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Robust active compliance control for a robot hand

Jalani , Jamaludin (2013) Robust active compliance control for a robot hand. PhD thesis, University of Bristol.

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Abstract

This project deals with safety issues in human-robot interaction. A particular focus of this project is on a humanoid robot hand which requires (physical) safety to interact with objects/humans. A robust and active compliance control is proposed via an Integral Sliding Mode Controller (ISMC) to achieve safe object grasping. The ISMC allows us to introduce a model reference approach where a virtual mass-spring damper system can be used to design a compliant control. The first stage of the studies requires the derivation of the forward kinematics for the Bristol Elumotion Robot Hand (BERUL) by using the DH technique. With the help of the motion and image capturing tool, Roborealm, the kinematics data of the robot hand are obtained to compute the relationships between the joint angles. The forward kinematics results show that a suitable model for a single robot finger can be represented via a pulley-belt type system. The second stage requires the investigation of the ISMC for tracking and positioning control. The results reveal that the ISMC is the most suitable candidate for tracking and positioning control in particular to eliminate friction and stiction, also in comparison to standard PID, adaptive and traditional sliding mode control. The third stage of the PhD-research introduces a novel model reference approach for active compliance control via the ISMC in simulation and experiment. The ISMC provides a non scheduled compliant control where transition from positioning to force control can be eliminated. It is practically proven that the BERUL fingers can perform at different, specially designed compliance levels for specific objects. Further improvement for practical grasping is proposed by introducing a spherical coordinate system for the thumb finger and exploiting a cylindrical coordinate system for the other remaining fingers. The operational space control approach is proposed to permit finger (i.e. hand) posture optimization for practical grasping; this also reduces the need for high accuracy. Finally, an automatic tuning procedure is introduced for the compliance reference model which will allow to find suitable compliance level parameters for specific objects.

Item Type: Thesis (PhD)
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ210.2-211 Mechanical devices and figures. Automata. Ingenious mechanisms.
Depositing User: Normajihan Abd. Rahman
Date Deposited: 24 Dec 2013 00:57
Last Modified: 24 Dec 2013 00:57
URI: http://eprints.uthm.edu.my/id/eprint/4638
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