Accelerometer

Claim 1

An accelerometer comprising: a. an electromagnet adapted to produce a levitational magnetic field directed downward therefrom, said levitational field being contoured in a manner such that the field intensity for a given excitation has an extreme value at a vertical axis of symmetry, said value varying monotonically with radial displacement from said axis; b. first means coupled to said electromagnet to energize same and being responsive to a variable feedback signal to vary the magnetic field intensity, the intensity varying monotonically with variations of said feedback signal; c. a magnetic body positioned below said magnet and being subject both to the levitational force of said field and an oppositely directed gravitational force whereby the body is positioned within a predetermined vertical zone spaced apart from and below the magnet; d. first body position indication means rendered responsive when said body is positioned within said zone to generate a first output signal varying with incremental changes of vertical acceleration of the body and thus varying with said vertical acceleration; e. second body indication means rendered responsive when said body is positioned in the zone to produce a second output signal varying with incremental changes of horizontal acceleration of the body and thus varying with the horizontal acceleration, the incremental changes in horizontal body position, due to the field contour, always being accompanied by incremental changes in vertical body position whereby the first output signal can be produced in the absence of the second output signal but the second output signal is always accompanied by the first output signal; and f. second means coupled between said first indication means and said first means to obtain said feedback signal from said first output signal and to supply said feedback signal to said first means, said feedback acting in opposition to the acceleration of said body to prevent said body From escaping from the zone.