On-road object detecting system

• US 5,883,585 A
• Filed: 06/25/1997
• Issued: 03/16/1999
• Est. Priority Date: 06/27/1996
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ohkuwa, Yoshihiro, Akutsu, Eisaku
• Primary Examiner(s): TONG, NINA C
• Application Number:
  US08/882,159
• Time in Patent Office: 629 Days
• Field of Search: 240/933, 240/988, 240/991, 240/992, 240/993, 240/942, 240/941, 240/940, 240/938, 240/939, 342/70, 342/71, 200/85 R, 200/86 A, 200/86 R, 324/236, 324/238, 324/244, 324/654, 324/655, 364/436, 364/438, 364/565, 701/117, 701/118, 701/119, 701/301
• US Class Current: 340/933
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G08G 1/02 using treadles built into the road pads or other sensitive devices responsive to passage of vehicles E01F11/00
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

A system for detecting an object located on a travelling path even in bad weather or during nighttime in which conducting wires having a predetermined impedance value are laid along a travelling path, and a signal is supplied to the conducting wires from a signal source. If a vehicle exists on the path, the impedance of the conducting wires changes at the position where the vehicle is present. A signal reflected from the impedance change position is detected by a detector. The position of the vehicle can be determined from the timing of the received reflection signal. It is also possible to detect a vehicle changing lanes or the like by means of a plurality of conductive wires laid along the travelling path. Instead of a conducting wire, an optical fiber may be provided for determining the position of a vehicle using the refractive index change in the optical fiber due to the weight of the vehicle.

Claims

1. An on-road object detecting system comprising:

propagating means for propagating a signal along a travelling path and having propagation characteristics that change due to the presence of an on-road object;

signal generating means for feeding the signal to the propagating means;

the signal propagated by the propagating means being reflected not from the object but in the propagating means at the occurrence of a change in the propagation characteristics;

signal receiving means for receiving the reflection signal reflected from the change in propagation characteristics of the propagation means caused by the on-road object; and

detecting means for detecting the position of the on-road object based on the timing of the received reflection signal at the signal receiving means.

2. An on-road object detecting system according to claim 1, wherein said propagating means is at least one conductive wire having a predetermined impedance value and said change in propagation characteristics occurs in the at least one conductive wire where an impedance inconsistency is caused by the on-road object.

3. An on-road object detecting system according to claim 1, wherein said propagating means is an optical fiber having a predetermined refractive index and said change in propagation characteristics occurs in the optical fiber where the refractive index is changed due to the on-road object.

4. An on-road object detecting system according to claim 1, wherein an on-road object may undergo a positional change, a plurality of the propagating means are located in the direction of width of the travelling path, and the detecting means detects the position of the on-road object at each of the propagating means,

the system further comprising judging means for judging at least the type of on-road object based on the positional change of the on-road object as time elapses.

5. An on-road object detecting system according to claim 4, wherein each of said plurality of propagating means is at least one conductive wire having a predetermined impedance value and said change in propagation characteristics occurs in each of the at least one conductive wire where an impedance inconsistency is caused by the on-road object.

6. An on-road object detecting system according to claim 4, wherein each of said plurality of propagating means is an optical fiber having a predetermined refractive index and said chance in propagation characteristics occurs in each of the optical fibers where the refractive index is changed due to the on-road object.

7. An on-road object detecting system comprising:

a cable for propagating a signal along a travelling path and having propagation characteristics that change due to the presence of an on-road object;

a signal generator for supplying a signal to the cable;

the signal being propagated in the cable being reflected not from the object but in the cable at the occurrence of a change in the propagation characteristics;

a signal receiver for receiving the reflection signal reflected from the change in propagation characteristics caused by the on-road object; and

a processor for detecting the position of the on-road object based on the timing of the received reflection signal at the signal receiver.

8. An on-road object detecting system according to claim 7, wherein said cable is at least one conductive wire having a predetermined impedance value, and said signal generator supplies an alternating signal to the cable.

9. An on-road object detecting system according to claim 7, wherein said cable is at least one conductive wire having a predetermined impedance value, and said signal generator supplies a pulse signal to the cable.

10. An on-road object detecting system according to claim 7, wherein said cable is an optical fiber having a predetermined refractive index, and said signal generator supplies a laser beam to the cable.