One challenge in multimodal interface research is the lack of robust subsys
tems that support multimodal interactions. By focusing on a chair-an object
that is involved in virtually all human-computer interactions, the sensing
chair project enables an ordinary office chair to become aware of its occu
pant's actions and needs. Surface-mounted pressure distribution sensors are
placed over the seatpan and backrest of the chair for real time capturing
of contact information between the chair and its occupant. Given the simila
rity between a pressure distribution map and a grayscale image, pattern rec
ognition techniques commonly used in computer and robot vision, such as pri
ncipal components analysis, have been successfully applied to solving the p
roblem of sitting posture classification. The current static posture classi
fication system operates in real time with an overall classification accura
cy of 96% and 79% for familiar (people it had felt before) and unfamiliar u
sers, respectively. Future work is aimed at a dynamic posture tracking syst
em that continuously tracks not only steady-state (static) but transitional
(dynamic) sitting postures. Results reported here form important stepping
stones toward an intelligent chair that can find applications in many areas
including multimodal interfaces, intelligent environment, and safety of au
tomobile operations.