A system can include a housing; a hinge assembly operatively coupled to the housing for rotation of the housing about a hinge axis, where the hinge assembly includes permanent magnets that generate a first magnetic field and a second magnetic field orientable with respect to each other via rotation of the housing, where the first magnetic field and the second magnetic field include an aligned orientation, generate a clockwise restoring torque responsive to rotation of the housing in a first rotational direction from the aligned orientation, and generate a counterclockwise restoring torque responsive to rotation of the housing in a second, opposite rotational direction from the aligned orientation; and an electromagnetic mover operatively coupled to the housing for rotation of the housing about the hinge axis.