Ergonomic support device for the body of the occupant, for chairs or seats, particularly for motor-vehicle seats

A chair or a seat, in particular a seat for motor vehicles, includes an ergonomic device for supporting the body of the occupant, comprising a supporting panel having supporting laths, set at a distance from one another, which can be arched towards the body of the occupant, each independently of the others, by a respective actuator, which includes an actuator element constituted by a shape-memory material, which undergoes a reduction in length following upon heating above a predetermined transition temperature, higher than ambient temperature. Associated to the panel are electrical-supply means for supply of the shape-memory actuators and electronic control means for activating the laths independently and/or in succession according to any predetermined logic, in particular according to successive waves of activation, for example from above downwards, or from below upwards, or alternately from above and from below, so as to obtain a massaging effect.