Al-Fadhli, Mohammed

Branson, David T.

McNally, Donal

Name not available

Achieving powered assisted motion of the trunk without an articulated exoskeleton

Nottingham eTheses

Al-Fadhli, Mohammed and McNally, Donal and Branson, David (2016) Achieving powered assisted motion of the trunk without an articulated exoskeleton. In: 22nd Congress of the European Society of Biomechanics (ESB 2016), 10-13 July 2016, Lyon, France. (Unpublished) Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/34450/1/Abstract%20Mohammed%20Al-Fadhli.pdfCopyright and reuse: The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions.This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence.  For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdfA note on versions: The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher’s version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk  22nd Congress of the European Society of Biomechanics, July 10 - 13, 2016, Lyon, France ACHIEVING POWERED ASSISTED MOTION OF THE TRUNK WITHOUT AN ARTICULATED EXOSKELETON Mohammed Al-Fadhli, Donal McNally, David Branson  University of Nottingham, Faculty of Engineering, Nottingham, United Kingdom, NG7 2RD. Background Currently, wearable exoskeletons, based on rigid link systems, are widely used in medical rehabilitation, rescue operations, military, etc. focussed mainly on providing support to the lower body [1]. A major shortcoming in current exoskeleton systems is that none of them are capable of achieving correct whole body motion support because the torso is locked in position and cannot perform the normal movements required for correct postural motion and gait. Furthermore, the bulkiness and weight of such articulated systems make them unsuitable and unattractive for patient use, particularly in older, frailer individuals, and/or in a home setting. In such cases, the patients own skeleton and joints are usually relatively healthy, while it is muscle strength and control that is the problem (e.g. following a stroke). What is needed is a soft exoskeleton based support structure capable of providing motion assistance to the torso and upper back.  Methods and Results This project aims to develop a soft exo-suit (Figure 1) that is flexible, lightweight, and able to provide safe motions for the human trunk. The ability of the actuator system was evaluated using a full musculoskeletal model of the human lumbar spine (Figure 2) in OpenSim software [2]. The soft actuator system was found to reduce muscle forces required for motion from standing posture to full flexion by up to 90% (Figure 3). Additionally, as the soft actuators act on a larger lever arm than the corresponding muscles, they were found to reduce the compressive forces acting on the lumbosacral disc by 15% (Figure 4). Maximum compression force on the lumbosacral joint with the exoskeleton engaged was determined to be 1.35 KN, less than half of the maximum allowable compression force of 3.4 KN [3].       Fig 1: The suit prototype.  Fig 2: The soft model. Future Work A prototype of the powered soft exo-suit has been constructed and full laboratory tests of the suit on healthy volunteers are planned. This work will look at muscle activation reduction, wearer comfort and ability to achieve motion. It will also consider the use of muscle activation and force sensors, in the development of a feedback control system. In future the soft torso suit will be expanded to a soft full body suit to provide actuation support.  Fig 3: Assisted & unassisted Erector Spinae force  Fig 4: Assisted & unassisted Lumbo-Sacral Compression Force. References 1. Tsukahara, A., Hasegawa, Y., & Sankai, Y. (2009). Standing-up motion support for paraplegic patient with robot suit HAL. IEEE International Conference on Rehabilitation Robotics, ICORR 2009 (pp. 211–217). 2. Christophy, M., Faruk Senan, et, al. (2012). A Musculoskeletal model for the lumbar spine. Biomechanics and Modeling in Mechanobiology. 3. Division, I. H., Gallagher, S., et, al. (2002). Effects of posture on dynamic back loading during a cable lifting task. Ergonomics, 45(5), 380–398. Mohammed is studying for his PhD in Biomechanics at the University of Nottingham on the development of soft exoskeletons. He has previously achieved his BSc and MSc in Mechanical Engineering in 2007 and 2009 respectively from the University of Basrah, Iraq. 

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Achieving powered assisted motion of the trunk without an articulated exoskeleton

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