Shape Memory Actuator for Drones

In compact drone systems, mechanical functions must be implemented reliably within very limited space. Conventional solutions using electric motors, gearboxes, or electromagnetic actuators often increase weight, installation space, and complexity. Actuators made from shape memory alloys offer an alternative.

Together, the Fraunhofer Institute for Machine Tools and Forming Technology IWU and Vectorbirds Airborne Systems GmbH & Co. KG developed such an actuator for locking the battery tray of a drone.

Compact Locking Mechanism with Nickel-Titanium Wire

Shape memory alloys can change their shape through a controlled change in temperature. When the nickel-titanium wire used in the actuator is electrically heated, it contracts and thereby generates mechanical movement. After cooling, a return spring moves the mechanism back to its initial position.

The developed solution is used in the AERIS Recon S7 from Vectorbirds. This compact reconnaissance drone system was previously marketed under the name Grabbit G7.

During flight operations, a spring-loaded slider securely holds the battery tray in position. This prevents the power supply from being disconnected unintentionally. When the battery needs to be replaced, the nickel-titanium wire is briefly heated electrically. It retracts the slider against the spring force and releases the battery tray.

After cooling, the return spring automatically moves the slider back into the locked position. At the same time, the wire is preloaded for the next switching cycle. In the configuration examined, the wire used has a diameter of only 76 micrometers.