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Position referenced force augmentation in teleoperated hydraulic manipulators operating under delayed and lossy networks: a pilot study.

Maddahi, Yaser; Liao, Stephen; Fung, Wai-keung; Sepehri, Nariman


Yaser Maddahi

Stephen Liao

Wai-keung Fung

Nariman Sepehri


Position error between motions of the master and slave end-effectors is inevitable as it originates from hard-to-avoid imperfections in controller design and model uncertainty. Moreover, when a slave manipulator is controlled through a delayed and lossy communication channel, the error between the desired motion originating from the master device and the actual movement of the slave manipulator end-effector is further exacerbated. This paper introduces a force feedback scheme to alleviate this problem by simply guiding the operator to slow down the haptic device motion and, in turn, allows the slave manipulator to follow the desired trajectory closely. Using this scheme, the master haptic device generates a force, which is proportional to the position error at the slave end-effector, and opposite to the operator's intended motion at the master site. Indeed, this force is a signal or cue to the operator for reducing the hand speed when position error, due to delayed and lossy network, appears at the slave site. Effectiveness of the proposed scheme is validated by performing experiments on a hydraulic telemanipulator setup developed for performing live-line maintenance. Experiments are conducted when the system operates under both dedicated and wireless networks. Results show that the scheme performs well in reducing the position error between the haptic device and the slave end-effector. Specifically, by utilizing the proposed force, the mean position error, for the case presented here, reduces by at least 92% as compared to the condition without the proposed force augmentation scheme. The scheme is easy to implement, as the only required on-line measurement is the angular displacement of the slave manipulator joints.


MADDAHI, Y., LIAO, S., FUNG, W.-K. and SEPEHRI, N. 2016. Position referenced force augmentation in teleoperated hydraulic manipulators operating under delayed and lossy networks: a pilot study. Robotics and autonomous systems [online], 83, pages 231-242. Available from:

Journal Article Type Article
Acceptance Date Apr 12, 2016
Online Publication Date May 4, 2016
Publication Date Sep 30, 2016
Deposit Date May 9, 2016
Publicly Available Date May 5, 2017
Journal Robotics and autonomous systems
Print ISSN 0921-8890
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 83
Pages 231-242
Keywords Position error referenced force; Haptics; Hydraulic manipulator; Teleoperation; Wireless network; Dedicated network; Time delay; Packet loss
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