Abstract: The device comprises three parts, the first part being constituted by a rigid frame of rectangular shape with means for support and flexible elements to be attached to the body of the operator and a rigid element adapted to support the second part. The second part comprises three structures of which: (1) the first structure consists essentially of a longitudinal rigid element (11) connected at one end to the rigid support element (10) of the first part by coupling means which permit freedom of rotation according to a vertical axis; (2) the second structure consists of a rigid elongated box (12) connected to the other end of said first element (11) by coupling means with freedom of rotation around a vertical axis; and (3) the third structure consists of a lever (13) which has its fulcrum in the second structure by means of coupling means with freedom of rotation around a horizontal axis.