Paris-based startup Wandercraft, which makes a signature robotic exoskeleton that allows wheelchair users to stand and walk, just announced a €15 million B round.

The founders plan to use the money to gain necessary certifications and bring what amounts to a stunning new version of an old idea to market. Wandercraft's unique offering? Its device actually replicates the biomechanical marvel of the human gait, which the company claims is a first for an exoskeleton.

But technological breakthroughs aren't always business successes.

Wandercraft's competitors include Ekso Bionics, ReWalk, and SuitX, among other manufacturers. All make devices that allow mobility-impaired persons to stand and walk. To date, the primary use for such devices is in rehab centers, where there's evidence they may help alleviate secondary complications associated with sitting in a wheelchair and can assist in rehabilitation from accident or stroke.

Will Wandercraft's advanced technology offer enough of an advantage to appeal to end users and rehab centers?

I had a chance to speak with founder and general manager Matthieu Masselin about his company's strategy as it enters a space that's seen more established companies struggle to achieve broad adoption. His answers provide a glimpse into how the technology is changing, as well as what the future may hold for current wheelchair users.

GN: You guys claim to be the first company to have figured out how to replicate the human gait. We've heard similar claims from others, notably Ekso Bionics and ReWalk. How is Wandercraft's exo different?

MM: We have a great respect for these pioneers. We have addressed the issue differently, starting by fully modeling how it to achieve a fully balanced, autonomous (e.g. without crutches) gait. Specifically, the exo walks without crutches and is self-balanced.

We use dynamic robotics, including algorithmic frameworks which are widely more complex to implement but able to create dynamic balance and are highly robust to perturbations. In particular, they handle motion as a dynamically controlled fall (hence 'dynamic') and not as a succession of static balance states.Typically, with some differences, Boston Dynamics uses the same sort of algorithms for Atlas.

GN: So you're actually replicating the biomechanics, the falling forward that makes walking so difficult to model and recreate?

MM: We deliver a truly bipedal walk compared to Ekso or ReWalk, which are actually offering quadrupedal walk -- the exo's two legs are completed with two other contact points. Nor is It like Rex [created by Rex Bionics] which is relying on static walking control strategies, i.e., allowing close to 0 acceleration and monitoring the center of mass of the system.

We implement strategies developed by the teams of Jessy Grizzle in Ann Harbor and Aaron Ames in Caltech for bipedal walk which have shown incredible robustness in real hardware and extreme likeness to human walk (see here for example). We collaborate closely with them, through publications such as this one and others we will disclose at the next ICRA conference.

These theories, generally referred to as HZD (for Hybrid Zero Dynamics) allow 3D walking on uneven terrain.

GN: Why go to all that trouble? Why replicate the human gait exactly?

MM: This is all for one purpose: getting rid of the crutches and achieving a device that will ensure system (exo + user) stability, rather than relying on the user for it. This is extremely important, as in the case of Rewalk or Ekso, physicians' feedback is that [the crutches] can hurt shoulders quite a lot and do not allow for effective treatment.

We really see ourselves as bringing the latest advances from humanoid robotics and dynamic walking to the first true use case of walking robots, which is rehab exoskeletons.

GN: What are the use cases for Wandercraft's exo? You mentioned wheelchairs. I'm curious if that's the primary market you're going after. Ekso Bionics, for example, started out going after wheelchair users but figured out there wasn't enough demand, so they broadened their approach. They've since pivoted to using their device to help stroke patients and spinal cord injury sufferers learn to walk again through gait training.

MM: We do focus on mobility impaired persons. It is a business and a cause. In the Northern Hemisphere, there are 3 to 5 million mobility impaired persons and 3000 large rehab centers that are immediately relevant to our technology. This is largely more than construction workers or military [two other current uses for exoskeletons].

The problem with unbalanced exos, using static robotics and requiring to walk on crutches, is twofold. First, treatments in healthcare centers is very limited because, one, gait is not realistic, and, two, walking with crutches puts a lot of strain on patients' shoulders and upper limbs. Thus you can't have frequent and intensive sessions.

Exos that are not self balanced offer no perspective for autonomous usage in activities of daily living. Which is our medium term goal.

GN: So further out you do see people using your technology in day-to-day life, and not just at rehab clinics?

MM: The potential synergy between autonomy and treatment is huge. This has been discussed in depth with many physical medicine physicians and physios.

We expect that the need for such exos is one order of magnitude higher than for unbalanced exos.

If you take France for instance. There are 357 rehab centers, 30 major ones (130+ beds). All have seen Ekso and ReWalk demos and only two have acquired their devices. The idea is great but the implementation is not satisfactory.

GN: So in the simplest terms, the model is ...

MM: Sell / lease clinical exos to healthcare centers in Europe by the end of 2018 and in the US by the end of 2019, offering better treatments. Then, "in some years," sell / lease personal exos to people for more autonomy in daily living.

GN: Take me through the technical specs of your suit.

MM: It runs on a typically core i7 with added processing power soon for more and different functions. Regarding batteries, today you get three to four hours of continuous usage, which allows one full day of typical rehab center work, also equivalent to one full day of urban usage. Dynamic robotics is extremely energy efficient as long phases of the gait cycle are not or little actuated.

The suit weighs more than 50kg, which is acceptable for rehab centers but will be slimmed for personal versions. But weight is not as critical as volume, since the exo carries itself.

GN: How much will units cost? And will they be available off the shelf or do they require customization?

MM: Cost is undisclosed to date. Rehab price will be comparable to comparable equipment.

The target personal version price is expected to be comparable to to-end powered wheelchairs--but we still have some work to do.

We expect to get CE Marking (European certification) in the second half of 2018 and the sell to European rehab centers.