Electronic inclination gauge with acceleration compensation
First Claim
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1. Electronic inclination gauge for use in a moving vehicle subject to an acceleration, comprising:
- a tilt sensitive transducer for providing an output corresponding to said acceleration and to the angle and direction of said transducer along a reference axis with respect to a gravitational field,a velocity sensor driven by said vehicle for providing an output signal corresponding to a velocity component of said vehicle along said reference axis,means coupled to receive said velocity output for deriving a signal representative of a component of said acceleration along said reference axis,means for algebraically combining said acceleration signal component and said transducer output to provide a signal representative of the inclination of said reference axis with respect to said gravitational field, independent of said component of acceleration, andmeans responsive to said combined signal to provide an output indicative of said inclination.
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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.
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Citations
16 Claims
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1. Electronic inclination gauge for use in a moving vehicle subject to an acceleration, comprising:
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a tilt sensitive transducer for providing an output corresponding to said acceleration and to the angle and direction of said transducer along a reference axis with respect to a gravitational field, a velocity sensor driven by said vehicle for providing an output signal corresponding to a velocity component of said vehicle along said reference axis, means coupled to receive said velocity output for deriving a signal representative of a component of said acceleration along said reference axis, means for algebraically combining said acceleration signal component and said transducer output to provide a signal representative of the inclination of said reference axis with respect to said gravitational field, independent of said component of acceleration, and means responsive to said combined signal to provide an output indicative of said inclination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An instrument for continuously indicating the instantaneous grade of a roadbed during operation thereupon of a motor vehicle equipped with a speedometer, comprising:
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means coupled to said speedometer for deriving a signal proportional to the speed of said vehicle, said means including an optical light source, a shutter coupled to a drive element of said speedometer for interrupting said light source, an optical sensor coupled to said shutter and responsive to said interrupted light source, said sensor providing a pulsed signal corresponding to the speed of said vehicle, circuit means for receiving said pulsed signal and providing a plurality of unipolar pulses of predetermined pulsewidth and duration, circuit means for integrating said plurality of unipolar pulses to provide a direct current signal whose amplitude is proportional to said speed, circuit means for differentiating said direct current signal with respect to time, thereby to provide a velocity signal representing the rate of change of said speed with respect to time, and first potentiometer means coupled to said velocity signal, for scaling said signal; circuit means for providing a bipolar excitation signal, including a stabilized source of reference voltage, said source including active voltage divider means adapted to provide balanced positive and negative voltages with respect to a common ground potential, means for deriving a source of bipolar pulses from said reference voltage, including pulse oscillator means coupled to said source, for providing a plurality of pulses of predetermined amplitude, polarity, and duty cycle, and means for deriving a phase inverted pulse of said predetermined amplitude and duty cycle, but of opposing polarity, from said plurality of pulses; bubble level potentiometer means, coupled to receive said bipolar excitation signal, and having a tilt axis aligned with a longitudinal axis of said vehicle, for providing an output signal whose phase and amplitude is indicative of the inclination of said tilt axis with respect to a gravitational field, said level means providing a null output signal when said axis is aligned in a plane perpendicular to said gravitational field; synchronous demodulation means coupled to receive said output signal and a reference signal from said pulse oscillator means, said demodulation means biased by said reference signal and including phase sensitive rectifier means, adapted to provide a unidirectional signal of variable amplitude and polarity responsive to said output signal; second potentiometer means for scaling said unidirectional signal, coupled to receive said scaled velocity signal; and means for driving an indicator responsive to the algebraic sum of said scaled unidirectional signal and said scaled velocity signal, thereby to provide an output indicative of the inclination of said longitudinal axis of said vehicle with respect to said gravitational field, free from errors induced by accelerations of said vehicle.
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12. A circuit for providing a regulated bipolar voltage output from a unipolar power source and for providing an output voltage across first and second terminals, comprising:
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a ground bus coupled to one of said first or second terminals, means for deriving a regulated reference voltage from said power source, said voltage comprising at least a portion of said output voltage, said means coupled to one other than said one of said first and second terminals and to said ground bus, voltage follower means coupled to receive said reference voltage and to said ground bus, thereby to provide a regulated output voltage with respect to said ground bus representative of said portion of said output voltage, and means for coupling said regulated output voltage to a signal bus, thereby providing a predetermined regulated potential difference between said ground bus and said signal bus. - View Dependent Claims (13, 14, 15)
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16. A method for compensating an acceleration sensitive inclination gauge mounted in a moving vehicle, comprising:
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providing a tilt-sensitive accelerometer, having an output responsive to the acceleration and inclination of said vehicle with respect to a gravitational field, providing a velocity sensor coupled to said vehicle for deriving an output corresponding to an acceleration component of said vehicle along a tilt axis with respect to said gravitational field, algebraically combining said outputs to provide a signal representative of the inclination of said vehicle with respect to said gravitational field, and providing an output indicative of said inclination.
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Specification