Abstract: A device for providing an indication of brushing activity of a toothbrush comprises an accelerometer configured to produce acceleration data from motion of the toothbrush, and components for filtering the acceleration data to produce gravitational components and filtering the acceleration data to produce linear acceleration components. The device further comprises a component for projecting the gravitational components and the linear acceleration components into an n-dimensional space, where and for performing a clustering process on the projections of gravitational components and linear acceleration components into n-dimensional space to produce clustering results. The clustering results comprise a plurality of clusters each of which represents a brushing area.

Abstract: A system for determining the orientation of a toothbrush (4), the system comprising an orientation sensor (27) configured for attachment to a toothbrush (4) and one or more processors (29) configured to receive orientation information from the orientation sensor (27). The one or more processors (29) are further configured to determine whether the sensor (27) is in a first orientation (41) or a second orientation (33). The first orientation (41) corresponds to use of the toothbrush (4) on a surface of teeth on the left (42) of a user's mouth. The second orientation (33) corresponds to use of the toothbrush (4) on a surface of teeth on the right (40) of a user's mouth.