Design and control strategies for SMA actuators in a feed axis for precision machine tools

Abstract

In a current project, the Chair of Production Systems (LPS) is examining the use of standardized shape memory alloy (SMA) actuators in the feed axis of a small machine tool. These machines are used to manufacture small work pieces with high precision. Therefore, the actuators must be qualified to handle movements in the micrometer range. To achieve this goal, different design elements for the actuators are considered, as well as different measures to control the actuator. In the scope of this paper, binary actuators with just two possible positions are examined next to actuators that can reach every possible intermediate position. For the latter, different control strategies are proposed. The displacement of the actuators can either be measured by external sensors or by using the change in resistance in the SMAs during transformation as feedback.