title: Anthropomorphic finger antagonistically actuated by SMA plates.
abstract: Most robotic applications that contain shape memory alloy (SMA) actuators use the SMA in a linear or spring shape. In contrast, a novel robotic finger was designed in this paper using SMA plates that were thermomechanically trained to take the shape of a flexed human finger when Joule heated. This flexor actuator was placed in parallel with an extensor actuator that was designed to straighten when Joule heated. Thus, alternately heating and cooling the flexor and extensor actuators caused the finger to flex and extend. Three different NiTi based SMA plates were evaluated for their ability to apply forces to a rigid and compliant object. The best of these three SMAs was able to apply a maximum fingertip force of 9.01N on average. A 3D CAD model of a human finger was used to create a solid model for the mold of the finger covering skin. Using a 3D printer, inner and outer molds were fabricated to house the actuators and a position sensor, which were assembled using a multi-stage casting process. Next, a nonlinear antagonistic controller was developed using an outer position control loop with two inner MOSFET current control loops. Sine and square wave tracking experiments demonstrated minimal errors within the operational bounds of the finger. The ability of the finger to recover from unexpected disturbances was also shown along with the frequency response up to 7 rad s(-1). The closed loop bandwidth of the system was 6.4 rad s(-1) when operated intermittently and 1.8 rad s(-1) when operated continuously.
authors: Florida Atlantic University, Ocean and Mechanical Engineering Department, 777 Glades Road; Bldg. 36, Room 190, Boca Raton, FL 33431, USA. The University of Akron, Mechanical Engineering Department, ASEC, Room 101, Akron, OH 44325-3903, USA.
authors: Erik D
authors: ED
authors: Engeberg
authors: Savas
authors: S
authors: Dilibal
authors: Morteza
authors: M
authors: Vatani
authors: Jae-Won
authors: JW
authors: Choi
authors: John
authors: J
authors: Lavery
mesh_terms: D000497:Alloys / Q000737:chemistry*; D032701:Biomimetics / Q000295:instrumentation*; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005385:Fingers / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012371:Robotics / Q000295:instrumentation*; D013314:Stress, Mechanical; D014159:Transducers
chemical_list: D000497:Alloys