A passivity-based control strategy for nonlinear bilateral teleoperation employing estimated external forces
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(2020) 42:616
TECHNICAL PAPER
A passivity‑based control strategy for nonlinear bilateral teleoperation employing estimated external forces M. Namnabat1 · A. H. Zaeri2 · M. Vahedi3 Received: 7 July 2018 / Accepted: 30 August 2019 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract Teleoperation systems have been presented to handle objects in environments in which the presence of operators are impracticable, unsafe or less effective. In this paper, a passive control strategy employing the new outputs to state synchronization of the master and slave robots is developed to attain position coordination during contact tasks. The proposed control scheme includes position signals plus force signals. However, force measurement in such applications is a major limitation. Therefore, a modified force estimation algorithm is proposed to predict external forces applied on the master and slave robots. The closed-loop bilateral teleoperation system is investigated by employing Lyapunov stability criteria. Finally, the experimental results demonstrate the efficiency of the proposed control scheme. It is observed that, in the presence of the estimated external forces in the control scheme, the slave robot follows the master position in both free and contact motion, and force reflecting occurs properly as well. Moreover, it is verified that the external forces are estimated appropriately through the proposed force estimation algorithm. Keywords Teleoperation systems · Time delay · Force estimation algorithm
1 Introduction Teleoperation systems include master and slave robots interacting with each other through communication channels. Spacebased robotics, underwater exploration, telesurgery, etc. are such applications of them [1–3]. Various control strategies are presented for teleoperation systems to attain two main objectives: transparency and stability of closed-loop teleoperation system. Transparency concept is defined in order to the operator in the master side feels properly as if he is manipulating the remote object in the slave side directly. Therefore, it could be expressed that transparency is achieved when the slave position Technical Editor: Victor Juliano De Negri. * A. H. Zaeri [email protected] 1
Department of Control Engineering, College of Technical Engineering, Saveh Branch, Islamic Azad University, Saveh, Iran
2
Department of Electrical Engineering, Shahinshahr Branch, Islamic Azad University, Isfahan, Iran
3
Department of Mechanical Engineering, College of Technical Engineering, Saveh Branch, Islamic Azad University, Saveh, Iran
follows master position appropriately as well as the operator in the master side feels the reflected environmental force, if the slave robot collides with the remote environment. The PD controllers without scattering transformation are most conventional approaches for nonlinear teleoperation systems, which usually employ position and velocity signals [4–7]. The mentioned control schemes guarantee closed loop system stability as well as force fe
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