Moving object detection system

• US 4,187,487 A
• Filed: 04/28/1978
• Issued: 02/05/1980
• Est. Priority Date: 04/28/1977
• Status: Expired due to Term

• Current Assignee: Omron Tateisi Electronics Co. (Omron Corporation)
• Original Assignee: Omron Tateisi Electronics Co. (Omron Corporation)
• Inventors: Mizuno, Masao, Numata, Hiroshi, Otani, Akihiko
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/901,396
• Time in Patent Office: 648 Days
• Field of Search: 340/1 T, 340/1 R, 340/1 C, 340/38 S
• US Class Current: 367/93
• CPC Class Codes: G01S 15/50 Systems of measurement, based on relative movement of the target
• CPC Class Codes: Y10S 367/902 Speed of sound compensation

Abstract

This invention relates to a detection system for detecting presence of moving objects such as vehicles, etc. through utilization of ultrasonic energy which includes a predetermined location provided in memory unit and having stored therein time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto from a road surface, circuitry for computing difference a between immediately preceding time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto stored in the predetermined memory location and current time from transmission of ultrasonic energy and reception of reflected energy corresponding thereto, circuitry for storing in the predetermined memory location the current time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto when the difference a is less than a predetermined time α, and circuitry for outputting vehicle detection signal when the difference a is larger than a preset time β which is larger than the time α.

Claims

1. A detection system for detecting the presence of moving objects and the like through utilization of ultrasonic energy which comprises a predetermined location provided in a memory unit and having stored therein time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto from a standard surface, means for computing the difference a between the immediately preceding time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto stored in said predetermined location and current time from transmission of ultrasonic energy and reception of reflected energy corresponding thereto, means for storing in said predetermined location said current time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto when the difference a is smaller than a predetermined time α

and means for outputing a moving object detection signal when said difference a is larger than a preset time β

which is larger than said time α

.

2. A detection system as claimed in claim 1, wherein said moving objects are vehicles and the like.

3. A detection system as claimed in claim 1, wherein said standard surface is a road surface.

4. A detection system as claimed in claim 1, further including gate means which is arranged to be opened through discrimination of time period for receiving the reflected energy and is closed after judging time from ultrasonic energy transmission till reception of reflected energy corresponding thereto.

5. A detection system as claimed in claim 4, wherein said gate means is arranged to be selectively opened and closed through processing by a micro-processor.

6. A detection system as claimed in claim 1, wherein said current time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto is stored in said predetermined location only at an initial state and when said difference a is smaller than said preset time β

which is larger than said predetermined time α

.

7. A detection system as claimed in claim 6, further including a first wave reception counter location in said memory unit in which the time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto is stored and a second wave reception counter location in said memory unit in which said immediately preceding time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto is stored.

8. A detection system as claimed in claim 1, wherein the initial state of the system is determined based on number of moving objects to be detected.

9. A method of automatically setting a standard plane in a traffic detection system employing a microprocessor, said method comprising the steps of providing in a memory a predetermined location in which a time after transmission of ultrasonic energy till reception of a reflected energy corresponding to said energy from a road surface is stored, determining a time after transmission of ultrasonic energy till reception of reflected energy corresponding to said energy by means of said micro-processor, loading the micro-processor with data from said predetermined location to compute a difference a from a time after a current transmission of ultrasonic energy till reception of reflected energy corresponding thereto, storing said current time in said predetermined location when said difference a is smaller than a preset time α

, storing data representing said current time till reception of reflected energy in said predetermined location when said difference a is smaller than β

which is a preset time larger than said time α and

only in an initial state, and outputting a vehicle detection signal when said difference a is larger than said time β

.

10. A method of automatically setting a standard plane in a traffic detection system employing a microprocessor, said method comprising the steps of providing in a memory a predetermined location in which a time after transmission of ultrasonic energy till reception of reflected energy corresponding to said energy from a road surface is stored, a first wave-reception counter location in said memory in which a time after transmission of ultrasonic energy till reception of reflected energy corresponding to said energy is stored and a second wave-reception counter location in said memory in which a time after an immediately preceding transmission of ultrasonic energy till reception of reflected energy corresponding thereto is stored, determining a time after transmission of ultrasonic energy till reception of reflected energy corresponding thereto, storing this said time in said first wave-reception counter location, computing a difference a between data in said first reception counter area and data in said second reception counter location, storing said data of said first reception counter location in said second reception counter location and predetermined location when said difference a is smaller than a preset time α

, storing said data of said first reception counter location in said second reception counter location when said difference a is larger than said time α and

smaller than β

which is a preset time larger than said time α and

only in an initial state, and storing said data of said predetermined location in said second wave-reception counter location, and producing a vehicle detection signal when said difference a is larger than said time β

.

11. A method of detecting the presence of objects such as vehicles and the like through utilization of ultrasonic energy with employment of a micro-processor, said method comprising the steps of arranging a detection gate to be opened through discrimination of the time period for receiving reflected energy by the micro-processor and to be closed after judging by the micro-processor the time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto, computing a difference a between the time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto from a road surface and the current time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto by loading the microprocessor from a memory location in which the time from transmission of ultrasonic energy till reception of reflected energy corresponding thereto from the road surface is stored, storing data representing time from said current transmission of ultrasonic energy till reception of the reflected energy corresponding thereto in said memory location when said difference a is smaller than a predetermined time α

, and outputting a vehicle detection signal when said difference a is larger than a time β

which is larger than said time α

.