A posture support system for a person supporting appliance comprising: a module (300), each module (300) comprising: an expandable body (20), means (60) for changing the degree of expansion of the expandable body (20) a sensor (27) configured to produce measurement data corresponding to the degree of expansion of the expandable body (2) a processor (116) arranged to process the measurement data generated from the sensor (27) and a wireless communication unit (114) arranged to transmit the measurement data wirelessly to a controller (320) and receive control data to control the degree of expansion of the expandable body (20).
