Force sensor for cable actuator

A measuring method for measuring a force applied at the output of a cable actuator comprising:

• a frame;
• a screw mounted on the frame and extending along a first axis;
• a nut co-operating with the screw;
• a first cable coupled to the nut and functionally connected to an output of the cable actuator;
• and
• a motor arranged to drive the screw in rotation;
• the first cable being arranged to exert forces opposing the nut being driven in rotation by the screw so as to constitute anti-rotation means such that rotation of the screw under drive from the motor causes the nut to move along the screw;
• the measuring method for measuring a force comprising the following steps:
• determining the actual position of the nut relative to the frame;
• comparing the actual position of the nut relative to the frame with a theoretical position for the nut relative to the frame in order to obtain a position deviation of the nut;
• and
• determining a force applied to the output of the cable actuator as a function of the position deviation of the nut.

A method of determining prior loading of a cable actuator comprising:

• a frame;
• a screw mounted on the frame and extending along a first axis;
• a nut co-operating with the screw;
• a first cable coupled to the nut and functionally connected to the output of the cable actuator;
• and
• a motor arranged to drive the screw in rotation;
• the first cable being arranged to exert forces opposing the nut being driven in rotation by the screw so as to constitute anti-rotation means such that rotation of the screw under drive from the motor causes the nut to move along the screw;
• the method of measuring the prior loading comprising the following steps:
• bringing the nut to a predetermined position relative to the frame;
• holding the output of the cable actuator stationary;
• controlling the motor so that it applies a predetermined torque to the screw determining the actual position of the nut relative to the frame;
• comparing the actual position of the nut relative to the frame with the predetermined position for the nut relative to the frame in order to obtain a position deviation of the nut;
• and
• determining the prior loading acting at least on the first cable as a function of the position deviation of the nut.