In this research, commercially available Nickel-Titanium based shape memory alloy actuators are used to design and develop a novel bundled actuator. The bundled actuators are then used in a special configuration to actuate and control a low cost one degree of freedom (dof) anthropomorphic finger. SMAs possess hysteretic and nonlinear behaviour when heated (actuated) and cooled (relaxed). Hence, a full understanding of the behaviour of these actuators is essential to control them. In order to characterise the behaviour of the actuators, an instrumented test rig was designed and developed to characterise the commercially available Nickel-Titanium SMA actuators obtained from the two manufacturers. The test rig was equipped with the laser displacement sensor, the load cell and the thermocouple. All the measurements were taken by a PC based data acquisition system. Nickel-Titanium based SMA actuators (Flexinol® and Biometal'") obtained from the two manufacturers were characterised using the test rig. The Flexinol'" actuator was selected for the use in the bundled actuator on the basis of better drift property. The existing bundle designs are merely a parallel arrangement of individual actuators crimped or screwed to the end plates on both sides. However, this may cause uneven strains (and forces) in individual actuators of the bundle. The novel bundle proposed in this research used a single 960 mm long actuator looped around frictionless supports to form a 12-string bundled actuator. Design and simulation of a one dof finger was carried out by using a set of three bundled actuators arranged in a special configuration. This made it possible to use a simple control to achieve seven possible for the proposed finger.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:578624 |
| Date | January 2012 |
| Creators | Daudpoto, Jawaid |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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