Communications: directive radio wave systems and devices (e.g. – Combined with diverse type radiant energy system
Reexamination Certificate
2003-01-10
2004-01-20
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Combined with diverse type radiant energy system
C342S027000, C342S053000, C342S054000, C342S059000, C342S118000, C342S195000, C342S070000, C367S093000, C367S099000, C367S117000, C367S118000, C367S124000, C367S128000, C356S003000, C356S004010, C701S001000, C701S300000, C701S301000, C340S435000, C340S436000, C340S438000
Reexamination Certificate
active
06680688
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a measuring system and method for detecting an object distance, and more particularly, to a measuring system and method for detecting an object distance using more than one of the transmitted media with different wave velocities, respectively.
BACKGROUND OF THE INVENTION
The use of automatic measuring systems has become increasingly important with the rapid development of industrial techniques. For example, to avoid collisions, drivers must carefully park cars in parking spaces and an automated guided vehicle (AGV) transports goods to suitable position to keep away from obstacles.
U.S. Pat. No. 4,500,977 discloses “a method and apparatus for measuring a distance using ultrasonic echo signals, particularly for use on a motor vehicle” to detect and show the distance between vehicle and obstacles. Additionally, U.S. Pat. No. 4,015,232 discloses “Ultrasonic distance detector for vehicles”. The ultrasonic distance detector for vehicles uses a plurality of transducers located around the sides of the vehicle. Each of the transducers is connected to a receiver for detecting sonic echoes from too close objects. The output of each receiver is connected to individual indicator lamps and if any of the lamps are energized, the driver is warned that a part of the vehicle is in danger of a collision.
Particularly, a space position system has to detect a distance of the articles to locate precisely and quickly the objects. Conventionally, the measuring system uses ultrasonic waves as measuring media in the air and detects the object distance by reflective ultrasonic waves.
FIG. 1
shows a reflective measuring system using ultrasonic waves in the prior art.
The conventional measuring system using reflective ultrasonic waves usually has an ultrasonic transducer-transmitted
100
, an ultrasonic transducer-received
102
, an object
104
and a peripheral circuit (not shown). The ultrasonic transducer-transmitted
100
and the ultrasonic transducer-received
102
are connected to the peripheral circuit. There is a distance between the object
104
and the ultrasonic transducer-transmitted
100
and the ultrasonic transducer-received
102
.
During an operation, incident sound waves
106
generated by the ultrasonic transducer-transmitted
100
are partially reflected off the surface of the object
104
. A portion
106
a
of the reflected sound waves is received by the ultrasonic transducer-received
102
and another portion
106
b
of the incident sound waves
106
form reflected sound waves
106
b
in the air due to obstructive articles
108
in the environment. Also, the reflected sound waves
106
b
are often reflected to the transducer-received
102
. Afterwards, the incident sound waves
106
are formed by the ultrasonic transducer-transmitted
100
and processed by the peripheral circuit to compute the distance between the object
104
and the ultrasonic transducer-transmitted
100
. However, the effect of the reflected waves of the obstructive articles
108
is totally ignored.
A conventional measuring system with reflective ultrasonic waves uses a principle, 2L=T×V. L is a measurement distance between the object
104
and the ultrasonic transducer-transmitted
100
, T is the time for transmission of ultrasonic waves from the ultrasonic transducer-transmitted
100
to ultrasonic transducer-received
102
, and V is the velocity of the sound waves.
The conventional measuring system has many disadvantages. For example, during measurement, many obstacles
108
other than the desired object
104
interfere with the sound wave reflections so that the ultrasonic transducer-received
102
receives reflective sound waves
106
b
resulting from the desired object
104
and the obstacles
108
. If the obstacles
108
are closer to the ultrasonic transducer than to the desired object
104
, the ultrasonic transducer-received
102
acquires instantly the reflective sound waves
106
b
from the obstacles
108
. Therefore, the sound waves
106
a
reflected from the object
104
interfere with those of the obstacles, resulting in an imprecise measurement of object distance.
U.S. Pat. No. 6,166,995 discloses “Apparatus for distance measurement by means of ultrasound” that the ultrasonic pulses from respective ultrasonic transducers are superimposed on each other when no obstacle is detected during sequentially propagating ultrasonic pulses. In addition, U.S. Pat. No. 5,508,974 describes “Method and device for ultrasonic distance measuring.” In a device for measuring the distance to an obstacle, a second transmission pulse as a control measurement for an ultrasonic distance measurement is transmitted only when an echo signal has been received for a first transmission pulse. Further, a timing window, within which the expected echo signal falls when it is reflected by an obstacle, is created.
Specifically, when positioned in an open space, the object
104
is difficult to measure since the geometric shapes of the object
104
is irregular due to an uncertain transmission time of the sound waves resulting in a poor computation precision for the peripheral circuit. Moreover, the intensity of the ultrasonic waves is inversely proportional to a distance away from the ultrasonic transducer-transmitted
100
in the air when a reflective measuring system is used for distance measurement. As a result, the signal
oise (S/N) ratio of the reflective ultrasonic detecting system is severely degraded, which leads to a poor measurement precision.
Furthermore, the transmission distance of the ultrasonic waves is at least double distance comparative to the distance between the object
104
and the ultrasonic transducer-transmitted
100
. Even with the irregular surface of the object
104
, the transmission distance of the sound waves is much higher than the object distance leading to poor measurement efficiency. U.S. Pat. No. 5,418,758 discloses “Distance measurement system” utilized two reflectors mounted in different positions, respectively to receive reflected signals. U.S. Pat. No. 5,140,859 describes “Long range ultrasonic distance measuring system” that two transducers are placed different locations. A pulse signal is generated by the master transceiver, which requires a time period of t
1
to travel to the slave transceiver. After a time delay of t
2
upon the receipt of the pulse signal by the slave transceiver it transmits a response signal back to the master transceiver. The response signal requires the same time period of t
1
to be received by the master transceiver. The distance between the master transceiver and the slave transceiver is determined by an equation of 2×t
1
+t
2
.
Consequently, how to eliminate the interference with the reflective sound waves is a problem and how to reduce the transmission length of the sound waves for the measuring system manufacturers is currently a main issue.
SUMMARY OF THE INVENTION
One object of the present invention is to utilize a measuring system and method of detecting an object distance using a plurality of transmitted media with different wave velocities including light-speed waves (infrared rays or radio waves) and sound waves (ultrasonic waves). By simultaneously emitting the ultrasonic waves and infrared waves from a secondary detector to a primary detector and recording a time difference between the ultrasonic waves and the infrared waves, the object distance equal to the primary and secondary detector is obtained.
Another object of the present invention is to use a measuring system and method of detecting an object distance using transmitted media with different wave velocities including light-speed waves and sound-speed waves. The secondary detector is notified of the transmission of the light-speed waves and the sound-speed waves by using another light-speed waves so that the primary detector directly receives the sound-speed waves and light-speed waves from the secondary detector to compute a time difference between light-speed waves and sound-speed waves. Therefore, a ref
Chang Hsin-Ming
Chien Hung-Chuan
Huang Chuan-Fu
Jiang Shyh-Biau
Lee Dong-Liang
Gregory Bernarr E.
Pennie & Edmonds LLP
Viewmove Technologies, Inc.
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