Self-sensing actuator based on MSM

AdaptaMat Oy, manufacturer of single crystal Magnetic Shape Memory (MSM) smart metals, has built a self-sensing actuator demonstrates functional properties of MSM alloy by combining two material features in one practical application. Simultaneous proportional elongation in a magnetic field (MSM effect) and proportional resistance change of the very same MSM element makes it possible to have a proportionally controllable actuator without any external position sensors or devices. Thus any MSM actuator can be turned into a proportionally controllable and self-sensing device simply by measuring the resistance of the MSM-element within the device.

When an actuator is built, its movements can be controlled by controlling the strength of the magnetic field, and the position is known by measuring the resistance of the same piece of material. This combination may be used for open or closed loop control of the device. In control mode, the elongation of the actuator can be set accurately in a fraction of a second to any given position within the full operating range of the actuator.

Other functional properties of the MSM alloy are:
1. Villari effect i.e. inverse magnetostriction.
2. Permeability of the material changes proportionally to element's length.
3. Material can be used as a traditional Shape Memory Alloy, but up to very high temperatures of 400ºC