Three-degrees-of-freedom joint with force feedback

Joint with three degrees of freedom for a robot, comprising a platform (2), three motors (3a, 3b, 3c) each connected to a ring (4, 4a, 4b, 4c) by means of a pinion (5a, 5b, 5c), each ring (4, 4a, 4b, 4c) being disposed inside a hollow disc (6a, 6b, 6c) stacked on a base (B), so that each disc (6, 6a, 6b, 6c) is secured to a ring (4, 4a, 4b, 4c), each disc (6, 6a, 6b, 6c) is moreover itself secured to a disc head (7, 7a, 7b, 7c) extending in the same direction as the stack of the base (B) and discs (6, 6a, 6b, 6c), for each disc head (7, 7a, 7b, 7c), an arm (8, 8a, 8b, 8c) is rotatably connected firstly to the disc head (7, 7a, 7b, 7c) and secondly to the platform (2), the platform being connected to the base (B) and to the hollow discs only by the three arms (8, 8a, 8b, 8c), characterised by the fact that the joint with three degrees of freedom comprises a sphere(S) connected to the base (B) by a cylindrical bar (T), the sphere(S) being disposed at the centre of a cylindrical opening provided at the centre of the platform (2), the sphere(S), the cylindrical bar (T) and the base (B) cooperating in order to achieve a transfer of forces from those generated at the platform (2) and arms (8, 8a, 8b, 8c).