1. A method of providing postural feedback comprising: receiving by a microprocessor at repeated intervals data from a tri-axial accelerometer, the microprocessor and the tri-axial accelerometer comprising a sensor device attached to a user, the sensor device further comprising memory, an actuator, and a power source; normalizing by the microprocessor the received accelerometer data; determining by the microprocessor a postural description of the user based on the normalized received accelerometer data, wherein the postural description comprises a movement state and posture quality, wherein determining the postural description of the user comprises: computing a sequence of accelerometer data features from the normalized received accelerometer data, analyzing the sequence of accelerometer data features according to a rule-based model to determine, in part, the movement state and the postural description; and triggering by the microprocessor the actuator to output sensory feedback based on the postural description of the user.