Abstract: A cross axis acceleration or roll angle insensitive angle sensor is constructed as a tubular body defining a closed tubular chamber with annular sensing plates soldered to each end. The tubular chamber is partially filled with partially electrically conductive liquid such that the resistance between the annular sensing plates and the tubular body is a function of the immersed area of the sensing plates. A variation in the inclination of the sensor causes a corresponding variation in the fluid level on the surface of the sensing plates and thus a variation in the electrical resistance between each sensing plate and the tubular body. The monitoring circuit for the angle sensor comprises a detecting means for sensing variations of the resistance between each sensing plate and provides an indication of any deviation from level position of the fluid within the tubular chamber.

Abstract: Angle and angular acceleration sensors are fabricated as a layered sandwich structure having a central sensing plate, left and right insulating spacers positioned outside the sensing plate, left and right driver plates positioned outside the insulating spacers, and left and right molded plastic housing shells positioned outside the driver plates for sealing the sensor structure. In an angle sensor embodiment of the invention, the sensing plate includes a peripheral frame and a central plate area mechanically connected to one side of the peripheral frame by way of a pair of beams that serve as a hinge to allow the central plate area of the sensing plate to rotate toward and away from the driver plates sandwiched on either side thereof.

Abstract: Disclosed is an improved inclination sensor and an improved inclinometer. A pair of plates in combination with a metallic housing provides accurate inclination information over ranges of 0.degree..+-.60.degree. and 180.degree..+-.60.degree.. A second pair of plates rotated 90.degree. in the plane of the first pair of plates, provides accurate inclination information over ranges of 90.degree..+-.60.degree. to 270.degree..+-.60.degree.. Coverage is thereby provided over 360.degree.. The inclination sensor is combined with a microprocessor which is programmed to weight the contribution of the plates so as to provide a smooth transition for angles in the region of coverage overlap. A EEPROM memory stores and provides calibration input information to correct the inclination sensor output to accurate output angles.

Abstract: A two axis sensor is provided for detecting angular movement relative to either of two mutually perpendicular axes. The device includes a two-axis sensor comprising an upwardly directed, spherically shaped common electrode, an upwardly directed spherically shaped insulating member uniformly spaced from the common electrode to form a cavity therebetween, the common electrode and the insulating member being sealed to each other about respective peripheries thereof, with a dielectric fluid contained in the cavity, a plurality of detecting electrodes provided on an underside of the insulating member, the detecting electrodes formed by a selectively applied conductive surface coating on the underside, and means for detecting variations in capacitance proportional to movement of the sensor relative to each of two mutually perpendicular axes by reason of movement of the dielectric fluid within the cavity.

Abstract: A two axis sensor is provided for detecting angular movement relatice to either of two mutually perpendicular axes. The device includes a two-axis sensor comprising an upwardly directed, spherically shaped common electrode, an upwardly directed spherically shaped insulating member uniformly spaced from the common electrode to form a cavity therebetween, the common electrode and the insulating member being sealed to each other about respective peripheries thereof, with a dielectric fluid contained in the cavity, a plurality of detecting electrodes provided on an underside of the insulating member, the detecting electrodes formed by a selectively applied conductive surface coating on the underside, and a device for detecting variations in capacitance proportional to movement of the sensor relative to each of two mutually perpendicular axes by reason of movement of the dielectric fluid within the cavity.

Abstract: Disclosed is a fluid level sensor including a float mounted for movement in a mounting tube by a pair of spiral springs which are relatively rigid in a radial direction but relatively flexible in a longitudinal direction. At the top of the float a magnet is located and at the top of the mounting tube, a Hall effect device is located. As fluid enters the mounting tube through apertures in the lower portion, the float is gradually buoyed and moves closer to the Hall effect device changing its electrical output. Because the springs position the float inside the mounting tube, striction and hysteresis in conventional float supports is eliminated as well as wear between the float and the outer tube. Measurement range may be changed by changing float length and outer tube length as well as the spring constants themselves.

Abstract: An inclinometer includes two coplanar electrodes positioned within a chamber of a metallic housing containing a high relative dielectric constant fluid and a gas. With the inclinometer positioned on a level surface equal areas of the two electrodes are immersed in the dielectric fluid creating two equal capacitors formed by the electrodes and the metallic housing. When the inclinometer is rotated through an inclination angle, unequal areas of the electrodes are immersed in the fluid causing a capacitance differential that is a measure of the inclination angle.

Abstract: A differential capacitance detector comprising two pulse generators and a comparator. The width of each pulse generator output is representative of the capacity of each of two capacitors whose differential is to be determined. A comparator provides a third pulse whose width is the difference of the width of the pulses input from the pulse generators and is representative of the capacitance differential between the two capacitors.

Abstract: An apparatus for sensing and measuring changes in inclination and providing a digital readout. By sensing pulse width changes rather than amplitude, the apparatus provides improved immunity to instability and environmental changes. A variable frequency scale factor oscillator allows choice of readout units. Any preset angle may be selected as a zero reference. The capability is provided to hold any reading displayed for any desired period of time. An overrange indicator is actuated when the linear range of the sensor has been exceeded. Digital output signals derived from the sensor are applied to gate an angle generator which is responsive to correction factor signals to adjust the digital count in accordance with stored offset data. The digital signal count is incremented or decremented in accordance with a signal representing the sign of inclination, derived from the sensor pulse widths and applied to gate the angle generator accordingly.

Abstract: A null-adjusting tool for aligning a tilt sensor of the electrolytic liquid type to the vertical is provided. A sensor mounting plate with a tilt-sensing element attached thereto is rotated about a pivot pin by the rotation of a coarse and fine adjustment screw. The coarse adjustment screw acts directly on the sensor mounting plate. The fine adjustment screw provides a high degree of position resolution control through a combination of screw thread and lever type mechanical advantage. A digital readout containing a liquid crystal display and self-contained power source is mounted on the null-adjusting tool to provide a visual indication of the angular deviation of the tilt sensor from the vertical during the alignment process.

Abstract: An angular measuring system consisting of one or more sensors that transmit angular measurements to a central control unit where numerical readout of any selected sensor is provided. A threshold can be preset at individual sensors or the control unit for an allowable angular deviation, beyond which a warning device is actuated. The circuitry permits locating the sensors remotely from the console and provides precision and stability of operation. Low power consumption permits extended operating periods with internal batteries. False alarms are minimized by incorporating a hysteresis loop in the threshold detection circuitry.

Abstract: An apparatus for providing dynamic measurements of the grade of a road bed provides correction for accelerations of the carrying vehicle. A tilt transducer, responsive to both the angle and sense of inclination and to accelerations of the vehicle is used to measure the angle of displacement. The time rate of change of velocity signal derived from the motion of the vehicle is used to provide a signal corresponding to the vehicular acceleration. The acceleration signal level is adjusted to cancel acceleration sensed by the transducer, thereby providing an output reflecting the true angular grade reading.

Abstract: A temperature stable apparatus for mounting an arcuate glass enclosed electrolytic bubble gravity sensor utilizes epoxy cement having a low temperature coefficient of expansion for bonding an end face of a post having a temperature coefficient of expansion equal to that of glass to the center of the glass enclosure of the sensor, and the other end of the post to the center of a rectangular aluminum plate, such that the longitudinal axis of the post is orthogonal to the plate and the plane of the arcuate axis of the enclosure, and such that a chord connecting the ends of the arcuate axis is parallel to the longitudinal axis of the plate.

Abstract: An inclinometer providing a digital numerical readout includes a level sensor responsive to orientation and means for driving a liquid crystal display to indicate the inclination of a surface with a high degree of precision. Features include high stability with changes in battery voltage and surrounding temperature, a battery condition monitor, freedom from operational adjustments after the initial calibration, and partial blanking of the display to alert a user that the linear inclination limit has been reached. The direct reading digital readout permits ease of operation and a high degree of accuracy and repeatability. Circuitry is especially adapted for low power consumption.

Abstract: A display pointer is driven back and forth along a predetermined path by a geared-down miniature d.c. servomotor in accordance with a command signal. The path is determined by an elongated printed circuit board base having closely adjacent, elongated, coextensive triangularly shaped plates thereon, constituting stationary capacitor plates of a pair of variable capacitors. The printed circuit board includes a dielectric material which also overlays the triangular plates. A relatively narrow, electrically conductive slider member extends laterally across the triangular plates and is supported by and rides on the printed circuit board and constitutes a common movable capacitor plate for the variable capacitors. The display pointer is attached to and positioned by the slider. The slider in turn is displaced along the printed circuit board by means of a cable and pulley mechanism coupled to the servomotor.

Abstract: In a device having a synchro resolver and a microprocessor, the apparatus of the present invention utilizes a pulse excitation technique for converting a synchro output signal to a digital format. A pulsed waveform is selectively applied to the input windings of synchro resolver and output voltages are induced in the output windings. A sample and hold circuit is selectively enabled and selectively coupled to the output windings of the synchro resolver, and the sampled output signal of the output windings is converted into a digital format via an analog-to-digital converter.

Abstract: The outputs of a three-wire synchro are applied to a multiplexer which provides the multiplexed synchro outputs to an amplifier and demodulator. The demodulated synchro outputs are applied to a demultiplexer whose outputs are filtered to provide demodulated d.c. voltages corresponding to the synchro output signals. The demodulated d.c. voltages are applied to a conversion circuit for providing the sine and cosine of the angular position of the three-wire synchro device. The multiplexer, demultiplexer and demodulator are synchronized by the synchro a.c. reference signal.

Abstract: A synchro resolver angular position sensor provides the sine and cosine of angular position by applying a square wave excitation to the resolver stator winding. The corresponding square wave outputs of the sine and cosine windings of the resolver rotor are sampled in time synchronism with the excitation at a predetermined time phase of the square wave excitation cycle. The sampled sine and cosine amplitudes are converted into digital format via an analog-to-digital converter for application to a digital processor. The upper corners of the positively-going leading edges and the lower corners of the negatively-going leading edges of the square wave excitation waveform are rounded to minimize ringing of the sine and cosine square wave outputs from the resolver.

Abstract: A full rotational freedom, substantially zero friction electrical conductor assembly for conducting electrical currents between relatively rotatable members of sensitive instruments such as gyroscopic devices and the like is disclosed. Each electrical transfer unit of the assembly comprises a pair of coaxial, concentric, coplanar, continuous, concave conductor rings, one mounted on a relatively fixed member and the other mounted on the rotatable member, the relative diameters of the rings providing a substantial annular radial gap therebetween. A resilient, electrically conducting, continuous, filamentary loop is disposed in the radial gap such that its generally flat outside surface contacts and rolls on the concave surfaces of the concentric conductor rings.

Abstract: A toroidal accelerometer including a toroidal shaped housing having first and second oppositely disposed arcuate shaped electrodes and a third electrode which is a common electrode, all three electrodes being partially immersed in an electrolytic fluid and subject to differential wetting in accordance with the angle of tilt about a horizontal axis of rotation or axis of symmetry of the toroid. A fourth electrode positioned between the first and second electrodes, equi-distant from the third electrode is at all times completely immersed in the electrolytic fluid.