Detecting degree of slack of a length of shape memory alloy wire

摘要

Images of a shape memory alloy (SMA) wire 20 are captured from different orientations, analysis is performed on the images to derive a measure of the degree of slack of the wire. Performing an analysis of the images may comprise determining a three-dimensional (3D) path of the wire. Determining the 3D path of the wire may comprise detecting the wire in the images, determining the two-dimensional (2D) path of the wire in each image, and deriving the 3D path from the 2D paths. The measure of the degree of slack of the wire may be the difference between the length of the 3D path of the wire and the distance between the ends of the wire. The images may be captured from at least two orthogonal orientations. The resolution of the images may be selected so that the width of the wire corresponds to at least 3 pixels. The degree of slack of the wire may be adjusted in response to the derived measure.