the present invention provides a dynamic chair having a deterministic motion path that allows a variety to different paths to be selected depending of needs of user . by changing the ratio between drive wheels that control the pitch and roll of the seat , motion paths can be selected to help a person assume and / or avoid certain postures while seated . embodiments of the present invention move the seat of the dynamic chair through a deterministic path to dictate how often and when the seat is in a level position with respect to pitch and roll .