Artificial Biometric Finger Driven by Shape‐Memory Alloy Wires

Abstract

This paper presents the design and testing of an artificial finger based partly on biomechanics. The prototype was manufactured in acrylonitrile butadiene styrene plastic using a rapid prototyping three-dimensional printer. The flexing of the finger was realized by Ni-Ti shape-memory alloy (SMA) wires with diameters of 0.3 mm, activated by resistive heating. The results obtained show the new prototype to be superior in performance, mainly in terms of angles of rotation of the phalanges, compared with some SMA fingers discussed in the literature.

Stress serration and arch-shaped Lüders stress plateau behaviour of Ti–50.8 at% Ni wire prepared by selective electrical resistance over-aging

“…The superelastic behaviour of laser welded NiTi was also studied recently [30]. Joule heating of NiTi wires is also used for some specific applications, such as shape setting for artificial biometric fingers [31] and microelectromechanical system (MEMS) devices [32,33]. Such unconventional heat treatment techniques also offer opportunities to create novel properties, such as functionally graded NiTi materials [22,34].…”

Application of artificial vision as measurement validation tests on a robotic hand driven by shape-memory alloys

“…Observing Figure 7, it is possible to verify the obtained result. Although Silva [12] have obtained the result to the proximal phalanx of 90°, i.e., 3° or even 3.33% more than this work, it is important to note that was demanded about 40 seconds to reach its maximum . Already in Figure 6 it can be seen that the proximal phalanx reached a maximum angle of 87° in just 5 seconds.…”

“…The angle obtained by the proximal phalanx θpp, with activation in open loop was 87° in a time of about 5 seconds. In this aspect, it is possible to make a comparison with Silva work [12], which defined the start and end position as human physiology, i.e. initially 40° and 90° in the final position, driven by SMA wire.…”

“…Silva et al [12] have developed a robotic finger with three phalanges, and the measurement of the angles made by image processing. Bundhoo et al [6] have developed a finger wherein phalanges angle measurements were performed using a resistive sensor, Flexsensor.…”

“…Activation and response of the proximal phalanx to open loop of the finger developed by Silva[12]. a) Step of current of 0.9 A b) the angular response as a function of time.…”