Daniel Gordon

Research project title: 
Modelling of a human/exoskeleton system
Research project: 

Principal goal of the project: by implementing a dynamic multi-contact model of a human subject wearing an exoskeleton device, accurately and efficiently calculate the forces which should be applied by the exoskeleton to achieve a specified behaviour of the combined human/exoskeleton system.

Description of the project: Modern techniques for torque-based dynamic planning and control of humanoid robots have been demonstrated with increasing sophistication - in particular for locomotion. A common approach is to create a series of constraints (dynamics, contact forces, joint limits, posture and gaze) and to resolve these via optimization for the required joint positions and torques to achieve a desired motion. This project will take inspiration from these techniques in order to model the dynamic interaction between a human subject and a wearable exoskeleton, with a view to being able to calculate the exoskeleton forces required to achieve a desired motion. If successful this research would greatly simplify the process of prescribing exoskeleton-based assistive or rehabilitative regimes to patients with walking difficulties.

During the project significant use will be made of the state of the art equipment available as part of the Edinburgh Centre for Robotics Robotarium. This includes a split-belt instrumented treadmill, 6-camera Vicon system and hip exoskeleton (the Active Pelvis Orthosis - APO). This equipment will be used to collect ground reaction forces, kinematic data and APO force data for model testing and validation. The open-source musculoskeletal modelling software OpenSim is used perform scaling, inverse kinematics and inverse dynamics on the experimental data based on accurate models of the human body, and is also used for validation of the multi-contact model. The Rigid Body Dynamics Library (RBDL) is used to implement the rigid body dynamics behind the multi-contact model.   

References:

  • Ansari, A., Atkeson, C.G., Choset, H., Travers, M. 2015 A Survey of Current Exoskeletons and Their Control Architectures and Algorithms. Carnegie Mellon University. 
  • Delp, S.L., Anderson, F.C., Arnold, S.S., Loan, P., Habib, Al., John, C.T., Guendelman, E., Thelen, D.G. 2007 OpenSim: Open-Source Software to Create and Analyze Dynamic Simulations of Movement. IEEE Transactions on Biomedical Engineering, vol. 54 (11) 1940-1950.
  • Jimenez-Fabian, R., Verlinden, O. 2012 Review of control algorithms for robotic ankle systems in lower-limb orthoses, prothesis, and exoskeletons. Medical Engineering & Physics, vol. 34, 397-408. 
  • Featherstone, R. 2008 Rigid Body Dynamics Algorithms, Springer, New York. 
  • Saab, L., Ramos, O., Mansard, N., Soures, P., Fourquet J-Y. 2011 Generic dynamic motion generation with multiple unilateral constraints. IEEE/RSJ International Conference on Intelligent Robotics and Systems, San Francisco, California, USA, 4127-4133. 
  • Flores, P., Lankarani, H.M. 2016 Contact Force Models for Multibody Dynamics. Solid Mechanics and Its Applications, vol. 226, Springer.  
About me: 

I am a first year PhD student in the Centre for Doctoral Training in Robotics and Autonomous Systems run jointly by the University of Edinburgh and Heriot-Watt University. My home institution is the University of Edinburgh. I am working on modelling human/exoskeleton systems under the supervision of Prof Sethu Vijayakumar.  

I hold an MMath in Mathematics from the University of St Andrews, and will be graduating in November 2016 with an MSc (research) in Robotics and Autonomous Systems from the first year of the CDT programme.   

As an undergraduate, my primary interest was in applied mathematics, specifically within the research areas of Solar Theory and Fluid Dynamics. In 2012 I undertook a summer research project at the University of St Andrews on modelling flux emergence under the guidance of Dr Vasilis Archontis and Prof Alan Hood. Additionally, I participated in the 2013 Summer REU programme in Solar Physics at Montana State University, Bozeman, US, where I completed a project on modelling shocks and other properties of retracting field lines following magnetic reconnection events - this was under the guidance of Prof Dana Longcope, and a project website/blog is available here. For my MMath dissertation I completed a project titled 'Gravity currents in stratified fluids' under the guidance of Dr Stuart King. 

My current main research interest is in using rigid body and contact dynamics to model the interactions and full dynamics of a human/exoskeleton system. The goal is to be able to accurately and efficiently calculate the forces which should be applied by an exoskeleton to achieve a specified behaviour of the human/exoskeleton system. Significant inspiration is taken from recent advances in whole-body control of humanoid robots which use optimisation based methods on key dynamic properties combined with constraints on contact forces to carry out motion plans. Additional interests include gait analysis, musculoskeletal modelling, and (the identification of) invariant gait metrics.   

 

Student type: 
Current student