◽  
Common Control ◽  
Control Scheme ◽  
External Forces

Cooperative teleoperation combines two traditional areas of robotics, that is, teleoperation and collaborative manipulation. Cooperative telerobotic systems consist of multiple pairs of master and slave robotic manipulators operating in a shared environment. The most common control frameworks for nonlinear systems, that is, Proportional Derivative (PD) controllers, possess considerable deficiency in contact motion. In this paper, a novel control scheme is proposed for a nonlinear bilateral cooperative teleoperation system with time delay. In addition to position and velocity signals, force signals are employed in the control strategy. This modification significantly enhances the poor transparency when the slave robots are in collision with the environment. To cope with external forces measurement, a modified force estimation algorithm is proposed to estimate human and environment forces. The closed loop stability of the nonlinear cooperative teleoperation system with the proposed control scheme is investigated using the Lyapunov theory. The main achievement of this research is the stability of the closed loop cooperative teleoperation system in the presence of estimated operator and environmental forces. In addition, it is theoretically and experimentally proved that force reflection occurs and transparency is improved at the same time. Experimental results demonstrate the efficiency of the presented control strategy in free motion as well as when the slave robots are in contact with the environment.

A novel multilateral teleoperation scheme with power-based time-domain passivity control

2016 ◽  
Vol 40 (11) ◽  
pp. 3252-3262 ◽  
Author(s):  
Zheng Chen ◽  
Ya-Jun Pan ◽  
Jason Gu ◽  
Shane Forbrigger
Keyword(s):  
Time Domain ◽  
Communication Channel ◽  
Communication Channels ◽  
Bilateral Teleoperation ◽  
Communication Structure ◽  
Remote Operation ◽  
Teleoperation System ◽  
Control Scheme ◽  
Weighting Coefficients ◽  
Teleoperation Systems

Multilateral teleoperation systems, which are extended from the traditional bilateral teleoperation, have become subject to increasing attention in current years, with increasing industrial requirements, such as the remote operation of larger objects and more complex tasks. In this paper, a general multilateral teleoperation control problem is discussed, in which n masters remotely control n slaves through delayed communication channels. A novel communication structure is proposed to satisfy the multiple master–slave communication requirement, in which weighting coefficients are chosen freely to perform the weighted effects of different masters or slaves. Power-based time-domain passivity control is subsequently developed for the complex multiple master–slave communication channel, to achieve the passivity of multilateral teleoperation systems under time delay. Experiments on a teleoperation system with two masters and two slaves are described; the results verify the effectiveness of the proposed control scheme.

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.

scholarly journals Nonlinear bilateral teleoperation using extended active observer for force estimation and disturbance suppression

Robotica ◽  
2014 ◽  
Vol 33 (1) ◽  
pp. 61-86 ◽  
Author(s):  
Linping Chan ◽  
Fazel Naghdy ◽  
David Stirling ◽  
Matthew Field
Keyword(s):  
Position Tracking ◽  
Bilateral Teleoperation ◽  
Force Estimation ◽  
Teleoperation System ◽  
Inertial Parameters ◽  
Disturbance Suppression ◽  
Force Tracking ◽  
Accurate Position ◽  
Teleoperation Systems ◽  
Robot Position

SUMMARYA novel nonlinear teleoperation algorithm for simultaneous inertial parameters and force estimation at the master and slave sides of the teleoperation system is proposed. The scheme, called Extended Active Observer (EAOB), is an extension of the existing active observer. It provides effective force tracking at the master side with accurate position tracking at the slave side in the presence of inertial parameter variation and measurement noise. The proposed method only requires the measurement of robot position, and as a result significantly reduces the difficulty and cost of implementing bilateral teleoperation systems. The approach is described and its stability is analytically verified. The performance of the method is validated through computer simulation and compared with the Nicosia observer-based controller. According to the results, EAOB outperforms the Nicosia observer method and effectively rejects noise.

Bilateral coordination control of flexible master–slave manipulators using a partial differential equation model

2020 ◽  
pp. 107754632094547
Author(s):  
Le Li ◽  
Hongjun Yang ◽  
Jinkun Liu
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Dynamic Model ◽  
Vibration Suppression ◽  
Equation Model ◽  
Partial Differential ◽  
Bilateral Coordination ◽  
Teleoperation System ◽  
Control Scheme ◽  
Teleoperation Systems

In this study, we evaluate the coordination tracking control problem of a flexible master–slave teleoperation system. The system under consideration is based on a dynamic model described by a set of partial differential equations. Existing research on bilateral controllers is based on teleoperation systems composed of rigid master robots and rigid or flexible slave robots. In this work, we consider teleoperation systems with flexible master and slave robots. We dynamically model flexible master–slave manipulators using partial differential equations. Based on the dynamic model, a bilateral coordination controller is developed to realize the coordination angle tracking and vibration suppression of flexible master–slave manipulators. The teleoperation system is proven to be asymptotically stable under the control scheme. Numerical simulation results illustrate that the proposed controller is effective.

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.

Bilateral Adaptive Control of Nonlinear Teleoperation Systems With Uncertain Dynamics and Dead-Zone

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Xia Liu ◽  
Mahdi Tavakoli
Keyword(s):  
Adaptive Control ◽  
Function Analysis ◽  
Dead Zone ◽  
Adaptive Controller ◽  
Bilateral Control ◽  
Uncertain Dynamics ◽  
Teleoperation System ◽  
Control Scheme ◽  
Teleoperation Systems ◽  
Dynamic Uncertainties

Dead-zone is one of the most common hard nonlinearities ubiquitous in master–slave teleoperation systems, particularly in the slave robot joints. However, adaptive control techniques applied in teleoperation systems usually deal with dynamic uncertainty but ignore the presence of dead-zone. Dead-zone has the potential to remarkably deteriorate the transparency of a teleoperation system in the sense of position and force tracking performance or even destabilizing the system if not compensated for in the control scheme. In this paper, an adaptive bilateral control scheme is proposed for nonlinear teleoperation systems in the presence of both uncertain dynamics and dead-zone. An adaptive controller is designed for the master robot with dynamic uncertainties and the other is developed for the slave robot with both dynamic uncertainties and unknown dead-zone. The two controllers are incorporated into the four-channel bilateral teleoperation control framework to achieve transparency. The transparency and stability of the closed-loop teleoperation system is studied via a Lyapunov function analysis. Comparisons with the conventional adaptive control which merely deal with dynamic uncertainties in the simulations demonstrate the validity of the proposed approach.

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