Sound-Off: How to Simulate the Impacts of an Exoskeleton

July 18, 2017

Over the past decade, warfighters’ personal loads have increased, leading to more injuries, pain, and discomfort. To relieve the burden, the military is investigating performance-enhancing exoskeletons. But how does an exoskeleton impact the soldier wearing it?

With funding from the U.S. Army, RE2 Robotics has developed the Biomechanical Exoskeleton Simulator System (BESS) to accurately model injury risk, gait, and forces or torque on the user’s muscles.

Dr. Andrew B. Mor, Principal Investigator for RE2 Robotics, leads the simulation efforts.

In a Tech Briefs presentation titled “Advances in Wearable Technologies,” an attendee asked Mor:

What assumptions can you make about the mechanical boundary or interface between the subject and the exoskeleton?

Dr. Andrew B. Mor: The assumptions that we're making in our current iteration are that the contacts are effectively point contacts between the exoskeleton and the user skeleton, mainly because that is the constraint in how the forces are incorporated into OpenSim .

We know that, even with the exoskeleton we're simulating and validating with now, the interface is through about a one- or two-inch-wide strap. But at this point we're isolating the contact into a single force/torque sensor input, and effectively welding that force and torque into a point on the skeleton in the model.

In the future, when we go to more deformable contacts, I see extending that to having a pressure array that's being applied to the model in OpenSim.

What do you think? Share your comments and questions below.