Smart insole uses cheap sensors, AI to analyze gait

Smart insole developed at Stevens Institute of Technology
Stevens Institute of Technology researchers have developed an AI-powered, smart insole that instantly turns any shoe into a portable gait-analysis laboratory. (Stevens Institute of Technology)

Taking one step might be trivial for most people, but Stevens Institute of Technology researchers believe that analyzing how someone walks can tell a lot for people who have trouble moving or have injuries.

According to research published in IEEE Transactions on Neural Systems and Rehabilitation Engineering, the scientists have developed an AI-powered, smart insole that instantly turns any shoe into a portable gait-analysis laboratory. The work could give clinical researchers a new way to precisely measure walking function in patients with movement disorders or musculoskeletal injuries, in their living environments. The technology could also help athletes improve their running technique. 

“From a practical standpoint, that’s invaluable,” said Damiano Zanotto, lead author and director of Stevens Wearable Robotic Systems Lab. “We’re now able to accurately analyze a person’s gait in real time, in real-world environments.”

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Capturing reliable information about a person’s gait in real-life environments remains challenging for researchers. Standard gait-analysis technologies, such as camera-based motion-capture systems and force plates, are expensive and can only be used inside laboratories, so they offer few insights into how people walk around in the real world. Emerging wearable technologies such as smart shoes, pods, and insoles can potentially overcome this limitation, but the existing products cannot provide accurate gait data.

In their work, Zanotto and his team show that their smart insole can deliver real-time data on the length, speed, and power of a wearer’s stride with better accuracy than existing foot-worn technologies—and at a fraction of the cost of traditional laboratory equipment.

The team’s SportSole technology uses accelerometers and gyroscopes to monitor its own movement and orientation in space and an array of force sensors to detect plantar pressure, allowing it to capture 500 readings per second—around a fivefold improvement over smart pedometers and other wearable gait-analysis tools. 

Because wearable motion sensors are inherently noisy, Zanotto processes those 500 measurements per second down to just a few key features, then feeds the results into an AI algorithm that can rapidly extract gait parameters that are accurate to within a couple of percentage points.

The smart sole works regardless of whether the wearer is walking or running and generates accurate results without requiring calibration or customization for individual users. Preliminary testing suggests the SportSole even works with children as young as three years of age and elderly users with vestibular disorders, whose gait patterns are very different from those of healthy adults. 

Noteworthy in the smart insole is the use of off-the-shelf sensors that will ultimately make the technology easier to scale. According to the researchers, the sensors used cost around $100, accompanied by AI to extract reliable data. “We’re achieving the same or better results at a far lower cost, and that’s a big deal when it comes to scaling this technology,” said Zanotto.

The team is currently focusing on testing the SportSole for clinical use.

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