Abstract: An angular rate sensor that utilizes the Coriolis effect and which includes two dithered accelerometers having proof masses suspended by a hinge fabricated out of a Silicon substrate, the proof masses are provided with support struts that can be adjusted by applying heat to the struts to compensate for misalignment of the proof masses along the dither axis. In one embodiment, the hinges are located on the same side of the substrate and a vibrating beam force transducers are connected between each of the proof masses and associated accelerometer frames in a push-pull arrangement.

Abstract: An angular rate sensor includes a plurality of spaced apart vibrating beams, for example, four beams, defining a pair of outer beams and a pair of inner beams. Each outer beam is mechanically coupled to an inner beam by way of an interconnecting member. The outer beams are excited to cause them to vibrate in the plane of the beams and 180 degrees out of phase with the inner beams. In order to compensate for bias errors due to geometric mismatches between the beams, electrode patterns are deposited on the beams up to the point of inflection of the beam during vibration. The electrodes enable an electric field to be applied either parallel or normal to the longitudinal axis of the drive beams, which, in turn, cause the beams to twist about their longitudinal axis. Such twisting forces the quadrature acceleration components to cancel and thus electrically compensates for such bias errors due to quadrature acceleration components.

Abstract: An angular rate sensor includes a plurality of spaced apart vibrating beams, for example, four beams, defining a pair of outer beams and a pair of inner beams. Each outer beam is mechanically coupled to an inner beam by way of an interconnecting member. The outer beams are excited to cause them to vibrate in the plane of the beams and 180 degrees out of phase with the inner beams. In order to force the quadrature acceleration components to cancel out when geometric mismatches between the beams exist, the drive beams are driven separately at different amplitudes. By driving the beams at different amplitudes, the quadrature acceleration components of both beams can be matched, forcing such components to cancel to enable a single demodulator to be used for the Coriolis or angular rate signal.

Abstract: By configuring a mounting ring connected to a center block with a pair of flexures and having a pair of vibrating beam force transducers connected between the mounting ring and the center block, an angular rate sensor utilizing Coriolis acceleration can be fabricated out of silicon. In this sensor, vibration of the sides of the mounting ring along an axis normal to the angular rate axis is provided by a source of magnetic flux which interacts with a drive current applied through conductors deposited on the mounting ring. The magnetic flux is provided by a permanent magnet and a pair of pole pieces that encompass the mounting ring. A digital representation of angular rate is generated by demodulating the frequency of the force transducers by the frequency of vibration drive frequency to obtain the difference in the force transducer frequencies.

Abstract: A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.

Abstract: A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.

Abstract: An up/down counter within a phase locked loop is gated to count high frequency clock pulses during the first cycle of the input signal. Upon detection of a transition in the input signal indicating the end of the first cycle, the direction of the count is reversed until the count is reduced to zero, thereby assuring equal widths for the first and second half cycles of each output cycle. The system may be implemented with or without a voltage controlled oscillator. In the latter implementation, the count in the up/down counter at the time of a reversal in the count direction is compared with the count in a preset counter. A difference counter compares the differences in a count in the two counters and adjusts the count in the preset counter to match that in the up/down counter at the time of transition. The widths of the successive cycles, rather than half cycles, may be made by doubling the output frequency relative to the input frequency.

Abstract: The invention comprises a velocity sensor (10, 30, 50, 60, 70, 110) that measures velocity in only one degree of freedom and is insensitive to the other five degrees of freedom. The velocity sensor uses differential flux splitting, and by sensing changes in flux, common mode effects are removed. In practicing the invention, a permanent magnet (17, 33, 55, 65, 71, 131) is used to create a flux field, and multiple return paths are used to split the flux. A plurality of pole pieces (20-21, 39-40, 58-59, 66-67, 72-73, 111-112) simultaneously move an equal amount in relation to the return paths for differentially varying the amount of flux carried by each return path (13-14, 34-36, 52-53, 63-64, 73A-C and 75A-C, 115-117), to thereby induce a differential voltage in secondary coils (15-16, 37-38, 56-57, 68-69, 80-83 and 90-93, 140-143 and 150-153). Detection means (not shown) is used to sense the change in voltage and provide an indication of the sensed velocity.

Abstract: A micromachined push-pull accelerometer formed with dual vibrating beam transducers in one plane of a silicon substrate includes a pair of proof masses or pendulums supported by flexures formed in a plane adjacent a surface of the silicon substrate opposite the vibrating beam transducers on opposing sides of the pendulums to define opposing pendulous axes. The accelerometer is configured such that the dual vibrating beam transducers are in a push-pull relationship (e.g., one transducer is subjected to a tension force while the other transducer is subjected to a compression force in response to accelerations along a sensitive axis SA). In order to form the push-pull configuration, one vibrating beam transducer is connected to one pendulum on a side opposite the hinge axis for that pendulum while the other vibrating beam transducer is connected to the other pendulum on the same side as the hinge axis for that pendulum.

Abstract: A micromachined vibrating beam accelerometer provides an acceptable mechanical Q at pressures above vacuum. Electrodes are formed on the beams for connection to a source of excitation voltage. In addition, electrodes are formed on a pick-off capacitance plate disposed adjacent the vibrating beams. The electrodes formed on the pick-off capacitance plate form capacitors with the electrodes formed on the beam. The output signals from these capacitors are connected in a feedback loop to the source of excitation voltage to form a relatively simple oscillator. In order to reduce the squeeze film damping, the pick-off capacitance plate is formed with grooves along one edge adjacent the vibrating beams. The grooves, which may be formed by either isotropic or reactive ion etching, reduce the squeeze film damping resulting from the vibratory motion to obviate the need to operate the vibrating beam accelerometer in a vacuum.

Abstract: A vibrating beam force transducer is comprised of an oscillating sensing element having an output frequency indicative of the force applied to the sensing element. The sensing element has a variable electrical resistance which can vary in accordance with temperature fluctuations over the operating range of the transducer.A drive circuit utilizes an AC drive signal source that is electrically coupled to the sensing element to drive the sensing element at its resonant frequency which is a function of the force applied to the sensing element. The drive circuit has a DC compensation circuit that alters the electrical characteristics of the drive circuit in response to variations in the electrical resistance of the sensing element.

Abstract: A triaxial sensor substrate is adapted for use in measuring the acceleration and angular rate of a moving body along three orthogonal axes. The triaxial sensor substrate includes three individual sensors that are arranged in the plane of the substrate at an angle of 120 degrees with respect to one another. Each sensor is formed from two accelerometers having their sensing axes canted at an angle with respect to the plane of the substrate and further being directed in opposite directions. The rate sensing axes thus lie along three orthogonal axes. In order to reduce or eliminate angular acceleration sensitivity, a two substrate configuration may be used. Each substrate includes three accelerometers that are arranged in the plane of the substrate at an angle of 120 degrees with respect to one another. The sensing axes of the accelerometers of the first substrate are canted at an angle with respect to the plane of the first substrate toward the central portion thereof so that they lie along three skewed axes.

Abstract: A combined transducer that measures force or displacement and temperature utilizes a pair of vibrating tines to provide a simultaneous output representative of temperature and force or displacement whereby the sum or average of the vibrating frequencies of the two tines is representative of temperature and the difference is representative of force or displacement.

Abstract: A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.

Abstract: A sensor (10) is disclosed for measuring the acceleration and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.

Abstract: 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.

Abstract: A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.

Abstract: An acceleration overload protection mechanism for use with a sensor unit. The sensor unit is generally defined by a sensor element or elements (i.e., proof mass, flexures, etc.) that are movable in relation to a sensor frame. The overload protection mechanism includes at least one arresting plate. The arresting plate includes a plate frame and an arresting element that are elastically coupled to one another to permit relative movement therebetween. The plate frame of the overload protection mechanism is placed in fixed alignment with the sensor frame to place the arresting element in spaced relation with the sensor element of the sensor unit. The arresting element and sensor element may move relative to one another to allow the arresting element to move to a position proximate the sensor element to limit the range of motion of the sensor element when the sensor unit is subject to an acceleration overload.

Abstract: A compact torque motor provides increased bidirectional, limited angle, reactionless torque to opposed structures. A torque motor (50) includes an X-shaped core (52), and first and second pole pieces (54) and (56), which are disposed at opposite sides of the core. Two opposite legs on the X-shaped core comprise a first core section (58), which is transverse to a similar second core section (60). A first electromagnetic coil (62) is formed on the first core section and a second electromagnetic coil (64) is formed on the second core section. The ends of the first core section thus become magnetic poles (66) and (68) when an electrical current flows through the first electromagnetic coil; and similarly, the ends of the second core section become magnetic poles (70) and (72) when an electrical current flows through the second electromagnetic coil. The sides of the magnetic poles are generally radially aligned about a central axis (88).

Abstract: A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers.