The second day of the 2021 Wearable Robotics Trade Association (WearRA) WearRAcon 21 continued on April 28th with presentations on wearable sensors, medical and industrial exoskeletons, virtual reality, and wearable robotics control systems. The Executive Director, Joe Hitt, opened the 2nd day of the virtual conference with an announcement that WearRA is in the process of transitioning to a non-profit organization, with more information expected to come at the closing of the event.
While attendees were becoming more familiar with the Brella events networking software utilized for WearRAcon 21, the conference moved to its first presentation of the day by BeBop Sensors on the need for wearable devices to become invisible. BeBop Sensors brings the world closer to this goal by fabricating smart fabrics, sensor-embedded textiles. We interact with fabrics all the time, be it our clothing or furniture. Why not have that fabric be able to sense and understand our intent with the goal of creating more responsive exoskeletons and wearable robots?
Dr. Marcel Reese, CEO Holotron, shared his vision of a suspended-in-air powered exoskeleton for the simulation of a virtual environment, much like a Star Trek Holodeck. Current man-machine interfaces use only a small part of the human body as an interface, notes Dr. Reese. The working prototype of a wearable with motion input and force feedback capability can replicate the feeling of climbing stairs, change in gravity, and control of a virtual skateboard. The current prototype is a historic first. Though it is bulky and not visually appealing, it is important to remember that this is the beginning of this work. Future versions will include extending the exoskeleton to include the arms and reduce the overall size and weight.
Daniel Ferris, Ph.D. Pathways to Advancing Robotic Exoskeletons and Bionic Prosthesis
Dr. Ferris had much to say about the current state of exoskeleton control and evaluation. The human brain is really good at moving the body with the minimum amount of energy cost. The added weight of an exoskeleton could easily make it that it ends up requiring more energy to move with an exoskeleton. More robotic power does not mean lower metabolic cost. But people can also choose to prioritize stability over metabolically efficient walking. Furthermore, we as humans normally move in short spurs of 40 steps or less. So is a treadmill test that lasts longer than five minutes reflective of how we move in real life, asks Dr. Ferris.
From his point of view, as an industry, we can’t look at just one metric for exoskeleton performance. Instead, we should look for an overall “embodiment.” In an ideal case, the user should forget that they are wearing an exoskeleton altogether. The human brain will have to have enough time to adjust to the device (usually around 30 minutes), the exo should have a consistent behavior (though how much error or perturbation is allowed is up for discussion), and the device should do what it was intended to (which may or may not be the reduction of the metabolic cost for movement).
The proper control mechanism is important to achieve the above goals, and Dr. Ferris gave an overview of sonography, EMG, ultrasonography, electroencephalography EEG, and cortical implants. The key for each, or a hybrid control, is to reduce response delay. It is possible that a control that looks good on a treadmill will do poorly in real life. But not all EMG or finite-state controllers are all the same and shouldn’t be lumped together.
The second day of WearRAcon 21 included a dozen presentations and spotlight demos. In addition to the ones listed above, there were talks on experimental design, virtual modeling, defining exoskeleton use envelopes, and separating propulsion with an exoskeleton from the rest of the walking cycle. A particularly fast-paced presentation was given by Dr. Ann M. Spungen on the learnings with working with medical exoskeletons for more than ten years.
The WearRA Innovation Challenge was also held on the second day of the conference. This year, all finalists submitted a pre-recorded video of their project. Information on the finalists and their work can be found on the main WearRA website (link). The winners of the competition and the fan favorites as voted by those attending will be announced on the third and final day of the conference.