Abstract
This paper presents a compact rotary motor based on SMA wire bundles. The high energy density of SMA wires enables the realization of high forces with minimal space and weight input and the SMA wire resistance provides sensing information, which can be used for position control.
The actuator system operates in a 90° range of motion. The linear force of two antagonistic SMA wire bundles are transmitted into a rotation by an innovative gear rack drive. This transmission is also key to the compact design because SMA force is transmitted into increased stroke and thus rotational motion. The forces are scaled by bundling of thin SMA wires. The design allows bundling of up to 20 SMA wires with a diameter of 100 μm in parallel.
Lastly, driving and sensing electronics based on a microcontroller is integrated, and standardized plugs or connectors provide the interface for different possible applications. The electronics can use the electrical resistance of the SMA wire bundles to track actuator position and provides different communication standards like LIN Bus for automotive applications.