Cable actuator with improved force sensitivity

A cable actuator (100) comprising:

• a frame (10);
• a screw (2) rotatably mounted on the frame (10) and extending along a first axis (Ox);
• a nut (4) cooperating with the screw (2);
• a first cable (6) coupled to the nut (4) and functionally connected to an outlet (16, 17, 22.4) of the actuator (100);
• a second cable (9) coupled to the nut (4) and functionally connected to the outlet (22.4) of the actuator (100);
• and
• a motor (3) arranged to drive the screw (2) in rotation;
• the first cable (6) being arranged to exert forces that oppose the nut (4) being driven in rotation by the screw (2) so as to constitute anti-rotation means such that turning of the screw (2) under drive from the motor (3) causes the nut (4) to move along the screw (2) between a first extreme position (E1) and a second extreme position (E2) that define a stroke (C) for the nut (4);
• and
• the cable actuator (100) also comprising:
• means (30) for estimating the angular movement of the nut (4) about the first axis (Lx) relative to the frame (10);
• and
• a control unit that estimates the force being applied to the outlet (22.4) of the cable actuator (100) as a function of the angular movement of the nut (4) about the first axis (Ox);
• wherein the means (30) for estimating the angular movement of the nut (4) comprise a distance sensor (30) secured to the frame (10) and using a thread (32) to sense distance, one end (32.1) of the thread (32) being connected to the nut (4) at a connection point (4.1);
• and
• wherein the distance sensor (30) is arranged in such a manner that the thread (32) changes curvature at a first point (34) situated in a first plane (P1) orthogonal to the first axis (Ox), the first plane (P1) being situated at a first distance (d1) from the first extreme position (E1) that lies in the range 30% to 70% of the stroke (C);
• and
• wherein the thread has at least a portion extending between the first point and the end of the thread connected to the nut, said portion extending orthogonally or at an incline relative to the first axis.