Distributed type of actuators of shape memory alloy and its application to underwater mobile robotic mechanisms.

Abstract

This paper reports the key features of a new type of actuator based on shape memory alloy (SMA) and its application to mechanisms of underwater mobile robots. The proposed actuator consists of several modes of SMA, so that any shapes can be produced as the synthesized sum of excited modes, like the mode expansion and synthesis. Thus, the actuator shows the characteristics of the distributed parameter type of actuators with a specified number of modes. In this paper, the following aspects are described: (i) A flat-belt type of SMA is employed and its bending characteristics are examined. (ii) A synthetic method of wave forms is presented. (iii) Applying the proposed distributed actuators to the underwater mobile robot, mechanisms such as fish fins are shown to obtain thrust forces in the water. (iv) The shape of the actuator is experimentally verified to be similar to the computed shape, as expected. As a result, the proposed distributed actuator shows the possibility of applications to distributed parameter shape control.