Shape memory actuators with inherent self guiding function
The down scalability of conventional actuators is limited by their physical working principles. This applies especially for micro actuators resulting in a massive disproportion between Workspace and cross section.
These scaling effects don’t apply to Shape Memory Alloys (SMA) resulting in an out-standing potential for micro actuator design. However, like conventional actuators SMA based actuators usually require guidance which negatively affect their cross section, mass and complexity. Hence, avoiding separate guidance would further reduce their mass, cross section and complexity. A possible approach is based on an angular difference between the direction of the SMA wire and working direction. Hereby, the stiffness of an SMA-wire is split into a longitudinal and a transversal component.
This approach possesses to design actuators with different workspace geometries like linear or rotary ones. The design process for the described solid state actuators is characterized by opposing demands. A high blocking force will, for example, lead to a small load-free stroke. This is a complex correlation between the vector of the variables for design and specification. To achieve a straightforward design process it can be formulated as a mathematical optimization problem to calculate the design parameters. This optimization process has been used to develop both a rotary and a linear actuator. For validation the actuators were experimentally investigated.