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st:roll, Smart helmet for personal mobility

A helmet capable of real-time interaction with the driving environment


What it does

Through the smart helmet St:roll which is capable of real-time interaction with the driving environment, users will be able to prevent road accidents in advance through the functions that ensure physical and psychological safety.

Your inspiration

As the number of micro-mobility users grows, related accidents have increased rapidly. As a result, the smart helmet market for micro-mobility users is growing, but existing smart helmets only provide functions for entertainment (e.g. Bluetooth mic, mp3, etc), and there are few safety functions to prevent accidents in advance. There is only a function that minimizes damage only in the case of an accident. Also, existing helmets are designed for bike users. Therefore, in this project, we developed a smart helmet that can interact with the driving environment in real-time to prevent accidents in advance for micro-mobility users.

How it works

The turn signal light is used to indicate the user's intention to change direction. A rolling type head gesture that tilts the head left or right is used to operate the turn indicator. When the users tilted more than 15° degrees, the right or left turn signal light blinks depending on the direction. A Kalman filter was used to correct the abnormal input value in the programming setup. The rear approach warning light is used to inform the user of the situation approaching mobility from behind. The radar sensor located on the back detects the speed and size of the rear object. If the relative velocity of an approaching object is more than 15 km/h, it is recognized as a fast-approaching vehicle and the rear approach warning light blinks 3 times. The rear stop light is used to inform the rear mobility of the user's stop. When the acceleration value measured by the IMU exceeds the threshold, it is recognized as a sudden stop and the rear stop light blinks 3 times.

Design process

In-depth interviews with a variety of micro-mobility users were conducted, and natural interactions were observed while riding on the road using the Shadowing method. We observed the user's natural interaction with the environment, people, objects, and information that affect the user's experience while driving. And we set our project goal as “Design smart helmet as a means of communication on the road for micro-mobility users.” Following that, three key functions of the smart helmet were set. First, in the use case of conveying the intention to change direction, the usability test was conducted to determine which method is more suitable for the micro-mobility user's input method among the existing hand button type and the head gesture with working prototypes. Second, in the use case of the rear approach warning light, we found an interaction method that could appropriately recognize information without interfering with micro-mobility users' driving experience. Third, in the case of the usage of the rear light when sudden stops, we detected the user's sudden stop through the IMU sensor built into the helmet. For a more user-centered product, helmet prototypes including the above functions were developed three times and more. Finally, we finished the fully working product.

How it is different

An existing smart helmet is not appropriate for micro-mobility users. First, only three helmet brands, SENA, LUMOS, and LIVALL, are equipped with a turn signal light. These are designed for bike riders because they are all controlled by a physical button mounted on the steering wheel. But micro-mobility has small wheels, unlike a bike, the rotational moment of inertia is low, so it is easy to lose balance when pushing buttons by hand, and some micro-mobility (e.g. electric wheel) does not have a handle to a mount push button. Second, information is only communicated in one way. Only some existing smart helmets are equipped with functions that convey the user's intention to the surrounding, such as the stop or slow down, so users cannot interact with the driving environment. So, users conduct head gesture to convey their intention to turn to the environment and are reassured by detecting the driving environment and recognizing it them in real-time with St:roll.

Future plans

First, we will complete the registration of patents in Korea and China. Through our St:roll, we will promote the safety of all stakeholders on the road, and further positively influence the flow of traffic throughout the city. We are also interested in developing a higher quality product with cost reduction and offering service with receiving royalties from shared mobility service providers.


15th Hongik University Capstone design fair, Grand Prize. 2021 Korea Capstone design fair, First prize Korea Patent No. 10-2021-0106568. China Patent No. 202111497302.0. (In-progress) Intellectual property rights in Korea. No. 30-2021-0034706. / No.30-2021-0034707. / No.30-2021-0034708.

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