Force sensor for cable actuator

Patent metadata

Field	Value
Publication number	US-11815417-B2
Application number	US-202016801723-A
Country	US
Kind code	B2
Filing date	Feb 26, 2020
Priority date	Feb 26, 2020
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

An actuator having a nut (4) co-operating with a screw (2); a first cable (6) coupled to the nut and functionally connected to an output (16, 17, 22.4) of the actuator (100); and a motor (3) arranged to drive the screw (2) in rotation. The actuator also has a mechanism (92) for comparing the actual position of the nut relative to the frame (10) with a theoretical position for the nut relative to the frame (10) in order to obtain a position deviation (δang4, δlin4) of the nut; and a mechanism (93) for determining a force applied to the output (22.4) of the cable actuator (100) as a function of the position deviation of the nut. Also disclosed is a method of measuring a force applied to an output (16, 17, 24.1) of an actuator (100), and to a method of determining prior loading (t6,9) of a cable actuator (100).

First claim

The invention claimed is:

1. A cable actuator comprising:
a frame;
a screw rotatably 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 actuator;
a second cable coupled to the nut and functionally connected to the output of the 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 cable actuator also comprising:
means for determining an actual position of the nut relative to the frame;
means for 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
means for determining a force applied to the output of the cable actuator as a function of the position deviation of the nut.

2. A cable actuator according to claim 1 , wherein the position deviation of the nut is an angular deviation measured about the first axis.

3. A cable actuator according to claim 2 , wherein the means for determining the actual position of the nut relative to the frame comprise a linear magnetic core secured to the frame and magnetic field induction means connected to the nut.

4. A cable actuator according to claim 2 , wherein the means for determining the actual position of the nut relative to the frame comprise a reflector secured to the frame and a distance sensor connected to the nut.

5. A cable actuator according to claim 4 , wherein the distance sensor comprises a wave transceiver.

6. A cable actuator according to claim 2 , wherein the means for determining the actual position of the nut relative to the frame comprise a distance sensor secured to the frame and a target connected to the nut.

7. A cable actuator according to claim 6 , wherein the distance sensor comprises a wave transceiver.

8. A cable actuator according to claim 2 , wherein the means for determining the actual position of the nut relative to the frame comprise a plurality of magnetic poles secured to the nut and a magnetic sensor.

9. An actuator according to claim 8 , including a magnetic exciter for applying a force on at least one magnetic pole.

10. A cable actuator according to claim 2 , wherein the means for determining the actual position of the nut relative to the frame comprise a mechanical coupling connecting a first element connected to the frame with a second element secured to the nut, the first element comprising:
a third shaft mounted on the frame to rotate about an axis substantially parallel to the first axis;
a bushing slidably mounted on the third shaft and provided with means for preventing relative rotation between the bushing and the third shaft; and
a rotary encoder for measuring rotation of the third shaft.

11. A cable actuator according to claim 10 , wherein the mechanical coupling comprises a flexible link.

12. A cable actuator according to claim 11 , wherein the flexible link has a first end provided with a ball joint connection with one of the first and second elements, the flexible link having a second end with a fixed connection to the other one of the first and second elements.

13. A cable actuator according to claim 10 , wherein the mechanical coupling comprises a rigid connecting rod having a first end provided with a ball joint connection with one of the first and second elements, the connecting rod having a second end provided with a pivot connection with the other one of the first and second elements.

14. A cable actuator according to claim 10 , wherein the mechanical coupling comprises a first branch having a first end connected by a ball joint connection to a first end of a second branch, the first branch having a second end secured to one of the first and second elements, and the second branch having a second end secured to the other one of the first and second elements, the second branch including a telescopic portion.

15. A cable actuator according to claim 10 , wherein the rotary encoder possesses a motor mode that applies an excitation force to the nut.

16. A cable actuator according to claim 1 , wherein the position deviation of the nut is a linear deviation measured along the first axis.

17. A cable actuator according to claim 16 , wherein the means for determining the actual position of the nut relative to the frame comprise a distance sensor having a wire winder secured to the frame, one end of a wire of the wire winder being connected to the nut.

18. A cable actuator according to claim 17 , wherein the distance sensor possesses a motor mode that applies an excitation force to the nut.

19. A cable actuator according to claim 16 , wherein the means for determining the actual position of the nut relative to the frame comprise a distance sensor secured to the frame and a target connected to the nut.

20. A cable actuator according to claim 1 , wherein the output of the cable actuator is a shaft rotatably mounted on the frame.

21. A cable actuator according to claim 1 , wherein the output of the cable actuator is slidably mounted on the frame.

22. 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:
determining an 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.

23. A measuring method according to claim 22 , wherein the position deviation of the nut is an angular deviation about the first axis.

24. A measuring method according to claim 22 , wherein the position deviation of the nut is a linear deviation along the first axis.

25. 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 determining prior loading comprising:
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

Assignees

• Commissariat Energie Atomique

Inventors

• Garrec Philippe

Classifications

• G01L5/06 Primary

  using mechanical means {(G01L5/042, G01L5/045 take precedence)} · CPC title

• B25J13/088

  with position, velocity or acceleration sensors · CPC title

• F16H25/2015

  Means specially adapted for stopping actuators in the end position; Position sensing means · CPC title

• G01D5/142

  using Hall-effect devices (measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06) · CPC title

• G01D5/26

  characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light · CPC title