Epitaxial coriolis rate sensor

Apparatus for measuring the specific force and angular rotation rate of a moving body, the apparatus comprising:

• a) a layer of epitaxial material having first and second opposing substantially planar surfaces disposed substantially parallel to each other;
• b) a frame formed of said layer of epitaxial material, said frame having first and third opposing inner peripheral edges disposed substantially parallel to one another, a vibration axis disposed substantially parallel to said first and third opposing inner peripheral edges, and a rate axis disposed substantially parallel to said first and second opposing planar surfaces and substantially perpendicular to said vibration axis;
• c) first and second substantially planar electrodes, one of said electrodes disposed substantially parallel to and spaced a predetermined distance away from each of said first and second planar surfaces of said layer of epitaxial material;
• d) a first accelerometer formed of said first and second electrodes and a first proof mass formed of said layer of epitaxial material and pivotally suspended from said first innerperipheral edge of said frame by a first pair of flexures for motion along each of said vibration axis and a first force sensing axis, said first force sensing axis perpendicular to said first and second surfaces and said vibration axis for producing a first output signal indicative of the acceleration of the moving body along said first force sensing axis;
• e) a second accelerometer formed of said first and second electrodes and a second proof mass formed of said layer of epitaxial material and pivotally suspended from said third innerperipheral edge of said frame by a second pair of flexures for motion along each of said vibration axis and a second force sensing axis, said second force sensing axis perpendicular to said first and second surfaces and said vibration axis for producing a second output signal indicative of the acceleration of the moving body along said second force sensing axis;
• f) a magnetic circuit generating a magnetic flux, said magnetic circuit disposed such that said magnetic flux intersects said first and second accelerometers;
• f) a conductive path deposited on at least one of each of said first and second pairs of flexures;
• and
• g) an electrical circuit coupled to said conductive path and generating a drive signal therein, said drive signal interacting with said magnetic flux to impart a dithering motion to each of said first and second accelerometers having a predetermined frequency along said vibration axis, whereby said first and second output signals have a Coriolis component indicative of the angular rotation of the moving body about said rate axis.

A method for measuring the specific force and angular rotation rate of a moving body, the method comprising:

• forming a frame of a layer of epitaxial material having first and second substantially planar surfaces disposed substantially parallel to each other, said frame formed with a vibration axis disposed substantially parallel to said first and second surfaces and a rate axis perpendicular to said vibration axis;
• forming a first accelerometer of said layer of epitaxial material, said first accelerometer formed with a first force sensing axis perpendicular to each of said vibration axis and said rate axis for producing a first output signal indicative of the acceleration of the moving body along said first force sensing axis, said first accelerometer formed with a proof mass and at least one flexure connecting said proof mass to said frame such that said proof mass can be moved along each of said first force sensing axis and said vibration axis;
• forming a second accelerometer of said layer of epitaxial material, said second accelerometer formed with a second force sensing axis perpendicular to each of said vibration axis and said rate axis for producing a second output signal indicative of the acceleration of the moving body along said second force sensing axis, said second accelerometer formed with a proof mass and at least one flexure connecting said proof mass to said frame such that said proof mass can be moved along each of said second force sensing axis and said vibration axis;
• and
• imparting a dithering motion to each of said first and second accelerometers of a predetermined frequency along said vibration axis, whereby said first and second output signals have a Coriolis component indicative of the angular rotation of the moving body about said rate axis.

A method for measuring the specific force and angular rotation rate of a moving body, the method comprising:

• forming a frame of a layer of epitaxial material having first and second opposing substantially planar surfaces disposed substantially parallel to each other, said frame having first and third opposing inner peripheral edges disposed substantially parallel to one another, a vibration axis disposed substantially parallel to said first and third opposing inner peripheral edges, and a rate axis disposed substantially parallel to said first and second planar surfaces and substantially perpendicular to said vibration axis;
• forming a first proof mass of said layer of epitaxial material and pivotally suspending said first proof mass from said first inner peripheral edge of said frame by a first pair of flexures for motion along each of said vibration axis and a first force sensing axis perpendicular to said first and second surfaces and said vibration axis;
• forming a second proof mass of said layer of epitaxial material and pivotally suspended from said third inner peripheral edge of said frame by a second pair of flexures for motion along each of said vibration axis and a second force sensing axis perpendicular to said first and second surfaces and said vibration axis;
• forming a link of said layer of epitaxial material, said link formed with first and second points connected respectively to said first and second proof mass, a pivot point disposed intermediate between said first and second connected points, and one or more supports affixedly disposing said pivot point with respect to said frame to permit said link to pivot thereabout and, when one of said first and second accelerometers is moved, to impart a substantially equal and opposite motion to said other of said first and second accelerometers;
• forming first and second substantially planar electrodes, each of said electrodes disposed substantially parallel to and spaced a predetermined distance away from a respective one of said first and second planar surfaces of said layer of epitaxial material;
• producing a first output signal indicative of the acceleration of the moving body along said first force sensing axis and a second output signal indicative of the acceleration of the moving body along said second force sensing axis;
• generating a magnetic flux intersecting said first and second accelerometers;
• and
• depositing a conductive path on at least one of each of said first and second pairs of flexures and generating a drive signal therein interacting with said magnetic flux to impart a dithering motion to each of said first and second proof mass having a predetermined frequency along said vibration axis, whereby said first and second output signals have a Coriolis component indicative of the angular rotation of the moving body about said rate axis.