Omnimagnet: An Omnidirectional Electromagnet for Controlled Dipole-Field Generation

An Omnimagnet is an omnidirectional electromagnet comprising a spherical ferromagnetic core inside of three orthogonal nested solenoids. It generates a magnetic dipole field with both a variable dipole-moment magnitude and orientation with no moving parts. The magnetic and physical properties (e.g., dipole moment, weight, resistance, and inductance) of any Omnimagnet are derived. These general relationships are used to design an optimal Omnimagnet subject to the constraints that it has the same dipole-moment per applied current in any direction, each solenoid has no quadrupole contribution to the magnetic field, and the spherical core size maximizes the strength of the resulting dipole field. This optimal design is analyzed using FEA tools and is verified to be dipole-like in nature. Finally, the optimal design is constructed and its utility is demonstrated by driving a helical capsule-endoscope mockup through a transparent lumen.