Method for determining the position of an object relative to the

Details Method for determining the position of an object relative to the Method for determining the position of an object relative to the

1996-08-02

1998-06-02

Lobo, Ian J.

Communications, electrical: acoustic wave systems and devices

Echo systems

Distance or direction finding

367 87, 367 98, G01S 752

Patent

active

057611556

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

P 42 38 262.9 discloses an object recognition system that works with a transmission and a reception ultrasound transducer. An individual ultrasound transducer emits an ultrasound signal in the direction of the object scene. The signal reflected thereat, the echo, contains the determining information of the structure of the object scene. The echo signal is in turn received by a single ultrasound transducer. The transducer principle employed is a matter of a directional sharp ultrasound transducer. The disadvantages of this arrangement and of the signal evaluation method deriving therefrom lie in the low sampling of the measuring system, as well as in the difficulty of evaluating a large object scene area in large-area fashion and in the low lateral resolution.


SUMMARY OF THE INVENTION

An object of the invention is to specify a method with which the position of an object relative to the background can be identified.
According to the method of the invention for determining a position of an object relative to a background with ultrasound, an ultrasound reference signal is emitted in a direction of the background where the reference signal is reflected. An amplitude and an occurrence time of a maximum of the reflected reference signal are stored. An ultrasound measurement signal is emitted in the direction of the object and of the background where the measurement signal is reflected. If a maximum occurs in the reflected measurement signal at the occurrence time of the maximum of said reflected reference signal, the amplitude of the maximum of the reflected measurement signal is stored. A first coverage degree is determined from the amplitude of the maximum of the reflected reference signal and the amplitude of the maximum of the reflected measurement signal, the first coverage degree being a criterion for a coverage of the background by the object and a criterion for a position of the object since the coverage of the background is greater the smaller the amplitude of the maximum of the reflected measurement signal is compared to the amplitude of the maximum of the reflected reference signal.
An advantage of the invention is the enhanced measuring precision.
The object contour is also detectable with the invention.
The entire width to be measured can be acquired in one step with the invention.
The invention makes it possible to increase the measuring rate.
It is also advantageous that the method of the invention can be simply adapted to many different types of available transducers.
The invention shall be explained in greater detail with reference to the FIGS.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the measurement format in a section transverse to the moving direction of the conveyor belt;
FIG. 2 illustrates the structure of an ultrasound transducer composed of piezopolymer film;
FIG. 3 shows the frequency response of an ultrasound transducer as shown in FIG. 3;
FIG. 4 shows the pulse response of an ultrasound transducer as shown in FIG. 3;
FIG. 5a is the curve of the ultrasound signal amplitude of an ultrasound transducer as shown in FIG. 3, in the yz-plane;
FIG. 5b is the curve of the ultrasound signal amplitude of an ultrasound transducer as shown in FIG. 3, in the xz-plane;
FIG. 6 shows the transmission link of the system;
FIG. 7 illustrates the procedure of transmitting and receiving an ultrasound signal given sequential transmission and reception;
FIG. 8 shows the procedure of sending and receiving an ultrasound signal on two frequency bands;
FIG. 9 shows in correlation the transmission, the reception and the processing of an ultrasound signal for a receiver;
FIGS. 10a and 10b illustrates the result functions;
FIGS. 11a and 11b show two possible reflections and the result functions belonging thereto;
FIG. 12a is a measuring situation wherein all types of reflection occur and 12b-f, the corresponding result functions;
FIGS. 13a and b show the affiliation functions for a fuzzy evaluation;
FIG. 14 illustrates a further affiliation function for the fuzzy evaluation;
F

REFERENCES:
patent: 3184969 (1965-05-01), Boiton
patent: 4868797 (1989-09-01), Soltz
patent: 5157639 (1992-10-01), Leszczynski
patent: 5587969 (1996-12-01), Kroemer et al.
Technisches Messen tm. 55 Jahrgang, Heft Oct. 1988--Ultraschall-Systeme fur die industrielle Objekterfassung J 099-16 pp. 367-376.

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