Data processing: measuring – calibrating – or testing – Measurement system – Dimensional determination
Reexamination Certificate
1999-01-27
2001-03-13
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Dimensional determination
C367S087000, C367S089000, C367S099000, C073S597000, C073S625000
Reexamination Certificate
active
06202034
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to ultrasonic ranging and, more particularly, to an ultrasonic ranging system and method for improving the accuracy of an ultrasonic transducer, especially for use in a vehicle.
Ultrasonic sensing techniques have become widely acceptable for use in ranging systems for determining the presence of and distance to a target object. In a conventional ultrasonic ranging system, an ultrasonic transducer is employed which converts electrical signal pulses into mechanical motion. In turn, the mechanical motion creates ultrasonic sound waves that are transmitted through the atmosphere in a desired direction. Provided there is a target in its path, the ultrasonic sound waves reflect off of the target and the reflected sound waves travel back to the ultrasonic transducer. The reflected sound waves, also referred to as the echo waves, mechanically deflect the ultrasonic transducer and, in response, a low voltage signal is generated. Since the speed of travel of the sound waves remains relatively fixed, the distance to the target is determined by measuring the time period between the transmitted and received signal pulses, and computing the distance as a function of the time period and the sound wave speed.
In the past, conventional ultrasonic ranging systems employed a series of gated signal pulses of uniform amplitude to drive the ultrasonic transducer. In order to compute the distance to a target, the conventional ultrasonic ranging system measured the time period between the beginning of the transmitted drive signal and the beginning of the received echo signal. The time period measurement between the transmitted and received signals was typically multiplied by one-half the speed of travel of the sound waves to compute the measured distance to the target. The conventional distance measurement approach has drawbacks in that the accuracy of the ultrasonic distance sensing system can be influenced to a large extent by several factors such as the geometry and the material of the target object, as well as variations in the transmit signal. Accordingly, conventional ultrasonic ranging systems are capable of providing inaccurate distance measurement.
Accordingly, it is one object of the present invention to provide for a method of effectively enhancing the accuracy of distance measurement with an ultrasonic ranging system. It is another object of the present invention to provide for an ultrasonic ranging system with enhanced accuracy for determining distance to a target. Yet, it is a further object of the present invention to provide for an enhanced accuracy ultrasonic ranging system for use in the passenger compartment of a vehicle.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, an ultrasonic ranging system and method are provided for producing accurate distance measurement with an ultrasonic transducer. The ultrasonic ranging system includes an ultrasonic transducer for converting an electrical drive signal to ultrasonic sound waves and transmitting the sound waves in a desired transmission path. The ultrasonic transducer further receives ultrasonic sound waves reflected from a target in the transmission path and converts the received reflected sound waves to an electrical signal. The ultrasonic ranging system includes a processor for receiving the transmitted electrical drive signal and the received reflected electrical signal. The processor determines a time value at the middle of the time width of the drive signal. In addition, the processor measures the time width of the received reflected electrical signal and determines a time value at the middle of the time width of the received reflected electrical signal. The time difference between the middle time values of the received and transmitted signals is determined to provide for an overall time period measurement. The distance to the target is computed as a function of the determined time period and speed of travel of the ultrasonic sound waves.
According to the method of providing accurate distance measurement with an ultrasonic transducer according to the present invention, a transducer drive signal is generated and applied to an ultrasonic transducer. The ultrasonic transducer converts the drive signal to ultrasonic sound waves and transmits ultrasonic waves in a transmission path. The ultrasonic transducer further receives sound waves reflected from targets in the path of the transmitted sound waves and converts the received reflected sound waves to an electrical signal. A middle time value of the transmitted drive signal is determined, and a middle time value of the received reflected electrical signal is determined. The time difference between the middle time values of the transmitted and received signals is determined to provide for an overall time period. The time period is employed to determine distance to the target as a function of the speed of travel of the ultrasonic sound waves.
REFERENCES:
patent: 4280580 (1981-07-01), Wojcik
patent: 4315325 (1982-02-01), Blades
patent: 4545250 (1985-10-01), Miwa
patent: 4630482 (1986-12-01), Traina
patent: 4674057 (1987-06-01), Caughman et al.
patent: 4701893 (1987-10-01), Muller et al.
patent: 5365442 (1994-11-01), Schmidt
Bui Bryan
Delphi Technologies Inc.
Funke Jimmy L.
Hoff Marc S.
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