Neuromechanical study of walking with a
Wearable Assistive Lower Leg eXoskeleton (WALL-X)

Enabling the development of efficient exoskeletons
by means of human movement experiments








WALL-X is a simple pneumatically powered robotic exoskeleton developed by the lab of Movement Science of Ghent University that assists ankle push-off, thus making walking easier. Traditionally, labs working on robotic exoskeletons have been focusing on the technological aspect. As movement scientists we focus on the human inside the device. We typically conduct experiments where we change the actuation pattern of the exoskeleton and measure the effect on the user via oxygen consumption measurement and motion capture techniques.

This approach was highly successful as in 2013 our simple but experimentally optimized exoskeleton was the first ever worldwide to be able to reduce the metabolic cost below the cost of walking with normal shoes. Put simply, this means that walking with the Ghent University exoskeleton requires less effort than walking with your normal shoes.

While practical use of exoskeletons seems to be something from science fiction the first exoskeletons have become commercially available over the last few years. It is expected that exoskeletons will replace wheeled devices such as mobility scooters for clinical populations such as stroke patients or elderly. In addition to advances in engineering, it is crucial to gain understanding on the presently insufficiently known human neuromechanics during assisted locomotion via movement science research methods.

Our mission is to enable the rise of a new generation of exoskeletons that augment mobility to a clearly perceivable degree, in able-bodied as well as impaired persons, by optimizing assistance patterns based on evidence from human neuromechanics experiments.

Companies or researchers who are interested to become involved in this project are highly welcome to reach out to us via the contact details at the bottom of this webpage. For companies we have a specific technology opportunity document.

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Research lines

Figure: Typical research approach for studying human neuromechanics during exoskeleton walking.


1) Experimental optimization of exoskeleton actuation pattern for reducing the metabolic cost of walking.
Representative study: 
Malcolm P, Derave W, Galle S, De Clercq D: A Simple Exoskeleton that Assists Plantarflexion Can Reduce the Metabolic Cost of Human Walking.
PLoS One 2013, 8:e56137.

2) Biomechanics and physiology of human adaptation to exoskeleton assistance during walking.

Representative studies:
- Galle S, Malcolm P, Derave W, De Clercq D: Enhancing performance during inclined loaded walking with a powered
ankle-foot exoskeleton.
Eur J Appl Physiol 2014.
- Galle S, Malcolm P, Derave W, De Clercq D: Adaptation to walking with an exoskeleton that assists ankle extension.
Gait Posture 2013, 38:495–499.

3) Application of an exoskeleton that reduces metabolic cost of walking in clinical populations.

Representative study: 
Galle S, Malcolm P, Derom E, Calders P, De Clercq D. Pilot test of a Wearable Assistive Lower Leg eXoskeleton in patients. In preparation.

4) Use of an exoskeleton as an experimental tool for investigating neuromechanics of human gait.

Representative study:
Malcolm P, Fiers P, Segers V, Van Caekenberghe I, Lenoir M, De Clercq D: Experimental study on the role of the ankle push off in the walk-to-run transition by means of a powered ankle-foot-exoskeleton.
Gait Posture 2009, 30:322–327.



July 27, 2014: Ghent University exoskeleton enhances maximal performance during inclined loaded walking.

While it was known by now that exoskeletons can reduce the metabolic cost of walking at normal intensity it was unsure whether subjects would still benefit from the exoskeleton during maximum intensity efforts. Our new paper shows that with the help of our exoskeleton subjects reach exhaustion at their normal physiological parameters but at a higher external workload. This signifies that aside from restoring patient mobility another possible application of exoskeletons could be allowing healthy subjects to transcend their biological limits.

Reference: Galle S, Malcolm P, Derave W, De Clercq D: Enhancing performance during inclined loaded walking with a powered ankle-foot exoskeleton. Eur J Appl Physiol 2014.



July 11, 2014: Two recent studies from MIT and North Carolina State University confirm our recent finding that it is possible to reduce metabolic cost below the level of normal walking with an ankle exoskeleton.

About one year after the Ghent University exoskeleton, two very recent studies with exoskeletons also broke the normal-walking barrier, this time with fully autonomous exoskeletons. In the study from MIT this result was achieved using the optimal timing and required adaptation period that were discovered by research with the Ghent University exoskeleton thus indirectly confirming the practical relevance of our own research. The second study uses exclusively elastic actuation which means that this exoskeleton has unrestricted autonomy. Both results clearly demonstrate that it is possible to assist ‘free’ walking with exoskeletons which emphasizes the opportunities of this new technology for assisting mobility in clinical populations (cfr. own research line no. 3) . Congratulations to Mooney, Rouse and Herr from MIT and Wiggin, Collins and Sawicki from NCSU and CMU for their exciting results.


June 12, 2014: Ghent University exoskeleton is presented at the hardware demonstration of the 2014 Dynamic Walking conference at ETH Zürich.

Several leading authorities in the field of walking biomechanics and robotics were given the opportunity to experience firsthand how it feels to walk with the Ghent University exoskeleton.

June 12, 2013:Results from the timing optimization study are presented at the 2013 Dynamic Walking conference in Carnegie Mellon University, Pittsburgh.


February 2013:Ghent university exoskeleton breaks the 'normal-walking' barrier.

This result was obtained by optimizing actuation timing confirming a hypothesis from a mathematical model of walking saying that push-off timing is important. Previously, no exoskeletons from university labs or commercial companies were able to reduce metabolic cost below the level of walking without exoskeleton. This result gets covered in national television and popular scientific press.

VTM News, February 18, 2013: “Prolonged walking with Robot Shoe”.
EOS Magazine,
February 15, 2013, I-pad edition: “Wearable robots”.



Funding and technical support

§  This research is supported by BOF10/DOC/288 (drs. S. Galle, Prof. D. De Clercq, Prof. W. Derave). 

§  Technische Orthopedie België ( has been helping us since the very beginning in 2007 by custom-designing the different iterations of the orthotic part of our exoskeletons.



·         Steve Collins, Carnegie Mellon University. In 2013, Philippe Malcolm from Ghent University was given the opportunity to study the effect of push-off timing now using the robotic prosthesis emulator from Caputo and Collins at the lab of Experimental Biomechatronics of Carnegie Mellon University

·         Delft University of Technology, Biorobotics lab

·         University of Twente Neuromechanics and Biomechatronics section

·         Industrial Design Center, Ghent University, Campus Kortrijk

·         Eric Derom and Patrick Calders of the Department of Physical Therapy and Motor Rehabilitation of the Ghent University Hospital

·         Joris Degrieck of the Department of Materials Science and Engineering of Ghent University has supported our research with improvements in the actuator attachments, force sensing and modeling of our exoskeleton.

·         Wim Derave, Ghent University Department of Movement and Sports Sciences, lab of exercise physiology.

·        Robo8 Leadership Board



Call for collaboration

We are highly interested in partnerships with:

·         Companies who are interested in using our database of optimal actuation and/or optimization method and infrastructure (see technology opportunity document).

·         Engineering scientists who are interested in working on the hardware and/or control of our exoskeletons.

·         Scientists who are interested in using our experimental data to develop and validate simulation models of exoskeleton-assisted walking.

·         Clinicians who are interested to test the exoskeleton in specific patients populations.

·         Engineering labs who develop exoskeletons or prostheses looking for support with conducting walking experiments to test their designs. From 2015 we will have a brand new lab and equipment that is optimally suited to this end.

·         Orthopedic, pneumatic, electronic or mechatronic suppliers who are interested to sponsor the material needs of our research. 


You are welcome to contact drs. Samuel Galle to discuss collaboration opportunities.
Telephone: 0032/