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.

Internet-Based Bilateral Teleoperation Based on Wave Variable With Adaptive Predictor and Direct Drift Control

2005 ◽  
Vol 128 (1) ◽  
pp. 86-93 ◽  
Author(s):  
Ho Ching ◽  
Wayne J. Book
Keyword(s):  
Force Feedback ◽  
Transmission Delay ◽  
Recursive Least Squares ◽  
Bilateral Teleoperation ◽  
Practical Applications ◽  
Wave Variable ◽  
Environmental Force ◽  
Rigid Contact ◽  
The Cost ◽  
Drift Control

In a conventional bilateral teleoperation, transmission delay over the Internet can potentially cause instability. A wave variable algorithm guarantees teleoperation stability under varying transmission delay at the cost of poor transient performance. Adding a predictor on the master side can reduce this undesirable side effect, but that would require a slave model. An inaccurate slave model used in the predictor as well as variations in transmission delay, both of which are likely under realistic situations, can result in steady-state errors. A direct drift control algorithm is used to drive this error to zero, regardless of the source of the error. A semi-adaptive predictor that can distinguish between free space and a rigid contact environment is used to provide a more accurate force feedback on the master side. A full adaptive predictor is also used that estimates the environmental force using recursive least squares with a forgetting factor. This research presents the experimental results and evaluations of the previously mentioned wave-variable-based methods under a realistic operation environment using a real master and slave. The algorithm proposed is innovative in that it takes advantage of the strengths of several control methods to build a promising bilateral teleoperation setup that can function under varying transmission delay, modeling error, and changing environment. Success could lead to practical applications in various fields, such as space-based remote control, and telesurgery.

Internet-Based Bilateral Teleoperation Based on Wave Variable With Semi-Adaptive Predictor and Direct Drift Control

2005 ◽  
Author(s):  
Ho Ching ◽  
Wayne J. Book
Keyword(s):  
Control Algorithm ◽  
Force Feedback ◽  
Transmission Delay ◽  
Bilateral Teleoperation ◽  
Robust Methods ◽  
Wave Variable ◽  
Rigid Contact ◽  
The Cost ◽  
Source Of Error ◽  
Drift Control

In a conventional bilateral teleoperation, transmission delay over the internet can potentially cause instability. One of the more robust methods of dealing with this problem is the wave variable. Wave variable guarantees teleoperation stability even under varying transmission delay at the cost of poor transient performance. Adding a predictor on the master side can reduce this undesirable side-effect, but that would require a slave model. Inaccurate slave model used in the predictor as well as variations in transmission delay, both of which are likely under realistic situations, can result in steady state errors. A direct drift control algorithm is used to drive this error to zero regardless of the source of error. A semi-adaptive predictor that can distinguish between free space and rigid contact environment is also used to provide a more accurate force feedback on the master side. This research presents the experimental results and evaluations of the previously mentioned wave variable based methods under realistic operation environment using real master and slave.

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.

Unifying bilateral teleoperation and tele-impedance for enhanced user experience

2019 ◽  
Vol 39 (4) ◽  
pp. 514-539 ◽  
Author(s):  
Marco Laghi ◽  
Arash Ajoudani ◽  
Manuel G. Catalano ◽  
Antonio Bicchi
Keyword(s):  
Force Feedback ◽  
Physical Interaction ◽  
Environment Interaction ◽  
Bilateral Teleoperation ◽  
Operator Experience ◽  
Stability Performance ◽  
Control Framework ◽  
Remote Environment ◽  
The Stability ◽  
Favorable Conditions

Usability is one of the most important aspects of teleoperation. Ideally, the operator’s experience should be one of complete command over the remote environment, but also be as close as possible to what they would have if physically present at the remote end, i.e., transparency in terms of both action and perception. These two aspects may coincide in favorable conditions, where classic approaches such as the four-channel architecture ensures transparency of the control framework. In the presence of substantial delays between the user and the slave, however, the stability–performance trade-off inherent to bilateral teleoperation deteriorates not only transparency, but also command. An alternative, unilateral approach is given by tele-impedance, which controls the slave–environment interaction by measuring and remotely replicating the user’s limb endpoint position and impedance. Not including force feedback to the operator, tele-impedance is absolutely robust to delays, whereas it completely lacks transparency. This article introduces a novel control framework that integrates a new, fully transparent, two-channel bilateral architecture with the tele-impedance paradigm. The result is a unified solution that mitigates problems of classical approaches, and provides the user with additional tools to modulate the slave robot’s physical interaction behavior, resulting in a better operator experience in spite of time inconsistencies. The validity and effectiveness of the proposed solution is demonstrated in terms of performance in the interaction tasks, of user fatigue and overall experience.

scholarly journals Experimental Testing of Bandstop Wave Filter to Mitigate Wave Reflections in Bilateral Teleoperation

Robotics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 24
Author(s):  
Isaac O. Ogunrinde ◽  
Collins F. Adetu ◽  
Carl A. Moore ◽  
Rodney G. Roberts ◽  
Keimargeo McQueen
Keyword(s):  
Time Delay ◽  
Experimental Testing ◽  
Fixed Time ◽  
Stable Operation ◽  
Bilateral Teleoperation ◽  
Wave Reflections ◽  
Wave Variable ◽  
Frequency Components ◽  
Wave Filter ◽  
Robot Path

A bilateral teleoperation system can become unstable in the presence of a modest time delay. However, the wave variable algorithm provides stable operation for any fixed time delay using passivity arguments. Unfortunately, the wave variable method produces wave reflection that can degrade teleoperation performance when a mismatched impedance exists between the master and slave robot. In this work, we develop a novel bandstop wave filter and experimentally verify that the technique can mitigate the effects of wave reflections in bilaterally teleoperated systems. We apply the bandstop wave filter in the wave domain and filtered the wave signal along the communication channel. We placed the bandstop wave filter in the master-to-slave robot path to alleviate lower frequency components of the reflected signal. With the lower frequency components reduced, wave reflections that degrade teleoperation performance were mitigated and we obtained a better transient response from the system. Results from our experiment show that the bandstop wave filter performed better by 67% when compared to the shaping wave filter respectively.

Simulation Research on Hydraulic Stewart Force Feedback Master-Slave System

2013 ◽  
Vol 347-350 ◽  
pp. 3954-3959
Author(s):  
Jing Wei Hou ◽  
Ding Xuan Zhao ◽  
Ying Zhao ◽  
Yu Xin Cui
Keyword(s):  
Force Feedback ◽  
Controller Design ◽  
Load Force ◽  
Force Model ◽  
Slave System ◽  
Simulation Research ◽  
Control Framework ◽  
Hydraulic Servo ◽  
The Relationship ◽  
Master Slave System

a virtual prototype program of hydraulic Stewart force feedback master-slave system is developed to solve the modeling problems when plant developing and controller design. The following work is done based on the Stewart manipulator simulation program built in Matlab/SimMechanics platform: 1. Master/slave force feedback control framework is built based on the relationship between force on cylinders and upper platform.; 2. A new Stewart platform with load force model on the upper platform hydraulic servo system is built as the slave hand. The validity of the functions is verified by simulation experiment.

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.

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