What device is characterized as a self-balancing, electric-powered vehicle designed for a single rider?

The device described in the question is best characterized as an Electric Personal Assistive Mobility Device, commonly abbreviated as EPAMD. This classification includes vehicles that are designed for individual mobility and are operated electrically. The term encompasses various types of devices, often emphasizing their self-balancing feature and suitability for a single rider, which aligns perfectly with the definition provided in the question.

While options like the Segway and hoverboard are also self-balancing electric vehicles, they are specific examples of EPAMDs. A Segway is a well-known brand that fits this description but is not synonymous with the broader category, whereas a hoverboard typically refers to a more casual device that uses foot movement for operation rather than a handle or control mechanism.

Electric scooters, on the other hand, do not typically exhibiting the self-balancing feature associated with the other options. They are designed for a different riding experience, usually requiring the rider to stand on a platform without the balance technology. Therefore, the most encompassing term applicable to the described device is Electric Personal Assistive Mobility Device.