Active Gravity Compensation Actuator Using the Multistability of Magnetic Shape Memory

An active contactless gravity compensation system is presented using multistable magnetic shape memory (MSM) actuators to adjust permanent magnet (PM) forces. MSM alloys are smart materials, which can be activated by a magnetic field to generate force and motion based on a solid state effect. Due to the solid state effect very low wear is generated. This makes the system beneficial for high precision and vacuum applications, in which a contamination of the system needs to be prevented. As MSM materials have a high strain of up to 6 %, the position of permanent magnets, and thus their forces to a movable object can be significantly changed and precisely adjusted. MSM elements have an internal holding force (so-called twinning force), so different positions can be actuated and will be held without the use of external energy. Thanks to this multistability, the power dissipation of the overall system can be significantly reduced.