阅读说明：本技术 检测一个长度段的形状记忆合金线的松弛程度 (Detecting the degree of relaxation of a length of shape memory alloy wire ) 是由 杰弗里·法默 于 2019-09-26 设计创作，主要内容包括：使用从不同的取向捕捉的一个长度段的SMA线的图像来检测该长度段的SMA线的松弛程度。对图像进行分析,以确定该长度段的SMA线的三维路径,并由此导出松弛程度的度量。该方法提供了可以在SMA致动器组件的制造期间使用的精确度量。(The degree of slack in a length of SMA wire is detected using images of the length of SMA wire captured from different orientations. The image is analysed to determine the three-dimensional path of the length of SMA wire and to derive therefrom a measure of the degree of relaxation. The method provides accurate metrology that can be used during manufacture of the SMA actuator assembly.)

1. A method of detecting the degree of relaxation of a length of shape memory alloy wire which remains relaxed, wherein the method uses images of the shape memory alloy wire captured from different orientations and comprises performing an analysis on the images, the analysis deriving a measure of the degree of relaxation of the wire.

2. The method of claim 1, wherein the step of performing an analysis on the image comprises:

determining a three-dimensional path of the shape memory alloy wire from the image; and

deriving a measure of the slack of the line from the determined three-dimensional path.

3. The method of claim 2, wherein the step of determining the three-dimensional path of the shape memory alloy wire comprises:

detecting the shape memory alloy wire in the image;

determining a two-dimensional path of the detected shape memory alloy wire in each image; and

deriving the three-dimensional path from the determined two-dimensional path.

4. A method according to claim 2 or 3 wherein the measure of the degree of relaxation of the shape memory alloy wire is the difference between the length of the three dimensional path of the shape memory alloy wire and the distance between the ends of the shape memory alloy wire.

5. The method of any preceding claim, wherein the images of the shape memory alloy wire are images captured from at least two orthogonal orientations.

6. A method according to any preceding claim, wherein the resolution of the image is selected such that this width of the shape memory alloy wire corresponds to at least 3 pixels in the image.

7. The method according to any one of the preceding claims, wherein the length of shape memory alloy wire is held loose between crimped portions crimped around the length of shape memory alloy wire.

8. The method of claim 7, wherein the length of shape memory alloy wire is held loose between crimped portions crimped around the length of shape memory alloy wire in a shape memory alloy subassembly comprising at least one body portion integrally formed from a sheet of material with a pair of crimped portions.

9. The method of claim 7, wherein the length of shape memory alloy wire is held slack between crimping portions that are crimped around the length of shape memory alloy wire and mounted respectively on a static portion and a movable portion in a shape memory alloy actuator assembly, the movable portion being movable relative to the static portion.

10. The method of claim 8, wherein the movable portion is an optical element.

11. The method of claim 9, wherein the movable portion is a lens element comprising at least one lens.

12. The method of any preceding claim, further comprising adjusting the degree of relaxation of the length of shape memory alloy wire in response to the derived measure.

13. The method of claim 12, wherein the length of shape memory alloy wire initially remains relaxed between crimped portions partially crimped around the length of shape memory alloy wire, and the method further comprises fully crimping the crimped portions around the length of shape memory alloy wire after the step of adjusting the degree of relaxation of the length of shape memory alloy wire.

14. A non-transitory data carrier carrying processor control code to implement the method of any one of claims 1 to 13.

15. An apparatus for detecting the degree of slack in a length of shape memory alloy wire that remains slack, the apparatus comprising:

at least one camera for capturing images of the shape memory alloy wire from at least two different orientations; and

at least one processor configured to:

analyzing the captured image; and

deriving a measure of the extent of slack of the line from the analysis.

16. The apparatus of claim 15, wherein the apparatus comprises a single camera disposed on a moveable mount, and the at least one processor is configured to:

generating a control signal to move the moveable mount to enable the camera to capture images from the at least two different orientations.

17. The apparatus of claim 15 or 16, wherein the at least one processor:

adjusting a degree of relaxation of the length of shape memory alloy wire in response to the derived metric.