Passivity based task-space bilateral teleoperation with time delays

Author(s):  
Hanlei Wang ◽  
Yongchun Xie
Author(s):  
Hanlei Wang ◽  
Yongchun Xie

This paper investigates the task-space control framework for bilateral teleoperation with communication time delays. Teleoperation in task space R3 × SO(3) presents some distinctive features different from its joint-space counterpart, i.e., SO(3) is nonconvex and bears quite different structure from Euclidean space Rn. Through analyzing the energy flows at the two ports of the teleoperator, we rigorously define the task-space interaction passivity of the teleoperator. Based on this passivity framework, we propose delay-robust control schemes to achieve master–slave position/orientation synchronization. Singularity-free task-space interaction passivity of the closed-loop teleoperator is ensured by the proposed task-space control framework. Using Lyapunov–Krasovskii stability tool and Schwarz inequality, we analyze the performance of the proposed teleoperation control scheme. We also discuss the problems incurred by time-varying delays and the corresponding solutions. Simulation study on a master–slave teleoperator composed of two kinematically dissimilar six-degree of freedom (DOF) manipulators is performed to illustrate the performance of the proposed control approach.


Author(s):  
Xiao Gao ◽  
João Silvério ◽  
Sylvain Calinon ◽  
Miao Li ◽  
Xiaohui Xiao

AbstractTask space mapping approaches for bilateral teleoperation, namely object-centered ones, have yielded the most promising results. In this paper, we propose an invertible mapping approach to realize teleoperation through online motion mapping by taking into account the locations of objects or tools in manipulation skills. It is applied to bilateral teleoperation, with the goal of handling different object/tool/landmark locations in the user and robot workspaces while the remote objects are moving online. The proposed approach can generate trajectories in an online manner to adapt to moving objects, where impedance controllers allow the user to exploit the haptic feedback to teleoperate the robot. Teleoperation experiments of pick-and-place tasks and valve turning tasks are carried out with two 7-axis torque-controlled Panda robots. Our approach shows higher efficiency and adaptability compared with traditional mappings.


Robotica ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 859-875 ◽  
Author(s):  
Da Sun ◽  
Fazel Naghdy ◽  
Haiping Du

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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