Apparatus for measuring the rate of rotation and linear accelleration of a moving body in two perpendicular axes

• US 5,339,690 A
• Filed: 02/03/1993
• Issued: 08/23/1994
• Est. Priority Date: 11/05/1992
• Status: Expired due to Fees

• Current Assignee: State of Israel--Ministry of Defence Armament Development Authority Rafael
• Original Assignee: State of Israel--Ministry of Defence Armament Development Authority Rafael
• Inventors: Bar-Avi, Patrick
• Primary Examiner(s): Woodiel, Donald
• Application Number:
  US08/012,936
• Time in Patent Office: 566 Days
• Field of Search: 73/505, 73/517 AV, 73/511, 73/517 R, 73/518
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/28 Pick-offs, i.e. devices for taking-off an indication of the displacement of the rotor axis
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

An apparatus for measuring the rate of rotation and linear acceleration of a moving body in two perpendicular axis (X and Y). The rate of rotation is determined by measuring the force resulting from the Coriolus effect and the linear acceleration is determined by measuring the resulting force in the axis of acceleration. The apparatus includes an integral flexing unit which during rest extends in the Z axis, having a flexure zone with two degrees of flexing freedom. A proof mass is resiliently mounted on the flexing unit remote from the flexure zone with one degree of oscillation in parallel to the Z axis. The proof mass is caused to oscillate at constant amplitude by suitable electric means whereby, upon rotation of the body or linear acceleration thereof, the flexure unit oscillates by periodic bending of the flexure zone and the extent of flexure which is proportionate to the rate of rotation and/or linear acceleration, is determined by suitable electro optical means. The apparatus further includes processor means for calculating the angular velocity components about the axis of rotation and the linear acceleration components along the axis of acceleration from the extent of flexure.

Claims

1. An apparatus for measuring angular velocity components about first and second orthogonal axes of a moving body rotating about an axis of rotation located in the plane of said first and second axes and when the body is accelerating along an axis of acceleration within the same plane, for optionally also measuring the linear acceleration components of the moving body along said first and second axes, which apparatus comprises:

(i) an integral flexing unit comprising a base, a central shaft in alignment with a third normal to said first and second axes and having a free end, an axisymmetric flexure zone with two degrees of flexing freedom interposed between said base and shaft, and a deflector member at the free end of said shaft;

(ii) a proof mass resiliently mounted on said shaft remote from said flexure zone with one degree of freedom of oscillation in parallel to said third axis;

(iii) electric means with associated control means for causing said proof mass to oscillate;

(iv) whereby upon either or both of any rotation of said body around said axis of rotation and any acceleration of said body along said axis of acceleration, said flexure unit flexes in an oscillating fashion at the flexure zone thereof;

(v) electro-optical means for detecting any deflection of said deflector member; and

(vi) processor means for calculating either or both of the angular velocity components about and the linear acceleration components along said first and second axes from the deflection of said deflector member.

2. An apparatus according to claim 1, wherein said processor means are programmed for calculating only the angular velocity components about said first and second axes.

3. An apparatus according to claim 1, wherein said processor means are programmed for calculating only the linear acceleration components along said first and second axes.

4. An apparatus according to claim 1, wherein said processor means are programmed for calculating both the angular velocity components about and the linear acceleration along said first and second axes.

5. An apparatus according to claim 1, wherein said electrooptical means for detecting any deflection of said deflector member comprise a couple of non-contacting optical pick-of systems each of which have a light source and an electro-optic sensor.

6. An apparatus according to claim 1, wherein said electric means with associated control means for causing said proof mass to oscillate at constant amplitude is an electric coil connectable to an a.c. source.

7. An apparatus according to claim 1, wherein said proof mass is annular and is linked to the shaft of said flexure unit by radial spokes.

8. An apparatus according to claim 7, wherein said electric coil is annular and surrounds said proof mass in close proximity thereto yet clear thereof.