The first SEMA motors designed in 1990 were intended for use as high-torque, direct-drive servo motors. Since that time, a number of advances in manufacturing, motor cooling, and design tools for SEMA motors have been made. SEMA motors have a number of advantages over conventional motor designs that make them particularly good for both position and speed servo applications
Position Servo Applications
The high peak torque capability of SEMA technology makes it an excellent candidate for direct-drive position servo applications. An additional advantage of the ironless SEMA motor is that there is no preferred rotor position, common in other motors due to magnetic attraction of the rotor to the stator, because there is no iron in the stator for the permanent magnets of the rotor to be attracted to. The first tests of the SEMA motor design were position servo applications in industrial robots. Since that time, a number of other applications have been tested, including robotic weapons systems.
Speed Servo Applications
Some high-end speed servo applications, such as optical lens grinding, require very low ripple torque in the drive motor. In these demanding applications, there is no better choice than a SEMA motor. Ironless SEMA technology eliminates the cogging torque associated with typical iron-core motors. Additionally, the high torque capabilities of SEMA motors allow direct drive in most applications, eliminating the gear lash associated with gear-drive systems. Existing commercial partners have developed a number of products aimed at meeting the demands of precision servo applications, with new products currently in the works.