Research Papers - Dept of Computer Systems Engineering

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Author: search.filters.author.Jayawardena, T. S. SSubject: search.filters.subject.exoskeleton robot

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    Redundant upper limb exoskeleton robot with passive compliance
    (IEEE, 2014-12-22) Gunasekara, J. M. P; Gopura, R. A. R. C; Jayawardena, T. S. S
    Enhancing physical Human-Robot Interaction (pHRI) is an important design aspect in upper limb exoskeleton robots. The level of manipulation provided by an exoskeleton robot has a significant effect to perform daily tasks. This paper evaluate performance of a 6 degree of freedom (DoF) upper limb exoskeleton robot. The detailed mechanical design of the robot is presented with the novel features included in order to improve the pHRL The exoskeleton robot consists of six DoF and two flexible bellow couplings are used to provide translational DoF at wrist and elbow joints. Moreover, flexible bellow couplings are positioned at specific locations in order to enhance the kinematic redundancy. The benefit of compliance due to the flexible bellow coupling at wrist joint of the robot is verified with reference to manipulability variation of the kinematic model of human lower arm.
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    PublicationEmbargo
    Dexterity measure of upper limb exoskeleton robot with improved redundancy
    (IEEE, 2013-12-17) Gunasekara, M. P; Gopura, R. A. R. C; Jayawardena, T. S. S; Mann, G. K. I
    Exoskeleton manipulators are used for different applications in robotic field. Human motion is highly complicated and flexible; therefore obtain human like motion from exoskeleton manipulator becomes a challenge to researches in this field. This paper presents an improvement of dexterity measure as a result of adding redundancy to upper limb exoskeleton manipulator. Proposed manipulator has four degree of freedom. This takes the effect of DOF at human elbow and wrist of the upper limb. Dexterity of the manipulator is measured using manipulability index and minimum singular value. All measures are based on Jacobian of the manipulator. This four DOF manipulator is then modified by adding two more degrees of freedom to make total of six. Therefore with respect to task defined in operational space; modified exoskeleton manipulator operates as redundant. Manipulability index and minimum singular value are again determined for six degree of freedom modified exoskeleton manipulator. The effect of redundancy in order to improve the manipulation in upper limb exoskeleton robot is investigated in this study.
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    PublicationOpen Access
    6-REXOS: Upper limb exoskeleton robot with improved pHRI
    (SAGE Publications, 2015-04-29) Gunasekara, M; Gopura, R; Jayawardena, T. S. S
    Close interaction can be observed between an exoskeleton robot and its wearer. Therefore, appropriate physical human-robot interaction (pHRI) should be considered when designing an exoskeleton robot to provide safe and comfortable motion assistance. Different features have been used in recent studies to enhance the pHRI in upperlimb exoskeleton robots. However, less attention has been given to integrating kinematic redundancy into upper-limb exoskeleton robots to improve the pHRI. In this context, this paper proposes a six-degrees-of-freedom (DoF) upperlimb exoskeleton robot (6-REXOS) for the motion assistance of physically weak individuals. The 6-REXOS uses a kinematically different structure to that of the human lower arm, where the exoskeleton robot is worn. The 6-REXOS has four active DoFs to generate the motion of the human lower arm. Furthermore, two flexible bellow couplings are attached to the wrist and elbow joints to generate two passive DoFs. These couplings not only allow translational motion in wrist and elbow joints but also a redundancy in the robot. Furthermore, the compliance of the flexible coupling contributes to avoiding misalignments between human and robot joint axes. The redundancy in the 6- REXOS is verified based on manipulability index, mini‐ mum singular value, condition number and manipulability ellipsoids. The 6-REXOS and a four-DoF exoskeleton robot are compared to verify the manipulation advantage due to the redundancy. The four-DoF exoskeleton robot is designed by excluding the two passive DoFs of the 6- REXOS. In addition, a kinematic model is proposed for the human lower arm to validate the performance of the 6- REXOS. Kinematic analysis and simulations are carried out to validate the 6-REXOS and human-lower-arm model.