Micromachined rate and acceleration sensor having vibrating beams

Apparatus is disclosed for measuring the specific force and angular rotation rate of a moving body. A silicon substrate has first and second substantially planar and substantially parallel surfaces. An accelerometer is formed of the substrate and has a force sensing axis. An output signal is provided which is indicative of the moving body along the force sensing axis. The accelerometer is mounted so as to be movable along a vibration axis perpendicular to the force sensing axis. The accelerometer is driven so as to impart a dithering motion thereto of a predetermined frequency along the vibration axis. The accelerometer includes a frame, a proof mass and a hinge interconnected between the frame and the proof mass for rotating the proof mass about a hinge axis when the moving body is subjected to a force along the force sensing axis. The accelerometer further includes at least one vibrating beam having first and second ends respectively coupled to the frame and the proof mass, a longitudinal axis disposed perpendicular to the force sensing axis and the vibration axis, and a conductive path disposed along the vibrating beam. The hinge axis is substantially parallel to the vibration axis. A signal generator applies a periodic drive signal to the conductive path. The periodic drive signal has a resonant frequency that is a function of the force applied along the force sensing axis to the moving body.