The magnetic joint actuator is a relatively recent research technology that expands on the brushless DC motor to encompass rotation in three degrees-of-freedom. These actuators involve a stator with a series of electromagnetic coils oriented normal to a spherical permanent magnet rotor which can be controlled by modulating the current of the stator coils. The development of a magnetic joint actuator that operates without a physical connection between the stator and the rotor has wide applications for robotics in dust-sensitive environments, where a device with bearings would otherwise falter. This work details the design, sensing, and control of such a contactless actuator with separable levitation and rotation stages. The levitation and pose estimation capabilities of the device were tested with the prototype and work successfully within certain operating conditions. Through both simulation and prototype testing, the rotation of the device was shown to be accurately controllable for a variety of angular position and velocity setpoints.
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